Carboxylated nanocelluloses as binding and wetting agents for agricultural blends or soil conditioning

Abstract

Biodegradable growing media and soil conditioning compositions include nanocelluloses, such as carboxylated CNF, carboxylated LCNF, and carboxylated CNC, which serve as binding and / or wetting agents. Methods include mixing nanocelluloses with plant growth substrate materials. The compositions include the possible addition of monovalent, divalent, or trivalent inorganic salts that supply essential plant nutrients. These compositions can be processed into plug or mat forms suitable for supporting the germination and growth of crops. Carboxylated nanocellulose-based compositions can be directly applied as soil conditioners or amendments to enhance soil health and plant development.

Description

Attorney Docket No. 201291.4. PCTCARBOXYLATED NANOCELLULOSES AS BINDING AND WETTING AGENTS FOR AGRICULTURAL BLENDS OR SOIL CONDITIONINGCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Patent Application No. 63 / 656,308 filed on June 5, 2024. The entire contents of this application are hereby incorporated by reference.BACKGROUND OF THE INVENTION1. Field of the Invention

[0002] The present invention is related to a substrate including multifunctional compositions based on carboxylated nanocelluloses including carboxylated cellulose nanofibers (CNF), carboxylated lignin-containing cellulose nanofibers (LCNF), carboxylated cellulose nanocrystals (CNC), or a blends thereof. These nanocelluloses can be used as binding and / or wetting agents in manufacturing soilless growing media in the forms of a plug or a mat, including substrate scaffolds such as peat moss, coco-coir, wood fibers, perlite, or a combination thereof or as soil conditioners / amendments. Additionally, the present invention includes methods for producing plugs and mats suitable for growing, for example, lettuce and microgreens.2. Description of the Related Art

[0003] Peat moss is a valuable natural and renewable resource widely used in agricultural and horticultural practices because of its numerous beneficial properties. Its fibrous structure improves soil quality, its porosity helps retain moisture, and its capacity to increase soil acidity provides advantages. However, the extraction of peat moss raises environmental concerns. Peat moss is commonly used in agricultural blends, potting soils, and soil amendments for gardening purposes. Peat moss is also applied in turf maintenance on golf courses to improve water retention and reduce overall weight. While peat moss is popular, there are several alternative options for growing media, such as coir, coconut fibers, wood fibers, wood chips, wools, rice hulls, leaf mold, perlite, vermiculite, pumice, etc.

[0004] However, these alternatives often require additional materials to meet specific growing media requirements. For example, commercially available synthetic polymers havebeen utilized to crosslink the substrate plugs, such as Preforma, GrowTech, IHT, and Omni plugs. Among these synthetic polymers, polyurethane is most commonly used, but it poses significant environmental risks due to the non-biodegradable nature as well as the chemical waste generated during its production. For example, the production of polyurethane releases greenhouse gases, negatively impacting the environment. Furthermore, exposure to direct sunlight or organic solvents can significantly reduce the durability of polyurethane-based products. In addition to polyurethane, various synthetic binding and wetting agents are commonly used with peat moss and other fibers to have the desired growing media. However, most of these agents do not exhibit eco-friendly behavior. To address these limitations, there is a clear need for the development of fully biodegradable and biocompatible materials that can also be produced locally. These materials should possess the capability to enhance growing media by effectively binding and stabilizing soilless mediums for transplanting, all without requiring advanced production technology.

[0005] Soil conditioners / amendments play a crucial role in enhancing soil health by improving its physical, chemical, and biological properties. For example, soil conditioners, such as organic matter (e.g., compost, manure) or synthetic substances (e.g., gypsum, lime), can help improve soil structure by promoting aggregation and create pore spaces that improve water infiltration and air circulation, crucial for root growth and microbial activity. Additionally, soil conditioners can improve water retention in sandy soils by increasing their ability to hold moisture; create drainage in clay soils by preventing waterlogging; increase the soil's ability to retain essential nutrients like nitrogen, phosphorus, and potassium, preventing them from leaching away with water; regulate soil pH levels, provide organic matter that serves as a food source for soil microorganisms; and prevent soil erosion by binding soil particles together, reducing surface runoff and soil loss. Overall, soil conditioners are essential for maintaining and improving soil health, which is fundamental for sustainable agriculture, ecosystem health, and food security.SUMMARY OF THE INVENTION

[0006] The example embodiments of present invention demonstrate the use ofmultifunctional compositions based on carboxylated nanocelluloses including carboxylated cellulose nanofibers (CNF), carboxylated lignin-containing cellulose nanofibers (LCNF), carboxylated cellulose nanocrystals (CNC), or combinations thereof as binding and / or wetting agents to manufacture growing media using substrate scaffolding materials such as peat moss, coco-coir, wood fibers, wood chips, wools, rice hulls, leaf mold, perlite, vermiculite, pumice, or a combination thereof. The growing media can be soilless. Additionally, inorganic salts containing essential plant macro- and micro-nutrients, including monovalent, divalent, trivalent salts, or a combination thereof can be added. These inorganic salts encompass both cations and counter-anions. The inorganic salts can include potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), nitrogen (N), phosphorus (P) / phosphate (PO43), sulfur (S), boron (B), nitrate (NO3 ), nickel (Ni)-based salt ions, or a combination thereof. Alternatively, the inorganic salts can include calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe), or a combination thereof. In a specific example embodiment, calcium nitrate [Ca(NO3)2] has been used to crosslink carboxylated nanocellulose and the growing media fibers.

[0007] A composition including at least one carboxylated CNF, carboxylated LCNF, carboxylated CNC, or a combination thereof, in combination with one or more fibrous substrates selected from peat moss and coco-coir (e.g., Flexistart™ and Preforma™ fibers). When mixed with peat moss fibers, the resulting stable growing medium can be referred to as HydroPeat. Similarly, mixtures incorporating Flexistart™ fibers (without binder) can be referred to as FlexiGels, and those incorporating Preforma™ fibers (without binder) can be referred to as PreGels.

[0008] These compositions are formed by homogeneous dispersion of carboxylated nanocelluloses within the fibrous substrate matrix to enhance structural cohesion, water retention, and nutrient delivery properties of the growing media.

[0009] After mixing, the resulting stable growing medium or other combinations are incubated for about 1-about 2 days at about room temperature or can be dried at 50°C-60°C for about 0.5-about 24 h to optimize stability and regulate water retention capacity. This process results in improved physical and chemical properties while ensuring minimal to notoxicity to plants, including edible crops such as lettuce and microgreens. HydroPeat, FlexiGels, and PreGels have demonstrated effectiveness in germinating crop seeds and supporting the growth and propagation of the plants.

[0010] An example embodiment includes a highly stable growing media that can allow substrate fibers to be bonded together, improve water retention, and enable automated handling in nursery or greenhouse settings.

[0011] The approaches, detailed in the example embodiments, provide methods to create growing medium plugs and mats utilizing these stabilized substrates for efficient seed germination and subsequent plant growth.

[0012] An example embodiment also includes the use of carboxylated nanocelluloses as soil conditioners / amendments to enhance soil health by improving its physical, chemical, and biological properties. Specifically, carboxylated nanocellulose hydrogels can help improve the soil structure by promoting aggregation of some regions of soils and create pore spaces to improve water infiltration and air circulation. Carboxylated nanocellulose hydrogels can improve water retention in sandy soils by increasing their ability to hold moisture. Carboxylated nanocellulose hydrogels can increase the soil's ability to retain essential nutrients like nitrogen, phosphorus, and potassium, preventing them from leaching away with water. Carboxylated nanocellulose hydrogels can regulate soil pH levels. Carboxylated nanocellulose hydrogels can provide organic matter that serves as a nutrient source for soil microorganisms. Carboxylated nanocellulose hydrogels can also prevent soil erosion by binding soil particles together, reducing surface runoff and soil loss.

[0013] Carboxylated CNF, carboxylated LCNF, and carboxylated CNC can be present in about 0.01 wt% to about 99.99 wt% of the total composition. Alternatively, carboxylated CNF, carboxylated LCNF, and carboxylated CNC can be present in about 1.0 wt% to about 10.0 wt%.

[0014] The plant growth substrate (coir, coconut fibers, wood fibers, wood chips, wools, rice hulls, leaf mold, perlite, vermiculite, pumice) can be present in about 1.0 wt% to about 99 wt% of the total composition. The plant growth substrate can be present in about 1.0 wt% to about 50 wt% of the total composition.

[0015] In example embodiments for HydroPeat, the ratio between the plant growthsubstrate and carboxylated CNF, carboxylated LCNF, and carboxylated CNC ranges from approximately 100:1 to 1200:1, based on the dry mass weight of carboxylated CNF, carboxylated LCNF, and carboxylated CNC. In certain PreGel / FlexiGel example embodiments, the plant plug includes the plant growth substrate mixed with carboxylated nanocelluloses at a ratio of from about 3:1 to 7:1 (substrate:CNF / LCNF / CNC) based on the dry mass weight of carboxylated CNF, carboxylated LCNF, and carboxylated CNC. Additionally, the formulation may include one or more inorganic salts at concentrations ranging from about 0.1 mM to about 5000 mM, and alternatively from about 50 mM to 200 about mM.

[0016] An example embodiment of the present invention includes a method of conditioning soil including mixing soil and carboxylated CNF, carboxylated LCNF, and carboxylated CNC. This is particularly necessary for sandy soil with low water-holding capacity.

[0017] According to an example embodiment of the present invention, a method for producing a growing medium includes mixing a plant growth substrate material with one or more functionalized cellulose nanomaterials selected from the group including carboxylated cellulose nanofibers (CNF), carboxylated lignin-containing cellulose nanofibers (LCNF), and carboxylated cellulose nanocrystals (CNC); and adding a crosslinking agent selected from the group including inorganic salts, genipin, chitosan, citric acid, polydopamine, lignosulfonate, or a combination thereof, to form a growing medium composition.

[0018] The method can further include incubating the growing medium composition at room temperature for about 0.5 h to about 48 h at 60°C prior to planting. The plant growth substrate material can include one or more of peat moss, coir, coco-coir, bark or wood fibers or chips, wool, sand, rice hulls, natural biomass, clay pellets, perlite, vermiculite, compost, composted pine bark, animal manure, hardwood bark, softwood bark, compost, or combinations thereof.

[0019] The crosslinking agent can include monovalent, divalent, trivalent inorganic salts, or a combination thereof. The inorganic salts can include one or more selected from the group including potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), nitrogen (N), phosphorus (P) as phosphate (PC3-), sulfur (S), boron (B), nitrate (NO3“), nickel (Ni), or a combination thereof. Alternatively, the inorganic saltscan include calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe), or a combination thereof.

[0020] An amount of the one or more functionalized cellulose nanomaterials can be in a range from about 0.1% to about 99.99% by weight or volume of a total of the growing medium composition. An amount of the one or more functionalized cellulose nanomaterials can be in a range from about 1.0% to about 40.0% by weight. An amount of the one or more functionalized cellulose nanomaterials can be in a range from about 0.1% to about 1.0% by weight. An amount of the plant growth substrate material can be in a range from about 1.0% to about 99% by weight or volume. An amount of the plant growth substrate material can be in a range from about 1.0% to about 50% by weight or volume. A weight ratio of the plant growth substrate material to the one or more functionalized cellulose nanomaterials can be selected from the group including: 1:1, 1:2, 1:5, 1:10, 2:1, 3:1, 2:5, 3:5, 4:5, 7:10, or 9:10.

[0021] The method can further include combining cellulose sludge or macrofibers with the one or more functionalized cellulose nanomaterials prior to mixing with the plant growth substrate material. An amount of the cellulose sludge can be in a range from about 0.1% to about 100% by weight relative to a weight of the one or more functionalized cellulose nanomaterials.

[0022] According to an example embodiment of the present invention, a method of conditioning soil includes mixing soil with one or more functionalized cellulose nanomaterials selected from the group including carboxylated cellulose nanofibers (CNF), carboxylated lignincontaining cellulose nanofibers (LCNF), carboxylated cellulose nanocrystals (CNC), or a combination thereof.

[0023] The method can further include adding a crosslinking agent including one or more inorganic salts. The one or more inorganic salts can be selected from the group including potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), nitrogen (N), phosphorus (P) as phosphate (PC3-), sulfur (S), boron (B), nitrate (NO3“), nickel (Ni), or a combination thereof. The one or more inorganic salts can include calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe), or a combination thereof.

[0024] According to an example embodiment of the present invention, a growing medium including a plant growth substrate material; one or more functionalized cellulose nanomaterialsselected from the group including carboxylated cellulose nanofibers (CNF), carboxylated lignincontaining cellulose nanofibers (LCNF), and carboxylated cellulose nanocrystals (CNC); and a crosslinking agent including inorganic salts.

[0025] The plant growth substrate material can include one or more of peat moss, coir, coco-coir, bark or wood fibers or chips, wool, sand, rice hulls, natural biomass, clay pellets, perlite, vermiculite, compost, composted pine bark, animal manure, hardwood bark, softwood bark, or a combination thereof. The inorganic salts are selected from the group including potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), nitrogen (N), phosphorus (P) as phosphate (PC3-), sulfur (S), boron (B), nitrate (NO3“), nickel (Ni), or a combination thereof. The inorganic salts can include calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe), or a combination thereof.

[0026] A weight ratio of the plant growth substrate material to the one or more functionalized cellulose nanomaterials can be in a range from about 2:1 to about 1:2. A weight ratio of the plant growth substrate material to the one or more functionalized cellulose nanomaterials can be about 1:1. An amount of the inorganic salts can be in a range of about 0.1 mM to 5000 mM.

[0027] The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The patent or application file contains at least one drawing executed in color. The patent or application file also contains a corresponding black and white line drawing for each of the at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0029] Figs. 1A and IB show peat fibers from Jiffy as received. Fig. 1A is in black and white. Fig. IB is in color.

[0030] Figs. 2A and 2C show smaller peat fibers after sifting the as-received peat fibersusing a mesh strainer. Figs. 2B and 2D show leftover large peat fibers retained in the strainer. Figs. 2A and 2B are in black and white. Figs. 2C and 2D are in color.

[0031] Figs. 3A and 3B show a suspension based on carboxylated CNF derived from raw jute (Bangladesh) using a nitro-oxidation process. Fig. 3A is in black and white. Fig. 3B is in color.

[0032] Figs. 4A and 4B show carboxylated CNF added into the sifted peat fibers prior to mixing. Fig. 4A is in black and white. Fig. 4B is in color.

[0033] Figs. 5A and 5B show the CNF-peat paste prepared by mixing the finer peat fibers and carboxylated CNF. Fig. 5A is in black and white. Fig. 5B is in color.

[0034] Figs. 6A and 6E show a standard 30 mL medicine cup. Figs. 6B and 6F show the appropriate amount of dry carboxylated CNF (or carboxylated LCNF and carboxylated CNC) sample mixed with fine peat fibers. Figs. 6C and 6G show the process of pressing the mixture using a standard calibration weight scale of 200 g. Figs. 6D and 6H show the addition of 0.5 mL of 100 mM calcium nitrate as a crosslinking agent. Figs. 6A-6D are in black and white. Figs. 6E- 6H are in color.

[0035] Figs. 7A and 7B show a comparison of the sample state before (a) and after (c) conducting a compression test using a calibration weight (0.5 Kg) on top of a HydroPeat sample in (b). Fig. 7A is in black and white. Fig. 7B is in color.

[0036] Figs. 8A and 8B show a comparison of the lettuce growth for plugs (A)-(K). Fig. 8A is in black and white. Fig. 8B is in color.

[0037] Figs. 9A-9H show fully grown lettuce harvested after approximately 75 days. Figs. 9A and 9B and Figs. 9E and 9F show side and top views, respectively, using the (H) plug in Figs. 8A and 8B, including Jiffy's peat fiber without fertilizer. Figs. 9C and 9D and Figs. 9G and 9H show side and top views, respectively, using the (G) plug in Figs. 8A and 8B. Figs. 9A-9D are in black and white. Figs. 9E-9H are in color.

[0038] Figs. 10A-10H show lettuce growth using FlexiGel growing media. Figs. 10A and 10E show sample preparation 1. Figs. 10B and 10F show sample preparation 1 of Figs. 10A and 10E with extensive root coverage throughout the plug. Figs. 10C and 10G show a FlexiGel sample preparation 2. Figs. 10D and 10H show sample preparation 2 of Fig. 10C and 10G, demonstrating significant root growth and distribution within the plug. Figs. 10A-10D are inblack and white. Figs. 10E-10H are in color.

[0039] Figs. 11A-11H show lettuce growth using PreGel growing media. Figs. 11A and HE show a sample preparation 3. Figs. 11B and 11F show a sample preparation 3 of Figs. 11A and 11E. Figs. 11C and 11G show sample preparation 4. Figs. 11D and 11H show the sample preparation 4 of Fig. 11C and 11F. Figs. 11A-11D are in black and white. Figs. 11E-11H are in color.

[0040] Figs. 12A and 12C show a first mat according to an example embodiment of the present invention. Figs. 12B and 12D show the bottom view of a second mat according to an example embodiment of the present invention. Figs. 12A and 12B are in black and white. Figs. 12C and 12D are in color.DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0041] The disclosed example embodiments are given merely as illustrations and do not constitute a comprehensive compilation. The example embodiment of the present invention can be implemented in a number of different ways. The figures may not be accurate to scale, and some aspects may have been emphasized or downplayed to draw attention to particular areas. Thus, the particular structural and functional information provided should not be interpreted as restrictive, but rather as a basis for teaching how to modify the current invention in many ways.

[0042] The term "HydroPeat growing medium" as used herein can refer to a substrate including conventional peat moss that is mixed with carboxylated CNF and subsequently crosslinked a with salt solution. In contrast, the term "FlexiGel growing medium" can refer to a fibrous composite medium available in configurations such as plugs or mats, formed by integrating conventional peat fibers free of binders, such as Jiffy's Flexistart™, with one or more functionalized cellulose nanomaterials, including, for example, carboxylated CNF, carboxylated LCNF, and carboxylated CNC, or a combination thereof. Similarly, the term "PreGel growing medium" can refer to substrates— also in plug or mat form— including coco-coir fibers free of binders, such as Jiffy's Preforma™, blended with one or more functionalized cellulose nanomaterials, including, for example, carboxylated CNF, carboxylated LCNF, carboxylated CNC,or a combination thereof. The growing media can be soilless growing media. Alternatively, the growing media can include soil.

[0043] The integration of one or more functionalized cellulose nanomaterials, including, for example, carboxylated CNF, carboxylated LCNF, carboxylated CNC, or a combination thereof, into these substrates enhances the buffering capacity, organic mechanical support, and nutrient retention of the resulting growing media, thereby improving conditions for plant development. These formulations can reduce the volumetric dependence on traditional peat or coir components by substituting a portion with one or more functionalized cellulose nanomaterials, including, for example, carboxylated CNF, carboxylated LCNF, carboxylated CNC, a combination thereof.

[0044] A distinction among HydroPeat, FlexiGel, and PreGel growing media lies in the type and proportion of base substrate fibers employed. HydroPeat growing media include a high fraction of peat substrate fibers, whereas FlexiGel and PreGel growing media include lower quantities of substrate fibers, relying instead on the structural and functional contributions of one or more functionalized cellulose nanomaterials, including, for example, carboxylated CNF, carboxylated LCNF, carboxylated CNC, or a combination thereof.

[0045] The growing media of the example embodiments of the present invention can be engineered to offer physical support, retain water, introduce air space, and provide nutrients for plant growth. The growing media can hold the fibers together and make the plugs stable enough to facilitate seed germination and to support the establishment of a plant's root system within the growing media. The growing media can promote root growth as the roots extend into the spaces between individual substrate fibers and the one or more functionalized cellulose nanomaterials, including, for example, carboxylated CNF, carboxylated LCNF, carboxylated CNC, or a combination thereof, of the growing media.

[0046] Carboxylated CNF and carboxylated LCNF refers to a fibrous biomaterial with a diameter ranging from about 1 nm-about 20 nm, within manufacturing and / or measurement tolerances, and a length at the microscale (e.g., about several microns, within manufacturing and / or measurement tolerances). On the other hand, carboxylated CNC can have a length from about 100 nm-about 500 nm and / or a diameter about 5 nm-about 20 nm, withinmanufacturing and / or measurement tolerances. The fibrous biomaterial can be extracted from various biomass feedstocks and / or natural organic wastes. The fibers can be crosslinked with several salts, including both cations and counterions, including potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), nitrogen (N), phosphorus (P) / phosphate (PO43), sulfur (S), boron (B), nitrate (NO3 ), nickel (Ni)- based salt ions, or a combination thereof. The inorganic salts can include calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe), and combinations thereof to achieve multiple objectives, including enhancing the stability of the fibers through crosslinking and improving water and nutrient retention. Additionally, the fibers can securely anchor a seed on the surface of the growing medium for a duration sufficient for seed germination and root development within the plugs.

[0047] In some example embodiments, biomass feedstocks are sourced from both woody and nonwoody plants to produce carboxylated CNF, carboxylated LCNF, and carboxylated CNC, encompassing agricultural residues and natural fibers. These include materials derived from jute, palm trees, sugarcane bagasse, corn, wheat, oats, rice, sorghum, oil palm, bamboo, spinifex, coastal bermudagrass, miscanthus, switchgrass, azolla, seaweeds, flax, hemp, ramie, kenaf stalk fiber, kenaf core, abaca, sisal, pineapple, banana leaf, banana peel, banana fiber, curaua, lotus leaf stalk, roselle, seed hair fiber, cotton fiber, kapok fiber, areca nut fiber, coconut, potato, cabbage, tomato, rubberwood, Indian screw tree, achira fiber, citrus, soybean, soybean straw, spent grain, soy hull, pea hull, grape pomace, fruit pomace, manures, and various combinations thereof.

[0048] Cellulose extraction is not limited to plant sources; in some example embodiments, the cellulose can also be derived from bacteria, algae, tunicate, or their various combinations. The growing media of the example embodiments may include one or more cellulose components. The term "cellulose components" encompasses cellulose nanofibers (CNF), cellulose nanocrystals (CNC), tunicate cellulose, bacterial cellulose, or an amalgamation thereof.

[0049] Natural organic waste encompasses food waste, green waste, fruits and vegetable wastes, meat and fish wastes including the bones, food-soiled paper, non-hazardous wood waste, green waste, landscape waste, and other sources of waste products of organic origin.This includes by-products from gardening, agriculture, forestry, timber industry, food processing industries, and similar sources, which have garnered growing interest as potential starting materials for the production of various suitable products.

[0050] An illustration of the carboxylated CNF preparation through a nitro-oxidation process (NOP) is outlined in U.S. Patent No. 10,894,838 which is incorporated by reference. The NOP can employ various biomass feedstocks, allowing for the utilization of both hard and softwoods, including agricultural residues. However, softwoods with low lignin content, specifically agricultural residues, can provide certain benefits in this procedure.

[0051] Cross-linking refers to the interaction between negatively charged cellulose nanomaterials, including, for example, carboxylated CNF, carboxylated LCNF, and carboxylated CNC, and positively charged salt ions through electrostatic attraction. This interaction involves two particle types with opposite charges, leading to mutual attraction. Depending on the type of salt ions, such as transitional metal ions, interactions with cellulose nanomaterials, including, for example, carboxylated CNF, carboxylated LCNF and carboxylated CNC, functionalities can occur through ion-ion and metal-ligand interactions. This interaction may involve a coordinate covalent bond, also known as a dative bond, dipolar bond, or coordinate bond. The ions can crosslink the peat fibers or coir fibers or others with the functionalized cellulose nanomaterials, including, for example, carboxylated CNF, carboxylated LCNF, and carboxylated CNC, depending on the functionalities of the fibers. Besides salts, molecular compounds can be used to crosslink the cellulose fibers to form a growing medium according to an example embodiment of the present invention.

[0052] In certain example embodiments, the crosslinking agent primarily includes divalent cationic salts (valency +2); however, monovalent (+1) and trivalent (+3) cationic salts may also be employed. Suitable salts include, but are not limited to, ions of potassium (K+), calcium (Ca2+), magnesium (Mg2+), iron (Fe2+ / Fe3+), aluminum (Al3+), manganese (Mn2+), zinc (Zn2+), copper (Cu2+), molybdenum (Mo6+), nitrogen (as ammonium NH4+), phosphorus (as phosphate PO43"), sulfur (as sulfate SO42"), boron (B3+), chlorine (Cl"), and nickel (Ni2+), or a combination thereof.

[0053] These salt ions function dually as crosslinking agents for the fiber matrix of thegrowing media and as essential plant nutrients, encompassing both macronutrients and micronutrients. Application formats for these salts may include aqueous solutions, granules, powders, prills, or any equivalent particulate or dispersible forms suitable for integration into the growing medium.

[0054] In alternative example embodiments, one or more crosslinking agents, such as genipin, chitosan, citric acid, polydopamine, lignosulfonate, etc., may also be used along with carboxylated CNF, carboxylated LCNF and carboxylated CNC, and one or more plant growth substrate materials.

[0055] The manufacturing process can begin by blending one or more functionalized cellulose nanomaterials, including, for example, carboxylated CNF, carboxylated LCNF, carboxylated CNC, or a combination thereof, sourced from diverse feedstocks, including jute and bagasse, cow dung, horse dung, food wastes, etc., to form an initial nanocellulose concentration. Subsequently, the growing media, such as peats, coir, or a combination thereof possibly along with a variety of other fibers, is crosslinked using various divalent and trivalent ions at ambient temperature.

[0056] In this specific example embodiment, carboxylated CNF, carboxylated LCNF and carboxylated CNC is typically used in a range of about 0.1 wt%- about 1 wt%, within manufacturing and / or measurement tolerances. However, in certain example embodiments, particularly those focusing on a nanocellulose fiber composition or growing medium, the nanocellulose content can vary widely, ranging from about 0.1 wt% to about 99.99 wt%, within manufacturing and / or measurement tolerances. The ratio between the plant growth substrate material and the nanocellulose (e.g., carboxylated CNF, carboxylated LCNF, and carboxylated CNC) can vary, including ratios from about 1200:1 to about 100:1, based on the dry mass of the nanocellulose, within manufacturing and / or measurement tolerances, in HydroPeat growing media. In certain specific example embodiments, the plant plug includes the plant growth substrate material mixed with cellulose nanomaterials (e.g., carboxylated CNF, carboxylated LCNF, and carboxylated CNC) at a ratio of about 3:1- about 7:1 (substrate : nanocellulose), within manufacturing and / or measurement tolerances, in FlexiGels or PreGels growing media.

[0057] Alternatively, the composition may include about 1.0 wt% to about 10 wt% ofcellulose nanomaterials (e.g., carboxylated CNF, carboxylated LCNF, and carboxylated CNC), within manufacturing and / or measurement tolerances, and about 10 wt% to about 20 wt% of nanocellulose (e.g., carboxylated CNF, carboxylated LCNF, and carboxylated CNC) components, within manufacturing and / or measurement tolerances. Another variation might involve about 20 wt% to about 30 wt% of cellulose nanomaterials (e.g., carboxylated CNF, carboxylated LCNF, and carboxylated CNC), within manufacturing and / or measurement tolerances and about 30 wt% to about 40 wt% of nanocellulose (e.g., carboxylated CNF, carboxylated LCNF and carboxylated CNC) components, within manufacturing and / or measurement tolerances.

[0058] In another example embodiment, the growing medium fibers may include about 1%-about 50% or may include about 1%- about 99% of a given volume, within manufacturing and / or measurement tolerances. The composition may incorporate about 50% to about 75% or more or less of the substrate fibers and / or other components relative to the total volume or weight of the growing medium, within manufacturing and / or measurement tolerances.

[0059] In certain example embodiments, the growing media substrate may include one or more components selected from the group including peat moss fibers, coir, coco-coir, wood fibers, natural or synthetic wools, sands, rice hulls, clay pellets, perlite, vermiculite, composts, or any combination thereof, including other recognized soilless substrates.

[0060] The proportion of the plant growth substrate within a given plug or mat configuration may range from about 0.01% to about 100% by volume or weight, within manufacturing and / or measurement tolerances, depending on the application and desired agronomic performance.

[0061] In some example embodiments, plugs may specifically include about 40% to about 50% by volume of the growing media substrate components, within manufacturing and / or measurement tolerances.

[0062] Alternatively, compositions may contain about 50% to about 99% or more by weight of growing media substrates and / or other agronomically functional components, within manufacturing and / or measurement tolerances, relative to the total weight of the growing medium matrix.

[0063] In various example embodiments, the concentration of the crosslinking agent in thecomposition may range from about 1 mM to about 100 mM, within manufacturing and / or measurement tolerances. In alternative example embodiments, the concentration may be within the range of about 100 mM to about 200 mM, within manufacturing and / or measurement tolerances. In further example embodiments, higher concentrations may be utilized, including ranges from about 200 mM to about 5000 mM, or greater, within manufacturing and / or measurement tolerances, depending on the degree of crosslinking desired and the nature of the plant growth substrate and fiber matrix.

[0064] While carboxylated CNF and carboxylated CNC are major binding and wetting agents, example embodiments may also include lignin (e.g., carboxylated LCNF), hemicellulose, proteins, and fatty acids. The specific composition of lignin depends on the feedstock used. If softwood is utilized, then lignin can include coniferyl alcohol, and if hardwood is utilized, then lignin can include coniferyl alcohol and sinapyl alcohol. Grass lignin includes three monomers: coniferyl, sinapyl, and p-coumaryl alcohol. Hemicellulose encompasses xyloglucans, xylans, mannans, glucomannans, and beta-(l-->3,l-->4)-glucans. Additionally, cellulose may contain proteins and their derivatives, such as amino acids and fatty acids depending on the feedstock used. During an NOP, effluents can develop additional nutrients, which, when incorporated into the growing media matrix, enhance the overall nutritional value of the product or the growing medium, referred to as "feedstock nutrients."

[0065] In specific variations, the plant growth media composition maintains a pH range between about 5.5 and about 6.5, within manufacturing and / or measurement tolerances. In certain example embodiments, the pH of the plant growth media composition can be precisely 5.8-6.2.

[0066] The peat moss fibers, coir, coco-coir, wood fibers, wools, sands, rice hulls, clay pellets, perlite, vermiculite, composts, or a combination thereof or another growing medium can be mixed with one or more functionalized cellulose nanomaterials, including, for example, carboxylated CNF, carboxylated LCNF, and carboxylated CNC, using any suitable blender, including, for example, a regular blender or a standard handheld kitchen mixer. This ensures thorough mixing, necessary for a homogeneous mixture with optimal blending. Hand mixing can also be effective when shear mixing is unavailable. Following mixing, compression of thegrowing materials and nanocellulose mixture can be achieved using an appropriate weight percent to form compressed pellets. This process enhances the binding of the nanocellulose with the fibers, further strengthened using different ions or crosslinking agents.

[0067] The stability of the growing media of example embodiments, including, for example, HydroPeat, FlexiGels, PreGels, and other growing media, relies on its moisture level percentage. For example, plugs including HydroPeat growing media can exhibit very high stability when the plugs are nearly 90%-100% dry and moderate stability when the plugs are wet, about 50%- about 90%, within manufacturing and / or measurement tolerances. However, repeated watering may not be necessary since the hydrophilic carboxylated CNF, carboxylated LCNF, and carboxylated CNC can retain water or moisture inside the plugs.

[0068] If the peat moss fibers, coir, coco-coir, wood fibers, wools, sands, rice hulls, clay pellets, perlite, vermiculite, composts, or a combination thereof is too dry (e.g., a moisture level < 10%-20%), and because the addition of functionalized cellulose nanomaterials, including, for example, carboxylated CNF, carboxylated LCNF, and carboxylated CNC, can further increase the viscosity or stickiness of the mixture, then it can be necessary to add a sufficient volume of water with a ratio among the growing media fibers to nanocellulose to water (1:1:1). Regular deionized water or distilled water is sufficient, and the amount of water should be adjusted to achieve the desired viscosity or stickiness of the mixture.

[0069] The conductivity (EC) and acidity (pH) are two commonly measured characteristics of a substrate or plug. The pH of the stabilized growing media of example embodiments of the present invention, including, for example, HydroPeat, FlexiGels, PreGels, and other growing media described herein, typically ranges from about 5.5 to about 6.5. The conductivity of the stabilized HydroPeat growing media described herein generally ranges from about 100 pS / cm- about 500 pS / cm, within manufacturing and / or measurement tolerances. Both the pH and the conductivity of the stabilized growing media of example embodiments of the present invention, including, for example, HydroPeat, FlexiGels, PreGels, and other growing media, can be adjusted by adding suitable buffers or fertilizer ions.

[0070] The composition incubates at room temperature for 1 or 2 days before it is used for planting. The incubation time can be substantially decreased by placing the plugs or mats in anincubator or an oven at desired temperature.

[0071] Figs. 1A-7B show an example method of making a HydroPeat growing media according to an example embodiment of the present invention. Figs. 1A and IB show peat fibers from Jiffy as received. The fibers exhibit a wide distribution of sizes and moisture levels. Figs. 2A and 2C show smaller peat fibers after sifting the as-received peat fibers in Figs. 1A and IB using a mesh strainer. Figs. 2B and 2D is a photograph of leftover large peat fibers retained in the strainer.

[0072] Figs. 3A and 3B show a suspension based on carboxylated CNF derived from raw jute (Bangladesh) using a nitro-oxidation process (NOP). The carboxylated CNF was produced using a 50 L pressurized reactor with 50% nitric acid at 50°C for 9 hours. In the sample preparation, about 7 L of HNO3 was used for 500 g jute, and the pressure was kept below 75 psi. The carboxylated CNF was homogenized using 1 or 2 cycles, providing a yield of 40%. The degree of oxidation of the carboxylated CNF exceeded 1.7 mmol / g, and the pH of the carboxylated CNF was adjusted to 6.5 using 50% v / v ammonium hydroxide.

[0073] Figs. 4A and 4B show the carboxylated CNF of Figs. 3A and 3B added into the sifted peat fibers prior to mixing. Figs. 5A and 5B show a CNF-peat paste prepared by mixing the finer peat fibers and the carboxylated CNF. Depending on the moisture level of the peat fibers, water was added to achieve a specific sticky paste consistency.

[0074] Figs. 6A and 6E show a standard 30 mL medicine cup. Figs. 6B and 6F show the appropriate amount of dry carboxylated CNF (or carboxylated LCNF and carboxylated CNC) sample mixed with the fine peat fibers. Figs. 6C and 6G show the process of pressing the mixture using a standard calibration weight of 200 g. Figs. 6D and 6H show the addition of 0.5 mL of 100 mM calcium nitrate as a crosslinking agent.

[0075] Figs. 7A and 7B show a comparison of the sample of HyrdoPeat growing medium before (a) and after (c) conducting a compression test using a calibration weight of 0.5 Kg on top of the sample in (b). The HydroPeat growing media was dried for 1 dy to 2 days following crosslinking preparation using 50 mM calcium nitrate. Figs. 7A and 7B shown in (c) that plug has the same shape after removing the weight.

[0076] Figs. 8A and 8B shows plugs (A)-(K). Figs. 8A and 8B show a comparison of thelettuce growth using plugs (A)-(K), with the top portion showing 4 days of lettuce growth and with the bottom portion showing 12 days of lettuce growth. The plugs include the following compositions:(A) Jiffy's Blend 10,(B) Jiffy's Blend 10 + 0.5 mL of 100 mM Ca(NO3)2,(C) Jiffy's Blend 10 + 0.09 g carboxylated CNF (prepared from bagasse, about 333:1 weight ratio), crosslinked with 0.5 mL of 100 mM Ca(NO3)2,(D) Jiffy's peat fiber (w / o fertilizer),(E) (E) Jiffy's peat fiber (w / o fertilizer) + 0.5 mL of 100 mM Ca(NO3)2,(F) Jiffy's peat fiber (w / o fertilizer) + 0.1125 g carboxylated CNF (prepared from bagasse, about 222:1 weight ratio), crosslinked with 0.5 mL of 100 mM Ca(NO3)2,(G) Jiffy's peat fiber (w / o fertilizer) + 0.225 g carboxylated CNF (prepared from bagasse, about 111:1 weight ratio), crosslinked with 0.5 mL of 100 mM Ca(NO3)2,(H) Jiffy's peat fiber (w / o fertilizer),(I) Jiffy's peat fiber (with fertilizer) + 0.5 mL of 100 mM Ca(NO3)2,(J) Jiffy's peat fiber (with fertilizer) + 0.1125 g carboxylated CNF (prepared from bagasse, about 222:1 weight ratio), crosslinked with 0.5 mL of 100 mM Ca(NO3)2,(K) Jiffy's peat fiber (with fertilizer) + 0.225 g carboxylated CNF (prepared from bagasse, about 111:1 weight ratio), crosslinked with 0.5 mL of 100 mM Ca(NO3)2.The plugs were prepared by mixing carboxylated CNF with peat fiber paste in a specific weight ratio; the mixture was then compressed using a calibrated weight placed on top of the plugs. After adding the crosslinking agents on the top of the plugs, the plugs were incubated for 1 day-2 days, and then the seeds were placed on the plugs.

[0077] The preparation of 0.9 wt% carboxylated CNF suspension from bagasse (Jiffy) using a nitro-oxidation process (NOP) was as follows. About 80 grams of smaller-sized, non-ground bagasse fibers were added to a three-neck bottle flask. Next, 1.12 L of 50% HNO3acid was added and stirred at 200 rpm for 1 hour at 50°C. Then, 76.8 g of KNO2was added, and the reaction continued for 8 hours. The reaction was quenched with water, and the pH of the oxidized cellulose fibers was adjusted to 6.5 using 50% v / v ammonium hydroxide. The mixturewas then homogenized for 2 cycles.

[0078] Figs. 9A-9H show fully grown lettuce harvested after approximately 75 days. Figs. 9A and 9B and Figs. 9E and 9F show side and top views, respectively, using the (H) plug in Figs. 8A and 8B, including Jiffy's peat fiber without fertilizer. In contrast, Figs. 9C and 9D and Figs. 9G and 9H show side and top views, respectively, using the (G) plug in Figs. 8A and 8B, including Jiffy's peat fiber without fertilizer but with carboxylated CNF derived from bagasse using NOP in a 1:1 ratio, crosslinked with 0.5 mL of 100 mM CafNOsh-

[0079] Figs. 10A-10H show lettuce growth using a FlexiGel growing medium. All lettuce plants are 2.5 weeks old. The preparation methods for each type of plug and their resulting plant growth are detailed as follows. Figs. 10A and 10E show sample preparation 1 with a Flexigel growth medium. The plug of sample preparation 1 includes Jiffy's peat fibers without a binder mixed with carboxylated CNF at a ratio of about 3.5:1 by the dry mass of carboxylated CNF, crosslinked with 1 mL of 100 mM calcium nitrate [Ca(NO3)2] per plug. Figs. 10B and 10F show the sample preparation 1 in Figs. 10A and 10E with extensive root coverage throughout the plug. Figs. 10C and 10G show sample preparation 2 with a Flexigel growth medium. The plug of sample preparation 2 includes Jiffy's peat fibers without a binder mixed with carboxylated CNF at a ratio of about 7:1 by dry mass of carboxylated CNF, crosslinked with 1 mL of 100 mM calcium nitrate [Ca(NO3)2] per plug. Figs. 10D and 10H show sample preparation 2 in Fig. 10C and 10G, demonstrating significant root growth and distribution within the plug. These figures show the differences in root development and overall plant health between the plugs of sample preparations 1 and 2, indicating the effectiveness of both plugs to support early-stage lettuce growth.

[0080] Figs. 11A-11H show lettuce growth using PreGel plugs, focusing on their preparation and the resulting root development. All lettuce plants shown are 2.5 weeks old. Each plug of sample preparation 3 and 4 was prepared using different methods and materials. Figs. 11A and HE show sample preparation 3 using a PreGel growing medium. The plug of sample preparation 3 includes Jiffy's coco coir without a binder mixed with carboxylated CNF, which was derived from jute using the NOP method, at a ratio of about 3.5:1, by the dry mass of carboxylated CNF, crosslinked with 1 mL of 100 mM calcium nitrate [Ca(NO3)2] per plug. Figs.11B and 11F show preparation sample 3 of Figs. 11A and HE, highlighting the extensive root coverage throughout the plug. Figs. 11C and 11G show sample preparation 4. The plug of sample preparation 4 includes Jiffy's coco fiber without a binder mixed with carboxylated CNF at a ratio of about 7:1, by the dry mass of carboxylated CNF, crosslinked with 1 mL of 100 mM calcium nitrate [Ca(NO3)2] per plug. Figs. 11D and 11H show sample preparation 4 of Fig. 11C and 11F, demonstrating significant root growth and distribution within the plug. These figures show a clear indication of good root development and excellent plant health using the plugs of sample preparations 3 and 5, underlining the effectiveness of PreGel growing media in supporting lettuce growth during the early stages. Figs. 11A-11D are in black and white. Figs. 11E-11H are in color.

[0081] Figs. 12A-12D show mats according to example embodiments of the present invention. Figs. 12A and 12C show a first microgreen mat with a 0.5-inch thickness that was prepared using 218 g of Jiffy's peat moss with fertilizer, about 2.0 g of dry carboxylated CNF, 218 g of water, and 43.6 ml of CaNO3(200 mM). The preparation of the first mat is as follows. After the preparation of the peat - carboxylated CNF mixture, a mat was gently formed by pressing the mixture into a flat substrate, which was subsequently crosslinked with the CaNO3solution by spraying. Figs. 12B and 12D show the bottom view of a second mat with a 0.75-inch thickness that was prepared using 327 g of Jiffy's peat moss with fertilizer, about 3.0 g of CNF, by the dry mass of carboxylated CNF, 173 g of water, and 65.4 ml of CaNO3(50 mM). Figs. 12B and 12D show the density of root growth networks.

[0082] While example embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method for producing a growing medium, the method comprising: mixing a plant growth substrate material with one or more functionalized cellulose nanomaterials selected from the group including carboxylated cellulose nanofibers (CNF), carboxylated lignin-containing cellulose nanofibers (LCNF), and carboxylated cellulose nanocrystals (CNC); and adding a crosslinking agent selected from the group including inorganic salts, genipin, chitosan, citric acid, polydopamine, lignosulfonate, or a combination thereof, to form a growing medium composition.

2. The method of claim 1, further comprising incubating the growing medium composition at room temperature for about 0.5 h to about 48 h at 60°C prior to planting.

3. The method of claim 1 or 2, wherein the plant growth substrate material includes one or more of peat moss, coir, coco-coir, bark or wood fibers or chips, wool, sand, rice hulls, natural biomass, clay pellets, perlite, vermiculite, compost, composted pine bark, animal manure, hardwood bark, softwood bark, compost, or combinations thereof.

4. The method of one of claims 1-3, wherein the crosslinking agent includes monovalent, divalent, trivalent inorganic salts, or a combination thereof.

5. The method of claim 4, wherein the inorganic salts include one or more selected from the group including potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), nitrogen (N), phosphorus (P) as phosphate (PO43"), sulfur (S), boron (B), nitrate (NO3_), nickel (Ni), or a combination thereof.

6. The method of claim 4, wherein the inorganic salts include calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe), or a combination thereof.

7. The method of one of claims 1-6, wherein an amount of the one or more functionalized cellulose nanomaterials is in a range from about 0.1% to about 99.99% by weight or volume of a total of the growing medium composition.

8. The method of one of claims 1-6, wherein an amount of the one or more functionalized cellulose nanomaterials is in a range from about 1.0% to about 40.0% by weight.

9. The method of one of claims 1-6, wherein an amount of the one or more functionalized cellulose nanomaterials is in a range from about 0.1% to about 1.0% by weight.

10. The method of one of claims 1-9, wherein an amount of the plant growth substrate material is in a range from about 1.0% to about 99% by weight or volume.

11. The method of one of claims 1-9, wherein an amount of the plant growth substrate material is in a range from about 1.0% to about 50% by weight or volume.

12. The method of claim 1, wherein a weight ratio of the plant growth substrate material to the one or more functionalized cellulose nanomaterials is selected from the group including:1:1, 1:2, 1:5, 1:10, 2:1, 3:1, 2:5, 3:5, 4:5, 7:10, or 9:10.

13. The method of one of claims 1-12, further comprising combining cellulose sludge or macrofibers with the one or more functionalized cellulose nanomaterials prior to mixing with the plant growth substrate material.

14. The method of claim 13, wherein an amount of the cellulose sludge is in a range from about 0.1% to about 100% by weight relative to a weight of the one or more functionalized cellulose nanomaterials.

15. A method of conditioning soil comprising: mixing soil with one or more functionalized cellulose nanomaterials selected from the group including carboxylated cellulose nanofibers (CNF), carboxylated lignin-containing cellulose nanofibers (LCNF), carboxylated cellulose nanocrystals (CNC), or a combination thereof.

16. The method of claim 15, further comprising adding a crosslinking agent including one or more inorganic salts.

17. The method of claim 16, wherein the one or more inorganic salts is selected from the group including potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), nitrogen (N), phosphorus (P) as phosphate (PO43"), sulfur (S), boron (B), nitrate (NO3_), nickel (Ni), or a combination thereof.

18. The method of claim 16, wherein the one or more inorganic salts include calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe), or a combination thereof.

19. A growing medium comprising: a plant growth substrate material; one or more functionalized cellulose nanomaterials selected from the group including carboxylated cellulose nanofibers (CNF), carboxylated lignin-containing cellulose nanofibers (LCNF), and carboxylated cellulose nanocrystals (CNC); and a crosslinking agent including inorganic salts.

20. The growing medium of claim 19, wherein the plant growth substrate material includes one or more of peat moss, coir, coco-coir, bark or wood fibers or chips, wool, sand, rice hulls, natural biomass, clay pellets, perlite, vermiculite, compost, composted pine bark, animal manure, hardwood bark, softwood bark, or a combination thereof.

21. The growing medium of claim 19 or 20, wherein the inorganic salts are selected from the group including potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), nitrogen (N), phosphorus (P) as phosphate (PO43"), sulfur (S), boron (B), nitrate (NO3_), nickel (Ni), or a combination thereof.

22. The growing medium of claim 19 or 20, wherein the inorganic salts include calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe), or a combination thereof.

23. The growing medium of one of claims 19-22, wherein a weight ratio of the plant growth substrate material to the one or more functionalized cellulose nanomaterials is in a range from about 2:1 to about 1:2.

24. The growing medium of one of claims 19-22, wherein a weight ratio of the plant growth substrate material to the one or more functionalized cellulose nanomaterials is about 1:1.

25. The growing medium of one of claims 19-24, wherein an amount of the inorganic salts is in a range of about 0.1 mM to 5000 mM.

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