Method for producing a compost-based liquid organic fertiliser

Abstract

The invention relates to a method for producing a compost-based liquid organic fertiliser, the method comprising the following steps: producing a mixture by mixing, in a volume of water-based liquid, at least one first material composed of compost referred to as pure compost; allowing the mixture to infuse while oxygenating it, preferably by stirring; filtering the mixture at least once in order to deliver a filtered solution; and concentrating the solution, characterised in that, in the mixing step, at least one second material composed of solid residues which have been taken from at least one first compost infusion and which have been stored for a given period is added, this second material being referred to as infused compost.

Description

Description Title of the invention: Process for manufacturing a liquid organic fertilizer based on compost

[0001] The invention relates to a method for manufacturing a liquid organic fertilizer based on compost

[0002] The invention will be more particularly described as to a method for manufacturing a liquid organic fertilizer based on elements exclusively of plant and / or mineral origin. The liquid organic fertilizer of the invention is not of chemical origin.

[0003] Given that citizens are expecting to reduce the use of petrochemical products, including mineral nitrogen fertilizers derived from gas, the need to develop new, more environmentally friendly fertilizers is undeniably essential.

[0004] Liquid organic fertilizers currently sold, which are not of chemical origin, are based on proteins and amino acids often derived from beet molasses. However, for these fertilizers to be effective, it is necessary for these amino acids to be degraded into ammonium or nitrate by microorganisms. However, the degradation process is hazardous because it depends on many factors such as the oxygen level of the substrate, the microbial community present, the temperature, the water level in the substrate, etc.

[0005] In recent years, compost tea has also been on the rise. Compost tea is produced by infusing compost and comes in a liquid form. More specifically, it is mature compost mixed with water. The mixture is left to infuse for several hours or even days, preferably by oxygenating it (by stirring or adding air bubbles using an air pump), and then it is filtered to harvest the compost tea. Compost tea is supposed to be rich in nutrients and antioxidants to promote micronutrition, therefore plant growth, and better prevent plant diseases. Indeed, compost tea contains microorganisms that produce amino acids and enzymes that promote the release of nutrients such as nitrogen, phosphorus, potassium, calcium, but also trace elements (magnesium, iron, copper, zinc, etc.).

[0006] However, the nutritional quality varies greatly depending on the compost tea. In addition, compost tea has the disadvantage of not being able to be stored due to the activity of microorganisms and the evolution of their population; after a few days, compost tea loses all its nutritional qualities, which does not allow for large-scale marketing today. Compost today therefore remains purely artisanal and is not manufactured on an industrial scale.

[0007] The invention therefore aims to propose a method for manufacturing a liquid organic fertilizer which uses compost and which does not have the aforementioned drawbacks, in particular which can allow production on a larger scale and provides a fertilizer optimized in terms of its nutritional qualities while managing to retain its qualities over time, in particular to be marketed to professionals and even to individuals despite the length of the distribution chains for the latter.

[0008] Indeed, the process according to the invention makes it possible to obtain a liquid organic compost-based fertilizer that is rich in potassium and nitrogen and includes optimal NPK values. Unlike known compost teas, the process according to the invention does not seek to promote the presence of microorganisms, since they are eliminated by ultrafiltration. The fertilizer according to the invention also has the advantage of being able to be stored at room temperature.

[0009] According to the invention, the method for manufacturing a liquid organic fertilizer based on compost comprises the following steps: a. Step a): making a mixture by mixing in a volume of water-based liquid, a first material composed of so-called pure compost, preferably the pure compost being a mature compost that is at least six months old; b. Step b): letting the mixture infuse by oxygenating it, preferably by stirring; c. Step c): filtering the mixture at least once to deliver a filtered solution (or filtrate) and recovering the retentate, and d.Step d): concentrating the filtered solution, it being possible for steps c) of filtration and d) of concentration to be reversed, the filtered and concentrated solution constituting the liquid organic fertilizer (ready to use or ready to market), the process being characterized in that in step a) of the mixing, at least a second material is added which is composed of a retentate having been reserved (stored) for a given period, called infused compost of at least first generation, the retentate having been prepared in accordance with steps a) to c).

[0010] In the remainder of the description, the term “mixture” means a mixture of pure compost and infused compost, in a liquid volume.

[0011] Thus, the method of the invention is based on the principle of infusing two types of compost, a mature compost ready to use, particularly based on plants (pure compost) and a compost which has been infused and reserved (stored) for some time (infused compost).

[0012] Unexpectedly, the mixture of pure compost and infused compost allows to maintain over time the concentration of the nitric nitrogen (nitrate) level in the final solution of liquid organic fertilizer of the invention and thus to preserve the fertilizing properties of the fertilizer over time (several months after packaging). Unlike usual compost tea which cannot be preserved because it loses all its nitric nitrogen in ten days, the liquid organic fertilizer of the invention can be stored for several months after its manufacture while retaining all its fertilizing properties. Comparative tests have demonstrated the nutritional qualities of the organic fertilizer of the invention and its conservation over time. In addition, the liquid organic fertilizer is produced by processing from materials which are not of petrochemical essence.

[0013] According to a preferred characteristic, filtration step c) is systematically carried out before concentration step d).

[0014] According to one characteristic, the concentrated solution constitutes the liquid organic fertilizer of the invention (ready for marketing). It is preferable to concentrate the solution (the useful volume is reduced) for reasons of convenience in relation to packaging, transport and marketing. The inventors have demonstrated that the solution, even concentrated and then diluted for use, constitutes a liquid organic fertilizer that is efficient in providing nitrate. The concentration step is carried out in particular by vacuum evaporation.

[0015] Preferably, the infusion is made at room temperature (i.e. without heating).

[0016] Advantageously, the infusion is done for at least half an hour, preferably at least an hour.

[0017] According to another feature, the liquid of the mixture is only water, in particular dechlorinated water.

[0018] According to another characteristic, the reservation period of the infused compost is at least six weeks, in particular (of the order) eight weeks, preferably the reservation being carried out with a hygrometry between 30% and 50%.

[0019] According to another characteristic, the filtration is carried out using at least one filter whose cut-off threshold is less than 25 pm, preferably less than 0.5 pm, or even according to a filtration threshold of 0.2 pm. The filtration may comprise several filtration operations via filters of different sizes. Ultrafiltration with a filter having a cut-off threshold of 0.2 pm advantageously allows cold sterilization of the filtrate.

[0020] This step eliminates microorganisms to stabilize the compost, allowing storage at room temperature (therefore there is no nitrogen consumption and no fermentation).

[0021] According to another characteristic, the proportion in % of weight compared to the weight of the liquid of the mixture, of the first pure compost material is between 3 and 15%, preferably between 5 and 10%, and the proportion of infused compost is between 5 and 30%, preferably between 10 and 27%, even more preferably between 15% and 25%.

[0022] According to another characteristic, pure compost is a decomposition exclusively of plants, preferably plants from pruning and mowing such as lawns.

[0023] According to yet another characteristic, in the filtered and concentrated solution, elements of mineral or animal origin can be added to adjust the PK (proportion of phosphorus and potassium).

[0024] According to yet another characteristic, the filtered and concentrated solution is packaged in bottles or cans or in Bag-in-Box.

[0025] The filtration retentate (solid particles collected after filtration) from the mixture of pure compost and infused compost will, after storage for several weeks, form a so-called second-generation infused compost which can be integrated into a new manufacturing mixture.

[0026] According to one characteristic, the method according to the invention comprises the addition before storage of the infused compost of at least one organic or mineral additive chosen from: crushed horn, fish meal, natural potash, and / or calco-magnesium amendment.

[0027] The present invention is now described with the aid of examples which are solely illustrative and in no way limitative of the scope of the invention, and from the attached illustrations, in which: [Fig.l] represents comparative curves over time of the nitrate rate between a usual compost tea called comparative tea and an example of the production of liquid organic fertilizer according to the invention. [Fig.2] illustrates a graph of the biomass of cabbage plants watered with water and the fertilizer of the invention in the form of an infused mixture and having been either filtered and concentrated (Cl), or concentrated without filtration (SI), or concentrated then filtered (Fl). [Fig.3] shows a photo of cabbage plants in relation to the graph in [Fig.2], [Fig.4] illustrates a graph of the biomass of cabbage plants watered with the fertilizer of the invention and in comparison with water and a commercial liquid organic fertilizer. [Fig.5] shows a photo of cabbage plants in relation to the graph in [Fig.4],

[0028] The process of manufacturing a liquid organic fertilizer based on se- compost The invention has the particularity of using in combination as raw materials for the composition, on the one hand, a ready-to-use mature compost, called pure compost, and on the other hand, a solid material extracted from a compost infusion and which has remained stored for a certain period before being used as compost called infused compost.

[0029] The manufacturing method according to the invention of a liquid organic fertilizer based on compost comprises the following steps: a. Step a): making a mixture by mixing in a volume of liquid a first material composed of so-called pure compost and at least one second material (therefore distinct from the first material) composed of solid residues which have been extracted from a compost infusion (retentate of at least a first generation) and which have been reserved for a given period, this second material being called infused compost; b. Step b): letting the mixture infuse by oxygenating it; c. Step c): filtering the mixture at least once to deliver a filtered solution (filtrate); d. Step d): concentrating the filtered solution to obtain a concentrated solution; the concentration step d) can be carried out before the filtration step c); e. Step e): packaging the concentrated solution.

[0030] Pure compost is mature compost obtained from the decomposition of plant residues. Plant residues include, for example (but not limited to), residues from plant prunings such as hedge trimmings, including conifers, and possibly lawn mowing. Mature compost is compost that is at least six months old.

[0031] Infused compost is a compost that corresponds to the solid extraction by filtration (retentate) of at least a first infusion of a mixture of pure compost and water, this solid extraction having been reserved for a period of several weeks, preferably for at least 6 to 8 weeks. The solid particles extracted from the first infusion have been stored for several weeks in an aerobic and not too dry environment; the storage location must have a humidity of at least 30%, preferably at least 40%, preferably between 40% and 50%.

[0032] More specifically, the infused compost from a first infusion (first generation retentate having been reserved for a given period such as 6 to 8 weeks) was obtained in the following manner. A quantity of pure compost (between 5 and 30%, in particular 30% or 10%) was mixed with water (qsp, or in particular 70% or 90%), preferably non-chlorinated, the mixture having in- infused for at least a quarter of an hour, preferably an hour. During the infusion, the mixture has preferably been stirred continuously (in order to oxygenate the mixture) or not. The objective at this stage is to obtain at least 1,200 mg NO3- / 1, preferably at least 2,400 mg NO3- / 1.

[0033] After infusion, the solid particles were separated from the infused liquid; the separation was done by filtration and possibly, prior to filtration of the infused liquid by draining and / or decanting and / or pressing.

[0034] The mixing steps, followed by the filtration and stirring steps, allow the diffusion of water-soluble nutrients and organic elements, and the separation of large solid particles from the water.

[0035] The separation was carried out using at least one filter with a mesh size of at most 25 pm, preferably at most 10 pm. The retentate extracted from the infused mixture was reserved for a period of several weeks, preferably for 8 weeks, to form the infused compost. As for the infused liquid from this first infusion and concentrated, it could have been recovered as usual compost tea. However, this usual compost tea will be used immediately or within a few days because the nitrate level drops very quickly; there is no point in keeping it. As can be seen in the graph in [Fig.l], the usual compost tea ("Comparative Tea") which corresponds to this first infusion which was concentrated (low concentration according to a concentration between 0.2 and 0.3), certainly has a high initial nitrate level of 11,000 mg / L, but drops in 5 days to 7,000 mg / L and drops to zero in ten days.On the contrary, in an exemplary embodiment of the liquid fertilizer of the invention (“Example”) obtained with infused compost from this first infusion, according to a mixture of 80% water, 5% pure compost and 15% infused compost, and whose filtered solution has a concentration between 0.2 and 0.3, it can be seen that the initial nitrate level and the relatively stable average nitrate level is 7,000 mg / L during the first 80 days and beyond, only drops to 6,000 mg / L and is still at 6,000 mg / L at 140 days, which demonstrates the nutrient stability of the liquid organic fertilizer of the invention.

[0036] The steps of the process for manufacturing the liquid fertilizer of the invention are now described in more detail.

[0037] The liquid in which the pure compost and the infused compost are mixed is water, preferably dechlorinated water. Preferably, the proportion in % by weight relative to the weight of the liquid of the mixture, of the first pure compost material is between 3 and 15%, preferably between 5 and 10%, and the proportion of infused compost is between 10 and 27%, preferably between 15% and 25%. In an example of a mixture embodiment, the proportions are as follows: 70% water, 5% pure compost and 25% infused compost.

[0038] During the infusion of the mixture, oxygen is added, preferably by stirring the mixture. The infusion of the mixture lasts at least one hour. Preferably, stirring is carried out throughout the infusion time, so it lasts at least one hour. Stirring can be continuous or not.

[0039] The solution is then filtered and concentrated, or it is concentrated and then filtered. Preferably, the solution is filtered and then concentrated.

[0040] After infusion, the solid particles of the mixture are separated from the liquid infusion. This separation step can be done in several operations, in particular depending on the particle size of the compost and whether or not a basket containing the compost is used and which was initially immersed in water to infuse instead of having introduced the compost in bulk into the water. The separation step is done by filtration from one or more passages in one or more filters of different mesh sizes. Optionally, prior to filtration, draining and / or decantation and / or pressing operations can be implemented. Filtration is carried out from filters whose cut-off threshold is less than 25 pm and can even be less than 0.5 pm, or even 0.2 pm.

[0041] The filtered solution is then concentrated, preferably by evaporation, particularly by vacuum evaporation. Such an operation is known per se. The concentration factor (which corresponds to the ratio of the filtered solution to the concentrated solution) is, for example, 10. The concentration factor can be a maximum of 20. The concentration factor will be chosen based in particular on the use over time, the type of plants that will receive the fertilizer, and the target nitrogen concentration, allowing this nitrogen concentration to be obtained.

[0042] It may be considered to add elements of mineral origin to the concentrated solution, in particular depending on the intended application for the fertilizer.

[0043] The filtered and concentrated solution obtained constitutes the liquid organic fertilizer of the invention and is ready to use.

[0044] The filtered and concentrated solution is packaged in bottles or cans. Preferably, the packaging will correspond to a volume of at most 5 L, and can be from 1 L to 3 L. The packaging can also be of the Bag-in-Box type, which would be new on the liquid fertilizer market.

[0045] The quantity of nitrate in the liquid organic fertilizer of the invention may vary depending in particular on the type of plants producing the pure compost, the duration of reservation of the infused compost, the duration of infusion and the manner of extracting the filtrate (draining, decantation, size of the filter). The quantity of nitrate in the liquid organic fertilizer of the invention (concentrated solution to corn- mercalisiser) is notably in the order of 48,000 to 96,000 mg / L. The NPK (proportions of nitrogen, phosphorus and potassium) is notably 1 - 0.1 - 2 without the addition of P or K. Elements of mineral origin can be added to adjust the PK, such as the addition of magnesium (Mg), calcium (Ca) and iron (Fe), and achieve for example an NPK of 1 - 0.1 - 3.

[0046] Comparative tests were carried out relating to the production of cabbage plants after sowing the same seeds in identical soil trays and watering them at the same times, during the same period, with the same quantity of liquid and with four different solutions: a solution based solely on water and three comparative solutions derived from the same infused solution of the invention and concentrated in the same way, the differences between the solutions are with regard to filtration. For the infused solution, it was obtained as in the example given above from a mixture of 70% water, 5% pure compost and 25% infused compost, the mixture having infused and having been stirred for 1 hour. Then, three comparative solutions were carried out: a. the SI solution: the infused solution was not filtered and it was concentrated with a nitrate level of 10,000 mg / L; b.solution Fl: the infused solution was concentrated to a nitrate level of 10,000 mg / L, then it was filtered with a first pass through a 10 pm filter and then a second pass through a 0.5 pm filter (therefore a filtration step after concentration); c. solution Cl: the infused solution was filtered with a first pass through a 10 pm filter and then a second pass through a 0.5 pm filter, then it was concentrated to a nitrate level of 10,000 mg / L (therefore a filtration step before concentration).

[0047] [Fig. 2] illustrates a graph of the biomass of cabbage plants (average weight in g) after the watering period with each of the four solutions mentioned above. [Fig. 3] shows the photos of the cabbage plants watered with each of the solutions. It is clearly seen that a nutrient supply is effective, the tank watered with only water being much less supplied (by half or even more) with cabbage plants than the tank watered with the infused and concentrated solution of the invention, whether it was filtered (Fl and Cl) or unfiltered (SI). The fertilizer with the concentrated and unfiltered SI solution generates a greater biomass than that corresponding to the concentrated and filtered Fl solution after concentration or the concentrated and filtered Cl solution before Cl concentration, but it was actually observed that the plants degrade over time due to microorganisms remaining in the solution that was not filtered.It is therefore essential to filter the infused solution of the invention. As for the filtration step, figures 2 and 3 show that it is preferable to filter before concentration (solution Cl), the biomass being greater for the solution Cl than for the solution Fl whose filtration is carried out after concentration (gain of the order of a little more than 15% in biomass between Cl and Fl). Consequently, the liquid organic fertilizer of the invention according to its concentrated solution is particularly effective and it will be preferred to implement the filtration step before the concentration step.

[0048] Finally, other comparative tests were carried out on the growth of cabbage plants by watering with the same quantity of liquid, at the same times and during the same period and according to three different solutions: water, a commercial organic fertilizer Ec having a nitrate level of 10,000 mg / L and an NPK of 3-2-5 and presenting after dilution a nitrate level of 300 mg / L, as well as the organic fertilizer of the invention by its concentrated solution Cl (infused solution of the invention and filtered then concentrated) having a nitrate level of 10,000 mg / L and an NPK of 1-0, 1-2 and presenting after dilution according to a solution C2 with a nitrate level of 300 mg / L. The solutions C2 and Ec have the same nitrate level of 300 mg / L. [Fig.4] illustrates a graph of the biomass of cabbage plants after a given period according to watering with each of the above-mentioned solutions: water, Ec and C2.Although the commercial organic fertilizer Ec clearly acts as a fertilizer compared to a water supply only, the organic fertilizer C2 of the invention is even more effective (a weight increase of 33% compared to the commercial fertilizer). [Fig. 5] shows the photos of the corresponding cabbage plants watered with each of the solutions. It is also clearly visible in this photo that the growth of the plants is much greater with the C2 solution of the invention than with the solution of the comparative commercial organic fertilizer Ec: the plants are taller and the leaves are more developed.

[0049] Therefore, the liquid organic fertilizer of the invention (filtered and concentrated solution), which is of organic origin and does not involve petrochemicals, has very high-performance nutritional qualities and retains its nutritional properties over time after being packaged and even after several months of storage.

Claims

Claims

1. A method of manufacturing a liquid organic fertilizer based on compost comprising the following steps: a. Step a): making a mixture by mixing in a volume of water-based liquid, a first material composed of so-called pure compost, preferably the pure compost being a mature compost which is at least six months old; b. Step b): letting the mixture infuse by oxygenating it, preferably by stirring; c. Step c): filtering the mixture at least once to deliver a filtered solution and recover the retentate, and d.Step d): concentrating the filtered solution, it being possible for steps c) of filtration and d) of concentration to be reversed, the filtered and concentrated solution constituting the liquid organic fertilizer, characterized in that in step a) of the mixing, at least one second material is added which is composed of a retentate having been reserved for a given period, called infused compost of at least the first generation, the retentate having been produced in accordance with steps a) to c), and in that the proportion in % of weight relative to the weight of the liquid of the mixture, of the first pure compost material is between 3 and 15%, and the proportion of infused compost is between 5 and 30%.

2. Manufacturing method according to claim 1, characterized in that the filtration step c) is systematically carried out before the concentration step d).

3. Manufacturing method according to claim 1 or 2, characterized in that the infusion is carried out at room temperature.

4. Manufacturing method according to any one of the preceding claims, characterized in that the infusion takes place for at least one hour.

5. Manufacturing method according to any one of the preceding claims, characterized in that the liquid of the mixture is only water, in particular dechlorinated water.

6. Manufacturing method according to any one of the preceding claims, characterized in that the reservation period of the infused compost is at least six weeks, in particular eight weeks, preferably the reservation being made in a place with humidity between 30% and 50%.

7. Manufacturing method according to any one of the preceding claims, characterized in that the filtration is carried out using at least one filter whose cut-off threshold is less than 25 pm, preferably less than 0.5 pm, or even according to a filtration threshold of 0.2 pm.

8. Manufacturing method according to any one of the preceding claims, characterized in that the proportion in % of weight relative to the weight of the liquid of the mixture, of the first pure compost material is between 3 and 15%, preferably between 5 and 10%, and the proportion of infused compost is between 10 and 27%, preferably between 15% and 25%.

9. Manufacturing method according to any one of the preceding claims, characterized in that the pure compost is a decomposition exclusively of plants, preferably plants resulting from pruning and mowing such as lawns.

10. Manufacturing process according to any one of the preceding claims, characterized in that elements of mineral origin are added to the filtered and concentrated solution to adjust the PK.

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