A method for producing soilless growing media and a product thereof

Abstract

The present invention relates to a method for producing soilless growing media and a product thereof for plants More particularly, the present invention relates to a method of producing sugarcane byproduct-based soilless growing media and the product thereof for plants.

Description

[0001] A METHOD FOR PRODUCING SOILLESS GROWING MEDIA AND A PRODUCT THEREOF

[0002] FIELD OF INVENTION

[0003] The present invention relates to a method for producing soilless growing media and a product thereof for growing crops in controlled environment agriculture. More particularly, the present invention relates to a method of producing sugarcane byproduct-based soilless growing media and the product thereof for growing crops in controlled environment agriculture.

[0004] BACKGROUND OF THE INVENTION

[0005] Fertile soil, quality water, and favourable climatic conditions are the primary needs for the growth of plants or crops. Among the three, soil plays a major role by providing nutrients and water besides anchoring the crop. Climate change is negatively impacting soil health, which in turn impacts crop growth, also industrialization coupled with population explosion is playing a key role in reducing the availability of arable land for crop cultivation. In this scenario, soilless agriculture, also known as soilless culture - the science of growing crops by substituting soil with artificial growing medium is globally emerging as an essential and viable alternative for open field agriculture.

[0006] Soil in an unrestricted open field contains organic matter, inorganic matter, mineral nutrients, water, air etc., besides microbes. Soil in a container, even though it has similar constituents, is functionally restrained, and hence crops grown in containers are subjected to stress when compared to crops grown in open fields. Interestingly, scientific studies over the years have confirmed that the usage of 'artificial growing medium' in place of soil would help certain specific crops to perform on par or even better.

[0007] Soilless growing medium is generally a mixture of organic substrates like peat, coir and, inorganic substrates like sand, perlite and vermiculite, along with mineral nutrients and water. In soilless cultivation, nutrients, along with water, are delivered close to the plant roots, facilitating easy availability and quick absorption by the roots. The nutrients remaining unutilized by the crop, along with water, are re-circulated, resulting in effective utilization and hence lesser requirement of water and nutrients. As majority of the crop diseases are soil born,soilless cultivation ensures effective protection of crops from soil-borne diseases. Thus, soilless culture ensures effective water and nutrient management, enables better crop growth, enhances crop yield and improves the quality of agricultural produce. Hence, soilless culture is emerging as a viable alternative for open field agriculture and an effective solution provider in areas where the availability of arable or fertile land for agriculture is very limited.

[0008] An ideal soilless growing medium should have properties like good aeration, sufficient water holding capacity, right drainage, air porosity, and stability. Traditionally commonly used soilless growing media have peat and coir as their major organic substrate constituent.

[0009] Peat soils are the most dominant type of organic soils developed over centuries under wetland conditions by the accumulation of partially decomposed and undecomposed plant residues. A vast expanse of peat soil is called a peatland, from which peat moss is excavated. Peat, even though, is a major component of growing media in soilless culture, its use has been questioned due to the environmental concern that peat per se is a non-renewable resource. Mining peat can significantly degrade natural habitats. The process disrupts ecosystems, alters hydrology, and releases carbon as peatlands act as carbon stores. Hence, European Union (EU) authorities are restricting the use of peat (Appleby, 2018; Barret et al., 2016; Carlie and Waller, 2013). Canada, Scandinavia and Russia are inclined to allow peat harvesting under strict conditions. Professional horticulture businesses are advised to be a part of the Responsibly Produced Peat (RPP) initiative and conduct commercial-scale trials, to identify suitable alternatives for peat, and develop peat-free growing media by 2030.

[0010] Coir, on the other hand, has high levels of sodium nitrate and chlorine, which can be harmful for plants if not flushed out carefully by washing. Washing of coir requires a significant amount of water, where, on average, for every cubic meter of coir pith, 300 to 600 litres of water is being used to flush out the sodium and chlorine contents. The chemical property of coir significantly impacts and reduces the availability of certain micronutrients like iron, copper, calcium and magnesium to plants. Further, coir has less water retention capacity when compared to peat.

[0011] Tamil Nadu in India is the country's top producer of coir and generates more than 70% of the country's coir fibre, from which 30 to 35% of the coir fibre is exported to other countries. As per CPCB (Central Pollution Control Board) Pollution Index, the coir industry has been movedfrom White to Orange in the year 2022. The coir industry has been directed to compulsorily use closed sheds for coir drying to avoid air pollution. They are also advised to use impervious platforms for washing and establish Effluent Treatment Plant (ETP) to ensure 100% water recycling and prevent polluting the water table.

[0012] All the above-stated disadvantages associated with the use of peat and coir-based growing media, are driving the researchers to look for alternatives which are equally efficient as well as cost-effective. Sugarcane bagasse is proving to be one such alternative.

[0013] The present invention provides a method of producing a soilless growing medium from sugarcane byproducts and a product thereof. The present invention provides a soilless growing media from sugarcane bagasse that meets the prescribed specifications, with respect to, porosity, water holding capacity, break-out volume / expansion, stability etc., and is also light in weight, easy to handle, durable, homogenous and reusable.

[0014] SUMMARY OF THE INVENTION

[0015] The present invention provides a method for producing soilless growing media from sugarcane bagasse, the method comprising of steps viz., seasoning of bagasse; drying of seasoned bagasse; grading and sieving of dried bagasse, and making of bales / blocks.

[0016] The seasoning step in the method comprises piling bagasse in pyramid shape having height of 8 feet to 15 feet, spraying a mixture of microbial consortium solution in demineralized water, and mechanical tilting of the piled bagasse at periodic intervals of 5 to 25 days. The microbial consortium used in the seasoning step comprises of bacteria and fungi and is sprayed at the rate of 2 to 20 Liters per metric ton of bagasse. The microbial consortium has CFU count of 108 / ml.

[0017] The microbial consortium comprises of bacteria selected from the group comprising Bacillus velezensis, Brachybacterium paraconglomeratum, Achromobacter xylosoxidans, Stenotrophomonas maltophilia, Brucella melitensis, Bacillus cereus and Pseudomonas florescens.

[0018] The microbial consortium comprises of fungi selected from the group comprising Trichoderma koningiopsis and Aspergillus niger.The seasoning step of the method is followed by the drying step which comprises drying the seasoned bagasse in pneumatic flash drying system at temperature range from 50 to 250 degree C. In the drying step, the seasoned bagasse is dried to moisture content in range from 5% to 25%.

[0019] In the grading step of the method obtained dried bagasse is sieved to obtain fibres of particle size in range from 0.05mm to 6mm, preferably from 0.6mm to 3.5mm. The oversized bagasse are subjected for shredding and is re-sieved while the under sized bagasse are removed as fines.

[0020] In the final step of making blocks or bales, the fibres of desired particle size are compressed with hydraulic machine at the rate of 6:1 with 100 to 300 bar pressure to form compressed block of bagasse based soilless growing media.

[0021] The soilless growing media based on bagasse obtained by method of the present invention have pH value of 6.0 to 8.0, porosity in the range from 10% to 50%, water holding capacity in the range from 40% to 80%, cation exchange capacity in range from 10 to 40 meq / lOOg, electrical conductivity is in range from 0.05 to 1.0 ms / cm, C:N ratio in range from 200:1 to 40:1 and bulk density in range from 55 to 450 kg / m3(drymin to wetmax).

[0022] The soilless growing media based on bagasse of the present invention can be used as an organic substrate for growing plants.

[0023] DETAILED DESCRIPTION OF THE INVENTION

[0024] The following detailed description is presented to enable any person skilled in the art to make and use the invention. For purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that these specific details are not required to practice the invention. The present application is not intended to be limited to the embodiments shown but is to be accorded the widest possible scope consistent with the principles and features disclosed herein.

[0025] It is to be noted that, as used in the specification, the singular forms "a", "an" and "the" include plural referents unless the context dictates otherwise. Thus, for example, reference to acomposition containing "a compound" includes a mixture of two or more compounds. It should also be noted that the term "or" is generally employed in its sense, including "and / or" unless the context clearly dictates otherwise.

[0026] Similarly, the words "comprise", "comprises", and "comprising" are to be interpreted inclusively rather than exclusively. Likewise, the terms "include", "including" and "or" should all be construed to be inclusive, unless such a construction is prohibited from the context. However, the embodiments provided by the present disclosure may lack any element that is not specifically disclosed herein. Thus, a disclosure of an embodiment defined using the term "comprising" is also a disclosure of embodiments "consisting essentially of" and "consisting of" the disclosed components. Where used herein, the term "example", particularly when followed by a listing of terms, is merely exemplary and illustrative, and should not be deemed to be exclusive or comprehensive. Any embodiment disclosed herein can be combined with any other embodiment disclosed herein unless explicitly indicated otherwise.

[0027] The present invention provides a method of producing bagasse-based soilless growing media and a product thereof for growing plants.

[0028] Soil is a mixture of organic matter, minerals, gases and liquids. It serves as a habitat for soil organisms, a recycling system for nutrients and organic wastes, a regulator of water and its quality, a modifier of atmospheric composition, and a medium for plant growth. Soil is the basic natural medium forgrowing plants and is indeed the cheapest source. Loamy and porous soil, rich in organic matter with neutral pH, is good for the growth of plants. Soil is mixed with sand and farmyard manure for better aeration, water-holding capacity and nutrient supply to the plants. However, it is difficult to maintain the nutritive status, pH and water-holding capacity of soil, especially when the crop is grown in contained conditions, as per the requirements of a particular crop for a long duration.

[0029] In recent years, due to the problems of using soil as a growing medium, artificial grow media is used as a base to grow plants under protected conditions and is called as soilless agriculture or soilless culture. Soilless agriculture helps to precisely serve the nutritional requirement of the plant, ensure pathogen-free cultivation, facilitate economical use of water and fertilisers, reduce labour usage for weeding and fertiliser applications, save doses of manure and make crop cultivation possible under problematic soil conditions.The artificial medium that has the properties of soil and can be a substitute for soil for growing crops is called a growing medium. In principle, the soilless grow medium provides plants with physical support, regulates the water flow, serves as a reservoir of nutrients and permits gas exchange to and from the roots.

[0030] In the field of soilless agriculture, both "the poting mix" as a whole, as well as "the substrate" which is a part of the whole, are commonly referred to as the term 'grow media'. Common substrates that are usually used for making of a growing media are peat, coir, sawdust, rice hulls, wood fibre, bark, vermiculite, etc.

[0031] Sugarcane bagasse, the fibrous material remaining after removing the sucrose, water, and other impurities (filter mud) from the millable sugarcane, is the preferred material of choice in the present invention for designing a growing medium as it is easily available in large volumes and is amenable to serve the agricultural purpose.

[0032] Every year, tons of sugarcane byproducts, including bagasse and others, are produced by industries using sugarcane as raw material. The sugarcane stalk consists of two parts, viz., the inner pith containing most of the sucrose and the outer rind with lignocellulosic fibres. During sugar processing, sucrose is extracted by crushing the sugarcane stalk. This procedure produces a good volume of bagasse residue, which contains both crushed rind and pith fibres. The fibre content of bagasse is around 65%, while pith is 30%, and other water-soluble material makes up the balance of 5%. The pith is the internal part of the sugarcane plant with short and variable fibre length, while the fibre has a long fibre length. Sugarcane pith offers several advantages in soilless growing media due to its high porosity, water retention, and nutrient content. It can improve aeration and drainage while providing plants with necessary water and nutrients. Sugarcane fiber improves water retention, aeration, and drainage, while also acting as a slow-release source of nutrients and organic mater. Sugarcane bagasse contains complex lignocellulosic material, which is prominently rich in cellulose, hemicellulose, and lignin. The majority of the bagasse is burned in sugar mills and alcohol distilleries for energy generation. Residual bagasse has great potential for the production of fuels, chemicals, and other value-added products.In the present invention, the soilless growing media, produced using sugarcane bagasse, uses the material as it is without separating the bagasse into pith and fibre and taking it through the steps of seasoning, drying, grading, sieving, and blocking.

[0033] The step of seasoning includes receiving sugarcane bagasse through a belt conveyor system from the sugar factory to the seasoning yard. The conveyor system is provided with a magnetic screener to prevent the inflow of metals along with bagasse to avoid metal contamination. Seasoning of the bagasse is done in the concrete yard provided with a well-designed drainage system.

[0034] In seasoning yard, the received bagasse is heaped / piled up in a pyramid shape to a certain height to avoid water stagnation during the rainy season. The piled bagasse is maintained at a specific moisture percentage. Preferably, the height of the pyramid shape is 8 feet to 15 feet, and the moisture content in the piled bagasse is 50% to 90%. The piled bagasse is seasoned by spraying a solution of microbial consortium in demineralized water. The microbial consortium is added to the piled bagasse to consume sugar and other nutrients from the bagasse to get pure fibre. Microbes are selected based on the cellulose and hemicellulose-degrading nature of bagasse. The microbial consortium comprises both bacteria and fungi. Primarily, the bacteria used in microbial consortium include but are not limited to Bacillus velezensis, Brachybacterium paraconglomeratum, Achromobacter xylosoxidans, Stenotrophomonas maltophilia, Brucella melitensis, Bacillus cereus and Pseudomonas florescens. The fungus used in microbial consortium includes but are not limited to Trichoderma koningiopsis and Aspergillus niger. The CFU count is 108 / ml. Preferably, 2 to 20 liters of microbial consortium is added per metric ton of bagasse. The microbial consortium used in the present invention is commercially sourced.

[0035] The moisture in the piled bagasse is maintained at the required levels to encourage microbial activity. The microbes added to the piled bagasse require oxygen and moisture to survive and to perform the function of converting the organic material of bagasse. The carbon dioxide, which is produced by the microbes because of microbial activity, needs to be removed by a flow of air, and if not, the microorganisms may not survive. Therefore, the step of seasoning involves mechanical tilting of piled bagasse at periodic intervals of 5 to 25 days for aeration and maintenance of the microbial population for speeding up the microbial activity. The seasoning process is carried out in an open yard / condition, i.e., aerobic condition, in the rowmethod to provide air to induce and hasten the growth of the aerobic microbes. The right distance between adjacent rows / heaps is maintained to provide aeration and to drain rainwater during the rainy season.

[0036] In the seasoning step, initially, the temperatures of the piled bagasse are very high due to microbial activity. Physical changes that indicate the completion of the seasoning step are temperature reduction to 20 to 50 degrees C, volumetric reduction and earthy smell. Additionally, the samples from piled bagasse are collected after each tilting and tested for Oxygen Uptake Rate (OUR) as per EN -16087 standard. The OUR rate of 15 and less than 15 millimole per kg of OM (Organic Matter) indicates the end of the seasoning step. The duration of seasoning is approximately 60 to 150 days.

[0037] In the drying step, the seasoned bagasse is pre-dried in open yards and further subjected to mechanical drying using a flash drying system and is sterilized till the seasoned bagasse reaches the ideal moisture levels for making blocks. The pre-dried bagasse may have moisture from a minimum of 40% to a maximum of 80%. The temperature for steam drying is usually 50 to 250 degree C and may vary depending on the physical and chemical properties of the seasoned bagasse. The dried bagasse preferably has a moisture content in the range from 5% to 25%. The drying may be through any suitable dryer known in art. In the present invention, a pneumatic flash drying system is preferred based on the volume of handling, the indirect heating system and reduction in dust emission.

[0038] In the grading / sieving step, the pre-dried bagasse is sieved for the removal of fines and oversized fibres. Oversized fibers are shredded into fibers of different sizes. Fibers above 6mm, preferably above 3.5mm in size are separated and passed through a shredder to reduce the particle size to less than 3.5mm. Fines of less than <0.05mm are removed. Fibres of size ranging from 0.05 to 6mm, preferably from 0.6 to 3.5mm are collected and further compressed. The blocking step comprises compressing the dried bagasse with 5 to 25% moisture through a hydraulic machine to make blocks. Hydraulic compression technology is used to compress the dried bagasse fibres. The compressing takes place at 100 bar to 300 bar pressure to form 5 kg blocks with a size of 30x30x10 cm to 30x30x11 cm. Preferably, the hydraulic compression is at the rate of 6:1 with 100 to 300 bar.The product, seasoned bagasse, is manufactured in a single-line process, and as it is exposed to heat while drying, the product is free from soil-borne diseases or pathogens and contaminants. The product, seasoned bagasse absorbs moisture fast and has good water retention properties.

[0039] The soilless growing media of the present invention has optimum physical and chemical properties to allow quick rooting and propagation and thus allows more seedling rotations per year and more efficient use of greenhouse equipment.

[0040] The compressed seasoned bagasse of the present invention may be used along with nutrients and organic supplements in crop fields in horticulture and floriculture. It may also be used as a rooting and growing medium for certain ornamental flowering plants. Since the product, soilless growing media, is produced under controlled conditions, it is suitable for usage in growing agricultural and horticultural crops in Controlled Environment Agriculture (CEA). The present invention can be understood more clearly and accurately by reading the following examples, which are indicative of preferred embodiments of the invention. They are provided for illustration in greater detail of the present invention, without introducing any limitation and without being limited to those applications.

[0041] Example 1: Method of production of soilless growing media

[0042] Bagasse from the sugarcane factory is received through a belt conveyor system and is transported to the seasoning yard. Any metal impurity in the bagasse is removed through magnets present in the conveyor system. The bagasse, having a moisture content from 50% to 90%, is piled in a pyramid shape of approximately 8 feet to 15 feet. 2 to 20 liters of microbial consortium per metric ton of bagasse is added to the piled bagasse. The piled bagasse is mechanically tilted after every 5-25 days for aeration. A sample is also taken from the piled bagasse and evaluated for Oxygen Uptake Rate (OUR). If the measured OUR is 15 or less than 15 mmol per kg of OM, then the seasoning step is completed. The seasoned bagasse usually has a moisture of around 40 to 80%. The seasoned bagasse is then pre-dried in a pneumatic flash drying system at temperatures of 50 to 250 degree C for approximately 10 to 100 seconds. After drying, the moisture in the dried bagasse is around 5 to 25%. Fibres of size ranging from 0.6 to 3.5 mm are collected and compressed through the hydraulic machine at a6:1 ratio at a pressure of 100 to 300 bar to form 5 kg blocks with a size of 30 cm x 30 cm x 10cm.

[0043] Example 2: Properties of soilless growing media

[0044] The soilless growing media in the form of compressed blocks obtained from Example 1 were tested for quality parameters like physical parameters, particle size distribution, and biological parameters. The soilless growing media obtained by the process of the present invention has pH in range from 6 to 8, porosity is in range from 10% to 50%, water holding capacity is in range from 40% to 80%, cation exchange capacity is in range from 10 to 40 meq / lOOg, electrical conductivity is in range from 0.05 to 1.0 ms / cm and C:N ratio is from 200:1 to 40:1. Bulk density of the soilless growing media product is in range from of 55 to 450 kg / m3(drymin to wetmax) wherein bulk density of dry growing medium ranges from 55 kg / m3to 98 kg / m3and bulk density of wet growing medium ranges from 400 kg / m3to 450 kg / m3.

[0045] The results are provided below in Table 1 in range for different samples.

[0046] Table 1: Properties of bagasse-based soilless growing media

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[0051] Example 3: Presence of heavy metals and nutrients in bagasse-based soilless growing media

[0052] The soilless growing media in form of compressed blocks obtained from Example 1 were tested for presence and number of heavy metals and nutrients. The results are provided in below table 2.

[0053] Table 2: Presence of heavy metals and nutrients

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[0058] *BLQ: Below the level quantification, LOQ: Limit of Quantification

[0059] Table 2 results show that bagasse based growing medium obtained by method of the present invention is free from heavy metal contamination and the nutrient analysis shows that the Primary, Macro and Micronutrient content of the bagasse-based substrate is on par with requirement to meet the quality substrate to use as for all kinds of crop cultivation under controlled conditions.

[0060] Example 4: Test for determining pesticides residue in bagasse based soilless growing media

[0061] The soilless growing media in form of compressed blocks obtained from Example 1 were tested for presence and amount of pesticides, Polynuclear Aromatic Hydrocarbons (PAH), and Polychlorinated Biphenyls (PCBs). The results are provided in below table 3.

[0062] Table 3: Presence of pesticides, Polynuclear Aromatic Hydrocarbons (PAH), and Polychlorinated Biphenyls (PCBs) in bagasse based soilless growing media

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[0072] Table 3 results show that there is no herbicidal and pesticidal residue found in bagasse based growing medium obtained by the method of the present invention and the bagasse media is free from pest and disease produced by pathogens.

[0073] Example 5: Comparative of the Coir pith and bagasse-based soilless growing media of the present invention.

[0074] The soilless growing media in form of compressed blocks obtained from Example 1 is compared with commercially available coir pith growing media for following parameters as shown in Table 4.Table 4: Comparative of properties of coir pith and bagasse based soilless growing media of the present invention

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[0082] The results ofTable4showthat bagasse based soilless growing media obtained by the method of the present invention is on par with buffered coco-pith without any calcium nitrate treatment and washing with water.

[0083] In view of the experimental results, it is established that the present invention provides bagasse based soilless growing media as an eco-friendly alternative to peat, coir pith and other synthetic substrates. It reduces agricultural waste and supports circular economic practices. Bagasse based soilless growing media breaks down naturally over time, contributing to soil health and reducing the need for synthetic fertilizers. Bagasse based soilless growing media can be enriched with compost, biochar, or nutrients to match the needs of specific crops.

[0084] While embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims

We claim:

1. A method for producing soilless growing media from sugarcane bagasse, the method comprising steps of:seasoning of bagasse;drying of seasoned bagasse;grading and sieving step; andblocking step.

2. The method as claimed in claim 1, wherein the seasoning step comprises seasoning the bagasse:by piling bagasse in pyramid shape having height of 8 feet to 15 feet; spraying a microbial consortium solution in demineralized water; and mechanical tilting of piled bagasse at periodic intervals of 5 to 25 days.

3. The method as claimed in claim 2, wherein the microbial consortium comprises of bacteria and fungi.

4. The method as claimed in claim 3, wherein the microbial consortium comprises bacteria selected from the group but not limited to comprising Bacillus velezensis, Brachybacterium paraconglomeratum, Achromobacter xylosoxidans, Stenotrophomonas maltophilia, Brucella melitensis, Bacillus cereus and Pseudomonas florescens.

5. The method as claimed in claim 3, wherein the microbial consortium comprises fungi selected from the group but not limited to comprising Trichoderma koningiopsis and Aspergillus niger.

6. The method as claimed in claims 2 to 5, wherein the microbial consortium has CFU count of 108 / ml.

7. The method as claimed in claims 2 to 6, wherein the microbial consortium is sprayed at rate of 2 to 20 liters of microbial consortium per metric ton of bagasse.

8. The method as claimed in claim 1, wherein the drying step comprises drying the seasoned bagasse in pneumatic flash drying system at temperature range from 50 to 250 degree C.

9. The method as claimed in claim 8, wherein the seasoned bagasse is dried to moisture content in range from 5% to 25%.

10. The method as claimed in claim 1, wherein the grading step comprises sieving of dried bagasse to obtain fibres of particle size in range from 0.05 mm to 6.0mm.

11. The method as claimed in claim 1, wherein the grading step comprises sieving of dried bagasse to obtain fibres of particle size preferably in range from 0.6mm to 3.5mm.

12. The method as claimed in claim 1, wherein the blocking step comprises compressing the graded bagasse with hydraulic machine at the rate of 6:1 with 100 to 300 bar pressure.

13. A soilless growing media obtained by method for producing soilless growing media from sugarcane bagasse as claimed in claims 1 to 12.

14. The soilless growing media as claimed in claim 13, wherein the soilless growing media has pH value in the range from 6.0 to 8.0.

15. The soilless growing media as claimed in claim 13, wherein the soilless growing media has porosity in the range from 10% to 50%.

16. The soilless growing media as claimed in claim 13, wherein the soilless growing media has water holding capacity in the range from 40% to 80%.

17. The soilless growing media as claimed in claim 13, wherein the soilless growing media has cation exchange capacity in the range from 10 to 40 meq / lOOg.

18. The soilless growing media as claimed in claim 13, wherein the soilless growing media has electrical conductivity in the range from 0.05 to 1.0 ms / cm.

19. The soilless growing media as claimed in claim 13, wherein the soilless growing media has C:N ratio in the range from 200:1 to 40:1.

20. The soilless growing media as claimed in claim 13, wherein the soilless growing media bulk density is in the range from 55 to 450 kg / m3(drymin to wetmax).

21. Use of a soilless growing media obtained by the method as claimed in claim 1 to 12 as a growing media for plants.

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