Soilless media for plant growth

Abstract

A medium for plant growth is provided. The medium can be prepared by combining at least one polysaccharide with at least one clay mineral and water to form a mixture and heating it to expand and dehydrate the mixture. The medium can be an insoluble composite soilless porous foam material. The medium can be in the form of pads, blocks, cylinders, aggregates or spheres. When the medium is in the form of aggregates or spheres placed into a container, additional porosity can be provided needed for effective plant growth.

Description

Our Ref: 14017-0130W01SOILLESS MEDIA FOR PLANT GROWTHCROSS REFERENCE

[0001] This application claims priority to U.S. provisional application number 63 / 701,917, filed October 1, 2024, which is incorporated by reference herein in its entirety.STATEMENT OF FEDERALLY SPONSORED RESEARCH

[0002] This invention was made with government support under Grant no. NI24HFPXXXXXG033, awarded by The United States Department of Agriculture / NIFA. The government has certain rights in the invention.TECHNICAL FIELD

[0003] The present disclosure relates to an insoluble composite soilless porous foam material for plant growth.BACKGROUND

[0004] The total land area used for farming has continued to decrease due to urbanization and soil degradation. Soil degradation occurs due to reduced organic matter, unfavorable changes in soil pH, increased salinity or alkalinity, exposure to harmful chemicals, decreased fertility, poor soil structure, erosion, pollution, excessive flooding and climate change. Soil degradation has been accelerated by various practices, such as intensive farming, deforestation, overgrazing, excessive cultivation, and the excessive use of chemical fertilizers. This is occurring as the growing population increases the demand for quail ly food.

[0005] Because of these issues, soilless production systems and urban farming that employ alternative soilless growing media are emerging as a promising solution to produce many horticultural crops in urban areas. By utilizing urban spaces efficiently for agriculture, urban farming employing soilless production systems can help address the decline in farmland while meeting the increasing food demand.

[0006] Soil is a commonly used growing medium for urban farming and presents many advantages and disadvantages. On the positive side, soil offers a natural, potentially nutrient-rich foundation for plant growth, fostering the development of a diverse ecosystem of beneficial microorganisms. However, concerns arise when dealing w ith the quality of the soil, which may be contaminated with heavy metals and other pollutants or may have poor health due to compaction and low organic matter content, posing risks to both plant and human health.Our Ref: 14017-0130W01Additionally, soil demands regular maintenance, including weeding and fertilization, and may not offer the precision of control over nutrients and water retention provided by soilless growing media. Given the increasing issue of soil degradation, the adoption of soilless growing systems is increasing and there is a pressing demand for alternative growing media capable of emulating or improving upon soil’s productivity, yield, and efficiency while also being cost effective and readily available in large quantities.

[0007] A diverse array of soilless growing media is available of organic and synthetic origin, including options like peat, coco coir, perlite, vermiculite, rock wool, foam-based materials, and more. Peat and peat-based growing media are the most common soil replacement due to their favorable physicochemical properties, and wide availability. Peat has great water-retaining properties, and good agronomic properties, but its harvest has a negative impact on the environment. Peatland plays a crucial role as the main reservoir for carbon dioxide. The extraction process of peat from these ecosystems leads to their degradation or destruction, resulting in a substantial loss of biodiversity and the release of carbon into the atmosphere. This disturbance significantly disrupts the delicate balance of the global carbon cycle which can contribute to climate change. While there are efforts to restore peatland after peat harvest, the restoration process is quite slow and may take centuries. For this reason, peat is not considered a renewable resource and some countries are limiting its harvest, driving the price high.

[0008] Due to these environmental concerns, and the increasing cost of peat, there is a great need to find more sustainable alternatives to the use of peat as a growing medium. Besides peat there are several other growing mediums available on the market, including synthetic substrates such as rock wool and polyurethane foam, or inorganic products of natural origin such as vermiculite, perlite, pumice and expanded clay aggregates. While these mediums have proven to be effective for crop cultivation, they often come with either a significant cost burden or pose environmental concerns when it comes to disposal at the end of their use.

[0009] An alternative to peat and to synthetic materials is represented by natural fiber products. Among those, the most popular is coconut coir which is a natural fiber extracted from the outer husk of a coconut. Most coir products need to be treated to be wettable. When treated, coir exhibits excellent moisture retention properties. It is also resistant to overwatering, as any excess w ater can easily drain out of it. However, the coconut tree often grows along coastal areas, and coconut coir is often composted along the coast and is contaminated with sea water, and consequently the composted coconut coir often may have a high concentration of saltsOur Ref: 14017-0130W01 which can limit plant growth unless the excess of salt is washed out. Coconut coir is mostly imported and is transported for long distances. Additionally, both peat and coconut coir are small particles making them just as messy as soil when handling. Because of the messiness of handling these small particles, people are increasingly turning to alternatives such as fabric to grow plants.

[0010] Other natural fiber products include burlap, hemp and kenaf fiber which are used for specific crops like microgreens. Burlap, for example, is one of the cheapest growing media. It is a breathable fabric that allows air to circulate freely. However, it does not absorb water as well as other materials and can be one of the most difficult media to use. Another eco-friendly fabric is the hemp mat. Compared to burlap, hemp mat has a higher water retention capacity, making it an ideal growing medium for some applications. However, one potential drawback of hemp mat is that it can be prone to ripping when wet. Other renewable products used as growing media include pine-bark, sawdust, and rice hulls, but these products are suitable only for specific applications and have several limitations in terms of agronomic performance. In short, none of the growing media currently available has ideal properties, and there is a need for sustainable, truly renewable, biodegradable, user-friendly, water-retentive, and cost-effective growing media to meet the demands of consumers and the horticultural industry.SUMMARY

[0011] Provided herein is a medium for plant growth. In some embodiments, the medium is an insoluble hydrophilic porous composite material comprising at least one polysaccharide and at least one clay mineral. Alternatively, the medium comprises at least one polysaccharide, at least one protein, and at least one clay mineral.

[0012] In some embodiments, the polysaccharide, clay mineral and optional protein is mixed with water and exposed to temperatures above 100 degrees Celsius and expanded to form a foam and dehydrated. The medium can be in the form of sheets, blocks, cylinders, aggregates, particles or spheres.

[0013] In one aspect, provided herein is a medium for plant growth comprising at least one polysaccharide and at least one clay mineral, wherein the medium is an insoluble solid foam.

[0014] In one aspect, provided herein is a medium for plant growth comprising at least one polysaccharide and at least one clay mineral, wherein the medium comprises two or more solid foam particles.Our Ref: 14017-0130W01

[0015] In one aspect, provided herein is a medium for plant growth comprising at least one polysaccharide and at least one clay mineral, wherein the medium is prepared by combining the at least one polysaccharide and the at least one clay mineral with water to form a mixture, heating the mixture to a temperature greater than 100 degrees Celsius, and dehydrating the mixture to form a foam.

[0016] In one aspect, provided herein is a medium for plant growth comprising at least one anionic polysaccharide and at least one clay mineral, wherein the medium is prepared by combining the at least one anionic polysaccharide and the at least one clay mineral with water to form a mixture, heating the mixture to a temperature greater than 100 degrees Celsius, and dehydrating the mixture to form a foam.

[0017] In one aspect, provided herein is a medium for plant growth comprising at least one cationic polysaccharide and at least one clay mineral, wherein the medium is prepared by combining the at least one cationic polysaccharide and the at least one clay mineral with water, to form a mixture, heating the mixture to a temperature greater than 100 degrees Celsius, and dehydrating the mixture to form a foam.

[0018] In one aspect, provided herein is a medium for plant growth comprising at least one polysaccharide, at least one protein, and at least one clay mineral, wherein the medium is prepared by combining the at least one polysaccharide, the at least one protein and the at least one clay mineral with waler to form a mixture, heating the mixture to a temperature greater than 100 degrees Celsius, and dehydrating the mixture to form a foam.

[0019] In one aspect, provided herein is a medium for plant growth comprising at least one anionic polysaccharide, at least one protein, and at least one clay mineral, wherein the medium is prepared by combining the at least one anionic polysaccharide, the at least one protein and the at least one clay mineral with water to form a mixture, heating the mixture to a temperature greater than 100 degrees Celsius, and dehydrating the mixture to form a foam.

[0020] In one aspect, provided herein is a medium for plant growth comprising at least one cationic polysaccharide, at least one protein, and at least one clay mineral, wherein the medium is prepared by combining the at least one polysaccharide, the at least one protein and the at least one clay mineral with w ater to form a mixture, heating the mixture to a temperature greater than 100 degrees Celsius, and dehydrating the mixture to form a foam.Our Ref: 14017-0130W01

[0021] In some embodiments, the medium has porosity ranging from < 0.5 pm to about 500 pm. In some embodiments, the medium is in the form of packed particles or spheres, and the packed material has an additional porosity of < 0.5 pm to 2000 pm or more.

[0022] The media disclosed herein can be used as a soilless medium for plant growth.

[0023] In another aspect, provided herein is a process for forming a medium for plant growth. In one aspect, the process includes combining at least one polysaccharide and at least one clay mineral with water to form a mixture; shaping the mixture into a form; placing the mixture into a mold that exhibits water vapor permeability; heating the mixture to a temperature greater than 100 degrees Celsius; and dehydrating the mixture to form a foam.

[0024] In one aspect, the process includes: combining at least one polysaccharide, at least one clay mineral and at least one protein with water to form a mixture; shaping the mixture into a form; placing the mixture into a mold that exhibits water vapor permeability ; heating the mixture to a temperature greater than 100 degrees Celsius; and dehydrating the mixture to form a foam.

[0025] In another aspect, provided herein is a device that comprises a medium described herein. In some embodiments, the medium is formed into, or becomes a part of, a device like a hollow sphere that can hold a seed. That device can include a feature like one or more projections or a screw that would hold the device in the other media such as soil to prevent animals like squirrels from removing the shape or seed.BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1A shows a cross section of an example spherical seed enclosure device 100 in two half pieces before closing.

[0027] Figure IB shows a cross section of an example spherical seed enclosure device 100 after closing with a seed inside.

[0028] Figure 2A shows a cross section of an example spherical seed enclosure device 200 in two pieces before closing.

[0029] Figure 2B shows a cross section of an example spherical seed enclosure device 200 after closing with a seed inside.Our Ref: 14017-0130W01

[0030] Figure 2C shows a cross section of an example spherical seed enclosure device 200 including two protrusions after closing with a seed inside.

[0031] Figure 2D shows a cross section of an example spherical seed enclosure device 200 including a screw feature after closing with a seed inside.

[0032] Figure 3 depicts images of spherical foam media of Example 1 after soaking in water and buffer for 12 days, demonstrating insolubility.

[0033] Figure 4 depicts a boxplot showing broccoli shoot and root lengths grown in different media (including example media disclosed herein and different comparative media) after 7 days. Lettering indicates the statistical differences.

[0034] Figure 5 A depicts images of broccoli grow th after 7 days in (a) peat, (b) nutrient enriched peat, (c) clay, and (d)-(f) various sized spheres of example media disclosed herein.

[0035] Figure 5B depicts an image of broccoli growth in an example medium disclosed herein (size 2 potato starch-montmorillonite spheres) removed from the container.

[0036] Figure 6A depicts an image of the pore structure of an example starch foam medium prepared from a mixture including 39.5% water.

[0037] Figure 6B depicts an image of the pore structure of an example starch foam medium prepared from a mixture including 44.9% water.DETAILED DESCRIPTION

[0038] Optimal soils exhibit many properties needed for the productive growth of healthy plants including the structure to support root growth, the ability to store and provide nutrients including the cations ammonium, potassium, magnesium and calcium, and the porosity to retain and deliver water as well as to enable gas exchange for root respiration. Ideal soils have a good balance of air filled porosity’ (approximately 10 % to 20 %) and available w ater accessible by the plant (10 % the 30 %). Available water is the difference between the water content at the field capacity and the water content at the wilting point. To achieve this balance, ideal soils have porosity. In general, there are three types of pores in soil including storage pores, transmission pores, and feeding pores. The storage pores in the soil range from about < 0.5 to 50 pm, while the transmission pores range from about 50 to 500 pm. The pores ranging from about 100 to 200 pm are used by feeding roots to grow into. The growth of roots is better when there is a greaterOur Ref: 14017-0130W01 proportion of transmission pores in the soil. These pores are the most important for good soil structure and for water movement in soil, which is positively correlated with root growth.

[0039] Provided herein is an engineered medium to replace soil. In some embodiments, the medium has one or more of the following attributes: (1) the mechanical properties needed to support plant grow th: (2) hydrophilic and wettable; (3) a pore size distribution including storage pores whose diameters are about < 0.5 to 50 pm, transmission pores whose diameters are about 50 to > 500 pm and feeding pores whose diameters are about 100 to 200 pm or more; (4) An air filled porosity of about 10 % to 20 %; (5) an available water content accessible to the plant of about 10 % to over 30 %; (6) cation exchange capacity allowing the important nutrient cations ammonium, potassium, magnesium and calcium to be stored in the medium, in addition to other nutrients; (7) insolubility and stability during the plant growth cycle; (8) compostable when disposed; (9) good for soils or environment when disposed; (10) low cost; (11) able to be manufactured in high volumes.

[0040] Provided herein is a medium for plant growth including at least one polysaccharide and at least one clay mineral. In some embodiments, the polysaccharide is a cationic polysaccharide. In some embodiments, the polysaccharide is an anionic polysaccharide. In some embodiments, the medium further comprises at least one protein. In some embodiments, the medium is a solid foam. In some embodiments, the medium is an insoluble solid foam.

[0041] In some embodiments, the medium comprises two or more solid foam particles. In some embodiments, the medium comprises two or more insoluble solid foam particles. In some embodiments, the medium comprises two or more solid foam particles that comprise the at least one polysaccharide and the at least one clay mineral. In some embodiments, the medium comprises two or more solid foam particles that comprise the at least one polysaccharide, at least one clay mineral, and at least one protein.

[0042] In some embodiments, provided herein is an insoluble solid foam medium for plant growth comprising at least one polysaccharide and at least one clay mineral. In some embodiments, provided herein is an insoluble solid foam medium for plant growth comprising at least one polysaccharide, at least one protein and at least one clay mineral. In some embodiments, provided herein is a medium for plant growth comprised of tw o or more insoluble solid foam particles comprising at least one polysacchande, at least one protein and at least one clay mineral. In some embodiments, provided herein is a medium for plant growth comprised ofOur Ref: 14017-0130W01 two or more insoluble solid foam particles comprising at least one polysaccharide and at least one clay mineral.

[0043] In some embodiments, the medium disclosed herein is produced by creating a composite material. In some embodiments, the medium comprises a starch, a clay mineral, and a thickening polysaccharide that acts as a rheology modifier. In some embodiments, the thickening polysaccharide is xanthan gum. In some embodiments the medium comprises about 69-89 wt.% starch, about 10-30 wt.% clay mineral, and about 0. 1-5 wt.% thickening polysaccharide. In some embodiments the medium comprises about 79 wt.% starch, about 20 wt.% clay mineral, and about 1 wt.% thickening polysaccharide.

[0044] In some embodiments, the medium comprises at least one anionic polysaccharide and at least one clay mineral. In some embodiments, the medium comprises at least one anionic polysaccharide, at least one protein, and at least one clay mineral.

[0045] In some embodiments, the at least one anionic polysaccharide comprises an anionic starch. In some embodiments, the medium comprises an anionic starch and a thickening polysaccharide. In some embodiments, the medium comprises an anionic starch and xanthan gum. In some embodiments, the medium comprises an anionic starch, an anionic xanthan gum, and montmorillonite. In some embodiments, the medium comprises an anionic starch, an anionic xanthan gum, gelatin, and montmorillonite.

[0046] In some embodiments, the anionic starch is potato starch. In some embodiments, the medium comprises potato starch, xanthan gum, and montmorillonite. In some embodiments, the medium comprises potato starch (PS), xanthan gum (XG), and montmorillonite (M) at ratios of PS:XG:M where PS ranges from 30 to 50, XG ranges from 0.2 to 5, and M ranges from 2 to 20. In some embodiments, the medium comprises potato starch (PS), xanthan gum (XG), gelatin (G) and montmorillonite (M) at ratios of PS:XG:G:M where PS ranges from 30 to 50, XG ranges from 0 to 5, G ranges from 0 to 15 and M ranges from 2-30.

[0047] In some embodiments, the anionic starch is ungelatinized potato starch. In some embodiments, the medium comprises ungelatinized potato starch, xanthan gum, and montmorillonite. In some embodiments, the medium is prepared from a mixture comprising ungelatinized potato starch, xanthan gum, montmorillonite and water at a ratio of (30-50): (0.2- 5):(2-20):(20-80), respectively. In some embodiments, the medium is prepared from a mixture comprising ungelatinized potato starch, xanthan gum, montmorillonite and w ater at a ratio ofOur Ref: 14017-0130W0140:1:8:32-40, respectively. In some embodiments, the medium is prepared from a mixture comprising ungelatinized potato starch, xanthan gum, montmorillonite and water at a ratio of 40:1:8:36, respectively. In some embodiments, the medium is prepared from a mixture comprising ungelatinized potato starch, xanthan gum, montmorillonite and water at a ratio of 40:1 : 8:32, respectively. In some embodiments, the medium is prepared from a mixture comprising ungelatinized potato starch, xanthan gum, montmorillonite and water at a ratio of 40: 1:8:40, respectively.

[0048] In some embodiments, the medium comprises at least one cationic polysaccharide and at least one clay mineral. In some embodiments, the medium comprises at least one cationic polysaccharide, at least one protein and at least one clay mineral.

[0049] In some embodiments, the at least one cationic polysaccharide comprises a cationic starch. In some embodiments, the medium comprises a cationic starch and montmorillonite. In some embodiments, the medium comprises a cationic starch, gelatin, and montmorillonite. In some embodiments, the material comprises a cationic starch (CS) and montmorillonite (M) at ratios of CS:M where CS ranges from 30 to 50 and M ranges from 2 to 20. In some embodiments, the medium comprises a cationic starch (CS), gelatin (G) and montmorillonite (M) at ratios of CS:G:M where PS ranges from 30 to 50, G ranges from 0.2 to 15 and M ranges from 2 to 30.

[0050] In some embodiments, the medium is prepared by combining the at least one polysaccharide, at last one clay mineral, and optional protein with water to form a mixture; heating the mixture; and dehydrating the mixture to form a foam. In some embodiments, the mixture is heated to a temperature greater than 100 degrees Celsius. For example, the mixture is heated to a temperature in the range of greater than 100 degrees Celsius to about 200 degrees Celsius. In some embodiments, heating the mixture also dehydrates the mixture to form the foam. In some embodiments, heating the mixture and dehydrating the mixture are carried out by microwave heating. In some embodiments, the medium is prepared by heating the mixture in a micro wave at 1000W to 1400 W of power. In some embodiments, the medium is prepared by heating the mixture in a microwave at 1000W to 1400 W of power for 60 to 90 seconds. In some embodiments, the medium is prepared by heating the mixture in a micro wave at 1000W to 1400 W of power for 70 to 80 seconds.

[0051] In some embodiments, the medium is prepared by combining at least one anionic polysaccharide and at least one clay mineral with water to form a mixture, heating the mixture toOur Ref: 14017-0130W01 a temperature greater than 100 degrees Celsius (e.g., greater than 100 degrees Celsius to about 200 degrees Celsius), and dehydrating the mixture to form a foam. In some embodiments, the medium is prepared by combining at least one cationic polysaccharide and at least one clay mineral with water to form a mixture, heating the mixture to a temperature greater than 100 degrees Celsius, and dehydrating the mixture to form a foam.

[0052] In some embodiments, the medium is prepared by combining at least one anionic polysaccharide, at least one protein and at least one clay mineral with water to form a mixture, heating the mixture to a temperature greater than 100 degrees Celsius, and dehydrating the mixture to form a foam. In some embodiments, the medium is prepared by combining the at least one polysaccharide, the at least one protein and the at least one clay mineral with water to form a mixture, heating the mixture to a temperature greater than 100 degrees Celsius, and dehydrating the mixture to form a foam.

[0053] In some embodiments, the medium is formed by combining ungelatinized potato starch, xanthan gum, montmorillonite and water at a ratio of (30-50):(0.2-5):(2-20):(20-80), respectively; and heating in a micro wave at 1000W to 1400W of power for 60 to 90 seconds to form a foam. In some embodiments, the medium is formed by combining ungelatinized potato starch, xanthan gum, montmorillonite and water at a ratio of 40:18:36, respectively, and heating in a micro wave at 1000W-1400W of power for 70 to 80 seconds to form a foam.

[0054] The medium can be in the form of a solid or a foam (e g., a solid foam). In some embodiments, the medium is in the form of a foam pad wherein said pad ranges in size from about 0.5 to 18 inches thick, 2 to 24 inches wide and 2 to 24 inches long or more. In some embodiments, the medium is in the form of a foam cylinder wherein said cylinder ranges in size from about 2 to 18 inches in diameter, and 2 to 24 inches high. The material can be in the form of foam particles including those with a spherical shape, whose diameters range from about 1 mm to about 50 mm. In some embodiments, the medium is in the form of solid foam particles (e.g., aggregates or spheres). In some embodiments, the particles, aggregates, or spheres have a diameter in the range of about 1mm to about 25mm.

[0055] The material can be a collection of particles, including those with a spherical shape, that have been poured or placed into another container of practically any size. In some embodiments, the medium is in the shape of a solid pot or a solid container. In some embodiments, the solid container is box-like (i.e., in the shape of a container having a generally rectangular footprint, e.g., a planter box). In some embodiments, the solid container is box-likeOur Ref: 14017-0130W01 with dimensions of 2 inches by 2 inches by 2 inches to 24 inches by 24 inches by 24 inches. In some embodiments, the solid container is cylindrical. In some embodiments, the solid container is cylindrical with dimensions of 2 inches in diameter to 24 inches in diameter and 2 inched in height to 24 inches in height.

[0056] In some embodiments, the medium is in a container. In some embodiments, the medium is in a container measuring about 1 inch by 1 inch by 1 inch to about 24 inches by 24 inches by 24 inches to over 25 feet by 25 feet by 24 inches or more. In some embodiments, the medium is in a container measuring about 1 inch by 1 inch by 1 inch to about 24 inches by 24 inches by 24 inches to 25 feet by 25 feet by 24 inches.

[0057] The medium (i.e., composite material) can be produced using extrusion or microwave processing. In some embodiments, thermal extrusion is used where the material is heated in the extruder. In some embodiments, the medium is produced using microwave expansion where at least one polysaccharide and at least one clay mineral is mixed with a solvent and heated to both expand the material into a foam and dehydrate the mixture. The material can be produced using microwave expansion where at least one polysaccharide, at least one protein and at least one clay mineral is mixed with a solvent and heated to foam and dehydrate the mixture.

[0058] Provided herein are processes for forming a medium for plant growth. In one embodiment, the process includes combining at least one polysaccharide and at least one clay mineral with water to form a mixture; shaping the mixture into a form; placing the mixture into a mold that exhibits water vapor permeability; heating to a temperature greater than 100 degrees Celsius; and dehydrating to form a foam.

[0059] In one embodiment, the process includes combining at least one polysaccharide, at least one clay mineral and at least one protein with water to form a mixture; shaping the mixture into a form; placing the mixture into a mold that exhibits water vapor permeability ; heating to a temperature greater than 100 degrees Celsius; and dehydrating to form a foam.

[0060] In some embodiments, the mixture is shaped into a form, wherein the form is spheres or a pad. In some embodiments, the mixture is shaped into spheres. In some embodiments, the mold is a silicone or Teflon mold with spherical pockets.

[0061] In some embodiments, the medium is produced by combining potato starch (PS), xanthan gum (XG), montmorillonite (M) and water (W) at ratios of PS:XG:M:W where PS ranges from 30 to 50, XG ranges from 0.2 to 5, M ranges from 2 to 30 and W ranges from 20 toOur Ref: 14017-0130W01100 to form a mixture, and wherein the mixture is exposed to a temperature higher than 100 degrees Celsius to expand the mixture into a foam and dehydrate the mixture. In some embodiments, the medium is produced by combining potato starch (PS), xanthan gum (XG), gelatin (G), montmorillonite (M) and water (W) at ratios of PS:XG:G:M:W where PS ranges from 30 to 50, XG ranges from 0 to 5, G ranges from 0 to 15, M ranges from 2 to 30 and W ranges from 20 to 100 to form a mixture, and wherein the mixture is exposed to a temperature higher than 100 degrees Celsius to expand the mixture into a foam and dehydrate the mixture.

[0062] In some embodiments, the medium is an expanded foam material. The expanded foam material can have an internal pore structure where said pore sizes range from < 0.5 pm to 500 pm or more.

[0063] The expanded foam material can be a collection of particles, including those with a spherical shape, that have been poured or placed into another container of practically any size, where the material then has both internal porosity inside the particle of < 0.5 pm to 500 pm or more, and an external porosity associated with the packing of the particles which ranges from < 0.5 pm to 2000 pm or more. In some embodiments, the medium exhibits an internal porosity of about 0.5 microns to about 500 microns.

[0064] In some embodiments, the medium (i.e., composite material) is insoluble as a result of electrostatic, ionic interactions or hydrogen bonding interactions between the anionic or cationic polysaccharides and clay minerals. In some embodiments, the medium (i.e., composite material) is insoluble as a result of electrostatic, ionic interactions or hydrogen bonding interactions between the anionic or cationic polysaccharides, protein and clay minerals.

[0065] In some embodiments, the at least one clay mineral is montmorillonite. Montmorillonite is a plate-like clay mineral known to have anionic negative charges on its top and bottom surfaces and cationic positive charges on its edges. The anionic charges provide clay minerals like montmorillonite cation exchange capacity and the ability to provide growing plants needed cation nutrients including ammonium, potassium, magnesium and calcium.

[0066] Other anionic or cationic polysaccharides can be used in addition to native or chemically modified starches or their purified amylose or amylopectin components including, for example, chemically modified celluloses, hemicelluloses, chitosan, pectin, carrageenan, xanthan gum, agar, gellan and alginate. Non-ionic polysaccharides may also be added to the composition, including to alter the rheology, such as, for example, uncharged native starches orOur Ref: 14017-0130W01 their purified amylose or amylopectin components, dextran, agar, guar gum, locus bean gum, konjac glucomannan and pullulan. Clay minerals in addition to montmorillonite include, for example, bentonite, kaolinite, illite, chlorite, vermiculite, attapulgite, halloysite, sepiolite and laponite. In some embodiments, the clay mineral is selected from the group consisting of montmorillonite, bentonite, kaolinite, illite, chlorite, vermiculite, attapulgite, halloysite, sepiolite, and laponite.

[0067] In some embodiments, the medium includes a protein, wherein the protein is gelatin. Proteins in addition to gelatin can include, for example, collagen, where gelatin is a hydrolyzed form of collagen, casein, albumin, soy, whey, fibrin or fibrinogen. In some embodiments, the protein is selected from the group consisting of gelatin, collagen, where gelatin is a hydrolyzed form of collagen, casein, albumin, soy, whey, fibrin and fibrinogen.

[0068] The medium (i.e., composite material) can be prepared using water with added acids and / or bases to adjust the pH to control the ionization state of ionizable groups on the polysaccharides, proteins or clay minerals. Acids include, for example, hydrochloric acid, boric acid, citric acid, phosphoric acid and formic acid. Bases include, for example, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium bicarbonate, sodium carbonate, magnesium hydroxide, calcium carbonate, and ammonium hydroxide. It may be advantageous to adjust the pH of the material to a value such that any relevant ionizable group on the polysaccharides is ionized and any relevant ionizable group on the clay mineral is ionized to facilitate electrostatic interaction. For example, the pKa of the phosphate on potato starch is around 1 .5 to 2.5 indicating that the phosphate is negatively charged at higher pH values. The pKa of the edge Mg-OH2-OH2+ group on montmorillonite is about 13-14 indicating that it is protonated at lower pH values. Thus, at a pH of 5-8, the potato starch will be negatively charged and the montmorillonite edges will contain positive charges. Promoting electrostatic interaction between the material components improves insolubility. Insolubility may also be achieved through extensive hydrogen bonding between the polysaccharides and clay minerals.

[0069] Other nutrients can be added to the medium (i.e., composite material) to support plant growth such as, for example, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, zinc, manganese, copper, boron, molybdenum and chlorine.

[0070] In some embodiments, the medium (i.e., composite material) is hydrophilic and wettable due to the highly polar nature of the polysaccharides that contain numerous polar -OHOur Ref: 14017-0130W01 groups and in some cases, ionizable groups, and clay minerals that also have abundant polar -OH or -O- groups.

[0071] In some embodiments, the medium is an insoluble starch foam composite comprising montmorillonite, starch, and xanthan gum. In some embodiments, the medium is formed by adding enough montmorillonite to crosslink the starch and xanthan gum. As explained herein, montmorillonite is a plate-like clay mineral that is rich in cationic sites on the edges and has numerous hydrogen bonding sites on the surface. The starch and xanthan gum are anionic polysaccharides that can engage in electrostatic complexation and hydrogen bonding with montmorillonite. Without wishing to be bound to theory, it is believed that the excellent insolubility of the foams is due to a combination of this electrostatic complexation and hydrogen bonding.

[0072] The starch foam pore size distribution can be controlled by several factors. One factor is the time and temperature dependence of the rheology of the dough mixture before and during thermal treatment where the starch gelatinizes in the heated water and increases the viscosity as the starch granule is disassembled and the starch molecules dissolve and bind water. In some embodiments, the addition of a small amount of xanthan gum allows for control over the mixture rheology and thus the final foam pore size distribution and density. However, each component of the overall mixture of PS:M:XG:W can play a role in pore formation during processing. Another factor is the processing time and temperature. At higher cooking temperatures (higher microwave powers in microwave cooking), the formation of steam in the starch is more rapid and leads to higher internal pressures which alters the pore size distribution. In some embodiments, by vary ing the PS:M:XG:W ratios and the cooking time and temperature, the pore size distribution of the insoluble starch foam composites can be controlled. In some embodiments, the medium comprises starch foam spheres of virtually any size (diameters of millimeters to centimeters). The ability to control the pore size distribution and particle size of the composite material can be beneficial for a soilless porous media.

[0073] In some embodiments, a mold is used to shape the medium (i.e., composite material). In some embodiment, by placing the formed dough mixture (e.g., mixture of a polysaccharide, clay mineral, and optional protein) into a mold, the final size of the foam product can be controlled. The shape and size of the mold, including having open regions of the mold, may be important to the final size, shape, porosity and spatial pore size distribution of the final foam product. The temperature of the mold, gas permeability’ and water vapor permeability of theOur Ref: 14017-0130W01 mold may be important to the size, porosity and spatial pore size distribution of the final foam product.

[0074] Other product configurations are also possible. For example, a starch foam pad or sphere-like particle can be formed with pockets by expanding the foam into a mold which contains features to form pockets or grooves in the foam surface. Such pockets can be filled with one or more seeds. Seeds can also simply be pressed into the foam using a variety of processes. A number of seeds can be deposited onto a foam pad and pressed into the foam using a flat plate. In some embodiments, seeds are adhered onto the surface of the foam by depositing a viscous polysaccharide or protein liquid which acts like a glue, then depositing the seeds onto the liquid, then dehydrading the liquid at a temperature that does not damage the seeds. For example, a 0.5- 2% solution of xanthan gum, pullulan or gellan can be used. Seeds may be incorporated into the polysaccharide or protein liquid and the liquid deposited onto the surface and dehydrated at a temperature that does not damage the seeds.

[0075] The medium (e.g., starch composite material) may also contain plant nutrients such as nitrogen, phosphorous, potassium, calcium, magnesium, sulfur, iron, manganese, zinc, copper, boron, molybdenum and chlorine. These can be provided by incorporating into the dough before thermal processing chemicals like ammonium nitride, ammonium sulfate, calcium ammonium nitrate, superphosphate, monoammonium phosphate, potassium chloride, potassium nitrate, calcium carbonate, calcium nitrate, magnesium sulfate, lime. Ferrous sulfate, manganese sulfate, zinc sulfate, copper sulfate, boric acid, sodium molybdate, potassium chloride, calcium chloride and others.

[0076] Also provided herein are devices including a medium described herein. In some embodiments, the device is in the shape of an enclosure comprised of two pieces that when connect form an enclosed space inside. In some embodiments, the enclosed space comprises a plant seed. In some embodiments, the device is a starch composite shell for protecting seeds from animals or other pests when planted to give them time to germinate and grow. In some embodiments, the starch composite is formed into a shell comprised of two pieces that can fit together to form an enclosed space. In some embodiments, the shell comprises holes of various shapes to allow roots to grow through, if needed. Roots and stems may also grow through the material. In some embodiments, the device or shell comprises one or more extended features that anchor the device into the planted medium such as soil. In some embodiments, the extended features prevent animals from easily removing the device as they would have to dig out a moreOur Ref: 14017-0130W01 complex or extended shape that was anchored in the soil. The extended feature can have many shapes including protrusions or a screw-like shape. In the case of planting in soil, the shape with a screw feature can be used by digging a hole in the soil, screwing the shape into the ground at the bottom of the hole to anchor it, then filling the hole with soil to cover the shape and seed within.

[0077] Figures 1 A and IB depict cross sections of an example seed enclosure device 100. Figure 1A shows two half pieces of device 100 before closing and Figure IB depicts closed device 100 with a seed inside (e.g., an acorn). The device 100 comprises a medium 102 as disclosed herein (e.g., starch composite material), wherein the medium is in two half pieces 106 and 108. The first piece 106 is a top half of a contiguous outer shell and the second piece 108 is a bottom half of a contiguous outer shell. Each of the pieces 106 and 108 can have optional holes 104. The device further comprises features 110 for joining the top half and the bottom half. The device 100 can be closed to protect a seed, as shown in Figure IB.

[0078] Figures 2A and 2B depict cross sections of an example seed enclosure device 200. Figure 2A shows two pieces of device 200 before closing and Figure 2B depicts closed device 200 with a seed inside (e.g., acorn). The device 200 comprises a medium 202 as disclosed herein (e.g., starch composite material), wherein the medium is in two pieces 206 and 208. The first piece 206 is a lid to close the device and the second piece 208 is a contiguous outer shell. The second piece 208 can have optional holes 204. The device 200 can be closed to protect a seed, as shown in Figure 2B. The device can include optional extended features. Figure 2C depicts an example of the seed enclosure device 200 with two protrusions 210. Figure 2D depicts an example of the seed enclosure device 200 with a screw-like feature 212.

[0079] As used herein, and unless otherwise specified, the term "about." when used in connection with a numeric value or range of values is to indicate that the value or range of values may deviate to an extent deemed reasonable to one of ordinary7skill in the art. In general, the term “about” is used herein to modify a numerical value above and below the stated value by a variance of 10% unless otherwise specified.OTHER EMBODIMENTS

[0080] Exemplary embodiments are provided below.

[0081] Embodiment 1 is a medium for plant growth comprised of at least one anionic polysaccharide and at least one clay mineral, where said polysaccharide and clay mineral areOur Ref: 14017-0130W01 combined with water, heated to a temperature greater than 100 degrees Celsius, and dehydrated to form a foam.

[0082] Embodiment 2 is a medium for plant growth comprised of at least one cationic polysaccharide and at least one clay mineral, where said polysaccharide and clay mineral are combined with water, heated to a temperature greater than 100 degrees Celsius, and dehydrated to form a foam.

[0083] Embodiment 3 is a medium for plant growth comprised of at least one anionic polysaccharide, one protein and at least one clay mineral, where said polysaccharide, protein and clay mineral are combined with water, heated to a temperature greater than 100 degrees Celsius, and dehydrated to form a foam.

[0084] Embodiment 4 is a medium for plant grow th comprised of at least one cationic polysaccharide, one protein and at least one clay mineral, where said polysaccharide, protein and clay mineral are combined with water, heated to a temperature greater than 100 degrees Celsius, and dehydrated to form a foam.

[0085] Embodiment is the anionic polysaccharide of Embodiments 1-2 where said polysaccharide is an anionic starch.

[0086] Embodiment 6 is the anionic starch of Embodiment 5 where said starch is an ungelatinized potato starch.

[0087] Embodiment 7 is the cationic polysaccharide of Embodiments 3-4 where said polysaccharide is a cationic starch.

[0088] Embodiment 8 is the clay mineral of Embodiments 1-4 where said clay mineral is montmorillonite.

[0089] Embodiment 9 is the protein of Embodiments 3-4 w here said protein is gelatin.

[0090] Embodiment 10 is the medium of Embodiments 1-4 where said medium is in the form of particles, aggregates or spheres whose sizes or diameters range from approximately 1mm to 25mm.

[0091] Embodiment 11 is the medium of Embodiments 1-4 where said medium is in the shape of a solid pot or solid container where said container can be box like with dimensions of 2Our Ref: 14017-0130W01 inches by 2 inches by 2 inches to 24 inches by 24 inches by 24 inches; or generally cylindrical in shape and measure 2 inches in diameter to 24 inches in diameter and 2 inched in height to 24 inches in height.

[0092] Embodiment 12 is the medium of Embodiments 1-4 where said medium exhibits an internal porosity7of approximately 0.5 micron to 500 microns.

[0093] Embodiment 13 is the containerized medium comprised of the medium of Embodiment 10 where said medium is used to fill a container measuring about 1 inch by 1 inch by 1 inch to about 24 inches by 24 inches by 24 inches to over 25 feet by 25 feet by 24 inches or more.

[0094] Embodiment 14 is the composition of Embodiment 1 where said composition consists of ungelatinized potato starch, xanthan gum, montmorillonite and water at a ratio of (30-50): (0.2-5): (2-20): (20-80), respectively, where said composition was heated in a microwave at 1000W to 1400W of power for 60 to 90 seconds to form a foam.

[0095] Embodiment 15 is the composition of Embodiment 1 where said composition consists of ungelatinized potato starch, xanthan gum, montmorillonite and water at a ratio of 40:18:36, respectively, where said composition was heated in a microwave at 1000W-1400W of power for 70 to 80 seconds to form a foam.

[0096] Embodiment 16 is a process for forming a medium for plant growth consisting of at least one polysaccharide and at least one clay mineral, where said polysaccharide and clay mineral are combined with water, mixed, shaped into a form, placed into a mold that exhibits water vapor permeability, heated to a temperature greater than 100 degrees Celsius, and dehydrated to form a foam.

[0097] Embodiment 17 is the process for forming a medium for plant growth consisting of at least one polysaccharide, at least one clay mineral and at least one protein, where said polysaccharide, clay mineral and protein are combined with water, mixed, shaped into a form, placed into a mold that exhibits water vapor permeability, heated to a temperature greater than 100 degrees Celsius, and dehydrated to form a foam.

[0098] Embodiment 18 is the device comprised of the starch composite of Embodiments 1-8 where said device is in the shape of an enclosure comprised of tw o pieces that when connected form an enclosed space inside.Our Ref: 14017-0130W01

[0099] Embodiment 19 is the device comprised of the starch composite of Embodiments 1-8 Wwhere said device is in the shape of an enclosure comprised of two pieces that when connected form an enclosed space inside to hold a plant seed.EXAMPLESExample 1 : Preparation of a Starch Foam Composite Material

[0100] Ungelatinized potato starch (PS) was combined with montmorillonite (M), a small amount of xanthan gum (XG) and water (W) and mixed until a uniform dough-like consistency was achieved. An example composition ratio is 40:8: 1 :36 PS:M:XG:W. The dough was formed into spheres and placed in a silicone or Teflon mold with spherical pockets with an open top and covered with a Teflon sheet for microwave expansion, which can take 70-80 s at high (1200W) power in a conventional kitchen microwave such as an LG Electronics model number LCRT2010ST. While heating, the water entered the vapor state, which gelatinized the starch, which increased the viscosity and trapped the water which caused the dough to expand into a foam. When the water was removed, a stable dry starch composite foam sphere was produced in the mold. This can also be done using thermal extrusion processing, which is used to make other spherical starch based products like Kix cereal.

[0101] Using this process, starch foam spheres were produced with final diameters of 12.7mm ± 0. 11mm (size 1) and 10.3mm ± 1.0mm (size 2). Spheres were placed into water and pH 6 buffer and soaked for 12 days, as shown in Figure 3. Mass loss ranged from 0. 12% to 1.7%, demonstrating their insolubility'.Example 2: Evaluation of the Starch Foam Composite Material as a Plant Growth Medium

[0102] Broccoli seeds were planted on peat, peat with fertilizer, expanded clay pebble, and two sizes of the potato starch-montmorillonite foam spheres (sizes 1 and 2) in a fully drainable container. Plants were provided 5 mL of water each day, then carefully removed from the media after 7 days, and the root lengths were measured from the base of the stem to the tip of the longest root using a ruler. Shoot lengths were measured from the base of the plant to the tip of the tallest leaf. The boxplot in Figure 4 present a comparison of shoot and root growth for broccoli seeds grown in various media. The potato starch-20% montmorillonite (PSMo20) spheres exhibited the longest shoot and rot lengths by a large margin. It was noted that thisOur Ref: 14017-0130W01 watering cycle resulted in more saturated peat soil, but this also demonstrated the superior drainability of the spherical media. The starch foam significantly outperformed the clay pebble which was also able to drain. Photographs of broccoli growth in various media are shown in Figures 5A and 5B. Figure 5A depicts photographs of broccoli growth after 7 days in comparative media including (a) peat, (b) nutrient enriched peat, and (c) clay pebbles; as well as the example potato starch-montmorillonite foam spheres disclosed herein in various sizes (d), (e), and (f). Figure 5B depicts broccoli grow th after 7 days in potato starch-montmorillonite foam spheres (size 2). removed from the container.Example 3: Variation of Pore Structure of the MediumIt can be beneficial to vary pore size in the foam to control the water retention characteristic or water retention curve. For example, by controlling the amount of storage pores, transmission pores, and feeding pores. In some embodiments, control over pore size distribution can be achieved by variations in composition. For example, the pore structure w as varied by adjusting the amount of water in the mixture used to prepare the medium (e.g.. foam composition). Figures 6A and 6B show7the pore structure of two foam compositions where the water content was adjusted such that the overall composition before thermal treatment was 40:8:1:32 (Figure 6A) and 40:8:1 :40 (Figure 6B), wherein the ratios refer to PS:M:XG:W. The larger amount of water produced larger pores. It is theorized that adjusting the amount of water in the mixture w ill also change the pore size distribution for pores <50 microns.

Claims

Our Ref: 14017-0130W01WHAT IS CLAIMED IS:

1. A medium for plant growth comprising at least one polysaccharide and at least one clay mineral, wherein the medium is an insoluble solid foam.

2. A medium for plant growth comprising at least one polysaccharide and at least one clay mineral, wherein the medium comprises two or more solid foam particles.

3. The medium of claim 1 or 2. further comprising at least one protein.

4. A medium for plant growth comprising at least one polysaccharide and at least one clay mineral, wherein the medium is prepared by combining the at least one polysaccharide and the at least one clay mineral with water to form a mixture, heating the mixture to a temperature greater than 100 degrees Celsius, and dehydrating the mixture to form afoam.

5. A medium for plant growth comprising at least one polysaccharide, at least one protein, and at least one clay mineral, wherein the medium is prepared by combining the at least one polysaccharide, the at least one protein and the at least one clay mineral with water to form a mixture, heating the mixture to a temperature greater than 100 degrees Celsius, and dehydrating the mixture to form a foam.

6. The medium of any one of claims 1 -5, wherein the medium comprises at least one anionic polysaccharide.

7. The medium of claim 6 wherein the at least one anionic polysaccharide comprises an anionic starch.

8. The medium of claim 7 wherein the anionic starch is an ungelatinized potato starch.

9. The medium of any one of claims 1-5, wherein the medium comprises at least one cationic polysaccharide.

10. The medium of claim 9 wherein the at least one cationic polysaccharide comprises a cationic starch.

11. The medium of any one of claims 1-10 wherein the at least one clay mineral is montmorillonite.

12. The medium of any one of claims 3 and 5-11, wherein the protein is gelatin.

13. The medium of any one of claims 1-12 wherein the medium is in the form of solidOur Ref: 14017-0130W01 foam particles, wherein the solid foam particles have a diameter in the range of about 1mm to about 25mm.

14. The medium of any one of claims 1-13, wherein the medium is in the shape of a solid pot or solid container.

15. The medium of claim 14, wherein the solid container is box-like w ith dimensions of 2 inches by 2 inches by 2 inches to 24 inches by 24 inches by 24 inches; or the container is cylindrical with dimensions of 2 inches in diameter to 24 inches in diameter and 2 inched in height to 24 inches in height.

16. The medium of any one of claims 1-15, wherein the medium exhibits an internal porosity of about 0.5 microns to about 500 microns.

17. A containerized medium comprising the medium of any one of claims 1-13 where said medium is in a container measuring about 1 inch by 1 inch by 1 inch to about 24 inches by 24 inches by 24 inches to 25 feet by 25 feet by 24 inches.

18. The medium of any one of claims 1-16, wherein of the medium is formed by combining ungelatinized potato starch, xanthan gum, montmorillonite and water at a ratio of (30-50):(0.2-5):(2-20):(20-80), respectively; and heating in a microwave at 1000W to 1400W of power for 60 to 90 seconds to form a foam.

19. The medium of any one of claims 1-16, wherein of the medium is formed by combining ungelatinized potato starch, xanthan gum, montmorillonite and water at a ratio of40: 1:8:36, respectively, and heating in a microwave at 1000W-1400W of power for 70 to 80 seconds to form a foam.

20. A process for forming a medium for plant growth comprising: combining at least one polysaccharide and at least one clay mineral with water to form a mixture; shaping the mixture into a form; placing the mixture into a mold that exhibits water vapor permeability; heating the mixture to a temperature greater than 100 degrees Celsius; and dehydrating the mixture to form a foam.

21. A process for forming a medium for plant growth comprising: combining at least one polysaccharide, at least one clay mineral and at least one protein with water to form a mixture;Our Ref: 14017-0130W01 shaping the mixture into a form; placing the mixture into a mold that exhibits water vapor permeability; heating the mixture to a temperature greater than 100 degrees Celsius; and dehydrating the mixture to form a foam.

22. A device comprising the medium of any one of claims 1-19 wherein said device is in the shape of an enclosure comprised of two pieces that when connected form an enclosed space inside.

23. The device of claim 22, wherein the enclosed space comprises a plant seed.

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