Agricultural spreading machine

Abstract

An agricultural spreading machine for spreading a suspension of Sphagnum onto a surface is provided. The machine 100 comprises a container 102 for storing a suspension of Sphagnum, wherein the suspension of Sphagnum comprises water, a thickening agent, and a plurality of fragments of Sphagnum. The machine also comprises a pump 104 connected to the container, wherein the pump is a positive displacement pump. The machine also comprises a manifold 106 connected to the pump, a plurality of outlet pipes 108 connected to the manifold, and a plurality of outlet apertures 110 having a diameter of at least 5mm. The pump is configured to move the suspension of Sphagnum from the container through the manifold, along the outlet pipes, and out of the outlet apertures for spreading the suspension of Sphagnum onto the surface, the machine providing a pressure loss due to resistance of at least 0.1bar. Also disclosed is a method of providing a suspension of Sphagnum comprising water, a thickening agent and a plurality of fragments of Sphagnum and supplying the suspension into the container of the spreading machine.

Description

The present disclosure relates to an agricultural spreading machine, in particular for spreading a suspension of Sphagnum onto a surface. The present disclosure also relates to a system comprising an agricultural spreading machine and a vehicle. The present disclosure also relates to a method of supplying a suspension of Sphagnum into an agricultural machine and a method of operating the machine. Conventional agricultural spreading machines are often used to spread material onto a surface, such as onto a field. For example, a machine may be used to spread fertilizer, slurry, or another material for agricultural purposes. The machine typically includes a tank holding the material, and a pump for driving the material onto the field through one or more outlets. However, conventional machines are not adapted for spreading Sphagnum, and would not be suitable for spreading Sphagnum since they would damage the Sphagnum or would be unable to effectively spread the Sphagnum evenly without blockages. Sphagnum is a genus of moss. It is a lower plant, or a non-vascular plant, and is an example of a bryophyte. It is often referred to as peat moss and typically grows in the wild in peatlands or wetlands. Examples of suitable habitats for Sphagnum include bogs, such as raised bogs and blanket bogs, moors, mires, and fens. Sphagnum has a particularly high capacity for maintaining water in its hyaline cells. As such, in its natural environment, Sphagnum typically grows in wet conditions such as in peatlands. Peatlands around the world are formed when lower layers of Sphagnum decay to form peat, while the upper layer continues to grow on the surface. As a result of this, carbon is stored within the peat while the actively-growing upper Sphagnum continues sequestering carbon dioxide from the atmosphere. Peatlands cover approximately 3% of the land on the Earth’s surface, but store over 500 Gigatonnes of carbon - more than all other vegetation types combined. However, due to adverse impacts on the peatlands (e.g., industrial pollution, drainage - particularly for agriculture, and peat harvesting) the actively-growing upper Sphagnum has been eroded (or is now absent) in many peatlands, thereby exposing the peat to the atmosphere. This absence of surface Sphagnum enables carbon to be released from the peatland. This is a pressing environmental issue, and damaged peatlands now contribute around 6% of global anthropogenic carbon dioxide emissions. As a result, there is a pressing need for effective peatland restoration and methods of effectively growing Sphagnum for restoration purposes. Conventional methods of peatland restoration typically involve translocating Sphagnum from other sites including peatlands, which is clearly not sustainable. Peat is also used as horticultural growing media. As this peat is harvested from the wild, this damages peatlands and ultimately exacerbates carbon emissions. There is a growing demand for alternatives to peat in growing media, and Sphagnum itself has been identified as a key peat alternative. Therefore, there exists a need for an effective and sustainable source of Sphagnum for the purposes of harvest, such as for growing media. Sphagnum may thus be grown in a field, and there is a need to provide an effective method of applying Sphagnum to the field. Unlike higher plants or vascular plants, Sphagnum does not have roots. This has several implications, one of which is that water is not primarily taken up from below (e.g., from roots), and instead water is absorbed through the main body of the plant, such as the stem, leaves, or branches. Sphagnum spreads primarily from new offshoots called innovations. As used herein, the term “innovation” may otherwise be referred to as a “growing point”. An individual plant of Sphagnum grows in a strand. A strand of Sphagnum comprises a stem with small leaves arranged intermittently along the length of the stem. The strand also comprises larger branches shooting off from the stem. At the top of the stem, the strand comprises a capitulum which is a head of new innovations. The capitulum is the primary growth point of Sphagnum. Due to this, water is primarily desired at the top of Sphagnum, which makes good use of collecting water e.g., from rain or irrigation from above. Sphagnum can also comprise innovations where branches sprout off from the main stem. The innovations can eventually result in new stems which break off from the original stem to form a new strand of Sphagnum. Multiple strands of Sphagnum together grow as a hummock. The creation of new strands is a result of vegetative reproduction of Sphagnum, and allows Sphagnum to grow into carpets covering a surface. Sphagnum can also reproduce via spores, but the abundance of spores of Sphagnum is often very low in the wild, and at most sites reproduction via spores is limited, and in any case is limited to a specific and narrow window of time in the year. As such, propagation via spores is often impractical. Another property of Sphagnum resulting from its lack of roots is that it cannot be planted in conventional ways. Typical methods of applying Sphagnum to a surface involve partially burying a clump of Sphagnum, such as in undergrowth on a peatland. Providing clumps of Sphagnum results in a non-uniform coverage of Sphagnum in the discrete areas of the clumps, and requires a large amount of starting material which can be expensive, especially if a high degree of initial coverage is desired. As Sphagnum is often translocated from other wild sources, using a large amount of starting material is of course damaging to the environment. Where a sustainable production of Sphagnum is possible, for example through tissue culture, the damage to the environment can be mitigated, but the cost of providing an initial large amount of starting material can be expensive, and often prohibitively so. Planting is also typically done by hand, which is inefficient, costly, and is not a scalable solution. Other methods of applying Sphagnum include dispersing strands of Sphagnum onto a surface, such as an exposed peatland for restoration. Such methods are ineffective as the strands are not secured to the ground, often dry out before establishing and anchoring themselves, and blow away in wind or rain - both of which are particularly significant factors particularly on peatlands. It is desirable to find a way of applying Sphagnum onto a surface effectively while providing even coverage. The present disclosure seeks to address one or more of the above problems. Aspects of the invention are set out in the independent claims and preferred features are set out in the dependent claims. According to a first aspect of the present disclosure, there is provided: an agricultural spreading machine for spreading a suspension of Sphagnum onto a surface, comprising: a container for storing a suspension of Sphagnum, wherein the suspension of Sphagnum comprises water, a thickening agent, and a plurality of fragments of Sphagnum', a pump connected to the container, wherein the pump is a positive displacement pump; a manifold connected to the pump; a plurality of outlet pipes connected to the manifold, wherein each outlet pipe comprises a length and an inner diameter, and wherein the inner diameter of each of the outlet pipes is at least 5 mm; and a plurality of outlet apertures having an outlet diameter, wherein the outlet apertures are arranged in an array having a width, and wherein the outlet diameter of each of the outlet apertures is at least 5 mm; wherein the pump is configured to move the suspension of Sphagnum from the container through the manifold, along the outlet pipes, and out of the outlet apertures for spreading the suspension of Sphagnum onto the surface; wherein the agricultural spreading machine is configured to move along the surface at a forward speed to allow spreading of the suspension of Sphagnum over the surface; and wherein the agricultural spreading machine provides a pressure loss due to resistance in the outlet pipes of at least 0.1 bar. The inventors have developed the machine of the present disclosure which is used to apply Sphagnum effectively and consistently onto a surface. In particular, the machine provides an effective mechanism for applying Sphagnum onto the surface by spreading the Sphagnum in the form of a suspension. The spreading of Sphagnum can be used for Sphagnum farming, where Sphagnum is grown as a crop for harvest, for example for use as a growing medium (such as a peat replacement for horticulture). Alternatively, the spreading of Sphagnum can be used as a long-term or permanent cover for the purposes of peatland restoration or carbon farming (where the carbon benefits of long-term Sphagnum cover can be used as a source of income). In some examples, the surface may be the ground. Preferably, the surface refers to the surface of a field. For example, the field may be farmland, such as lowland peat farmland. The soil may therefore largely be peat-based. For example, when used for Sphagnum farming, the surface may be farmland. In some examples, the surface may be the surface of a peatland. For example, when used for peatland restoration, the surface may be peatland, including upland peatland. In other examples, the surface may be in a covered environment, such as in a polytunnel or glasshouse. In some examples, the surface may be a surface of exposed peat or soil. A layer may be applied on top of the ground, such as a layer of peat (or other growing media, e.g., dried Sphagnum), straw (or other mulch), fleece (or other fabric), or another material, which is placed on the ground and defines the surface on which the Sphagnum is to be spread. The suspension comprises water, a thickening agent, and a plurality of fragments of Sphagnum. The suspension may comprise a fluid solution comprising the water and the thickening agent. The thickening agent may be dissolved in the water. The fragments of Sphagnum may be suspended in the fluid solution. In other words, the suspension may be referred to as a thickened solution in which the fragments of Sphagnum are suspended. The thickening agent can act to thicken the solution, i.e., it can increase the viscosity of the solution. The type and amount of thickening agent may define the viscosity. In some examples, the fluid solution may be referred to as a gel, for example a liquid gel. The suspension may be liquid at room temperature (e.g., 20 °C), and may be liquid at least at temperatures between 5 °C and 25 °C. The suspension provides a carrier for the Sphagnum, which allows the Sphagnum to remain on the surface when spread onto the surface, for example without blowing away in the wind. The suspension may provide adhesion to the surface. The suspension can also provide protection to the Sphagnum. The suspension can provide water and optionally nutrients to support initial growth of the Sphagnum, especially in early stages when the fragments are vulnerable. The suspension can also provide a supply of water and nutrients by capillary action from the surface to the Sphagnum suspended within the suspension. The suspension also provides a mechanism for improving the ease of application of the Sphagnum to the surface. Attempting to pump strands of Sphagnum onto the surface is difficult since the strands clump together and clog in pipework. If mixed with water, the mixture readily separates, and often the water is pumped through while the Sphagnum clogs. Providing a suspension of Sphagnum allows the strands of Sphagnum to be carried and retained as it is pumped through the system. This allows even distribution of Sphagnum onto the surface. The machine comprises a container for storing the suspension. In some cases, the container may otherwise be referred to as a tank or a vessel. In some examples, the machine comprises a tanker, similar to those used in a slurry tanker, for storing the suspension. In some examples, the machine comprises the suspension in the container. In other words, the suspension may be included as part of the machine of the first aspect. Said another way, the container may store the suspension. For example, the container may be configured to store the suspension of Sphagnum. In other examples, the container may be empty and may be adapted to receive the suspension during use. For example, the container may be supplied empty and may be filled on-site. In such cases, the container may be suitable for receiving the suspension. The machine comprises a pump connected to the container. In the first aspect, the pump comprises a positive displacement pump. A positive displacement pump provides fluid at a constant flow rate by pumping a fixed volume. Unless otherwise specified, references herein to “flow rate” are references to the volumetric flow rate. Providing a positive displacement pump means that the flow rate is not affected by pressure (unlike centrifugal pumps). This is particularly advantageous since, as explained herein, the pressure can be controlled to ensure even flow without impacting on the flow rate provided by the pump. In addition, a relatively low flow rate can be provided. Furthermore, pumps typically used in conventional machines such as slurry spreaders have been found to damage the Sphagnum or pump the suspension unevenly, whereas providing a positive displacement pump has been found to gently pump the suspension as required without damaging the Sphagnum. In particular, this arrangement avoids fragments of Sphagnum tangling around components of the pump and either causing blockages or reducing pump efficiency. In other aspects, the pump is not limited to a positive displacement pump and may be any other type of pump, such as a centrifugal pump. The pump may be configured to convey the suspension from the container and to the manifold. The machine comprises a manifold connected to the pump. The manifold is preferably a component that allows the flow to be divided into a plurality of different channels or branches. The manifold may be connected to an outlet of the pump. In some examples, an inlet of the manifold may be connected to the outlet of the pump. Thus, the manifold may be directly connected to the pump. In other examples, the manifold may be connected to the pump via a separate connector (which may be referred to as a pump connector). The suspension can flow out of the pump and into the manifold where it is split into a plurality of channels. In other words, the manifold may have a single inlet and multiple outlets. In some examples, the manifold may be formed of a manifold pipe with an inlet end of the manifold pipe connected to the pump (e.g., at the pump outlet), and a plurality of outlets connected to the manifold pipe. For example, the manifold pipe may comprise an elongated tube. The outlets of the manifold may be outlets arranged along the manifold pipe (e.g., at different positions along the length of the manifold pipe). As described herein, outlet pipes may be connected to those outlets. The manifold pipe may fill with suspension from the inlet, and the suspension may be passed through the outlets along the manifold pipe. In other examples, the manifold may comprise a component which branches into a plurality of different channels which each define the outlets. The manifold may be configured to convey the suspension from the pump and to divide the flow into the plurality of outlet pipes. The machine comprises a plurality of outlet pipes connected to the manifold. The outlet pipes may otherwise be referred to as tubes or conduits. In some examples, inlet ends of the outlet pipes may be connected to the outlets of the manifold. Thus, the outlet pipes may be directly connected to the manifold. In this case, the outlet pipes may effectively define the plurality of channels connected to the outlets of the manifold. In other examples, the outlet pipes are connected to the manifold via a separate connector (which may be referred to as a manifold connector) between the outlet of the manifold and the inlet of the outlet pipe. In some examples, the plurality of outlet pipes comprises 2 or more outlet pipes, preferably 10 or more outlet pipes, more preferably 20 or more outlet pipes, even more preferably 50 or more outlet pipes. The outlet pipes may be configured to convey the suspension from the manifold and to each of the outlet apertures. Each outlet pipe comprises a length. The length is preferably defined as the longitudinal dimension of the pipe (i.e., along the central axis of the pipe). In other words, if there are bends within the pipe, the length is preferably unchanged. The length is preferably the distance between the two ends of the pipe. For example, the length preferably refers to the length when the pipe is extended in a straight line. Each outlet pipe also comprises an inner diameter. The inner diameter is preferably the diameter of the internal bore of the pipe. The outlet pipes may also have an outer diameter, which is equal to the inner diameter plus the thickness of the pipe. The inner diameter may alternatively be referred to as the internal diameter. Unless otherwise specified, references herein to the “diameter” of the outlet pipes is a reference to the inner diameter rather than the outer diameter. In the first aspect, the inner diameter of each of the outlet pipes is at least 5 mm. This improves the flow of the suspension, since at smaller diameters the flow becomes too restricted along the outlet pipes, for example due to the viscosity of the suspension. This may lead to blockages and the flow may cease altogether. It has been found that providing an inner diameter of at least 5 mm avoids clogging of the outlet pipes and ensures even flow along the outlet pipes. The machine comprises a plurality of outlet apertures having an outlet diameter. The outlet aperture may otherwise be referred to as an outlet hole or an outlet opening. In other words, each outlet aperture has an outlet diameter. In some examples, the outlet apertures are part of the outlet pipes. For example, the outlet aperture may be the outlet end of the outlet pipe. In other words, the outlet pipe may comprise the outlet aperture. The outlet pipes may have a first end which is an inlet end and a second end which is an outlet end. The length can thus be defined as between the inlet end and the outlet end. In other examples, the outlet end of the outlet pipe is connected to a separate connector (which may be referred to as an outlet connector). The outlet connector may then define the outlet aperture. In other words, the outlet aperture may be connected to the outlet pipe. For example, the outlet connector may be a nozzle attachment to the outlet end of the outlet pipe. This can be used to change the diameter of the outlet pipe to the outlet aperture, for example, or otherwise control the flow at the outlet aperture. The outlet apertures may be configured to release the suspension from the machine and onto the surface. In the first aspect, the outlet apertures are arranged in an array having a width. In some examples, the array is a line. In other words, the outlet apertures may be arranged next to one another in a line. For example, the array may be referred to as a row. In other words, the array may be a one-dimensional array. The array extends in a width. The width is the distance between the first and last outlet aperture in the line along the array. In this manner, each outlet aperture can provide the suspension onto the surface at a different point along the width. Preferably, the width is in a dimension perpendicular to the direction of movement of the machine (forwards movement). This means that each outlet aperture can provide a column of suspension onto the surface, wherein the column extends in the direction of movement of the machine, as the machine moves forwards. In other examples, the array may be a two-dimensional array. For example, the array may comprise a plurality of lines or rows of outlet apertures. This can be used to increase the application rate without increasing the flow rate per outlet pipe. For example, the array may comprise a grid, such as a square or rectangle. In other examples, the array may be offset so that different rows provide outlet apertures at non-aligned, different, positions along the width. For example, a second row may comprise outlet apertures positioned between adjacent outlet apertures of a first row in the direction along the width. This can provide a higher density (i.e., more columns per unit width) without overcrowding each row. The outlet diameter of each of the outlet apertures is at least 5 mm. This improves the flow of the suspension, since at smaller diameters the flow becomes too restricted through the outlet apertures, for example due to the viscosity of the suspension. It has been found that providing an outlet diameter of at least 5 mm avoids clogging at the outlet apertures and ensures even flow out of the outlet apertures. In addition, this avoids increases in pressure that may damage the Sphagnum, such as hitting the surface with a larger force. The pump is configured to move the suspension of Sphagnum from the container through the manifold, along the outlet pipes, and out of the outlet apertures for spreading the suspension of Sphagnum onto the surface. In other words, the pump may provide a sufficient pressure to drive the suspension out of the machine and onto the surface. Preferably, the pump provides the suspension through substantially all of the outlet pipes at the same time (and more preferably, through all of the outlet pipes). Preferably, the pump provides the suspension through each of the outlet pipes at substantially the same flow rate. The machine is configured to move along the surface at a forward speed to allow spreading of the suspension of Sphagnum over the surface. This allows continuous spreading of the suspension while the machine moves along the surface. By moving along the surface, the machine can spread the suspension onto the surface over a larger area. Preferably, the forward speed is in a direction perpendicular to the width of the array of outlet apertures. As explained herein, the machine may be self-propelled or may be towed by another vehicle (such as a tractor) in order to move along the surface. For example, the machine may move over a field, applying the suspension in strips over the surface of the field. The machine may turn around and apply adjacent strips or return over the same strip to provide another layer at the same or offset position. In some examples, the machine may reverse to apply the suspension while moving backwards. In the first aspect, the machine provides a pressure loss due to resistance in the outlet pipes of at least 0.1 bar. In this manner, the pump operates above a particular pressure. In other words, the machine may provide a pressure loss of at least 0.1 bar. In particular, the pressure loss is preferably the pressure loss across the outlet pipes. Thus, the pressure loss across the outlet pipes may be at least 0.1 bar. Specifically, the pressure loss may be the pressure difference between the inlet ends of the outlet pipes and the outlet ends of the outlet pipes, such as at the outlet apertures. For example, the pressure may be measured at the manifold and compared to the pressure at the outlet aperture (environmental, atmospheric pressure). The difference between the internal pressure of the machine and the external pressure of the environment at the open outlet apertures defines a pressure loss. The pressure loss may otherwise be referred to as a pressure drop or a back pressure. The pressure loss is due to resistance in the outlet pipes. For example, the resistance is due to frictional losses as a result of flow resistance in the system. As explained herein, various parameters such as the length of the outlet pipes, the inner diameter of the outlet pipes, and the flow rate through each outlet pipe will each contribute to the pressure loss. The pump may be configured to overcome the pressure loss in order to pump the suspension out of the machine and onto the surface. The present disclosure deliberately increases the pressure loss in order to improve the flow uniformity. Providing a pressure loss of at least 0.1 bar has been found to surprisingly increase the flow consistency of the suspension. It has been found that, at pressures below 0.1 bar, the pressure is not sufficient to pump the suspension out of all of the outlet pipes evenly. As set out herein, the physical configuration of the outlet pipes and the flow of suspension will define the resistance to flow and thus the pressure loss. Meanwhile, any variations between different outlet pipes will lead to different pressure losses for different outlet pipes. With such a small overall pressure loss of below 0.1 bar, any variations in pressure loss between the different outlet pipes will have a significant impact. For example, if there are variations in length or diameter between different outlet pipes, then this will cause a different pressure loss for different outlet pipes. In addition, other structural differences that are harder to control such as surface roughness or the angle of tight bends within the pipes will also lead to significant changes in resistance. When the overall pressure loss is small, this variation can be large compared to the overall pressure. This means that the resistance to flow between different outlet pipes is significantly different. As a result, the suspension flows unevenly through different outlet pipes, and in some cases will not flow at all down particular outlet pipes. This is because the flow will take the easiest flow with least resistance. The inventors have realised that, by providing a pressure loss of at least 0.1 bar, the pressure is sufficient that any small variations between outlet pipes provides a small contribution to the overall pressure, meaning that the pressure can be substantially similar across the different outlet pipes. This provides greater consistency in flow between different outlet pipes. This may be further improved by avoiding differences between outlet pipes, such as ensuring the inner diameter and the length of each of the outlet pipes are substantially the same, as explained herein. As described herein, the pressure loss in the outlet pipes may be increased by increasing the length of the outlet pipes, reducing the diameter of the outlet pipes, and / or increasing the flow rate of the suspension. The machine therefore provides a sufficient pressure loss that ensures even flow of the suspension. This improves the uniformity of application of the suspension, and in turn provides a more consistent coverage of Sphagnum onto the surface. This improves the chances of successful establishment and growth. Conventional machines such as slurry spreaders are not suitable for spreading a suspension of Sphagnum. Spreading Sphagnum onto the surface is a much more precise task than spreading slurry, which ultimately is a waste product. Since the material in slurry spreaders is primarily water with a low viscosity, as long as the slurry is sufficiently macerated, the resistance to flow is relatively low and there is no need for increasing the pressure in order to obtain a desired flow. However, because the slurry is poorly mixed and does not form a suspension, clumps are often present in the slurry and negatively impact the flow. In particular, the clumps can cause blockages. One typical way of mitigating this is to provide large diameters to avoid blockages. In addition, uneven flow is largely unimportant with slurry spreaders since there is no need for precise application. Accordingly, large variations in pressure loss between pipes can be accepted. In fact, the lengths of pipes are not controlled at all, and are solely determined by the length needed to route the pipe from a manifold to the desired location. As a result, pipes in the centre are often much shorter than those at the edge of the array, and the lengths are hugely different. In addition, since slurry spreaders conventionally use a centrifugal pump, any pressure loss would have an impact on the flow rate of the pump, which would not be desirable. Therefore, the combination of the positive displacement pump with the pressure loss defined by the present disclosure provides an improved system adapted for spreading a suspension of Sphagnum, and in particular provides even flow for uniform application of Sphagnum to the surface. Optionally, one or more of the length of each of the outlet pipes, the inner diameter of each of the outlet pipes, and / or a volumetric flow rate for each of the outlet pipes are selected to provide the pressure loss. In other words, each of these parameters may affect the pressure loss, and the values may be selected to ensure the desired pressure loss. The relationship between these parameters is defined in the Darcy-Weisbach equation. In particular, the pressure loss depends on a factor, f, where the factor is proportional to the parameters according to the following relationship: J D4 The factor (f) is equal to the volumetric flow rate (Q) multiplied by the length of the outlet pipes (L) and divided by the fourth power of the inner diameter of the outlet pipes (D). In other words, the pressure loss is proportional to the volumetric flow rate. The pressure loss is also proportion to the length of the outlet pipes. The pressure loss is also inversely proportional to the fourth power of the inner diameter. Therefore, increases to the flow rate and length will cause an increase in the pressure loss, and a decrease in the inner diameter will cause an increase in the pressure loss. It is noted that while the pressure loss is directly proportional to the flow rate and length, the pressure loss is much more affected by the inner diameter since it is inversely proportional to the fourth power. Therefore, a change in inner diameter will have a larger effect on the pressure than the flow rate or length. The factor is therefore an effective representation of the pressure loss contribution due to these parameters. In some examples, the factor is at least 150. In other words, QL / D4 >150. Q has units of m3 per s, L has units of m, and D has units of m. In one example, for a flow rate of 2 L per minute, a length of 3 m, and a diameter of 16 mm, the factor is approximately 1525. In some examples, the parameters may be varied within the range of the factor. For example, if the diameter is increased to 40 mm, the length can be increased to around 12 m in order to provide a factor of 150 within the range. To provide a similar factor of around 1500, the length would have to be around 120 m (without changing the flow rate). For a flow rate of 2 L per minute, and a maximum length of 20 m, the inner diameter can be no more than 45 mm in order to provide a factor of greater than 150. In some examples, the factor is at least 200. In some examples, the factor is preferably at least 300, more preferably at least 450, even more preferably at least 600, still more preferably at least 750, and yet more preferably at least 1000. In some examples, the factor is up to 15,000. For example, the factor may be up to 10,000. Preferably, the factor is up to 7500, more preferably up to 5000, even more preferably up to 3750, still more preferably up to 3000, and yet more preferably up to 2000. In some examples, the factor is between 150 and 15,000. In some examples, the factor is between 200 and 10,000. Preferably, the factor is between 300 and 7500, more preferably between 450 and 5000, even more preferably between 600 and 3750, still more preferably between 750 and 3000. Most preferably, the factor is between 1000 and 2000. The ranges of factors disclosed herein may be combined with ranges of the parameters of the factor. In other words, the range of factors may be combined with ranges of the flow rate, length, and inner diameter. For example, the length may be up to 20 m, and the factor may be between 150 and 15,000. This imposes additional restrictions on the values of the flow rate and inner diameter in order to ensure the factor is within the range. Each of the ranges of the factor disclosed herein may be combined with each of the ranges of the different parameters disclosed herein. In some examples, one or more of the length of each of the outlet pipes, the inner diameter of each of the outlet pipes, a viscosity of the suspension, and / or a volumetric flow rate for each of the outlet pipes are selected to provide the pressure loss. The pressure loss may also be proportional to the dynamic viscosity of the suspension. In some examples, the viscosity may be kept constant, and the other parameters may be adjusted according to the relationship set out above. In some examples, the ranges and values of the factor described herein may be multiplied by the viscosity (such as any of the ranges and values of viscosity described herein) to define a new factor which accounts for viscosity. For example, the factor, f, may be at least 150, and the viscosity may be 8 Pa s (8000 mPa s), providing a new factor of at least 1200. Optionally, the length of each of the outlet pipes is substantially the same. In other words, different outlet pipes may have the same approximate length. Preferably, the length of each of the outlet pipes is the same. This allows the pressure loss in each outlet pipe to be the same, so that there is a reduced variation between outlet pipes. This means that the uniformity of the flow can be improved. In some examples, the variation in length between each of the outlet pipes may be less than 5 %, preferably less than 2 %, more preferably less than 1 %. For example, the variation in length may be less than 12.5 cm, preferably less than 5 cm, more preferably less than 2.5 cm. Optionally, the inner diameter of each of the outlet pipes is substantially the same. In other words, different outlet pipes may have the same approximate inner diameter. Preferably, the inner diameter of each of the outlet pipes is the same. This allows the pressure loss in each outlet pipe to be the same, so that there is a reduced variation between outlet pipes. This means that the uniformity of the flow can be improved. In some examples, the variation in inner diameter between each of the outlet pipes may be less than 10 %, preferably less than 5 %, more preferably less than 1 %. For example, the variation in inner diameter may be less than 2 mm, preferably less than 1 mm, more preferably less than 0.2 mm. In some examples, the inner diameter of each of the outlet pipes may be constant along the length of each of the outlet pipes. This allows the flow to be more even. In other examples, the diameter of the pipe may vary, and the inner diameter may refer to the minimum diameter. For example, the pipe may taper between a maximum and a minimum diameter. If a change of diameter is required, a gentle taper (or a series of small step changes) may be preferable to a large step change in diameter in order to avoid clogging. Optionally, the outlet diameter of each of the outlet apertures is substantially the same. In other words, different outlet apertures may have the same approximate outlet diameter. Preferably, the outlet diameter of each of the outlet apertures is the same. This allows the aperture for each outlet pipe to be the same, so that there is a reduced variation between outlet apertures. This means that the uniformity of the flow can be improved. In some examples, the variation in outlet diameter between each of the outlet apertures may be less than 10 %, preferably less than 5 %, more preferably less than 1 %. For example, the variation in outlet diameter may be less than 2 mm, preferably less than 1 mm, more preferably less than 0.2 mm. In some examples, the outlet diameter of the outlet apertures is the same as the inner diameter of the outlet pipes. In some examples, the outlet diameter of the outlet apertures is the same or larger than the inner diameter of the outlet pipes (e.g., the outlet diameter is no smaller than the inner diameter). In some examples, the outlet apertures may be the outlet end of the outlet pipes, and therefore the outlet diameter is the same as the inner diameter. In other examples, an outlet connector may be attached to the outlet pipes, wherein the outlet connector defines the outlet aperture. In such cases, the outlet aperture may be the same diameter as the inner diameter. This avoids a further restriction on the flow of the suspension. In some examples, the outlet aperture may be larger than the inner diameter. This may be used to control the flow of the suspension just as it leaves the outlet aperture, for example to reduce damage to the Sphagnum under high pressures or speeds when it contacts the surface. The outlet connector may also be used to direct the released flow as desired. In other examples, the outlet aperture may be smaller than the inner diameter to add an additional restriction, and the outlet connector may be used to reduce the diameter from the inner diameter of the outlet pipe to the outlet diameter of the outlet connector. For example, the outlet connector may be in the form of a nozzle. In some examples, the machine may comprise a flow control device for each outlet pipe. For example, each outlet pipe may comprise a flap over the outlet aperture which can automatically control flow to ensure even flow out of each outlet aperture. For example, the flaps may be self-sealing due to pressure. In some examples, the flaps can be controlled to deliberately prevent flow out of certain outlet pipes, for example to control the number of outlet pipes without disconnecting the outlet pipes. Optionally, the length of each of the outlet pipes is between 0.5 m and 20 m. Providing a length of at least 0.5 m allows the length of the pipe to be selected to provide a sufficient pressure loss contribution. In addition, providing a length of less than 0.5 m may not be practical and hinders the arrangement of the outlet apertures. For example, where the manifold pipe is smaller than the width of the array, and / or where the outlet pipes run from a central manifold, the length of the outlet pipes at the end of the array must be sufficient to reach the end of the array. Thus, in some examples, the length may be at least half of the width of the array. And therefore, if the length is less than 0.5 m, this can limit the width of the array in this arrangement, and therefore reduces the area that can be applied. In other cases, the manifold pipe can be a similar width to the width of the array, and the outlet pipes need not extend substantially in the width direction, and thus a small pipe length is possible. Meanwhile, providing a maximum length of 20 m ensures that the length does not provide a pressure loss which is too high, or which means the other parameters must be adjusted to unworkable values. In addition, providing a length of less than 20 m improves the practicality of the machine, since extremely long pipes can be avoided. In a preferred example, the length of each of the outlet pipes may be between 1 m and 10 m. This further improves the practicality of the machine and optimises the pressure drop contributed by the length of the outlet pipes. In some examples, the length is at least 0.5 m, preferably at least 1 m, more preferably at least 2 m. In some examples, the length is up to 20 m, preferably up to 10 m, more preferably up to 5 m. In some examples, the length is between 0.5 m and 20 m, preferably between 1 m and 10 m, more preferably between 2 m and 5 m. As mentioned above, each of these ranges of values for the length may be combined with the ranges of the factor (QL / D4) or with ranges of the pressure. As one example, the length may be between 1 m and 10 m, and the factor may be between 150 and 15,000 or between 1000 and 2000. As one example, the length may be between 1 m and 10 m, and the pressure may be at least 0.5 bar or between 0.5 bar and 3 bar. Optionally, the inner diameter of each of the outlet pipes is between 5 mm and 50 mm. As set out above, providing an inner diameter of at least 5 mm avoids clogging and improves the flow uniformity. Providing a smaller diameter may also lead to a pressure drop which may be too high and cause damage to the Sphagnum. In addition, providing an inner diameter of up to 50 mm ensures that the pressure drop is sufficient to ensure even flow. In particular, this range avoids the diameter providing a pressure loss contribution which is so large that the other parameters must be adjusted to unworkable values in order to provide the desired pressure drop. For example, increasing the diameter significantly may require extremely long outlet pipes which are not practical. This is especially important since the pressure is related to the fourth power of the diameter. In a preferred example, the inner diameter of each of the outlet pipes may be between 10 mm and 25 mm. This further optimises the pressure drop provided by the inner diameter. In some examples, the inner diameter is at least 5 mm, preferably at least 8 mm, more preferably at least 10 mm, even more preferably at least 12 mm. In some examples, the inner diameter is up to 50 mm, preferably up to 32 mm, more preferably up to 25 mm, even more preferably up to 20 mm. In some examples, the inner diameter is between 5 mm and 50 mm, preferably between 8 mm and 32 mm, more preferably between 10 mm and 25 mm, even more preferably between 12 mm and 20 mm. As mentioned above, each of these ranges of values for the inner diameter may be combined with the ranges of the factor (QL / D4) or with ranges of the pressure. Each of these ranges of values for the inner diameter may also be combined with the ranges of the length, and further optionally with the ranges of the factor or the pressure. As one example, the inner diameter may be between 10 mm and 20 mm, and the factor may be between 150 and 15,000 or between 1000 and 2000, optionally the length may also be between 1 m and 10 m, for example. As one example, the inner diameter may be between 10 mm and 20 mm, and the pressure may be at least 0.5 bar or between 0.5 bar and 3 bar. Optionally, the outlet diameter of each of the outlet apertures is between 5 mm and 50 mm. As set out above, providing an outlet diameter of at least 5 mm avoids clogging and improves the flow. In addition, providing an outlet diameter of up to 50 mm ensures that the pressure drop is sufficient to ensure even flow. Furthermore, this ensures the suspension is released through an appropriately sized aperture to avoid clogging at the outlet. In a preferred example, the outlet diameter of each of the outlet apertures may be between 10 mm and 20 mm. This further optimises the pressure drop provided by the outlet diameter. In some examples, the outlet diameter is at least 5 mm, preferably at least 8 mm, more preferably at least 10 mm, even more preferably at least 12 mm. In some examples, the outlet diameter is up to 50 mm, preferably up to 32 mm, more preferably up to 25 mm, even more preferably up to 20 mm. In some examples, the outlet diameter is between 5 mm and 50 mm, preferably between 8 mm and 32 mm, more preferably between 10 mm and 25 mm, even more preferably between 12 mm and 20 mm. As mentioned above, each of these ranges of values for the outlet diameter may be combined with the ranges of the factor (QL / D4) or with ranges of the pressure. Each of these ranges of values for the outlet diameter may also be combined with the ranges of the inner diameter, and further optionally with the ranges of the factor, and / or further optionally with the ranges of the length. As one example, the outlet diameter may be between 10 mm and 20 mm, and the pressure may be at least 0.5 bar or between 0.5 bar and 3 bar. In some examples, each of the outlet pipes comprises a smooth internal bore. In other words, the internal surface of the outlet pipes may be smooth. By avoiding a rough surface, this avoids an increase in pressure loss due to resistance in the pipes caused by surface roughness. In some examples, each of the outlet pipes does not comprise a connector at any point along the length of the outlet pipe between the inlet and the outlet. For example, the outlet pipes may be continuous. This avoids additional restrictions on the internal surface of the outlet pipe. In some examples, the outlet pipes do not include a bend which has a bend radius of less than 50 mm. In some examples, the outlet pipes include fewer than 5 bends of a radius of 100 mm or less, preferably fewer than 3. In some examples, the outlet pipes include fewer than 5 bends of a radius of 5 cm or less, preferably fewer than 3. Preferably, the bend radius of any bends in the pipe is greater than a radius which introduces a kink into the pipe. In some examples, the outlet pipes are made from a flexible material which can bend. The outlet pipes can then be bent gently as desired without kinking. It is preferable that the outlet pipes do not comprise any kinks in which the outlet pipe is folded. In some examples, the outlet pipes are routed over a support to provide a more compact system. In other words, by routing the outlet pipes around a support, the bends can be introduced to accommodate the length of the outlet pipes in a compact manner. For example, the support may be a support pipe, and the pipe may have a diameter of at least 50 mm, preferably at least 100 mm. This ensures the bends are gentle and kinking is avoided. In some examples, the outlet pipes are wound multiple times around the support, which provides a more compact system, and may be helpful when the length is very large. In other examples, the outlet pipes are only routed over the support once, which avoids introducing further pressure losses due to increased contact of the suspension with the sides of the pipe. In some examples, the outlet pipes are transparent. This allows the suspension within the outlet pipes to be seen, to readily identify any blockages. In other examples, the outlet pipes need not be transparent. The outlet pipes may be made from plastic, for example, but other materials such as rubber or metal may be used. Providing a flexible pipe is advantageous and allows bends to be introduced. Optionally, the pressure loss is at least 0.2 bar. This provides improved uniformity to the flow. For example, the pressure loss due to resistance provided by the outlet pipes is at least 0.25 bar, preferably at least 0.3 bar, more preferably at least 0.4 bar, even more preferably at least 0.5 bar. In some cases, the pressure loss may be at least 0.75 bar, such as at least 1 bar. Providing a threshold pressure loss, in particular above around 0.5 bar, has been found to provide desired uniformity of flow of the suspension. In some examples, the pressure loss is up to 10 bar. It has also been found that, at pressures above 10 bar, the pressure is so high that damage to the suspension may occur. In particular, damage to the Sphagnum can occur. Since the Sphagnum will be used for later growth, it is desirable to avoid such damage. The high pressures can result in significant force on the pipework or connections, or on the surface as the suspension is released from the outlet apertures, especially if high speeds result. These forces can damage the fragments of Sphagnum. In some examples, the pressure loss is up to 10 bar, preferably up to 5 bar, more preferably up to 3 bar, even more preferably up to 2 bar. Optionally, the pressure loss is between 0.1 bar and 10 bar. In some examples, the agricultural spreading machine provides a pressure loss of between 0.2 bar and 5 bar. This provides a further optimisation of the pressure loss which provides the desired advantages of improved flow uniformity and avoiding damage to the Sphagnum. Providing a pressure of less than 5 bar significantly reduces the risk of damage to the Sphagnum. In a particularly preferred example, the pressure loss is between 0.5 bar and 2 bar. This further optimises the pressure loss. In some examples, the pressure loss is between 0.2 bar and 5 bar, preferably between 0.25 bar and 3 bar, preferably at least 0.5 bar and 2 bar, more preferably between 0.75 bar and 1.5 bar. Each of these ranges of pressure may be combined with the each of the ranges of other parameters such as length, inner diameter, and / or outlet diameter disclosed herein. As one example, the pressure may be between 0.5 bar and 3 bar, and the length may be between 1 m and 10 m. Optionally, the agricultural spreading machine is configured to provide an application rate of between 1 L and 5 L of the suspension per m2. In some examples, the application rate is between 2 L and 4 L per m2, preferably about 3 L per m2. In some examples, the application rate is at least 1 L per m2, preferably at least 2 L per m2, more preferably at least 3 L per m2. This provides even coverage which increases the chance of successful establishment of the Sphagnum. This is particularly important for Sphagnum farming, for example, where rapid establishment is required. Higher application rates may be possible, but may result in wastage and higher costs, and may require higher flow rates which may have undesirable consequences on the pressure. In other examples, especially when used for restoration (where slower establishment is more acceptable), the application rate may be reduced. For example, the application rate may be at least 0.05 L per m2, preferably at least 0.1 L per m2, more preferably at least 0.5 L per m2. Optionally, the width of the array of outlet apertures is between 0.5 m and 20 m. For example, the width may be small enough such that the array of outlet apertures can be attached to a vehicle, such as a tractor, and the structure can be carried by the vehicle. In other examples, the width may be larger, and the array can be supported by a structure towed by the vehicle. Increasing the width allows for a larger area to be covered with a single pass of the machine but increases the cost and complexity. A heavier machine may also create a larger indentation in the surface which may not be desirable. In addition, depending on the design, increasing the width significantly may result in increasing the length of the pipes (in order for the pipes to reach the ends of the array from the manifold pipe if the manifold pipe is shorter than the width of the array) which may incidentally affect the pressure drop. In a preferred example, the width may be between 1 m and 10 m. Larger than around 10 m is very large in agricultural terms and such a machine may be difficult to operate and manoeuvre. In some examples, the width is at least 0.5 m, preferably at least 1 m, more preferably at least 2 m. In some examples, the width is up to 20 m, preferably up to 10 m, more preferably up to 7.5 m. In some examples, the width is between 0.5 m and 20 m, preferably between 1 m and 10 m, more preferably between 2 m and 7.5 m. The width of the array of outlet apertures can be varied, allowing a wider or narrower application area for the desired use. The width of the array may be increased proportionally to the number of outlet pipes. For example, if the number of outlet pipes is doubled but the density remains the same, the width of the array can be doubled. In some examples, the width of the array is arranged between supports of the vehicle, such as wheels of the structure or the vehicle (e.g., tractor). In this manner, indentations in the surface, for example due to tyre tracks, are not provided within the area on which the suspension is spread. For example, the width of the array may be arranged between the wheels of the tractor pulling the machine. In other examples, the width is larger, and the suspension is spread over the indentations made by the tyres or other support. In such cases, it is desirable to reduce the indentations, for example by minimising the ground pressure exerted by the wheels. In some examples, the outlet apertures are arranged evenly spaced along the width of the array. For example, the spacing between outlet apertures may be the same. In some examples, the spacing may be between 10 mm and 500 mm, such as between 20 mm and 100 mm for Sphagnum farming. For example, providing a spacing of 20 mm provides approximately 50 outlet apertures per m width. The spacing may be defined as the distance (along the width) between adjacent mid-points of the outlet apertures. This is therefore independent of the diameter. The spacing may therefore include the diameter of the outlet apertures and the external separation. The external separation may be the distance between the outer surface of one outlet aperture and the next. This may be reduced to 0 mm when adjacent outlet apertures are touching. Optionally, the forward speed is between 0.2 m per s and 5 m per s. Controlling the forward speed allows the application rate to be controlled based on a given flow rate for the outlet pipes. For example, for a given flow rate, the application rate can be increased by travelling slower across the surface. Providing a forward speed of at least 0.2 m per s corresponds to a typical minimum speed at which a vehicle (such as a tractor) can move consistently over a surface (such as field), without causing difficulty in navigating terrain or causing uneven distribution over the surface. Meanwhile, providing a speed of up to 5 m per s corresponds to a typical maximum speed at which the vehicle can move over the surface whilst producing a consistent output. In other examples, the speed may be between 1 km per hour and 20 km per hour. In a preferred example, the forward speed may be between 2 m per s and 4 m per s. This provides an optimum speed which ensures uniform application and without approaching undesirable limits of the speed of the vehicle. In some examples, the forward speed is at least 0.2 m per s, optionally at least 0.4 m per s, further optionally at least 1 m per s. In some examples, the pump is configured to provide a total volumetric flow rate of the suspension of Sphagnum to the plurality of outlet pipes of between 1 L per second and 5 L per second, multiplied by the width (e.g., in m), and multiplied by the forward speed (e.g., in m per s). This ensures that the application rate is within a desired range. For example, this may assume the density is constant (so doubling the width doubles the number of outlet pipes). In other examples, the speed may be controlled based on the number of outlet pipes. The total volumetric flow rate preferably refers to the total flow rate provided by the pump. In other words, this may correspond to the sum of the individual flow rates for each outlet pipe. For example, for a width of 1 m, and a forward speed of 1 m per s, the total volumetric flow rate may be between 1 L per second and 5 L per second. For a higher width or speed, the total volumetric flow rate may increase. For example, for a width of 2 m, and a forward speed of 1 m, the flow rate may be between 2 L per second and 10 L per second. Likewise, for a width of 1 m, and a forward speed of 2 m, the flow rate may be between 2 L per second and 10 L per second. Similarly, for a width of 2 m, and a forward speed of 2 m, the flow rate may be between 4 L per second and 20 L per second. In other words, the total flow rate scaled based on the number of m of the width and the number of m per s of the speed. In some examples, the forward speed may be controlled based on the total volumetric flow rate, and vice versa. For example, the forward speed may be adjusted proportionally based on the total volumetric flow rate. In one example, if the total volumetric flow rate is doubled, then the forward speed may be doubled to ensure the same application rate (in L per m2). This can be used to keep the desired application rate. Optionally, a volumetric flow rate for each of the outlet pipes is at least 0.02 L per s. The volumetric flow rate for each outlet pipe may correspond to the total flow rate provided by the pump divided by the number of outlet pipes. For example, the volumetric flow rate for each outlet pipe may be an average flow rate across the plurality of outlet pipes. Providing a flow rate of at least 0.02 L per s improves uniformity of flow since it avoids clogging and clumping within the pipes. In one preferred example, the volumetric flow rate for each of the outlet pipes may be at least 0.04 L per s. In some examples, the volumetric flow rate for each outlet pipe is up to 2 L per s, preferably up to 1 L per s, more preferably up to 0.5 L per s. For a higher individual flow rate, the density (number of outlet pipes per unit width) may be reduced, or the speed may be increased to provide the same application rate. In some examples, the pump provides a total volumetric flow rate of between 0.02 L per s and 0.5 L per s, multiplied by the number of outlet pipes. In other words, the flow rate through each outlet pipe may be between 0.02 L per s and 0.5 L per s. In other examples, the flow rate may be between 1 L and 100 L per minute, optionally between 1 L and 25 L per minute. The total flow rate through the system is equal to the flow rate per outlet pipe multiplied by the number of outlet pipes. The higher the number of outlet pipes, the higher the overall flow rate. Therefore, the more outlet pipes provided, the larger the size of the pump. Providing the range of flow rates ensures that the suspension is provided onto the field at the desired rate in order to provide even coverage. By ensuring the flow rate is high enough, the amount of suspension (and in turn, the amount of Sphagnum) is sufficient to provide the desired amount of Sphagnum over the area of the surface. In addition, by ensuring the flow rate is not too high, the amount of suspension applied can be controlled to avoid wastage of the suspension and to ensure that the Sphagnum establishes effectively over the surface. In addition, providing the flow rate ensures that the suspension is passed through the machine in a desired manner. In particular, this avoids the suspension separating. By ensuring that the flow rate through each outlet pipe is high enough, this avoids the Sphagnum being pumped out and the leaving the remainder of the suspension (e.g., the fluid solution comprising the water and the thickening agent) behind. In addition, by ensuring the flow rate is not too high, this avoids the suspension being pumped out (e.g., the fluid solution comprising the water and the thickening agent) without the Sphagnum. The flow rate therefore optimises the flow through the outlet pipes and avoids the suspension separating. In some examples, the viscosity of the suspension is fixed. For example, with a particular viscosity, any impact of changes in viscosity on the pressure loss is removed. In some examples, the viscosity of the suspension (before Sphagnum is added) is at least 1000 mPa s. The viscosity may be measured at 25 °C. In other words, the viscosity of the fluid solution comprising water and the thickening agent may be measured before the Sphagnum is added. For example, the viscosity may be between 1000 mPas and 50,000 mPa s. More preferably, the viscosity is between 3000 and 20,000 mPa s. Even more preferably, the viscosity is between 4000 and 10,000 mPa s. Most preferably, the viscosity is between 5000 and 8000 mPa s. As used herein, the viscosity is measured using the standard Brookfield scale, such as using a Brookfield Dial Reading Viscometer LVF, commercially available from Brookfield Engineering Laboratories, Inc, USA. In some examples, the thickening agent comprises a cellulose-based thickening agent or a starch-based thickening agent. Preferably, the thickening agent comprises a cellulose-based thickening agent. More preferably, the thickening agent comprises a cellulose ether. Even more preferably, the thickening agent comprises hydroxyethyl cellulose. Hydroxyethyl cellulose is often referred to as HEC. Hydroxyethyl cellulose has been found to be particularly preferable as it is compatible with Sphagnum, and has been found to be non-toxic and to support growth of the Sphagnum. It has also been found to provide the desired physical characteristics of the fluid solution, including the ability to suspend Sphagnum. In some examples, the hydroxyethyl cellulose has an average molecular weight of at least 500,000 Da (daltons, or unified atomic mass unit), more preferably at least 750,000 Da, even more preferably at least 1,000,000 Da, still more preferably at least 1,250,000 Da. In one example, the average molecular weight is between 1,000,000 Da and 1,500,000 Da. Providing a higher average molecular weight allows the viscosity to be higher for a given concentration in aqueous solution. For example, the thickening agent may be Natrosol™ hydroxyethyl cellulose, commercially available in powder form from Ashland, USA. In some examples, the thickening agent may comprise Natrosol™ 250 HHW. More preferably, the thickening agent comprises Natrosol™ 250 HX or HHX. Natrosol™ 250 HX has an average molecular weight of 1,000,000 Da, Natrosol™ 250 HHX has an average molecular weight of 1,300,000 Da, and Natrosol™ 250 HHW has an average molecular weight of 1,300,000 Da. Most preferably, the thickening agent comprises Natrosol™ 250 HHX. Hydroxyethyl cellulose can be dissolved in water at room temperature in order to thicken the fluid solution. As such, it has been found to be a particularly preferable thickening agent. In some examples, the fluid solution comprises between 1 g and 20 g of hydroxyethyl cellulose per L of water, more preferably between 2 g and 18 g, even more preferably between 3 g and 15 g, and still more preferably between 4 g and 12 g. Even more preferably, the fluid solution comprises between 5 g and 10 g of hydroxyethyl cellulose per L of water. This has been found to provide an optimum viscosity to provide the benefits as described herein. For Natrosol™ HX, preferably the solution comprises between 5 g and 15 g of thickening agent per Lof water, more preferably between 8 g and 10 g, most preferably about 9 g per L. For Natrosol™ HHX, preferably the solution comprises between 2 g and 10 g of thickening agent per L of water, more preferably between 5 g and 8 g. Most preferably, the fluid solution comprises between 7 g and 8 g of hydroxyethyl cellulose (HHX) per L of water. This corresponds to a viscosity of around 5000 to 8000 mPas at 25 °C. In some examples, the fluid solution comprises between 2 g and 13 g of hydroxyethyl cellulose per Lof water, wherein the hydroxyethyl cellulose has an average molecular weight of between 1,000,000 Da and 1,300,000 Da. More preferably, the fluid solution with the hydroxyethyl cellulose having an average molecular weight of between 1,000,000 Da and 1,300,000 Da comprises between 3 g and 12 g of hydroxyethyl cellulose per Lof water, even more preferably between 4 g and 11g, and still more preferably between 5 g and 10 g. In some examples, the ratio of an average molecular weight of the hydroxyethyl cellulose (Da) to a weight of hydroxyethyl cellulose per L of water is between 50,000 and 500,000, preferably between 75,000 and 350,000, more preferably between 100,000 and 200,000. In some examples, the thickening agent comprises a starch-based thickening agent. Starch can be dissolved in water by heating the starch and water. Depending on the starch, the mixture can be heated to around 55 °C - 85 °C in order to dissolve the starch in the water. This is known as starch gelatinization. By dissolving starch in water in this manner, a thickened fluid solution can be obtained. In some examples, the fluid solution comprises between 10 g and 100 g of starch per L of water, preferably between 20 g and 50 g, more preferably between 30 g and 40 g. For example, the thickening agent may comprise a natural starch, such as a maize starch. In some examples, the thickening agent comprises a partially pregelatinized starch. In such examples, the thickening agent may comprise between 30 g and 40 g of a partially pregelatinized starch. In one example, the thickening agent comprises LYCATAB™ PGS, commercially available from Roquette Pharma. In some examples, the thickening agent comprises a pregelatinized starch (i.e., fully pregelatinized). This is soluble is cold water, which is preferable for providing the thickening agent dissolved in water. In one example, the thickening agent comprises PREGEFLO™ CH 40, commercially available from Roquette Pharma. In some examples, the thickening agent does not comprise sodium alginate or other algin-based thickening agent, since in combination with calcium (either as a nutrient in the suspension, or often found in the field or by water) it forms cross links and solidifies into calcium alginate which is not soluble in water and no longer forms a suspension (e.g., a liquid gel) which can be spread. In some examples, the thickening agent does not comprise agar, which is a solid at room temperature (e.g., 20 °C), and therefore would not provide a fluid solution and a suspension (e.g., a liquid gel) which can be spread. In some examples, the suspension comprises nutrients. The nutrients can facilitate growth of the Sphagnum, which is important during initial establishment. Various different nutrients may be provided. For example, the nutrients may comprise nitrogen, potassium, and / or phosphorus. In one example, the nutrients comprise each of nitrogen, potassium, and phosphorus. In some examples, the nutrients may additionally or alternatively comprise calcium and / or magnesium. In some examples, the nutrients may additionally or alternatively comprise sulfur, iron, sodium, manganese, copper, zinc, boron, molybdenum, and / or chloride. In some examples, the suspension does not comprise sugar, vitamins, and / or plant growth hormones. Any suitable Sphagnum species (or optionally a combination thereof) may be used in the present disclosure. As different species of Sphagnum may have different growth requirements, the Sphagnum species for use in the present disclosure may be selected depending on the environment. The suspension comprises one or more Sphagnum species. Any species could be used, but in one example the present disclosure comprises the use of one or more Sphagnum species selected from the group consisting of: Sphagnum angustifolium, Sphagnum australe, Sphagnum capillifolium, Sphagnum centrale, Sphagnum compactum, Sphagnum cuspidatum, Sphagnum denticulatum, Sphagnum fallax, Sphagnum fimbriatum, Sphagnum fuscum, Sphagnum imbricatum (austinii), Sphagnum inundatum, Sphagnum magellanicum (medium), Sphagnum palustre, Sphagnum papillosum, Sphagnum pulchrum, Sphagnum russowii, Sphagnum squamosum, Sphagnum subnitens, Sphagnum tenellum, and Sphagnum cristatum. In one example, the method comprises the use of one or more Sphagnum species selected from the group consisting of: Sphagnum palustre, Sphagnum capillifolium, Sphagnum capillifolium rubellum, Sphagnum subnitens, Sphagnum denticulatum, Sphagnum squamosum, Sphagnum fallax, Sphagnum fimbriatum, Sphagnum cuspidatum, Sphagnum magellanicum, and Sphagnum papillosum. In one example, the present disclosure comprises the use of one or more Sphagnum species selected from the group consisting of: Sphagnum palustre, Sphagnum capillifolium, Sphagnum capillifolium rubellum, Sphagnum subnitens, Sphagnum squamosum, Sphagnum magellanicum, and Sphagnum papillosum. In one example, a Sphagnum species for use in the present disclosure may be one or more selected from the group consisting of: Sphagnum palustre, Sphagnum capillifolium, Sphagnum fallax, Sphagnum magellanicum, Sphagnum papillosum, and Sphagnum squamosum. Most preferably, the Sphagnum species is Sphagnum palustre. For example, Sphagnum palustre may be preferable for use in a growing medium because of its physical properties. It is also envisaged that the present disclosure could be applied to any hybrid Sphagnum species. In some examples, the plurality of fragments of Sphagnum comprises at least one of the Sphagnum species disclosed herein. In some examples, the plurality of fragments of Sphagnum comprises at least 2, 3, 4, 5 or more Sphagnum species. As the plurality of fragments of Sphagnum are suspended in the solution, preferably this means that the fragments of Sphagnum are held dispersed within the solution, and at least some of the fragments of Sphagnum do not float on the solution and / or do not sink beneath the solution. In other words, the fragments are not left behind when the solution is moved, such as by being poured or spread. This means that the Sphagnum can be distributed onto a surface effectively when the suspension is applied. Once the suspension has been applied, the suspension also retains the Sphagnum substantially in position such that the Sphagnum does not fall out of the suspension e.g., by sinking to the bottom. This enables the Sphagnum to be generally fixed in position with the suspension, and not for example to be washed away while the rest of the suspension is left behind. This also allows the Sphagnum to absorb the nutrients in the suspension over an extended period of time, which is particularly advantageous for the initial period of growth after application, where nutrient supply can aid establishment. In some examples, the suspension comprises at least 1000 fragments of Sphagnum per L of fluid solution. For example, the suspension may comprise at least 1000 fragments of Sphagnum having a length of at least 5 mm per L of fluid solution. Preferably, the suspension comprises at least 2000 fragments of Sphagnum having a length of at least 5 mm per L of fluid solution. In some examples, the suspension comprises a total mass of fragments of Sphagnum of at least 50 g per L of fluid solution. In some examples, the suspension comprises a total mass of fragments of Sphagnum of between 50 g and 450 g per L of fluid solution, preferably between 75 g and 300 g per L, more preferably between 100 g and 200 g per L, most preferably about 150 g per L. In some examples, the suspension comprises a total mass of fragments of Sphagnum of at least 50 g per L of fluid solution, preferably at least 75 g per L, more preferably at least 100 g per L. In some examples, the suspension comprises a total mass of fragments of Sphagnum of less than 450 g per L of fluid solution, preferably less than 300 g per L, more preferably less than 200 g per L. The total mass can be calculated by compressing the Sphagnum to a standardised mass per volume by compressing with a force of 16 g / cm2 to remove excess water to ensure a standardised mass. In some examples, the suspension comprises a total dry mass of fragments of Sphagnum of at least 1 g per L of fluid solution. The dry mass can be calculated by drying the Sphagnum to remove the water. As is standard in the art, the drying can be performed by heating the Sphagnum at around 110 °C for at least 24 hours. Alternatively, the drying can be performed by drying at around 25 °C in a humidity of less than 50 % until no further weight loss is measured. This ensures that all water has been evaporated, and that remaining is the dry mass of the Sphagnum. Of course, this will kill the Sphagnum, so this merely provides a useful method for calculation of the dry mass. In some examples, the suspension comprises a total dry mass of at between 0.5 g and 4.5 g per L, preferably between 0.75 g and 3 g per L, more preferably between 1 g and 2 g per L, most preferably about 1.5 g per L. In some examples, the suspension comprises a total dry mass of fragments of Sphagnum of at least 0.5 g per L of fluid solution, preferably at least 0.75 g per L, more preferably at least 1 g per L. In some examples, the suspension comprises a total mass of fragments of Sphagnum of less than 4.5 g per L of fluid solution, preferably less than 3 g per L, more preferably less than 2 g per L. Optionally, the pump is a progressive cavity pump. A progressive cavity pump, sometimes referred to as a progressing cavity pump, a helical pump, or an eccentric screw pump, is a type of positive displacement pump in which a fixed volume of fluid is pumped through fixed volume cavities that progress from the inlet to the outlet. This is particularly useful since it is adapted for pumping viscous fluids. This pump has surprisingly been found to be particularly useful for pumping the suspension since the fragments of Sphagnum do not tangle within the pump or become damaged by the pump. The pulse of the pump is also very low, providing a constant flow rate, improving uniformity. This pump also provides low levels of shearing to the suspension. In other examples, the pump may be another type of positive displacement pump. For example, the pump may be a peristaltic pump. Optionally, the agricultural spreading machine is configured to be connected to a vehicle for moving the agricultural spreading machine along the surface. For example, the agricultural spreading machine is connected to a vehicle for moving the agricultural spreading machine along the surface. For example, the vehicle may be an agricultural vehicle such as a tractor. In other words, the vehicle may move the machine along the surface. This may be done, for example, by the vehicle pushing the machine in front of the vehicle. For example, the machine may be front-mounted. Alternatively, this may be done by pulling, which preferably avoids the vehicle travelling immediately over the suspension applied to the ground (for example, avoiding wheels running over the suspension). For example, the machine may be rearmounted. In some examples, the machine is arranged on a trailer pulled by the vehicle. In some examples, the agricultural spreading machine comprises a linkage for connecting to the vehicle. For example, the linkage may be a three-point linkage. This provides a common connection to allow the machine to be connected to the vehicle. In some examples, the linkage may be rigid or may be pivotable. In some examples, the vehicle is configured to support the agricultural spreading machine above the ground. For example, the machine may be suspended in a similar manner to conventional mounted implements on a tractor such as buckets. The linkage can be rigid so that the machine can be supported by the vehicle without the machine contacting the surface. In other examples, the machine may contact the surface (and may be supported by its own wheels). The linkage may therefore act to allow the vehicle to tow the machine along the surface. In some examples, the agricultural spreading machine comprises a support for supporting the agricultural spreading machine on the surface. The vehicle may be configured to tow the agricultural spreading machine with the agricultural spreading machine supported on the surface by the support. For example, the support may comprise a fixed support or a moving support. For example, the support may comprise wheels. In other examples, the support may be tracks such as a continuous track. In some examples, the support may comprise skids or skis. The support may comprise an air cushion, such as used in a hovercraft. Other propulsion systems used in vehicles or agricultural equipment may be used. Alternatively, the agricultural spreading machine may move in the air, such as by helicopter or by drone. In some examples, the agricultural spreading machine is configured to be propelled by a vehicle to move the agricultural spreading machine along the surface. For example, the vehicle may be an agricultural vehicle such as a tractor. In some examples, the agricultural spreading machine is self-propelled for moving along the surface. For example, the machine may comprise an engine or electric motor for moving along the surface. In some examples, the agricultural spreading machine further comprises a motor configured to operate the pump. The motor may be the same motor as used to propel the machine along the surface. In some examples, an electric pump may be used. In other examples, a hydraulic motor may be used. In some examples, power for the pump may be provided by the vehicle, for example from the vehicle engine. For example, power may be provided by a power takeoff (PTO) from a vehicle such as a tractor. In some examples, the machine comprises a control for operating the pump. For example, the control may allow a user to turn the pump on or off and optionally control the flow rate (such as by controlling the rpm of the pump). The pump operation may also be automated. The pump may also be controlled dynamically and automatically based on the speed of vehicle, for example in order to provide a consistent application rate. In some examples, the manifold comprises a manifold pipe. The manifold pipe may be an elongated pipe, comprising apertures (or outlets) along the length of the pipe. The manifold pipe may be arranged generally horizontally relative to the surface. The suspension can enter one end of the pipe, flow along the pipe, and exit the manifold through each of the apertures along the length of the pipe. The other end of the pipe may be sealed. The manifold pipe may have a large diameter in order to provide a capacity to ensure the suspension flows out of the outlets. In particular, the manifold pipe may function to slow down the flow to enable it to leave through the apertures. This may be achieved by providing a larger diameter. This can also avoids separating the suspension. Preferably, the diameter of the manifold pipe (internal diameter) is sufficiently large such that the area of the manifold pipe is larger than the sum of the areas of the outlet pipes connected to the manifold pipe. For example, with 20 outlet pipes of 16 mm diameter, this provides a total area of around 0.004 m2. Accordingly, the area of the manifold pipe may be larger than this. For example, the manifold pipe may have a diameter of at least 72 mm. Preferably, the manifold pipe diameter is larger than the minimum diameter, such as at least 5 %, preferably at least 10 %, more preferably at least 25 % larger. For example, the diameter may be around 90 mm. For 20 outlet pipes of 5 mm diameter, the manifold pipe may have a diameter of at least 23 mm. This ensures that the flow is encouraged to pass out of the outlets instead of continuing along the manifold pipe. In some examples, the manifold pipe may have a diameter of at least 20 mm, preferably at least 50 mm, more preferably at least 70 mm, even more preferably at least 90 mm. If more pipes are provided, or the inner diameter of the outlet pipes is increased, then the manifold pipe diameter may be increased. The manifold pipe may be arranged aligned with the width of the array of outlet apertures. The outlets of the manifold can then be arranged along the width of the array. The outlet pipes connected to the outlets of the manifold can then be positioned so that the array of outlet apertures extends along the width. This enables the outlet pipes to be the same length. In other words, the outlet pipes need not extend significantly in the direction of the width of the array, since the manifold outlets are already arranged in an array along the direction of the width. In some examples, the manifold may comprise a plurality of manifold pipes. For example, the manifold may comprise a first manifold pipe and a second manifold pipe. The different manifold pipes may be arranged with their lengths aligned with the width of the array. However, the different manifold pipes may be arranged at different height locations or different locations in the direction of movement (i.e., forwards). The different manifold pipes may be connected to a central manifold which is connected to the pump outlet. In other words, the flow from the pump splits up into two (or more) manifold pipes. Thus, the multiple manifold pipes may be arranged in parallel. Each manifold pipe has a set of outlets and outlet pipes connected. For example, there may be two manifold pipes each with 20 outlet pipes connected (total of 40). In this manner, the outlet pipes may be connected to the manifold without the manifold pipes being as long. This makes the machine more compact, and also avoids a larger pressure drop across the length of the manifold pipe. In this way, the machine provides more uniform flow to the set of outlet pipes. In addition, the manifold pipes can have a smaller diameter since the number of outlets per manifold pipe is smaller. Optionally, each of the outlet pipes is connected to the manifold by a manifold connector. For example, a pipe connecting section may be coupled between the outlet pipe and the manifold outlets. This may be used to provide a seal between the outlet pipe and the manifold outlet. This also may be used if the diameter is changed. Optionally, the manifold connector comprises a first inner diameter at a position connected to the manifold and a second inner diameter at a position connected to the outlet pipe. For example, the manifold may have an outlet of an aperture to which the manifold connector connects. For example, the outlet of the manifold may be the first inner diameter. This may be larger than the inner diameter of the outlet pipe. For example, the inner diameter of the outlet pipe may be relatively small (e.g., around 10-20 mm, such as 16 mm) in order to provide the pressure loss as described herein. However, pumping the suspension directly into an aperture of that size may lead to blockages. Accordingly, it is advantageous for the first inner diameter to be at least 25 mm. This avoids blockages where the suspension exits the manifold to the outlet pipe (in this case into the manifold connector). The first inner diameter is preferably at least 10 % of the diameter of the manifold pipe, more preferably at least 20 %, and even more preferably at least 25 %. The first inner diameter may change based on the diameter of the manifold pipe. The first inner diameter is preferably at least 25 % larger than the inner diameter of the outlet pipe (and the second inner diameter of the manifold connector), preferably at least 50 %. The first inner diameter may change based on the inner diameter of the outlet pipes. In some examples where the inner diameter of the outlet pipes is sufficiently large that the pressure drop from the manifold to the outlet pipes is not particularly large, the first inner diameter may be less large compared to the inner diameter, or may even be the same size. In some examples, the second inner diameter is less than the first inner diameter. In this way, the manifold can reduce the diameter from the manifold aperture to the outlet pipe inner diameter. In some examples, the manifold connector may taper between the second inner diameter and the first inner diameter. In other examples, the manifold connector may comprise a plurality of step changes to the diameter which gradually decrease the diameter over the length of the manifold connector. For example, the manifold connector may change the diameter from the first inner diameter of 25 mm at the manifold to a second inner diameter of 16 mm at the outlet pipe. Optionally, the outlet pipes are connected to the manifold at an upwards angle relative to the surface in use. As used herein, the upwards angle preferable refers to an angle which is oriented generally upwards in use. In particular, the angle is measured around the circumference of the manifold pipe (i.e., the angle is about an axis corresponding to the width of the array). The angle may vary from vertical forward or backwards, relative to movement of the machine along the surface. The angle may be relative to vertically upwards. In otherwords, the outlet pipes are connected to the manifold at an orientation which has an angle pointed away from the surface. In otherwords, the angle may be less than 90° from vertically upwards. This ensures that the suspension flows out of the top section of the manifold pipe. This avoids clogging of the apertures and ensures even flow through each of the outlet pipes, rather than encouraging more flow into apertures which are closer to the inlet of the manifold. It also allows the manifold pipe to substantially fill before flowing out of some outlets. In some examples, the angle is within 45° from vertically upwards. Other angles are possible in other examples. In some examples, the angle is vertically upwards. Optionally, adjacent outlet pipes are arranged in an offset configuration at the connection to the manifold. For example, adjacent outlet pipes connected to the manifold may be in a different orientation. For example, adjacent outlet pipes may not be aligned along the length of the manifold pipe (the width of the array of outlet apertures). For example, one outlet pipe may be connected at an angle of 45° from vertically upwards towards the forwards direction (i.e., direction of forward movement), and the adjacent outlet pipe may be 90° from this, such as 45° from vertically upwards but towards the backwards direction (i.e., opposite to the direction of forward movement). In some examples, adjacent outlet pipes are offset by 90° from each other. Other angles are possible in other examples. In some examples, adjacent outlet pipes are oriented at an angle qual in magnitude but in opposing directions (e.g., forwards and backwards). This allows a higher density of connections to the manifold within a given space. For example, if connections larger than the outlet pipes are required (e.g., 25 mm each), then the space required by the connections would be significantly larger than the space of those outlet pipes adjacent to each other (e.g., 16 mm each). By offsetting adjacent connections, the space between adjacent connections in the direction along the length of the manifold pipe can be reduced. This makes the machine more compact. In addition, this allows the separation between adjacent connectors to be increased to avoid clogging. In other examples, the outlet pipes may not be offset, and may be arranged in a line along the width (for example, oriented vertically upwards). In such cases, the length of the manifold pipe may be larger, or smaller connectors may be used. Optionally, adjacent outlet pipes are arranged with a minimum separation at the connection to the manifold of at least 10 mm. In other words, the distance between the openings at the manifold is at least 10 mm. This avoids clogging due to Sphagnum fragments folding over the bridge between adjacent openings. The separation is the closest dimension between the openings. Since the openings may be offset, this may not be in the direction of the length of the manifold pipe. In some examples, the minimum separation is at least 15 mm, preferably at least 20 mm. Preferably, the minimum separation is larger than an average length of the fragments of Sphagnum in the suspension. For example, if the fragments of Sphagnum have an average length of between 5 mm and 10 mm, then the minimum separation may be at least 10 mm, such as at least 15 mm or at least 20 mm. For example, if at least 50 % of the fragments of Sphagnum have a length of between 5 mm and 10 mm, then the minimum separation may be at least 10 mm, such as at least 15 mm or at least 20 mm. Optionally, the outlet apertures are arranged with a density across the width of between 2 outlet apertures per m and 150 outlet apertures per m. A higher density provides reduced spacing between application points of the suspension to the surface and improves surface coverage. In Sphagnum farming applications, it may be preferable to maximise this to ensure rapid establishment. For example, the density may be between 5 outlet apertures per m and 100 outlet apertures per m, preferably between 10 and 50. In some examples, with an outlet diameter of between 10 mm and 20 mm, there may be between 15 and 40 outlet apertures per m. In one example, with an outlet diameter of around 16 mm, there may be around 25 outlet apertures per m. For a larger diameter or larger flow rate, the density may be reduced in order to provide a constant application rate. In some examples, the agricultural spreading machine further comprises an outlet frame configured to retain the outlet pipes in position. For example, the outlet frame may be supported by the support, such as wheels. The outlet frame may retain the outlet pipes in position relative to the manifold and secure the outlet apertures at a fixed location. Optionally, the outlet apertures are positioned at a height of up to 100 cm from the surface in use. This allows the suspension to be smoothly spread from a maximum height above the surface. The height can be controlled to ensure that it does not fall too far or with too much velocity when it hits the ground. This avoids damaging the Sphagnum. In some examples, the height may be up to 20 cm. In some examples, the outlet apertures are oriented at a downwards angle relative to the surface in use. As used herein, the downwards angle preferable refers to an angle which is oriented generally downwards in use. In particular, the angle is about an axis corresponding to the width of the array. The angle may vary from vertical forward or backwards, relative to movement of the machine along the surface. The angle may be relative to vertically downwards. In other words, the outlet apertures are arranged at an orientation which has an angle pointed towards the surface. In other words, the angle may be less than 90° from vertically downwards. This allows the suspension to flow down to the surface from above. In some examples, the outlet apertures are oriented at an angle of 0° from vertically downwards. In other examples, the angle may be in a direction away from a direction of the movement of the agricultural spreading machine along the surface. For example, the outlet apertures may be oriented at an angle of up to 45° in the direction away from the direction of movement. In other words, the outlet apertures may be oriented vertically downwards or generally downwards and backwards. This improves flow as the machine moves forwards. In some examples, the storage tank has a volume capacity of at least 10 L. For example, the volume may be at least 50 L, such as at least 100 L. At large scale, a tanker may be used. In some examples, the volume may be at least 1000 L, for example up to 25,000 L. With large tanks, instead of the tank being carried by the vehicle, it may be supported on its own wheels. In some examples, the container has an outlet. The pump may be connected to the container via the outlet. In other words, the container outlet may be connected to the pump. Thus, the suspension may pass through the outlet from the container to the pump. The outlet may be arranged towards the bottom of the container to ensure that all of the suspension can pass out of the container. The machine may include a container connector between the container outlet and the pump. For example, the container connector may be a pipe. Thus, a pipe may be arranged between the container outlet and the pump. In some examples, the container has an inlet. The container may be filled via the inlet. The inlet may be arranged towards the top of the container to allow maximum filling without requiring complex seals. For example, the inlet may be a lid to the container. The inlet may be closable to avoid leakage, and for example may be sealed. In other examples, the container may comprise one or more filling inlets as with conventional tankers. In some examples, the pump has an inlet. The pump may be connected to the container via the inlet. Thus, the suspension may pass from the container through the inlet to the pump. In other words, the inlet of the pump may be connected to the container. For example, the inlet of the pump may be connected to the outlet of the container. In some examples, the inlet of the pump may be connected to the container connector. Thus, suspension may pass from the container through the outlet, along the container connector, and through the inlet and into the pump. Disclosed herein is an agricultural spreading machine for spreading a suspension of Sphagnum onto a surface, comprising: a container for storing a suspension of Sphagnum, wherein the suspension of Sphagnum comprises water, a thickening agent, and a plurality of fragments of Sphagnum- a pump connected to the container, wherein the pump is a positive displacement pump; a manifold connected to the pump; a plurality of outlet pipes connected to the manifold, wherein each outlet pipe comprises a length and an inner diameter, and wherein the inner diameter of each of the outlet pipes is at least 5 mm; and a plurality of outlet apertures having an outlet diameter, wherein the outlet apertures are arranged in an array having a width, and wherein the outlet diameter of each of the outlet apertures is at least 5 mm; wherein the pump is configured to move the suspension of Sphagnum from the container through the manifold, along the outlet pipes, and out of the outlet apertures for spreading the suspension of Sphagnum onto the surface; wherein the agricultural spreading machine is configured to move along the surface at a forward speed to allow spreading of the suspension of Sphagnum over the surface. In other words, a pressure loss other than at least 0.1 bar may be provided. Disclosed herein is an agricultural spreading machine for spreading a suspension of Sphagnum onto a surface, comprising: a container for storing a suspension of Sphagnum, wherein the suspension of Sphagnum comprises water, a thickening agent, and a plurality of fragments of Sphagnum-, a pump connected to the container, wherein the pump is a positive displacement pump; a manifold connected to the pump; a plurality of outlet pipes connected to the manifold, wherein each outlet pipe comprises a length and an inner diameter; and a plurality of outlet apertures having an outlet diameter, wherein the outlet apertures are arranged in an array having a width, and wherein the outlet diameter of each of the outlet apertures is at least 5 mm; wherein the pump is configured to move the suspension of Sphagnum from the container through the manifold, along the outlet pipes, and out of the outlet apertures for spreading the suspension of Sphagnum onto the surface; wherein the agricultural spreading machine is configured to move along the surface at a forward speed to allow spreading of the suspension of Sphagnum over the surface. In other words, inner diameters of the outlet pipes other than at least 5 mm may be provided. Disclosed herein is an agricultural spreading machine for spreading a suspension of Sphagnum onto a surface, comprising: a container for storing a suspension of Sphagnum, wherein the suspension of Sphagnum comprises water, a thickening agent, and a plurality of fragments of Sphagnum-, a pump connected to the container, wherein the pump is a positive displacement pump; a manifold connected to the pump; a plurality of outlet pipes connected to the manifold, wherein each outlet pipe comprises a length and an inner diameter; and a plurality of outlet apertures having an outlet diameter, wherein the outlet apertures are arranged in an array having a width; wherein the pump is configured to move the suspension of Sphagnum from the container through the manifold, along the outlet pipes, and out of the outlet apertures for spreading the suspension of Sphagnum onto the surface; wherein the agricultural spreading machine is configured to move along the surface at a forward speed to allow spreading of the suspension of Sphagnum over the surface. In other words, outlet diameters of the outlet apertures other than at least 5 mm may be provided. Disclosed herein is an agricultural spreading machine for spreading a suspension of Sphagnum onto a surface, comprising: a container for storing a suspension of Sphagnum-, the suspension of Sphagnum stored within the container, wherein the suspension of Sphagnum comprises water, a thickening agent, and a plurality of fragments of Sphagnum-, a pump connected to the container, wherein the pump is a positive displacement pump; a manifold connected to the pump; a plurality of outlet pipes connected to the manifold, wherein each outlet pipe comprises a length and an inner diameter, and wherein the inner diameter of each of the outlet pipes is at least 5 mm; and a plurality of outlet apertures having an outlet diameter, wherein the outlet apertures are arranged in an array having a width, and wherein the outlet diameter of each of the outlet apertures is at least 5 mm; wherein the pump is configured to move the suspension of Sphagnum from the container through the manifold, along the outlet pipes, and out of the outlet apertures for spreading the suspension of Sphagnum onto the surface; wherein the agricultural spreading machine is configured to move along the surface at a forward speed to allow spreading of the suspension of Sphagnum over the surface; and wherein the agricultural spreading machine provides a pressure loss due to resistance in the outlet pipes of at least 0.1 bar. In other words, the container may include the suspension provided within the container. According to a second aspect of the present disclosure, there is provided a system, comprising: the agricultural spreading machine as disclosed herein; and a vehicle for propelling the agricultural spreading machine for moving the agricultural spreading machine along the surface. In some examples, the second aspect may comprise the agricultural spreading machine of the first aspect. The vehicle may propel the machine as described herein. For example, the vehicle may be an agricultural vehicle. For example, the vehicle may be a tractor. The vehicle may have an engine for propelling the machine along the surface. For example, the machine may be towed by the vehicle. According to a third aspect of the present disclosure, there is provided a method, comprising: providing a suspension of Sphagnum comprising water, a thickening agent, and a plurality of fragments of Sphagnum, and supplying the suspension of Sphagnum into the container of the agricultural spreading machine as disclosed herein. In some examples, the third aspect may comprise supplying the suspension into the container of the agricultural spreading machine of the first aspect. In some examples, the third aspect may comprise supplying the suspension into the container of the agricultural spreading machine of the system of the second aspect. For example, the method may involve filling the container with suspension. According to a fourth aspect of the present disclosure, there is provided a method, comprising: providing the agricultural spreading machine as disclosed herein; and operating the agricultural spreading machine to spread the suspension of Sphagnum onto the surface. In some examples, the fourth aspect may comprise providing and operating the agricultural spreading machine of the first aspect. In some examples, the fourth aspect may comprise providing and operating the agricultural spreading machine of the system of the second aspect. In some examples, the fourth aspect may comprise providing and operating the agricultural spreading machine into which the suspension is supplied according to the third aspect. For example, operating the machine may comprise carrying out the features described in relation to the first aspect. For example, operating the machine may comprise operating the pump to pump the suspension from the container and out of the outlet apertures. The flow rate of the pump may be controlled. The machine may also be operated to control the forward speed, for example to control a vehicle propelling the machine. The machine can then be operated to spread the suspension over the surface. Aspects of the present disclosure may be provided in conjunction with each other and features of one aspect may be applied to other aspects. Any feature in one aspect of the present disclosure may be applied to other aspects of the present disclosure, in any appropriate combination. It should also be appreciated that particular combinations of the various features described and defined in any aspects of the present disclosure can be implemented and / or supplied and / or used independently. Embodiments related to the machine may be applied to the method, and vice versa. For example, any features described in relation to the machine may be provided as corresponding method steps. Other definitions of terms may appear throughout the specification. Before the exemplary embodiments are described in more detail, it is to be understood that this disclosure is not limited to particular embodiments described, and as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be defined only by the appended claims. Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within this disclosure. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within this disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in this disclosure. Embodiments of the present disclosure are described below, by way of example only, with reference to the accompanying Figures. Figure 1 shows a schematic view of a machine according to a first embodiment. Figure 2 shows a photograph of a perspective view of a machine according to a second embodiment. Figure 3 shows a photograph of a close-up view of a manifold of the machine of the second embodiment. Figure 4 shows a photograph of a perspective view of a system comprising the machine of the second embodiment. Referring to Figure 1, an agricultural spreading machine 100 is shown according to a first embodiment. The agricultural spreading machine 100 is generally referred to as the machine 100. The machine 100 is provided for spreading a suspension of Sphagnum. The machine 100 comprises a container 102. The container 102 is configured to hold a suspension of Sphagnum. The machine 100 also comprises a pump 104. In the first embodiment, the pump 104 is a positive displacement pump. The pump 104 is connected to the container 102. In particular, an inlet of the pump 104 is connected to an outlet of the container 102. Specifically, a container connector is connected between the inlet of the pump 104 and the outlet of the container 102. In the first embodiment, the connector is a short section of pipe. The machine 100 also comprises a manifold 106. The manifold 106 is connected to the pump 104. In particular, an inlet of the manifold 106 is connected to an outlet of the pump 104. Specifically, a pump connector is connected between the inlet of the manifold 106 and the outlet of the pump 104. In the first embodiment, the connector is a short section of pipe. The manifold 106 divides the flow into a plurality of channels. In the first embodiment, the manifold 106 divides the flow into three channels. This is shown for illustrative purposes only, and other numbers of channels are possible. The manifold 106 comprises three outlets along the length of a manifold tube. This allows the suspension to flow from the inlet of the manifold 106 and out of the three outlets. In Figure 1, the inlet of the manifold 106 is partway along the length of the manifold tube, but in other examples (such as the second embodiment), the inlet of the manifold 106 is at one end of the manifold tube. The machine 100 also comprises a plurality of outlet pipes 108. In the first embodiment, the machine 100 comprises three outlet pipes 108. The outlet pipes 108 are connected to the outlets in the manifold 106. The outlet pipes 108 have a length. In the first embodiment, the length is 5 m. Other lengths are possible in other embodiments. The outlet pipes 108 also have an inner diameter. In the first embodiment, the inner diameter is 20 mm. Other diameters are possible in other embodiments. The machine 100 comprises a plurality of outlet apertures 110. In the first embodiment, the machine 100 comprises three outlet apertures 110. In the first embodiment, the outlet apertures 110 are defined by the ends of the outlet pipes 108. In other words, the ends of the outlet pipes 108 define the outlet apertures 110. The length of the outlet pipes 108 is therefore between the end connected to the manifold 106 and the end which defines the outlet aperture 110. In use, the pump 104 is operated to pump the suspension from the container 102 and into the manifold 106. In particular, the suspension is pumped out of the outlets of the manifold 106 and into the outlet pipes 108. The suspension then passes out of the outlet apertures 110. The suspension can then be applied from the outlet apertures 110 onto a surface. In the first embodiment, the surface is the surface of a peatland, and the suspension is applied for the purposes of peatland restoration. In other examples, the suspension may be applied for the purposes of Sphagnum farming. The parameters of the machine 100 may vary in different embodiments. For example, the number of outlet pipes 108 may vary. The inner diameter and the length of the outlet pipes 108 may also vary. The inner diameter and the length may be selected to define a pressure loss resulting from resistance to flow from the outlet pipes. By providing a sufficient pressure loss, the flow out of each outlet pipes 108 can be more uniform. Referring to Figure 2, an agricultural spreading machine 200 is shown according to a second embodiment. The machine 200 may have similar features to the first embodiment of the machine 100. The machine 200 comprises a container 202 storing a suspension of Sphagnum. The machine also comprises a pump 204. In the second embodiment, the pump 204 is a progressive cavity pump. In other embodiments, different kinds of pump may be provided, such as a positive displacement pump other than a progressive cavity pump. The machine 200 also comprises a manifold 206, which will be described in greater detail with reference to Figure 3 below. As can be seen, a section of pipe is used to route the suspension from the container 202 to the inlet of the pump 204, and a section of pipe is used to route the suspension from the outlet of the pump 204 to the manifold 206. The machine 200 also comprises a plurality of outlet pipes 208 and outlet apertures 210. As shown in Figure 2, the outlet pipes 208 are connected to the manifold 206 and are routed over a support pipe 212. Other supports different than a pipe may be used in other embodiments. The support pipe 212 allows the length of the outlet pipes 208 to be supported without folding or kinking the outlet pipes 208. The support pipe 212 has a diameter of 100 mm in the second embodiment, but other diameters are possible. As explained herein, the length of the outlet pipes 208 is selected to introduce an increase in pressure loss in order to provide a more even flow of suspension. As can be seen, the length of the outlet pipes 208 is larger than would be required simply to route the suspension from the manifold 206 to the outlet apertures 210. Instead, the added length serves to deliberately increase the pressure loss. Specifically, it is desired to increase the pressure loss to at least 0.1 bar, preferably at least 0.5 bar. In the second embodiment, the length of the outlet pipes 208 is 2.5 m. In the second embodiment, the inner diameter of the outlet pipes 208 is 16 mm. In other examples, other lengths and inner diameters are possible. Referring to Figure 3, the manifold 206 of Figure 2 is shown in more detail. The manifold 206 comprises a manifold tube 214. The manifold tube 214 has a relatively large diameter compared to the outlet pipes 208. In the second embodiment, the diameter of the manifold tube 214 is 90 mm, but other diameters are possible. The manifold pipe 214 receives the suspension from the pump 204, which flows relatively slowly due to the large diameter of the manifold pipe 214. The suspension is therefore able to exit the manifold pipe 214 through apertures arranged along its length. In particular, the manifold pipe 214 comprises 20 apertures, divided into two rows each having 10 apertures. A manifold connector 216 is connected to each aperture. In turn, an outlet pipe 208 is connected to each manifold connector 216. In the second embodiment, the manifold connector 216 has a diameter of 25 mm at the connection to the outlet, and a diameter of 16 mm at the connection to the outlet pipe 208 (the same as the inner diameter of the outlet pipe 208). This provides a fairly large diameter at the manifold to avoid restricting flow passing into the manifold connector 216, while gently changing diameter to a point where the outlet pipes 208 are connected, thereby avoiding a sudden increase in resistance due to a change in diameter. The outlets are arranged along a top section of the manifold pipe 214 (for example, in the upper half of the diameter). In this manner, the manifold connectors 216 are connected to a top section of the manifold pipe 214. Specifically, each row of the manifold connectors 216 is oriented at approximately 45° from vertical. This ensures that flow through the manifold connectors 216 is even. Rather than encouraging suspension to flow through the first aperture, the apertures are provided at the top section (rather than in the bottom section where gravity would encourage the flow to pass through the first apertures encountered along the length of the manifold pipe 214). This ensures that flow only occurs through the apertures when the manifold pipe 214 is substantially flowing full, thereby providing a consistent flow rate. Adjacent manifold connectors 216 are also oriented approximately 90° from each other. This provides a more compact machine 200 since the length of the manifold pipe 214 may be shortened. In addition, the spacing between adjacent apertures is increased in order to avoid fragments of Sphagnum bridging between adjacent apertures and causing a blockage. As indicated in Figure 3, there is a second manifold pipe without outlet pipes 208 connected, which is currently not in operation. This would allow more outlet pipes 208 to be connected. When used, the second manifold pipe is in parallel to the first manifold pipe 214. In other words, the flow in the manifold 206 splits into the two manifold pipes. This then increases the number of outlets and outlet pipes 208 without increasing the length of the manifold pipe 214. Referring to Figure 4, a system 300 is shown comprising the machine 200 of the second embodiment. The machine 200 is connected to a vehicle 250. In particular, the vehicle 250 is a tractor. The system 300 is shown on the surface of a field, in use. Specifically, the machine 200 is towed by the tractor 250. As shown in Figure 4, the outlet pipes 208 are connected to the manifold 206 as described above in relation to Figure 3. The outlet pipes are gathered, passed over the support pie 212, and attached to a support structure 216. The support structure 216 comprises a frame for the plurality of outlet apertures 210. In particular, a plurality of nozzles is provided which terminate in outlet apertures 210 having an outlet diameter of 16 mm. The outlet apertures 210 are fixed in position by the frame of the support structure 216 so that the spacing between the outlet apertures 210 is the fixed. In the third embodiment, 20 outlet apertures 210 are spaced within a width of 750 mm. This provides a spacing of approximately 27 mm, and a density of around 27 outlet apertures per m width. As shown, when the second manifold pipe is connected, a second set of 20 outlet pipes 208 and outlet apertures 210 may be arranged adjacent to the first set, utilising the full width. This would increase the number to 40 outlet apertures within a width of 1.5 m. In the second embodiment, the support structure 216 also comprises a set of wheels. This enables the position of the outlet apertures 210 to be controlled, and also helps supports the weight of the machine 200. In other examples, other support structures 216 are possible. The tractor 250 moves forward at a forward speed of 1.95 km per hour in the second embodiment, but other speeds, especially faster speeds (e.g., from 1 km per hour to 20 km per hour) are possible. At faster speeds, the flow rate may be increased to provide a similar application rate (in L per m2 area), for example providing an application rate of between 1 L and 5 L per m2. As shown in Figure 4, during operation, the suspension is released from the outlet apertures 210, leaving a trail of suspension 218 on the surface of the field. As can be seen, when the flow is properly controlled, this provides an even column of suspension from each outlet aperture 210. This provides a desired application rate of 3 L per m2. In the second embodiment, the flow rate per outlet pipe 210 is around 2.44 L per minute. The factor of the flow rate multiplied by the length and divided by the inner diameter to the power of four (QL / D4) is approximately 1551. In the second embodiment, the suspension comprises 7.5 g of hydroxyethyl cellulose per L of water, specifically Natrosol™ HHX. This provided a viscosity of around 8000 mPa s at 25 °C. The suspension also comprises approximately 150 g of Sphagnum per L. This was the wet weight calculated by compressing the Sphagnum to a standardised mass per volume by compressing with a force of 16 g / cm2 to remove excess water to ensure a standardised mass. In this arrangement, the machine 200 provided a measured pressure loss of around 1 bar. This provided even flow and application of the suspension onto the surface of the field. This allows the suspension to be applied to the field for rapid establishment and growth. For example, the applied Sphagnum can then be cultivated for Sphagnum farming, for example for harvest and processing into growing media.

Claims

1. An agricultural spreading machine for spreading a suspension of Sphagnum onto a surface, comprising:a container for storing a suspension of Sphagnum, wherein the suspension of Sphagnum comprises water, a thickening agent, and a plurality of fragments of Sphagnum',a pump connected to the container, wherein the pump is a positive displacement pump;a manifold connected to the pump;a plurality of outlet pipes connected to the manifold, wherein each outlet pipe comprises a length and an inner diameter, and wherein the inner diameter of each of the outlet pipes is at least 5 mm; anda plurality of outlet apertures having an outlet diameter, wherein the outlet apertures are arranged in an array having a width, and wherein the outlet diameter of each of the outlet apertures is at least 5 mm;wherein the pump is configured to move the suspension of Sphagnum from the container through the manifold, along the outlet pipes, and out of the outlet apertures for spreading the suspension of Sphagnum onto the surface;wherein the agricultural spreading machine is configured to move along the surface at a forward speed to allow spreading of the suspension of Sphagnum over the surface; andwherein the agricultural spreading machine provides a pressure loss due to resistance in the outlet pipes of at least 0.1 bar.

2. The agricultural spreading machine according to claim 1, wherein one or more of the length of each of the outlet pipes, the inner diameter of each of the outlet pipes, and / or a volumetric flow rate for each of the outlet pipes are selected to provide the pressure loss.

3. The agricultural spreading machine according to claim 1 or 2, wherein the length of each of the outlet pipes is substantially the same.

4. The agricultural spreading machine according to any claim, wherein the inner diameter of each of the outlet pipes is substantially the same.

5. The agricultural spreading machine according to any claim, wherein the outlet diameter of each of the outlet apertures is substantially the same.

6. The agricultural spreading machine according to any preceding claim, wherein the length of each of the outlet pipes is between 0.5 m and 20 m, optionally wherein the length of each of the outlet pipes is between 1 m and 10 m.

7. The agricultural spreading machine according to any preceding claim, wherein the inner diameter of each of the outlet pipes is between 5 mm and 50 mm, optionally wherein the inner diameter of each of the outlet pipes is between 10 mm and 25 mm.

8. The agricultural spreading machine according to any preceding claim, wherein the outlet diameter of each of the outlet apertures is between 5 mm and 50 mm, optionally wherein the outlet diameter of each of the outlet apertures is between 10 mm and 25 mm.

9. The agricultural spreading machine according to any preceding claim, wherein the pressure loss is at least 0.2 bar, optionally wherein the pressure loss is at least 0.5 bar.

10. The agricultural spreading machine according to any preceding claim, wherein the pressure loss is between 0.1 bar and 10 bar, optionally wherein the pressure loss is between 0.2 bar and 5 bar, further optionally wherein the pressure loss is between 0.5 bar and 2 bar.

11. The agricultural spreading machine according to any preceding claim, wherein the agricultural spreading machine is configured to provide an application rate of between 1 L and 5 L of the suspension per m2.

12. The agricultural spreading machine according to any preceding claim, wherein the width of the array of outlet apertures is between 0.5 m and 20 m, optionally wherein the width is between 1 m and 10 m.

13. The agricultural spreading machine according to any preceding claim, wherein the forward speed is between 0.2 m per s and 5 m per s, optionally wherein the forward speed is between 2 m per s and 4 m per s.

14. The agricultural spreading machine according to any preceding claim, wherein a volumetric flow rate for each of the outlet pipes is at least 0.02 L per s, optionally wherein the volumetric flow rate for each of the outlet pipes is at least 0.04 L per s.

15. The agricultural spreading machine according to any preceding claim, wherein the pump is a progressive cavity pump.

16. The agricultural spreading machine according to any preceding claim, wherein the agricultural spreading machine is configured to be connected to a vehicle for moving the agricultural spreading machine along the surface, optionally wherein the agricultural spreading machine comprises a linkage for connecting to the vehicle, further optionally wherein the linkage is a three-point linkage.

17. The agricultural spreading machine according to any preceding claim, wherein each of the outlet pipes is connected to the manifold by a manifold connector, optionally wherein the manifold connector comprises a first inner diameter at a position connected to the manifold and a second inner diameter at a position connected to the outlet pipe, further optionally wherein the first inner diameter is at least 25 mm, still further optionally wherein the second inner diameter is less than the first inner diameter, and even still further optionally wherein the manifold connector tapers between the second inner diameter and the first inner diameter.

18. The agricultural spreading machine according to any preceding claim, wherein the outlet pipes are connected to the manifold at an upwards angle relative to the surface in use, optionally wherein the angle is within 45° from vertically upwards.

19. The agricultural spreading machine according to any preceding claim, wherein adjacent outlet pipes are arranged in an offset configuration at the connection to the manifold.

20. The agricultural spreading machine according to any preceding claim, wherein adjacent outlet pipes are arranged with a minimum separation at the connection to the manifold of at least 10 mm, optionally wherein the minimum separation is at least 20 mm.

21. The agricultural spreading machine according to any preceding claim, wherein the outlet apertures are arranged with a density across the width of between 2 outletapertures per m and 150 outlet apertures per m, optionally wherein the density is between 10 outlet apertures per m and 50 outlet apertures per m.

22. The agricultural spreading machine according to any preceding claim, wherein the outlet apertures are positioned at a height of up to 100 cm from the surface in use, optionally wherein the height is up to 20 cm.

23. A system, comprising:the agricultural spreading machine according to any of claims 1 to 22; and a vehicle for propelling the agricultural spreading machine for moving the agricultural spreading machine along the surface.

24. A method, comprising:providing a suspension of Sphagnum comprising water, a thickening agent, and a plurality of fragments of Sphagnum', andsupplying the suspension of Sphagnum into the container of the agricultural spreading machine according to any of claims 1 to 22.

25. A method, comprising:providing the agricultural spreading machine according to any of claims 1 to 22;andoperating the agricultural spreading machine to spread the suspension of Sphagnum onto the surface.

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