Spongy plugs and mats including carboxylated cellulose nanofiber scaffolds

Abstract

A growing medium includes carboxylated cellulose nanofibers (CNFs) having an oxidation of DO > about 0.7 mmol / g and a sodium content of less than about 50 ppm or about 1.5% of a total base saturation in 1000 g of a 1 wt% CNF suspension and one or more crosslinkers. The growing medium has a water content of greater than about 90% by weight. A growing medium includes carboxylated cellulose nanofibers (CNFs) having an oxidation of DO > about 0.7 mmol / g and a sodium content of less than about 50 ppm or about 1.5% of a total base saturation in 1000 g of a 1 wt% CNF suspension and one or more crosslinkers. The growing medium is aerated and has a water content of less than about 10% by weight.

Description

SPONGY PLUGS AND MATS INCLUDING CARBOXYLATED CELLULOSE NANOFIBER SCAFFOLDSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Patent Application No. 63 / 682,458 filed on August 13, 2024. The entire contents of this application are hereby incorporated by reference.BACKGROUND OF THE INVENTION1. Field of the Invention

[0002] The present invention relates to growing media, such as spongy plugs or mats, that can be used as a complete or partial replacement for traditional growing media. The spongy cultivation media can be used for crop production, particularly in the form of plugs, mats, or their aggregate based substrates, that support seed germination, root development, vegetative growth, and plant development.2. Description of the Related Art

[0003] Peat is an effective and widely used growing medium in agriculture and horticulture because of its porous fibrous structure, excellent aeration capability, good moisture retention ability, and suitable acidity. Peat is also used as a blending component in potting soils, or a garden and lawn amendment in turf maintenance for golf courses because its unique properties. However, the extraction of peat poses significant environmental concerns. The extraction process, which often involves lowering water tables and drying peatlands, accelerates peat decomposition, releasing carbon dioxide (CO2) and other pollutants, disrupting ecosystems, and causing irreversible ecological changes. These negative impacts have lead to the growing trend to reduce peat use and to preserve peatlands, especially in agriculture, forestry, and commercial applications, to maintain ecological balance and sustainability.

[0004] Several alternatives to peat, such as coir, wood fibers, chips, coconut fibers, wools, sands, and rice hulls, have been demonstrated. However, these substitutes often fall short in sufficient water and nutrient retention. Recently, hydrogel-based growing media made from both synthetic and bio-based polymers have gained attention as alternative substrates, but these materials often suffer from limited water reabsorption capacity, poor compressibility, andcompromised structural stability, which restrict their practical application. Additionally, other crosslinked polymers and mineral substances have been suggested as water-absorbing growing media. While these polymer-based substrates are lightweight and easy to handle, they are non- biodegradable, persistent in the environment, and lack the ability to provide essential nutrients or organic matters to the soil, making them unsuitable for organic farming and long-term soil health. Additionally, many of these materials cannot be produced locally, resulting in high transportation costs. It is thus essential to develop sustainable and effective alternatives that can address the above challenges and complement the traditional growing practice.SUMMARY OF THE INVENTION

[0005] Example embodiments of the present invention provide biodegradable, biocompatible, and elastic growing media that are suitable as sustainable alternatives to conventional soil-based and soilless substrates. The growing media include carboxylated cellulose fibers, including nano-, micro-, and macro-scale fibrils, specifically derived via a zerowaste nitro-oxidation process (NOP), which serve as the primary structural scaffold. These fibers are ionically crosslinked using food-safe inorganic salts that also function as essential plant macro- and micronutrients. Through a controlled freeze-thaw and crosslinking process, example embodiments can yield two classes of substrates: (i) wet sponges, including, for example, HydroSponge, FlexiSponge, and PreSponge, that are water-retentive, elastic, and compressible and that can be included in plug or mat forms; and (ii) aerated sponge, including, for example, AeroSponge, AeroFlexiSponge, and AeroPreSponge, that are aerated, porous, and lightweight biodegradable foams that can be used in applications requiring enhanced aeration and drainage. The modular compositions and tunable physical properties of these sponge-like substrates support seed germination, root development, and plant growth across hydroponic, aeroponic, and organic cultivation systems. The growing media can mimic or replicate the properties of peat, coir, rock wool, or synthetic foam plugs, yet includes biodegradable, biocompatible, and renewable ingredients and is free of persistent synthetic polymers. A system including the growing medium can enable automated hydroponic, aeroponic, or soilless cultivation without the use of peat, rock wool, or polyurethane foam.

[0006] The biomass-based sponge type growing media can support plant growth and cultivation in an environmentally responsible manner.

[0007] Example embodiments of the present invention can be used as growing media and soil conditioners. The example embodiments include (i) HydroSponge, FlexiSponge, and PreSponge, and (ii) AeroSponge, AeroFlexiSponge and AeroPreSponge.

[0008] The growing medium products can be made by freeze-thawing of hydrogels or composite-hydrogels containing carboxylated cellulose nanofibers (CNF) with a high degree of oxidation (e.g., DO > about 0.7 mmol / g, about 0.7 mmol / g < DO < about 1.2 mmol / g, DO > about 1.2 mmol / g, or DO > about 1.3 mmol / g), such as nitro-oxidized cellulose nanofibers (NOCNFs), cross-linked by micronutrient metal ions or other crosslinking agents. Example embodiments of wet spongy products include HydroSponge that is made from neat NOCNFs, FlexiSponge that is made from NOCNFs mixed with Jiffy's Flexistart™, which is an enriched allnatural substrate, and PreSponge that is made from NOCNFs mixed with Jiffy's Preforma™, which is a mixture of binder and specific substrates. The wet spongy products in the form of plugs, mats, or their aggregates exhibit good elasticity / compressibility, high water retention capacity, excellent drainage, reabsorption properties, high porosity, squeezability, and nutrient delivery ability, which are suitable for a wide range of agricultural and horticultural applications.

[0009] Aerated products can be made by freeze-drying of wet HydroSponge, FlexiSponge and PreSponge to form AeroSponge, AeroFlexiSponge and AeroPreSponge, respectively. These aerated products exhibit a very high porosity (> 70%-98%), excellent water retention capacity, and good mechanical properties, which are suitable for a wide range of agricultural / horticultural as well as packaging applications.

[0010] The manufacturing processes according to example embodiments of the present invention use carboxylated cellulose nanofibers (CNFs) (negatively charged) prepared by a zerowaste nitro-oxidation process (NOP) to treat diverse lignocellulose biomass feedstocks. The NOP-produced CNFs (NOCNFs) are prepared by ionic crosslinking of carboxylated cellulose nanofiber scaffolds and suitable monovalent, divalent, and trivalent ions such as macronutrients, including, for example, potassium (K+), calcium (Ca2+), and magnesium (Mg2+),micronutrients, including, for example, boron (B), zinc (Zn2+), manganese (Mn2+), iron (Fe2+or Fe3+), copper (Cu2+) etc. or other crosslinking agents. Different from conventionally made carboxylated nanocellulose, such as cellulose nanofibers produced by TEMPO-mediated oxidation (TOCNF), NOCNFs contain only a minimum concentration of sodium (Na+) (e.g., below 50 ppm or 1.5% the total base saturation. Typically, the sodium content in 1000 g of a 1 wt% suspension of TOCNF with a degree of oxidation of 1.5 mmol / g is approximately 350 ppm. High sodium levels can negatively impact soil structure, water infiltration, and ultimately, plant growth.

[0011] To further enhance the properties of the resulting substrates, biochar, soils, sands and other natural fiber substrates can be incorporated in the nanocellulose hydrogels of example embodiments to prepare nanocellulose hydrogel composites.

[0012] Example embodiments of the present invention can replace or complement traditional growing media, such as peat, bark, wood fibers, compost, perlite, and vermiculite, as well as can restore the soil health as conditioners or amendments. The sponge-like structure in these spongy / aerated substrates is particularly advantageous for efficient absorption and retention of water and nutrients. Furthermore, example embodiments in the form of plugs, mats, or their aggregates can be used to cultivate a variety of plant growth.

[0013] In some example embodiments, a wet spongy growing media can include nitrooxidized cellulose nanofibers (NOCNFs), food-safe inorganic salts, and, optionally, natural substrate materials, wherein the growing media is spongy and contains over about 98% water.

[0014] In some example embodiments, an aerated growing media can include nitrooxidized cellulose nanofibers (NOCNFs), food-safe inorganic salts, and, optionally, natural substrate materials, wherein the growing media is spongy and contains less than about 1% water.

[0015] In example embodiments, a growing media can include: a) mechanically mixing nitro-oxidized cellulose nanofibers (NOCNFs) and, optionally, natural substrate materials and placing in a mold to form a mixture; b) freeze-thawing the mixture; c) crosslinking the mixture with food-safe crosslinking agents during thawing.d) removing the cross-linked mixture to form a wet spongy product containing 98% or more water.

[0016] In example embodiments, a method of making a growing media can include: a) mechanically mixing nitro-oxidized cellulose nanofibers (NOCNFs) and, optionally, natural substrate materials and placing in a mold to form a mixture; b) freeze-thawing the mixture; c) crosslinking the mixture with food-safe crosslinking agents during thawing; d) removing the cross-linked mixture from the mold to form a spongy product containing 98% or more water. e) freeze-drying the crosslinked mixture in a lyophilization process to form an aerated product containing 1% or less water.

[0017] According to an example embodiment of the present invention, a growing medium includes carboxylated cellulose nanofibers (CNFs) having an oxidation of DO > about 0.7 mmol / g and a sodium content of less than about 50 ppm or about 1.5% of a total base saturation in 1000 g of a 1 wt% CNF suspension and one or more crosslinkers. The growing medium has a water content of greater than about 90% by weight.

[0018] The growing medium can include a structurally spongy, flexible matrix. The water content of the growing medium can be greater than 98% by weight. The growing medium can support seed germination, root development, vegetative growth, and plant development.

[0019] According to an example embodiment, a growing medium includes carboxylated cellulose nanofibers (CNFs) having an oxidation of DO > about 0.7 mmol / g and a sodium content of less than about 50 ppm or about 1.5% of a total base saturation in 1000 g of a 1 wt% CNF suspension and one or more crosslinkers. The growing medium is aerated and has a water content of less than about 10% by weight.

[0020] The water content of the growing medium can be less than 1% by weight. The growing medium can have a lightweight structure (e.g., a mass between about 0.001 g and about 500 g) and / or a rehydration capacity. The growing medium has a porosity between about 70% and about 98%.

[0021] The growing medium can have a recoverability after compression of about 70%- about 95% of its original height after full water rehydration.

[0022] The carboxylated CNFs can include nitro-oxidation-process-produced CNFs (NOCNFs). The carboxylated CNFs can further include lignocellulose nanofibers. The NOCNFs can be derived from a biomass source selected from the group including 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, bacteria, algae, tunicate, cow manure, pig manure, or a combination thereof. The growing medium can further include nutrients recovered from the biomass or added as NOP effluent; and the nutrients can include one or more of a trace element, an amino acid, a micronutrient, or a combination thereof.

[0023] The one or more crosslinkers can include a food-safe ionic crosslinker and / or a foodsafe molecular crosslinker. The one or more crosslinkers can be selected from a group including sodium, potassium, calcium, magnesium, iron (Fe2+ / Fe3+), aluminum, manganese, zinc, copper, molybdenum, nitrogen, phosphorus, sulfur, boron, chlorine, nickel, or a combination thereof in a concentration ranging from about 0.0001 mM to about 1000 mM.

[0024] The growing medium can further include at least one substrate material selected from the group including an organic source, an inorganic source, a natural source, or a synthetic source. The natural source can include one or more selected from the group including biochar, cellulose sludge, nanomaterials, clays, chitosan, peats, coir, coconut fibers, wood fibers, wood chips, wools, rice hulls, clay pellets, perlite, vermiculite, composts, agricultural waste-derived fibers, or a combination thereof, in an amount ranging from about 0.01% to about 90% by total dry weight of the mixture. The ratio of CNFs to substrate material can be between about 1:0.1 to about 1:20 by dry weight.

[0025] The growing medium can be in the form selected from the group including a plug, a sheet, a mat, a shredded aggregate, a molded tray, or a seed-embedded disc or pouch.

[0026] According to an example embodiment of the present system, a system includes the growing medium of another example embodiment and at least one of an irrigation controller, a seed carrier, or a nutrient delivery substrate.

[0027] According to an example embodiment of the present invention, a method of producing a growing medium includes preparing a mixture of nitro-oxidized-process-produced cellulose nanofibers (NOCNFs); dispensing the mixture into a mold or tray to shape into plug, mat, or aggregate form to provide a shaped mixture; freezing the shaped mixture to provide a frozen mixture; and thawing the frozen mixture in the presence of a crosslinking solution including one or more crosslinkers to provide a crosslinked product.

[0028] The mixture can include at least one substrate material selected from the group including an organic source, an inorganic source, a natural source, or a synthetic source. The natural source can include one or more of selected from the group including biochar, cellulose sludge, nanomaterials, clays, chitosan, peats, coir, coconut fibers, wood fibers, wood chips, wools, rice hulls, clay pellets, perlite, vermiculite, composts, agricultural waste-derived fibers, or a combination thereof, in an amount ranging from about 0.01% to about 90% by total dry weight of the mixture. The ratio of NOCNFs to substrate material is between about 1:0.1 to about 1:20 by dry weight.

[0029] The freezing the shaped mixture can be conducted at a temperature between about 0°C to about -196°C for a duration of about 0.01 hours to about 48 hours.

[0030] The one or more crosslinkers can include a food-safe ionic crosslinker and / or a foodsafe molecular crosslinker. The one or more crosslinkers can be selected from a group including sodium, potassium, calcium, magnesium, iron (Fe2+ / Fe3+), aluminum, manganese, zinc, copper, molybdenum, nitrogen, phosphorus, sulfur, boron, chlorine, nickel, or a combination thereof in a concentration ranging from about 0.0001 mM to about 1000 mM.

[0031] The method can further include washing the growing medium to remove unbound salts.

[0032] The one or more crosslinkers can be applied via surface diffusion into at least one of a top, a side, or a bottom surface of the frozen mixture; ionic-bath immersion; or vapor-phase ionic exposure. After applying the one or more crosslinkers, incubating can be performed forabout 1 hour to about 48 hours at a temperature between about 0°C to about 100°C to provide the crosslinked product. The ionic-bath immersion can include calcium nitrate in an amount between about 50 mM-about 300 mM. The incubating can be performed at a temperature between about 0°C and about 30°C.

[0033] The NOCNFs can be derived from a biomass source selected from the group including 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, bacteria, algae, tunicate, cow manure, pig manure, or a combination thereof. The NOCNFs include lignocellulose nanofibers.

[0034] The growing medium can further include nutrients recovered from the biomass or added as NOP effluent, and the nutrients can include one or more of a trace element, an amino acid, a micronutrient, or a combination thereof.

[0035] The method can further include adjusting a pH of the crosslinked product between about 4.5 and about 7.5 and / or adjusting an electrical conductivity of the crosslinked product between about 300 pS / cm and about 25,000 pS / cm.

[0036] The preparing the mixture can include aerating the mixture to form bubbles or nanobubbles during mixing to enhance porosity and root aeration. The aerating can be performed with air, oxygen, or CO2. The method can further include drying the crosslinked product via lyophilization, air-drying, or flash freezing to reduce moisture and to form an aerated structure. The drying can be performed for about 1 hour-about 72 hours under vacuum or cryogenic conditions to form the aerated structure. The growing medium can be elastic and can have rehydration capacity and nutrient buffering capability.

[0037] The method can further include embedding seeds in the growing medium.

[0038] The above and other features, elements, characteristics, steps, and advantages of the present invention will become more apparent from the following detailed description of example embodiments of the present invention with reference to the attached drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0039] 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.

[0040] Fig. 1 is a schematic diagram of a formation process for different growing media in two different forms: plug and mat.

[0041] Figs. 2A and 2B are pictures of compressive strength and water reabsorption tests for HydroSponge without biochar. Fig. 2A is in black and white. Fig. 2B is in color.

[0042] Figs. 3A and 3B are picture of compressive strength and water reabsorption tests for HydroSponge with biochar. Fig. 3A is in black and white. Fig. 3B is in color.

[0043] Figs. 4A and 4B are pictures of lettuce growth on a HydroSponge plug. Fig. 4A is in black and white. Fig. 4B is in color.

[0044] Figs. 5A and SB are pictures of comparative lettuce growth trials on HydroSponge plugs prepared through top to bottom diffusion application of crosslinking ions. Fig. 5A is in black and white. Fig. SB is in color.

[0045] Figs. 6A and 6B are pictures of comparative lettuce growth trials on HydroSponge plugs with (bottom panel) and without (top panel) biochar prepared through immersion in an ion-enriched water bath for crosslinking. Fig. 6A is in black and white. Fig. 6B is in color.

[0046] Fig. 7A and 7B are pictures of comparative lettuce growth trials on AeroSponge plugs with (bottom panel) and without (top panel) biochar prepared through immersion in an ion- enriched water bath for crosslinking. Fig. 7A is in black and white. Fig. 7B is in color.

[0047] Figs. 8A and 8B are pictures of a comparative study on lettuce growth usingHydroSponge and FlexiSponge Plugs. Fig. 8A is in black and white. Fig. 8B is in color.

[0048] Figs. 9A and 9B are pictures of a comparative study on the lettuce growth usingHydroSponge and PreSponge plugs. Fig. 9A is in black and white. Fig. 9B is in color.DETAILED DESCRIPTION

[0049] Fig. 1 show a schematic diagram of a manufacturing process for creating various forms of growing media, including nanocellulose-based wet spongy products (e.g., HydroSponge, FlexiSponge, PreSponge); and sponge-derived aerated products (e.g., AeroSponge, AeroFlexiSponge, AeroPreSponge), which can be in either plug or mat configurations, which can be further processed into different shapes in the form of aggregates. For example, the wet spongy products and aerated products can be in the form of a plug, a sheet, a mat, a shredded aggregate, a molded tray, or a seed-embedded disc or pouch.

[0050] In step (a) and step (b), the neat NOCNF suspension (i) or the mixture (ii) of nanocellulose suspension and substrate material(s) are introduced into a plug mold (a) or a tray (b) at the desired size and volume to form either a plug or a mat substrate (in plug, w: width, d: depth; in mat: w: width, d: depth, I: length), respectively. The nanocellulose suspension and substrate material(s) mixture (ii) is mechanically mixed for approximately 5 minutes, within manufacturing and / or measurement tolerances, to create a uniform paste with evenly distributed texture. The substrate materials can include an organic source, an inorganic source, a natural source, or a synthetic source. The substrate materials from a natural source include, for example, biochar, cellulose sludge, nanomaterials, clays, chitosan, or other soilless growing media such as peats, coir, coconut fibers, wood fibers, wood chips, wools, rice hulls, clay pellets, perlite, vermiculite, composts, and agricultural waste-derived fibers. The substrate material(s) can be included in an amount ranging from about 0.01% to about 90% by total dry weight of the mixture, within manufacturing and / or measurement tolerances. The ratio of CNFs to substrate material can be between about 1:0.1 to about 1:20 by dry weight, within manufacturing and / or measurement tolerances.

[0051] In step (a) and step (b), there is an option to infuse the mixture with air / gas bubbles or nanobubbles (air and / or oxygen and / or CO2) using a nanobubble generator. The bubbles can be charged with nutrients in real-time to further promote the growth-stimulating properties of the growing medium.

[0052] In step (c), the sample undergoes a freeze-thaw process to create a sponge-like property and to create precursor products of the wet spongy products (e.g., HydroSponge, FlexiSponge, and PreSponge). The freeze-thaw treatment involves the cooling of the plug mold or the tray to a temperature between 0°C to -196°C for a duration of about 0.01 hours to about 48 hours, within manufacturing and / or measurement tolerances, and then the returning to about room temperature or higher temperature, within manufacturing and / or measurement tolerances. During the freezing period, a fraction of water within the plug mold or tray can form ice crystals. Without the freeze-thaw treatment, the samples would maintain the gel-like behavior with low elasticity.

[0053] In step (d), crosslinkers or crosslinking agents (iv) can include ionic crosslinkers or crosslinking agents, such as monovalent, multivalent or trivalent ions, molecular crosslinkers or crosslinking agents, such as other reactive molecules, or combinations thereof. The crosslinkers or crosslinking agents are added the plug or mat either through top-, bottom- side- diffusion facilitated by the capillary forces, dispersed into an ionic or crosslinking agent solution bath, or vapor-phase ionic exposure. For example, an ionic-bath immersion can include calcium nitrate in an amount between about 50 mM-about 300 mM, within manufacturing and / or measurement tolerances. To achieve comprehensive distribution and effective integration of the ions and / or crosslinking agents within the plug or mat, an incubation step can be maintained for a period ranging from about 1 to about 48 hours, within manufacturing and / or measurement tolerances, as in step (e). This incubation can occur either at room temperature or under refrigerated conditions, within a temperature range of about 1°C to about 20°C, a temperature range of about 0°C to about 100°C, a temperature range of about 0°C to about 30°C, or even at higher temperatures, within manufacturing and / or measurement tolerances. After crosslinking reactions, wet spongy products (e.g., HydroSponge, FlexiSponge, PreSponge) are produced. The wet spongy products can have a water content of > about 90% by weight or > about 98% by weight, within manufacturing and / or measurement tolerances, and can have structurally spongy, flexible matrix. The growing media can be washed to remove unbound salts.

[0054] In step (f), the products prepared in step (e) are subjected to a drying process, such as lyophilization, air drying, flash freezing, freeze-drying, etc., to rapidly remove moisture and form dry aerogel structures. The drying process can be performed for about 1 hour-about 72 hours, within manufacturing and / or measurement tolerances, under vacuum or cryogenic conditions to form an aerated structure. This drying process transform any hydrated product into an aerated product, retaining structural integrity but becoming very lightweight. The aerated products can have a mass between about 0.001 g and about 500 g, within manufacturing and / or measurement tolerances. The aerated products derived from wet spongy products include, for example, AeroSponge, AeroFlexiSponge, and AeroPreSponge. The drying process can reduce the water content from > about 90% by weight (or > about 98% by weight) , within manufacturing and / or measurement tolerances, to < 10% by weight (or < 1% by weight) , within manufacturing and / or measurement tolerances.

[0055] The wet spongy growing medium can include carboxylated cellulose nanofibers (CNFs) having an oxidation of DO > about 0.7 mmol / g and a sodium content of less than about 50 ppm or about 1.5% of a total base saturation in 1000 g of a 1 wt% CNF suspension, within manufacturing and / or measurement tolerances. The aerated growing medium can include carboxylated cellulose nanofibers (CNFs) having an oxidation of DO > about 0.7 mmol / g and a sodium content of less than about 50 ppm or about 1.5% of a total base saturation in 1000 g of a 1 wt% CNF suspension, within manufacturing and / or measurement tolerances. The oxidation of the wet spongy growing medium and the aerated growing medium can be high such that the DO satisfies any of the following: DO > about 0.7 mmol / g, about 0.7 mmol / g < DO < about 1.2 mmol / g, DO > about 1.2 mmol / g, or DO > about 1.3 mmol / g.

[0056] Seeds can be embedded in the wet spongy or aerated growing media.

[0057] The wet spongy or aerated growing media can be incorporated in a hydroponic, an aeroponic, or a soil-less cultivation system that can include an irrigation controller, a seed carrier, or a nutrient delivery substrate and that can be automated.

[0058] A difference between wet-spongy growing media and aerated growing media lies in their physical properties and water management characteristics. Wet-spongy growing media, such as HydroSponge, FlexiSponge, and PreSponge, exhibit elasticity and flexibility, allowingthem to compress and expand for efficient water release and reabsorption, making them suitable for applications with fluctuating moisture levels. The wet sponge imparts elasticity and dynamic water management capabilities, ideal for resilient, flexible substrates suitable for stable water retention and nutrient delivery. The corresponding aerated products provide high porosity, a lightweight structure, and rehydration capacity for reuse in crop production systems. The aerated products can have a porosity of between about 70% and about 98%, within manufacturing and / or measurement tolerances. The wet spongy and aerated growing media can have a recoverability after compression of about 70%-about 95%, within manufacturing and / or measurement tolerances, of its original height after full water rehydration.

[0059] The terms referring to aerated products (e.g., AeroSponge, AeroFlexiSponge, AeroPreSponge) correspond to their respective wet spongy products (e.g., HydroSponge, FlexiSponge, PreSponge). The primary difference is that the wet spongy products (e.g., HydroSponge, FlexiSponge, PreSponge) are composed of a large fraction of water (> 90% or > 98%), whereas the aerated products (e.g., AeroSponge, AeroFlexiSponge, AeroPreSponge,) contain less water, as the water molecules have been excluded through, for example, lyophilization. For different growing media, the corresponding composition, water content, and manufacturing method used are illustrated in Table 1.Table 1: The composition, water content, and preparation method used for different growing media.

[0060] The some wet spongy products, e.g., HydroSponge, and some aerated products, e.g., AeroSponge, can be free of peat, coir or other soilless growing media and can provide versatile growing media. These sponge products and aerated products without soilless growing media can be made in the form of plugs, mats, other shapes, or their aggregates. These two media are made entirely of either NOCNF or an NOCNF blend with other substrate materials, such as, for example, biochar. These two media can support plant growth by providing physical infrastructure, retaining water, enhancing aeration, and supplying essential nutrients. The two media can facilitate seed germination and root establishment by balancing water and nutrient levels. The wet spongy products without soilless growing media, e.g., HydroSponge, can allow root observation due to its transparency and is compressible for easy transport, recovering fully after water reabsorption. The corresponding aerated products without soilless growing media, e.g., AeroSponge, is a lightweight variant that also supports plant growth by improving aeration, water absorption, and providing nutrients, primarily aiding seed germination and root establishment.

[0061] Some wet spongy products, e.g., FlexiSponge, and some aerated products, e.g., AeroFlexiSponge, can provide growing media in various forms, including plugs or mats, that include peat or coco-coir, with or without additional materials such as soils, wood fibers, and wood chips. For example, FlexiSponge can be made by combining Jiffy's Flexi fibers (without binders) and NOCNF, significantly reducing the need for peat or coir fibers by over 90 wt%. FlexiSponge enhances buffering capacity, provides organic support, and offers superior water absorption and reabsorption. FlexiSponge also includes air bubbles to improve aeration and nutrient supply. The AeroFlexiSponge is a lightweight variant, heavier than AeroSponge but lighter than FlexiSponge, also available in various forms. AeroFlexiSponge is designed for easier transportation and combines Jiffy's Flexi fibers and NOCNF to reduce peat or coir fiber requirements. AeroFlexiSponge improves aeration and nutrient supply by include air bubbles of varying shapes and sizes.

[0062] Some wet spongy products, e.g., PreSponge, and some aerated products, e.g., AeroPreSponge, can be prepared by blending Jiffy's Preforma fibers (without binders) with NOCNF. This formulation enhances buffering capacity, provides organic physical support, and offers excellent water absorption and reabsorption. PreSponge can be fully loaded with water and nutrients for plant demand, while AeroPreSponge includes more air bubbles to improve aeration and to provide a slow, sustained release of nutrients. AeroPreSponge’s lightweight nature makes it easier to transport and handle compared to PreSponge, HydroSponge and FlexiSponge.

[0063] The term "cellulose" denotes a fibrous biomaterial ranging in size from macro to micro to nano, extractable from various biomass feedstocks and / or natural organic wastes. This cellulose is crosslinked with several salts or other crosslinking agents to fulfill multiple objectives, such as enhancing water and nutrient retention and anchoring a seed securely on the wet sponge or aerated plug or mat surface for a duration adequate for seed germination and root development within the plugs / mats.

[0064] Biomass feedstocks can be sourced from both woody and nonwoody plants, 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, and various combinations thereof.

[0065] The cellulose extraction is not limited to plant sources; it can also be derived from bacteria, algae, tunicate, non-plant biomasses such as cow manure, pig manure, etc. or their various combinations. The growing medium may encompass one or more cellulose components. The term ’cellulose components' encompasses cellulose nanofibers CNF, cellulose nanocrystals (CNC), tunicate cellulose, bacterial cellulose, or their amalgamation.

[0066] Natural organic waste encompasses food waste, green waste, fruits and vegetable wastes, meat and fish wastes including 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 cellulose production of for various suitable nanocellulose hydrogel products.

[0067] An illustration of NOCNF or cellulose nanofibers prepared by a nitro-oxidation process (NOP) in step (i) of Fig. 1, which is disclosed in U.S. Pat. No. 10,894,838, the entire contents of which are hereby incorporated by reference. NOPs can employ various biomass feedstocks, allowing for the utilization of both hard and softwoods, as well as agricultural residues and natural fibers. Softwoods, agricultural residues, and some natural fibers with low lignin content can be used with NOPs. The CNFs and NOCNFs used in the growing media can include lignocellulose nanofibers.

[0068] Cross-linking refers to the interaction between negatively charged cellulose fibers and positively charged salt ions through electrostatic forces. This interaction involves two oppositely charged ionic sites, resulting in mutual attraction. Depending on the type of salt ions, such as transitional metal ions, interactions with cellulose functionalities can occur through metal-ligand interaction. This interaction may involve a coordinate covalent bond, also known as a dative bond, dipolar bond, or coordinate bond. Besides salts, molecular compounds can be used to crosslink the cellulose fibers to form the wet spongy growing media. In alternative example embodiments, one or more crosslinking agents, such as genipin, chitosan, citric acid, polydopamine, lignosulfonate, etc., can also be used to crosslink NOCNF fibers and one or more plant growth substrate materials.

[0069] The crosslinking agent can include ionic crosslinkers, including, monovalent (n - +1), divalent (n - +2), as well as trivalent (n - +3) salts. These salts, including both cation and counterions, are food-safe and include sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), aluminum (Al), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), nitrogen (N), phosphorus (P), sulfur (S), boron (B), chlorine (Cl), nickel (Ni)-based salt ions, or a combination thereof. Alternatively, the salts include calcium (Ca), magnesium (Mg), zinc, iron(Fe), aluminum nitrogen (N), and combinations thereof. The crosslinkers can be included in a concentration ranging from about 0.0001 mM to about 1000 mM. The growing media can be washed to remove unbound salts.

[0070] The above components are considered macronutrients and micronutrients for the plants, and they are utilized to form wet spongy products and to form aerated products. These salts, and similar types, can be applied in the form of solution or granules, powder, pills, or equivalent forms.

[0071] The wet spongy and aerated growing media can include cellulose in the range of about 0.01 to about 99.99 wt%, within manufacturing and / or measurement tolerances, combined with a salt solution in the concentration range of about 1 mmol to about 1000 mmol, within manufacturing and / or measurement tolerances. In specific formulations, the plug and mat growing media can include about 0.01 wt% cellulose and about 1.0 wt% cellulose components, within manufacturing and / or measurement tolerances. Alternatively, cellulose can be included in the range of about 1.0 wt% to about 10 wt%, within manufacturing and / or measurement tolerances, and cellulose components can be included in the range of about 10 wt% to about 20 wt%, within manufacturing and / or measurement tolerances. Another variation might involve cellulose in the range of about 20 wt% to about 30 wt% and cellulose components in the range of about 30 wt% to about 40 wt%, within manufacturing and / or measurement tolerances. In an alternate formulation, the plugs or mats composition or growing medium may include about 40 wt% cellulose and about 50 wt% cellulose components, within manufacturing and / or measurement tolerances. Moreover, the composition may integrate around 50 wt% to about 100 wt% or more of additional components, within manufacturing and / or measurement tolerances, relative to the total weight of the growing medium.

[0072] To provide stability, the wet spongy growing media, including, e.g., HydroSponge, FlexiSponge, PreSponge, and the aerated growing media, including, e.g., AeroSponge, AeroFlexiSponge, AeroPreSponge, can be crosslinked by various ions, and include a cellulose content of at least about 0.5 wt%-about 2.0 wt% or about 1 wt%-about 5 wt%, with about 100mM-about 500 mM of divalent or about 100 mM-about 200 mM of trivalent ions, within manufacturing and / or measurement tolerances.

[0073] While cellulose is a major ingredient of the wet spongy and aerated growing media, lignin, hemicellulose, holocellulose, proteins, and fatty acids can also be included. The specific composition of lignin depends on the feedstock used. If softwood is utilized, lignin can include of coniferyl alcohol; for hardwood, lignan may include coniferyl alcohol and sinapyl alcohol; for grass, lignin is exclusively composed of three monomers: coniferyl, sinapyl, and p-coumaryl alcohol. Hemicellulose can encompass 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 feedstocks used. The NOP processed effluents including recovered nutrients from the feedstock can be incorporated into the cellulose matrix during the preparation of the wet spongy and aerated growing media. The inclusion of NOP recovered nutrients can enhance the overall nutritional value of the final product. The nutrients can include one or more of a trace element, an amino acid, a micronutrient, or a combination thereof.

[0074] In Fig. 1, the NOCNF suspension (i) is introduced into a plug mold or a tray at the desired size and volume to form either a plug or a mat, respectively. During these steps, additional materials can be incorporated, including but not limited to biochar, cellulose sludge, natural nanomaterials, clays, chitosan, or other soilless growing media such as peats, coir, coconut fibers, wood fibers, wood chips, wools, rice hulls, clay pellets, perlite, vermiculite, and composts, as well as a combination of these or other fibers at a particular wt% typically ranging from about 0.01 to about 100 wt% relative to the total volume of the plugs or mats growing media, within manufacturing and / or measurement tolerances.

[0075] As shown in step (a) and step (b) of Fig. 1, about 0.5 wt%-about 10 wt% of NOCNF or cellulose fibers in suspension can be used as the primary scaffolding components. These fibers are mixed with about 0.01 wt%-about 90 wt%, within manufacturing and / or measurement tolerances, of biochar, other soilless growing media fibers such as peat, coir, coconut fibers, wood fibers, activated carbon, compost, or combinations thereof. The mixing ratio of NOCNF to biochar and / or other fibers / materials components by weight can vary, with typical ratiosincluding about 1:0.1 to 1:20 by dry weight, within manufacturing and / or measurement tolerances, depending on the desired properties of the final product. This flexibility in the ratio allows for customization of the growing medium to optimize its performance for specific applications.

[0076] In step (a) and step (b) of Fig. 1, there is an option to infuse the mixture with air bubbles or nanobubbles (air and / or oxygen and / or CO2) using a nanobubble generator. This infusion process is designed to enhance root growth and contribute to the formation of the wet spongy and aerated growing media, or combinations thereof. The bubbles can be charged with nutrients in real-time to further promote the growth-stimulating properties of the medium. This incorporation has been shown to improve the pore volume, aeration, and water absorption capabilities of the medium while also contributing to its environmentally friendly attributes. These enhancements collectively foster a more supportive and efficient growing environment for plant roots.

[0077] The lyophilization (freeze-drying) process can be carried out in several approaches, including cryogenic freezing using liquid nitrogen or dry ice (solid carbon dioxide) exposing the NOCNF or its composite mixtures at temperatures as low as -196°C. Alternatively, other rapid freezing techniques can be employed, including flash freezing, quench cooling, immersion freezing, vapor compression freezing, plate freezing, blast freezing, spray freezing, or cryomilling. These freezing methods impose rapid and uniform freezing on the growing media, preserving the integrity and quality of the NOCNF or other fibers mixture within the growing media.

[0078] To reduce rapid evaporation of moisture in the wet spongy products, e.g., HydroSponge, FlexiSponge, PreSponge, or any combination of these materials, the wet spongy products can be stored in a refrigerator at about 4°C-about 8°C, within measurement tolerances, for an appropriate duration. These materials should not kept at room temperature for more than about 7 days-about 10 days to prevent the materials from shrinking except the plugs or mats forms of AeroSponge, AeroFlexiSponge, AeroPreSponge which are stored as a dehydrated form.

[0079] Table 2 shows detailed measurements for HydroSponge and AeroSponge evaluated with and without biochar supplementation and with or without deionized (DI) water washing, which can be used as a reference to choose the right growing medium for agricultural applications with specific substrate requirements.Table 2: Physical and Compositional Characteristics of HydroSponge and AeroSponge GrowingMedia

[0080] For example, as the pH level of the plug is a factor for hydroponic plant cultivation, obtaining a suitable pH level will be vital as it affects nutrient availability and plant growth. The ideal pH range for hydroponic lettuce is 5.5-6.5, with an optimal target of 5.8. In Table 2, the pH values for the substrates range from 4.65 to 6.59 depending on the growing mediums composition and post treatments such as washed vs unwashed, which are all suitable growing substrates for typical applications such as hydroponic lettuce cultivation. The slight variations in pH among the different growing media allow for flexibility in choosing the right growing medium based on other factors like water retention, ion concentration, and so on. The pH of the growing media can be adjusted in a range between about 4.5 and about 7.5, within manufacturing and / or measurement tolerances.

[0081] In hydroponics, electrical conductivity (EC) is another factor to consider, where EC can be determined by the conductivity measurement within the hydroponic nutrient solution. EC indicates the number of available nutrients in the hydroponic system. In Table 2, the electrical conductivity (EC) of the plugs is between 746 pS / cm and 26510 pS / cm, indicating ahigher ion concentration. In general, the unwashed plugs show higher EC levels, whereas washed plug has the lowest EC. These characteristics can guide the selection of substrates based on specific nutrient requirements and ion concentration needs in hydroponic systems. The electrical conductivity of the growing media can be adjusted in a range between about 300 pS / cm and about 25,000 pS / cm, within manufacturing and / or measurement tolerances.

[0082] In the context of hydroponic applications, the measured physical and compositional characteristics of HydroSponge and AeroSponge— with and without biochar, and with or without DI water washing— directly influence nutrient availability, seedling establishment, and plant growth performance. Hydroponic systems require substrates with stable pH in the range of about 5.5-about 6.5 for optimal nutrient uptake, and the data show that biochar addition consistently adjusted the pH of both HydroSponge and AeroSponge toward this ideal range.

[0083] Electrical conductivity (EC), a key indicator of soluble salts that can cause osmotic stress in hydroponics, was markedly reduced by DI water washing, particularly in biocharcontaining blends, with AeroSponge washed with biochar achieving an exceptionally low EC of 746.3 pS / cm— well within the safe range for sensitive seedlings. High germination rates observed in the biochar-enhanced and washed variants (up to 99% in AeroSponge and 95.8% in HydroSponge) indicate strong seedling compatibility, while the higher dry leaf and root biomass in washed HydroSponge with biochar (7.1 g leaf, 0.62 g root) demonstrates improved early- stage vigor, critical for hydroponic crop turnover efficiency. The combination of biochar's pH- buffering and nutrient-retentive properties with washing's salinity control suggests these growing media can provide an optimized root-zone environment in hydroponic systems, supporting rapid germination, healthy root development, and sustained nutrient availability without the risk of salt stress.EXAMPLESExample 1Preparation of NOCNF suspensions from untreated jute fibers:

[0084] To prepare jute-based NOCNF suspensions, 500 grams of non-ground untreated jute chips was placed in a 50-liter reactor. These samples were then treated with 50% nitric acid (HNO3) at 50°C and 25 psi for 1 hour. Then the pressure was gradually increased to 75 psi for atotal of 9 hours. After the reaction, the pH of the slurry was adjusted to 6.5. Finally, the slurry was homogenized to obtain the NOCNF suspension. This method yielded an anionic cellulose scaffold with a degree of oxidation about 1.7 mmol / g.Example 2Preparation of NOCNF suspensions from sugarcane bagasse:

[0085] For this sample preparation, we finely cut, non-ground bagasse fibers were provided. The samples were treated with 50% nitric acid (HNO3) at 50°C and atmospheric pressure under stirring for 1 hour. Subsequently, potassium nitrite (KNO2) was added to the reactor to allow the reaction to continue for an additional 8 hours. To stop the reaction, the mixture was quenched with water. Finally, the pH level of the cellulose slurry was adjusted to 6.5. Uniform NOCNF suspensions were then prepared by mechanical homogenization.Example 3NOCNF HydroSponge and NOCNF / biochar HydroSponge preparation:

[0086] The procedures for preparation of various hydrosponge plugs from NOCNF or NOCNF / biochar hydrogels were following those outlined in Fig. 1.Example 4Preparation of a Jute NOCNF-biochar mixture:

[0087] To prepare the jute NOCNF / biochar mixture, the received biochar was sieved through a 0.5 mm mesh. The sieved biochar was then added to the NOCNF paste with desired component weight ratio. Finally, an appropriate amount of water was added to the NOCNF / biochar mixture and stirred continuously to achieve a uniform consistency. This prepared mixture was subsequently used for the creation of plugs.Example 5Compressive strength and water reabsorption tests for HydroSponge without biochar:

[0088] Photographs in Figs. 2A and 2B show the results of compressive strength and water reabsorption tests conducted on a HydroSponge sample that does not include biochar. TheHydroSponge sample (a) was prepared by freeze-thaw treatment of a jute-based NOCNF suspension with 200 mM CafNOsh- The tests were performed using a standard calibration weight of 200 grams (b) to assess the material's structural integrity (c) and its ability to reabsorb water after compression (d). The HydroSponge prepared by NOCNF derived from jute demonstrated the ability to recover nearly 90% of its initial height (a and f) after undergoing a compressive test, followed by water reabsorption (d and e).Example 6Compressive strength and water reabsorption tests for HydroSponge made from the NOCNF / biochar mixture:

[0089] Photographs in Figs. 3A and 3B show the results of compressive strength and water reabsorption tests for a HydroSponge sample that incorporates biochar. These tests, also conducted with a 200-gram standard calibration weight, evaluate how the addition of biochar affects the material's durability and its capacity to reabsorb water post-compression. The biochar loaded HydroSponge was prepared by the freeze-thaw treatment of the NOCNF- biochar mixture and the sequentially crosslinked with 200 mM CafNCbh. It is seen that this HydroSponge can recover almost 70% of its initial height after compression and then water reabsorption.Example 7Lettuce growth on HydroSponge plugs:

[0090] Figs. 4A and 4B illustrate the progression of lettuce growth on a HydroSponge plug made from jute-based NOCNF. The preparation of the plug included the freeze-thaw treatment of NOCNF suspension and subsequent crosslinking with 200 mM CafNCHh, 200 mM MgSO4 and 200 mM FefNOsh- (a) The initial setup of the HydroSponge plug, (b-f) Sequential stages of lettuce growth on the HydroSponge plug: (b) Germination stage, right after seedling emergence, (c) After 5 days of growth, (d) After 10 days of growth, (e) After 5 weeks of growth, showing early vegetative stage, (f) After 8 weeks of growth, reaching the mature vegetative stage. Each photograph captures the development and vitality of the lettuce, demonstratingthe effectiveness of the HydroSponge plug in supporting plant growth from seed germination through to the mature vegetative stage.Example 8Lettuce growth trials on various HydroSponge plug formulations (prepared through top to bottom diffusion application of crosslinking ions):

[0091] The photographs in (i) of Figs. 5A and 5B show the results of several lettuce growth experiments conducted on HydroSponge plugs made with different formulations and conditions, labeled C-2, C-4, and C-8, corresponding to different trial setups over a span of 6, 5, and 3 weeks, respectively. The experiments explore the effects of varying the composition and freezing duration of NOCNF from the jute and biochar on plant growth. The plugs compositions are presented as follows:

[0092] C-2 Trials: (A) HydroSponge plugs prepared with a jute NOCNF suspension, frozen at-20°C for 16 hours, then treated with 50 mM Ca(NO3)2. (B) HydroSponge plugs prepared with a jute NOCNF suspension, frozen at -20°C for 16 hours, then treated with 100 mM Ca(NO3)2. (C) HydroSponge plugs prepared with a mixture of NOCNF and biochar, frozen at -20°C for 16 hours, then treated with 50 mM Ca(NO3)2. (D) HydroSponge plugs prepared with a mixture of NOCNF and biochar, frozen at -20°C for 16 hours, then treated with 100 mM Ca(NO3)2.

[0093] C-4 Trials: (A) HydroSponge plugs prepared with a jute NOCNF suspension, frozen at-20°C for 20 hours, then treated with 50 mM Ca(NO3)2and 50 mM MgS04. (B) HydroSponge plugs prepared with a jute NOCNF suspension, frozen at -20°C for 20 hours, then treated with 100 mM Ca(NO3)2. (C) HydroSponge plugs prepared with a mixture of NOCNF and biochar, frozen at -20°C for 20 hours, then treated with 50 mM Ca(NO3)2and 50 mM MgS04. (D) HydroSponge plugs prepared with a mixture of NOCNF and biochar, frozen at -20°C for 20 hours then treated with 100 mM Ca(NO3)2.

[0094] C-8 Trials: (A) HydroSponge plugs prepared with a mixture of NOCNF and jute cellulose sludge, frozen at -20°C for 18 hours, then treated with 50 mM Ca(NO3)2and 50 mM MgS04. (B) HydroSponge plugs prepared with a mixture of NOCNF, jute cellulose sludge and biochar, frozen at -20°C for 18 hours, then treated with 50 mM Ca(NO3)2and 50 mM MgS04.

[0095] The photographs in (ii) of Figs. 5A and 5B show a lettuce plant growing on aHydroSponge plug from the C-8 trial. The image highlights the robust root network encircling the plug, demonstrating the effectiveness of the material in supporting healthy root development.Example 9

[0096] Lettuce growth trials were conducted on various HydroSponge plug formulations with biochar (bottom panel) and without biochar (top panel) in Figs. 6A and 6B, each prepared through immersion in an ion-enriched water bath for crosslinking. The trays illustrate lettuce growth progression from germination at week 1 through to harvest at week 7. Top panel: HydroSponge plugs were fabricated by dispensing 30-35 mL of NOCNF suspension (1.0 wt%), freezing at -20 °C, and subsequently immersing the frozen plugs into a 200 mM calcium nitrate ionic bath during thawing to achieve crosslinking. Bottom panel: HydroSponge plugs containing biochar were prepared using 30-35 mL of NOCNF suspension (2.0 wt%) blended with biochar at a 1:6 ratio (biochar:NOCNF by mass), frozen at -20 °C, and subjected to the same ionic crosslinking process by immersion in a 200 mM calcium nitrate bath during thawing.Example 10

[0097] Lettuce growth trials were conducted on various AeroSponge plug formulations with biochar (bottom panel) and without biochar (top panel) in Figs. 7A and 7B, each prepared through immersion in an ion-enriched water bath for crosslinking. The trays illustrate lettuce growth progression from germination at week 1 through to harvest at week 7 / 8. Top panel: AeroSponge plugs were fabricated by dispensing 30-35 mL of NOCNF suspension (2 wt%), freezing at -20 °C, and subsequently immersing the frozen plugs into a 200 mM calcium nitrate ionic bath during thawing to achieve crosslinking. Following crosslinking, the plugs were subjected into lyophilization for 2 days to produce the final AeroSponge plug. Bottom panel: AeroSponge plugs containing biochar were prepared using 30-35 mL of NOCNF suspension (2 wt%) blended with biochar at a 1:6 ratio (biochar:NOCNF by mass), frozen at -20 °C, and subjected to the same ionic crosslinking process by immersion in a 200 mM calcium nitrate bathduring thawing. Following crosslinking, the plugs were subjected to lyophilization for 1-2 days to produce the final AeroSponge plug.Example 11A comparative study on lettuce growth using HydroSponge and FlexiSponge plugs:

[0098] Figs. 8A and 8B show a comparative analysis of lettuce growth on two types of growing media plugs: HydroSponge and FlexiSponge. All lettuce plants in the study are 2.5 weeks old (al-cl) and 7 weeks old (a2-c2), providing a comparison of growth and root development across the different plug formulations. The details of each preparation and their corresponding results are as follows: (al, a2) HydroSponge plug preparation: The plug is made from 18 mL of 0.8 wt% NOCNF from jute, frozen for 18 hours at -20°C, and then treated with 1 mL of 100 mM calcium nitrate [Ca(NO3)2] per plug, (bl, b2) FlexiSponge plug formulation 1: This plug includes 18 mL of 0.8 wt% NOCNF from jute combined with 0.5 g of Jiffy Flexistart (including fine peats without a binder), frozen for 18 at -20°C, followed by the addition of 1 mL of 100 mM calcium nitrate [Ca(NO3)2] per plug, (cl, c2) FlexiSponge plug formulation 2: In this preparation, the plug is composed of 18 mL of 0.8 wt% NOCNF from the jute mixed with 1.0 g of Jiffy Flexistart (without a binder), frozen for 18 hours at -20°C, and then treated with 1 mL of 100 mM calcium nitrate [Ca(NO3)2] per plug, (d) The photograph shows a close-up of the FlexiSponge plug from formulation (cl), highlighting the extensive root coverage and penetration throughout the plug, demonstrating its suitability for promoting healthy root growth.Example 12A comparative study on the lettuce growth using HydroSponge and PreSponge plugs:

[0099] Figs. 9A and 9B compare the growth of lettuce plants using two different types of growing media plugs: HydroSponge and PreSponge. All the lettuce plants observed in this study are 2.5 weeks old (top panel) and 7 weeks old (bottom panel). These photographs provide a visual comparison of root development and overall plant health between the different plug formulations. Each plug's preparation and their respective outcomes are detailed below: (al) A HydroSponge plug was made from jute-based NOCNF, frozen at -20 °C for 18 hours, and treatedwith 100 mM Ca(NO3)2per plug, (bl) A PreSponge plug Sample 1 was prepared by a mixture of jute-based NOCNF and Jiffy Preforma (coco coir fiber without a binder), frozen at -20°C for 18 hours, and then treated with 100 mM Ca(NO3)2per plug, (c) A photograph showing the PreSponge from formulation (bl) with extensive root coverage throughout the plug, (dl) A PreSponge plug Sample 2 was prepared by a mixture of jute-based NOCNF and 2 times of Jiffy Preforma as in (c), frozen at -20°C for 18 hours, and then treated with 100 mM Ca(NO3)2per plug, (e) A photograph shows the PreSponge from formulation (dl), demonstrating significant root growth and coverage within the plug.

[0100] It should be understood that the foregoing description is only illustrative of the present invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the present invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications, and variances that fall within the scope of the appended claims.T1

Claims

WHAT IS CLAIMED IS:

1. A growing medium comprising: carboxylated cellulose nanofibers (CNFs) having an oxidation of DO > about 0.7 mmol / g and a sodium content of less than about 50 ppm or about 1.5% of a total base saturation in 1000 g of a 1 wt% CNF suspension; and one or more crosslinkers; wherein the growing medium has a water content of greater than about 90% by weight.

2. The growing medium of claim 1, wherein the growing medium includes a structurally spongy, flexible matrix.

3. The growing medium of claim 1 or 2, wherein the water content of the growing medium is greater than 98% by weight.

4. The growing medium of one of claims 1-3, wherein the growing medium supports seed germination, root development, vegetative growth, and plant development.

5. A growing medium comprising: carboxylated cellulose nanofibers (CNFs) having an oxidation of DO > about 0.7 mmol / g and a sodium content of less than about 50 ppm or about 1.5% of a total base saturation in 1000 g of a 1 wt% CNF suspension; and one or more crosslinkers; wherein the growing medium is aerated and has a water content of less than about 10% by weight.

6. The growing medium of claim 5, wherein the water content of the growing medium is less than 1% by weight.

7. The growing medium of claim 5 or 6, wherein the growing medium has a mass between about 0.001 g and about 500 g and / or a rehydration capacity.

8. The growing media of one of claims 5-7, wherein the growing medium has a porosity between about 70% and about 98%.

9. The growing medium of one of claims 5-8, wherein the growing medium has a recoverability after compression of about 70%-about 95% of its original height after full water re hydration.

10. The growing medium of one of claims 1-9, wherein the carboxylated CNFs include nitro-oxidation-process-produced CNFs (NOCNFs).

11. The growing medium of claim 10, wherein the NOCNFs is derived from a biomass source selected from the group including 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, bacteria, algae, tunicate, cow manure, pig manure, or a combination thereof.

12. The growing media of one of claims 1-11, wherein the growing medium further includes nutrients recovered from the biomass or added as NOP effluent; and the nutrients include one or more of a trace element, an amino acid, a micronutrient, or a combination thereof.

13. The growing medium of one of claims 1-12, wherein the one or more crosslinkers include a food-safe ionic crosslinker and / or a food-safe molecular crosslinker.

14. The growing media of one of claims 1-13, wherein the one or more crosslinkers are selected from a group including sodium, potassium, calcium, magnesium, iron (Fe2+ / Fe3+), aluminum, manganese, zinc, copper, molybdenum, nitrogen, phosphorus, sulfur, boron, chlorine, nickel, or a combination thereof in a concentration ranging from about 0.0001 mM to about 1000 mM.

15. The growing medium of one of claims 1-14, further comprising at least one substrate material selected from the group including an organic source, an inorganic source, a natural source, or a synthetic source.

16. The growing medium of claim 15, wherein the natural source includes one or more selected from the group including biochar, cellulose sludge, nanomaterials, clays, chitosan, peats, coir, coconut fibers, wood fibers, wood chips, wools, rice hulls, clay pellets, perlite, vermiculite, composts, agricultural waste-derived fibers, or a combination thereof, in an amount ranging from about 0.01% to about 90% by total dry weight of the mixture.

17. The growing medium of claim 15 or 16, wherein a ratio of CNFs to substrate material is between about 1:0.1 to about 1:20 by dry weight.

18. The growing medium of one of claims 1-17, wherein the growing medium is in the form selected from the group including a plug, a sheet, a mat, a shredded aggregate, a molded tray, or a seed-embedded disc or pouch.

19. A system comprising: the growing medium of claim 18; and at least one of an irrigation controller, a seed carrier, or a nutrient delivery substrate.

20. A method of producing a growing medium comprising: preparing a mixture of nitro-oxidized-process-produced cellulose nanofibers (NOCNFs); dispensing the mixture into a mold or tray to shape into plug, mat, or aggregate form to provide a shaped mixture; freezing the shaped mixture to provide a frozen mixture; and thawing the frozen mixture in the presence of a crosslinking solution including one or more crosslinkers to provide a crosslinked product.

21. The method of claim 20, wherein the mixture includes at least one substrate material selected from the group including an organic source, an inorganic source, a natural source, or a synthetic source.

22. The method of claim 21, wherein the natural source includes one or more of selected from the group including biochar, cellulose sludge, nanomaterials, clays, chitosan, peats, coir, coconut fibers, wood fibers, wood chips, wools, rice hulls, clay pellets, perlite, vermiculite, composts, agricultural waste-derived fibers, or a combination thereof, in an amount ranging from about 0.01% to about 90% by total dry weight of the mixture.

23. The method of claim 21 or 22, wherein a ratio of NOCNFs to substrate material is between about 1:0.1 to about 1:20 by dry weight.

24. The method of one of claims 20-23, wherein the freezing the shaped mixture is conducted at a temperature between about 0°C to about -196°C for a duration of about 0.01 hours to about 48 hours.

25. The method of one of claims 20-24, wherein the one or more crosslinkers includes a food-safe ionic crosslinker and / or a food-safe molecular crosslinker.

26. The method of one of claims 20-25, wherein the one or more crosslinkers are selected from a group including sodium, potassium, calcium, magnesium, iron (Fe2+ / Fe3+), aluminum, manganese, zinc, copper, molybdenum, nitrogen, phosphorus, sulfur, boron, chlorine, nickel, or a combination thereof in a concentration ranging from about 0.0001 mM to about 1000 mM.

27. The method of one of claims 20-26, further comprising washing the growing medium to remove unbound salts.

28. The method of one of claims 20-27, wherein the one or more crosslinkers is applied via: surface diffusion into at least one of a top, a side, or a bottom surface of the frozen mixture; ionic-bath immersion; or vapor-phase ionic exposure; and after applying the one or more crosslinkers, incubating for about 1 hour to about 48 hours at a temperature between about 0°C to about 100°C to provide the crosslinked product.

29. The method of claim 28, wherein ionic-bath immersion includes calcium nitrate in an amount between about 50 mM-about 300 mM.

30. The method of claim 28 or 29, wherein the incubating is performed at a temperature between about 0°C and about 30°C.

31. The method of one of claims 20-30, wherein the NOCNFs is derived from a biomass source selected from the group including 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, bacteria, algae, tunicate, cow manure, pig manure, or a combination thereof.

32. The method of one of claims 20-31, wherein the growing medium further includes nutrients recovered from the biomass or added as NOP effluent; and the nutrients include one or more of a trace element, an amino acid, a micronutrient, or a combination thereof.

33. The method of one of claims 20-32, further comprising: adjusting a pH of the crosslinked product between about 4.5 and about 7.5; and / or adjusting an electrical conductivity of the crosslinked product between about 300 pS / cm and about 25,000 pS / cm.

34. The method of one of claims 20-33, wherein the preparing the mixture includes aerating the mixture to form bubbles or nanobubbles during mixing to enhance porosity and root aeration.

35. The method of claim 34, wherein the aerating is performed with air, oxygen, or CO2.

36. The method of one of claims 20-35, further comprising drying the crosslinked product via lyophilization, air-drying, or flash freezing to reduce moisture and to form an aerated structure.

37. The method of claim 36, wherein the drying is performed for about 1 hour-about 72 hours under vacuum or cryogenic conditions to form the aerated structure.

38. The method of one of claims 20-37, wherein the growing medium is elastic and has rehydration capacity and nutrient buffering capability.

39. The method of one of claims 20-38, further comprising embedding seeds in the growing medium.

40. The growing medium of claim 10, wherein the carboxylated CNFs further include lignocellulose nanofibers.

41. The method of one of claims 20-39, wherein the NOCNFs include lignocellulose nanofibers.

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