A phosphate-inositol chitosan composite organic fertilizer and its preparation method

Abstract

This invention relates to the field of agricultural fertilizer technology, specifically to a phosphoinositol-chitosan composite organic fertilizer and its preparation method. The organic fertilizer comprises modified phosphoinositol, chitosan graft, humic acid, sugar alcohol chelated zinc, alginate oligosaccharide, bentonite, and a well-rotted organic carrier. Specifically, the modified phosphoinositol and chitosan graft synergistically form a "dual-signal driven" system, effectively activating signaling pathways related to plant root development; the alginate oligosaccharide and sugar alcohol chelated zinc synergistically enhance plant stress resistance; and humic acid and bentonite jointly improve soil structure and achieve slow nutrient release. This organic fertilizer integrates nutrient supply, soil improvement, and physiological regulation, significantly promoting crop root growth, enhancing its resistance to drought, low temperatures, and diseases, and achieving stable yield increases. Furthermore, the raw materials are natural and environmentally friendly, the process is simple, and it is suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of agricultural fertilizer technology, specifically to a phosphate inositol chitosan compound organic fertilizer and its preparation method. Background Technology

[0002] Developing environmentally friendly and multifunctional fertilizer products has become an industry consensus. Against this backdrop, functional organic fertilizers have attracted widespread attention because they can provide nutrients while also improving soil physicochemical properties and biological activity. Natural or modified substances such as chitosan, humic acid, seaweed extracts, and mineral carriers have been applied in fertilizer development.

[0003] However, most functional organic fertilizer products currently on the market still share common problems such as uneven nutrient release, limited functionality, and limited effect on root growth. Therefore, developing a unified, multifunctional organic fertilizer that can significantly promote crop root development and improve stress resistance, while also being safe, environmentally friendly, and increasing yield and income, and simultaneously achieving "multi-signal synergy + structural stability + nutrient regulation," has significant practical implications and promotional value. Summary of the Invention

[0004] In view of this, the present invention provides a phosphate-inositol chitosan compound organic fertilizer and its preparation method. The present invention, through specific modification of phosphate-inositol and optimized compounding with chitosan grafts of a specific structure, forms a synergistic "dual-signal driven" system, achieving multiple synergistic effects of nutrient supply, soil improvement, and physiological regulation. This significantly promotes crop root development, enhances resistance to drought, cold, and disease, and achieves stable yield increases.

[0005] The technical solution of this invention is implemented as follows: In a first aspect, the present invention provides a phosphate-inositol chitosan compound organic fertilizer, comprising the following components: modified phosphate-inositol, chitosan graft, humic acid, sugar alcohol chelated zinc, alginate oligosaccharide, bentonite, and decomposed organic carrier, wherein the modified phosphate-inositol is a graft copolymer of phosphate-inositol and acrylate monomers; and the chitosan graft is a chitosan-vanillin Schiff base generated by the reaction of chitosan and vanillin.

[0006] Preferably, based on a total mass percentage of 100%, it includes: 8-10% modified inositol phosphate, 12-15% chitosan graft, 18-22% humic acid, 3-5% sugar alcohol chelated zinc, 0.1-0.3% alginate oligosaccharide, 15-18% bentonite, and the balance being a decomposed organic carrier.

[0007] Preferably, the modified inositol phosphate is prepared by a method comprising the following steps: S1. After crushing the rice bran, extract it with citric acid solution to obtain an extract containing inositol phosphate esters; S2. Add phytase to the extract for enzymatic hydrolysis; S3. Add an initiator and acrylate monomers to the enzymatically hydrolyzed system to carry out a graft copolymerization reaction; S4. Concentrate and dry the reaction solution to obtain powdered modified inositol phosphate.

[0008] Specifically, compared to unmodified inositol phosphate, this invention introduces hydrophobic segments by grafting acrylate monomers, resulting in a hydrophilic-hydrophobic balanced structure that enhances its migration and diffusion capabilities in soil and its absorption efficiency by plant roots. Furthermore, the conformational change after grafting strengthens its binding affinity to receptor proteins on plant cell membranes, thereby more effectively activating downstream Ca2+. 2+ The signaling pathway promotes the division of root tip meristem cells, resulting in stronger root viability.

[0009] Preferably, the effective phosphorus content in the modified inositol phosphomolybdate is determined by the gravimetric method of quinoline phosphomolybdate as specified in the national standard GB / T 8573-2017, and is ≥40%.

[0010] Preferably, the amount of phytase added is 1500-2500 U / g based on the initial mass of rice bran, and the enzyme activity of the phytase used is not less than 5000 U / mg.

[0011] More preferably, the initiator is ammonium persulfate.

[0012] Preferably, the method for preparing the chitosan graft includes: dissolving chitosan in an acidic solution, reacting it with vanillin under acidic conditions to generate a Schiff base, and obtaining a chitosan-vanillin Schiff base after precipitation, washing, and drying; wherein the molar ratio of the amino group in the chitosan to the aldehyde group in the vanillin is 1:(1.1-1.3).

[0013] Specifically, while ordinary chitosan has certain antibacterial and life-promoting properties, it is difficult to specifically activate the plant immune system. However, this invention reacts it with vanillin to generate a Schiff base structure, which mimics the spatial configuration of natural plant elicitors. This structure can efficiently bind to LRR receptor kinases on plant cell membranes and induce the synthesis pathways of ethylene and auxin (IAA).

[0014] Preferably, the sugar alcohol chelated zinc is prepared by zinc salt and mannitol; the molar ratio of zinc ions to mannitol in the zinc salt is 1:(1.2-1.8).

[0015] More preferably, the chelation rate of the sugar alcohol chelated zinc is 91.5%-95.5%.

[0016] Preferably, the average molecular weight of the alginate oligosaccharide is 500-2000 Da.

[0017] Specifically, alginate oligosaccharides with molecular weights in this range are most easily recognized by plant cell membrane receptors, stimulating the strongest systemic resistance response, exhibiting good plant elicitor activity, and can induce systemic resistance.

[0018] Preferably, the bentonite has a particle size of 200-300 mesh and a cation exchange capacity of ≥80 mmol / 100g.

[0019] Specifically, a high cation exchange capacity (CEC) can enhance the exchange capacity for K+. + Ca 2+ The adsorption and slow-release capacity of nutrients can be used as a carrier and conditioner to enhance the slow-release performance of fertilizers.

[0020] Preferably, the decomposed organic carrier is selected from one or more of livestock and poultry manure, straw compost or urban sludge humus, and its degree of decomposition is ≥90%.

[0021] Specifically, controlling the degree of decomposition to ≥90% can ensure harmlessness and eliminate the risk of seedling burn.

[0022] Secondly, the present invention provides an application of the phosphoinositol chitosan compound organic fertilizer as described in the first aspect in agricultural production.

[0023] Preferably, the phosphoinositol chitosan compound organic fertilizer is mixed and processed into granules or powders with a moisture content of ≤10%, and applied to vegetables, fruit trees or grain crops by means of basal application, spraying or drip irrigation, at a rate of 5-30 kg / mu.

[0024] Compared with the prior art, the advantages of the present invention are as follows: (1) The chitosan graft of the present invention forms a "dual signal driven" system with modified inositol phosphate to synergistically promote the activity of root meristems and significantly increase the length of the taproot and the number of lateral roots; inositol phosphate is an important precursor of signaling molecules in plants, and its hydrolysis product inositol phosphate can activate intracellular Ca2+. 2+ The pathway promotes cell division in the root tip meristem; chitosan grafts, as exogenous elicitors, can bind to receptor proteins on the plant cell wall, inducing the synthesis pathways of ethylene and auxin (IAA); under the synergistic effect of both, IAA / Ca... 2+ The signaling pathway was dually activated, significantly increasing the frequency of root primordia formation and elongation rate. Neither modified inositol phosphate nor chitosan grafts alone could effectively link IAA and Ca. 2+ Only when the two are combined can an interlocking generative mechanism be formed.

[0025] (2) The alginate oligosaccharide and sugar alcohol chelated zinc of the present invention jointly activate the plant antioxidant system and improve the crop's tolerance to stresses such as drought, low temperature and salinity; the alginate oligosaccharide (AOS) can activate the plant MAPK cascade reaction, upregulate the expression of pathogenesis-related proteins and phenylalanine ammonia-lyase (PAL) genes, and establish systemic acquired resistance (SAR); zinc is a core cofactor of superoxide dismutase (SOD) and participates in the removal of reactive oxygen species (ROS) under stress; under drought or low temperature stress, AOS provides early warning and zinc removes free radicals in time, and the two constitute a "warning-removal" double insurance mechanism, which significantly improves the crop's survival rate under stress.

[0026] (3) The chitosan grafted structure of the present invention forms a three-dimensional network coating system with bentonite, which prolongs the release cycle of functional components; humic acid and bentonite synergistically improve soil structure, enhance cation exchange capacity and water and fertilizer retention performance; humic acid molecules contain a large number of carboxyl groups and phenolic hydroxyl groups, which can connect soil particles through hydrogen bonds and electrostatic interactions, promoting the formation of aggregates; bentonite has a layered silica-alumina structure and high cation exchange capacity (CEC), which can adsorb NH4 + K + The isonutrient ions prevent leaching; when combined, the humic acid coats the surface of bentonite, forming a stable organic-mineral complex, which not only improves soil aggregate stability but also enhances fertilizer and water retention capacity. Long-term application can significantly improve soil health.

[0027] (4) All raw materials of this invention are natural or renewable resources, free from artificial hormones and harmful heavy metals, environmentally friendly and pollution-free; can be industrially prepared, the mixing and granulation process is stable, and it is suitable for large-scale promotion and application. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 The infrared spectrum of the modified phosphoinositol and chitosan graft in the preparation example of this invention; Figure 2 This is a comparison diagram of soybean traits under different fertilizers applied in Example 1 and Comparative Example 1 of the present invention; Figure 3 This is a schematic diagram of the Qijiawan experimental field in Huangpi District, Wuhan, in Embodiment 4 of the present invention. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0031] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0032] In this document, the terms “containing,” “comprising,” or “including” are open-ended expressions, meaning they include the contents specified in this invention but do not exclude other aspects.

[0033] In this document, the terms “optional,” “optionally,” or “optional” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0035] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0036] In an embodiment of the present invention, the modified inositol phosphate is prepared as follows: 1) Take rice bran raw material with a moisture content ≤10% (purchased from Shijiazhuang Rongze Agricultural Co., Ltd.), crush it and pass it through a 60-mesh sieve; add the crushed rice bran to a 0.1 mol / L citric acid extraction solution at a material-to-liquid ratio of 1:10 (g / mL); place the mixture in a constant temperature water bath at 60±2℃ and stir continuously for 2 hours; after the reaction is completed, centrifuge and collect the supernatant to obtain the extract containing inositol phosphate esters; 2) Add phytase to the above extract for enzymatic hydrolysis; the amount of phytase added is 1500-2500 U / g dry rice bran (based on the initial feed weight of rice bran), and the enzyme activity of the phytase used is not less than 5000 U / mg; the enzymatic hydrolysis reaction conditions are controlled as follows: temperature 50±1℃, pH value maintained at 5.0, and reaction time 4h; in this invention, the optimal amount of phytase added is 2000 U / g dry rice bran, using phytase with an enzyme activity of 5000 U / mg (purchased from Inner Mongolia Yiduoli Biotechnology Co., Ltd.), that is, 0.4 mg of phytase powder needs to be added per g of rice bran; 3) In the enzymatic hydrolysis reaction system, ammonium persulfate (purchased from Shanghai Maclean Biochemical Technology Co., Ltd.) was added sequentially as an initiator and methyl acrylate (purchased from Shanghai Sigma-Aldrich Trading Co., Ltd.) as a grafting monomer. Subsequently, under nitrogen atmosphere protection, the temperature of the reaction system was raised to 65°C, and the reaction was continuously stirred at this temperature for 3 hours. The amount of ammonium persulfate added was 0.03% of the mass of rice bran, and the amount of methyl acrylate added was 3% of the mass of rice bran. During this process, some inositol phosphate molecules underwent graft copolymerization with methyl acrylate to generate a modified inositol phosphate derivative with a hydrophobic-hydrophilic balance structure. 4) After the reaction is complete, the reaction solution is post-treated. First, the reaction solution is concentrated using an ultrafiltration membrane with a molecular weight cutoff of 3000 Da until the volume is reduced to 1 / 5 of the original volume. Then, the concentrated solution is spray-dried. The spray-drying process parameters are: inlet temperature 180℃, outlet temperature 80℃, and inlet air velocity 25 m / s. 3 / min; finally, a brownish-yellow powdery modified inositol phosphate extract was obtained; 5) The obtained powder product was tested; the gravimetric method of quinoline phosphomolybdate was used to determine the effective phosphorus content in the product, which was not less than 45%, according to the national standard GB / T 8573-2017. The presence of characteristic peaks of C=O and POC was confirmed by infrared spectroscopy (FTIR), which proved that the grafting was successful.

[0037] In an embodiment of the present invention, the chitosan graft is prepared as follows: 1) Chitosan with a degree of deacetylation ≥ 85% (purchased from Shanghai Maclean Biochemical Technology Co., Ltd.) was dissolved in 1 wt.% acetic acid solution to prepare a 3% (g / mL) chitosan solution; nitrogen gas was introduced into the solution for 30 min to remove dissolved oxygen; 2) Add vanillin (purchased from Shanghai Sigma-Aldrich Trading Co., Ltd.) to the above solution, and control the molar ratio of amino groups in chitosan to aldehyde groups in vanillin to be 1:1.2; adjust the pH of the reaction system to 5.0±0.5 with sodium hydroxide solution; then stir the reaction in a constant temperature water bath at 60±10℃ for 3 hours, and the reaction solution turns bright yellow. 3) After the reaction is complete, the reaction solution is poured into anhydrous ethanol to precipitate the product; after centrifugation, the precipitate is washed three times with anhydrous ethanol; the washed precipitate is placed at 45°C and vacuum dried for 6 hours to obtain a bright yellow powdered chitosan-vanillin Schiff base product. 4) The grafting was proven successful by infrared spectroscopy (FTIR).

[0038] like Figure 1 As shown, Figure 1 Infrared spectroscopy was performed on a small sample of the modified inositol phosphate and grafted chitosan; the product was measured at 1766 cm⁻¹. -1 A distinct absorption peak of the carbonyl (C=O) stretching vibration of the ester (characteristic of methyl acrylate) appears at 1683 cm⁻¹. -1 and 584 cm -1 A strong absorption peak (characteristic of phosphate ester bonds) appears at 2082 cm⁻¹, along with a peak at 2082 cm⁻¹. -1 Aliphatic CH stretching vibration peaks (-CH3 characteristic) were observed nearby.

[0039] At the same time, 3445 cm -1 The broad peak at 2082 cm⁻¹ is due to the superposition of OH and NH stretching vibrations, mainly originating from unreacted hydroxyl groups and residual amino groups in chitosan; -1 The absorption peak at 1633 cm⁻¹ corresponds to the saturated CH stretching vibration (e.g., -CH₃). This peak originates from the methoxy group (-OCH₃) of vanillin, confirming the introduction of the vanillin structure and its role in supporting hydrophobic modification. -1 The strong absorption peak at the point indicates the stretching vibration of the imine bond (C=N) (a characteristic peak of Schiff bases). This peak clearly shows that the amino group of chitosan undergoes a condensation reaction with the vanillin aldehyde group to form a Schiff base bond.

[0040] In an embodiment of the present invention, the method for preparing the sugar alcohol chelated zinc is as follows: 1) Dissolve zinc sulfate heptahydrate (ZnSO4·7H2O) in deionized water at 60±2℃ to prepare a zinc salt solution with a mass fraction of 20%; 2) Add zinc ions to mannitol (purchased from Guangdong Mingtong Biotechnology Co., Ltd.) at a molar ratio of 1:(1.2-1.8); adjust the pH of the reaction system to 6.5±0.2, and stir at 70±2℃ for 1.5±0.2h to carry out the chelation reaction; 3) After the reaction is complete, the system is cooled to room temperature and allowed to stand for crystallization for 2 hours; the crystals are separated by centrifugation and washed three times with anhydrous ethanol; the washed crystals are vacuum dried at 45±2℃ for 6 hours to obtain a white powdery sugar alcohol chelated zinc product. The chelation rate of the sugar alcohol chelated zinc is 91.5%-95.5%. The chelation rate is determined by the difference method. The specific steps are as follows: First, the total zinc content of the product is determined by atomic absorption spectrometry. Then, the sample is treated with 10wt% trichloroacetic acid solution to precipitate the unchelated free zinc ions. After centrifugation, the concentration of free zinc in the supernatant is determined.

[0041] The chelation rate is calculated using the following formula: Chelation rate (%) = (Total zinc content - Free zinc content) / Total zinc content × 100%.

[0042] Preparation Example 1 This preparation example aims to determine the optimal amount of phytase added in the preparation of the modified inositol phosphate. Based on the above preparation method, the phytase addition amounts were set to 1000, 1500, 2000, 2500, and 3000 U / g dry rice bran. Enzymatic hydrolysis was carried out under the same conditions, and the available phosphorus content of each group was determined using the quinoline phosphomolybdate gravimetric method. The results are shown in Table 1. Table 1. Optimization experiment of phytase addition amount in modified phosphoinositol

[0043] Table 1 shows that when the phytase addition amount is 2000 U / g dry rice bran, the available phosphorus content reaches its peak (45.6%). Further increasing the enzyme amount leads to increased side reactions, product degradation, and decreased efficiency. Therefore, 2000 U / g was determined to be the optimal addition amount for the subsequent preparation of modified phosphoinositol.

[0044] Preparation Example 2 In this preparation example, to determine the optimal ratio of zinc salt to mannitol in the preparation of the sugar alcohol chelated zinc, the molar ratio of zinc ions to mannitol was set to 1:1.2, 1:1.5, and 1:1.8 according to the above preparation method. Chelation was carried out under the same conditions, and the chelation rate of the sugar alcohol chelated zinc is shown in Table 2.

[0045] Table 2 Measured chelation rate of zinc chelated with sugar alcohol at different molar ratios

[0046] Table 2 shows that when Zn 2+ When the mannitol molar ratio was 1:1.5, the chelation rate reached its peak (95.5%). Further increasing the mannitol content led to a slight decrease in the chelation rate. This may be because excess mannitol increased the system viscosity, affecting molecular diffusion and coordination balance, or triggered steric hindrance, thus inhibiting further improvement in chelation efficiency. Therefore, the determination of Zn... 2+ The mannitol molar ratio was 1:1.5, which was used for the subsequent preparation of sugar alcohol chelated zinc.

[0047] Preparation Example 3 This preparation example aims to determine the molar ratio of amino groups in chitosan to aldehyde groups in vanillin during the preparation of the chitosan graft. Based on the above preparation method, the molar ratios of amino groups in chitosan to aldehyde groups in vanillin were set to 1:1.0, 1:1.1, 1:1.2, 1:1.3, and 1:1.4, with all other conditions remaining consistent. After the reaction was completed, the grafting rate of the product was measured. The grafting rate was calculated as: Grafting rate (%) = Increase in carbon content in the product / Theoretical maximum increase × 100%. The carbon content was determined by measuring the mass percentage of carbon in the sample using a CHNS elemental analyzer. The results are shown in Table 3.

[0048] Table 3 Optimization of the molar ratio of amino to aldehyde groups in the preparation of chitosan grafts

[0049] The results showed that the grafting rate reached its peak (83.7%) when the molar ratio was 1:1.2. Further increasing the vanillin content led to excessive cross-linking, decreased solubility, and was not conducive to subsequent compounding. Therefore, the optimal molar ratio was determined to be 1:1.2.

[0050] Example 1 This embodiment provides a modified phosphoinositol chitosan organic fertilizer, its preparation method, and its application, including the following steps: First, weigh the following components by weight percentage: modified inositol phosphate 8%; chitosan graft 12%; humic acid (purchased from Guangdong Best Chemical Technology Co., Ltd.) 18%; sugar alcohol chelated zinc 3%; alginate oligosaccharide (purchased from Hubei Kemaidi Chemical Co., Ltd., AOS, molecular weight 500 Da) 0.1%; bentonite (purchased from Tianjin Damao, 200 mesh, CEC 80 mmol / 100g) 15%; well-rotted livestock and poultry manure (purchased from Hebei Shanggutianfeng Biotechnology Co., Ltd.) 43.9%. After thoroughly mixing the above materials, they were granulated into granules using a disc granulator and dried until the moisture content was ≤10% to obtain the finished product, which was in the form of dark brown granules with a particle size of 2-4 mm. A pot experiment was conducted on soybean (variety: Zhonghuang 13) seeds in soil. 10 g of this fertilizer was applied to each pot and evenly mixed into the topsoil (15 cm deep). The control group was treated with a traditional compound fertilizer with the same nitrogen, phosphorus and potassium content (purchased from Handan Yuanwo Fertilizer Technology Co., Ltd., N+P2O5+K2O≥4, containing ≥30% organic matter). Ten pots were set up and randomly arranged, and the average value of the results was taken.

[0051] Depend on Figure 2The results after 28 days showed that compared with soybeans treated with traditional compound fertilizer, the organic fertilizer increased the number of pods per plant by 15, the pod filling rate by 14.00%, the seed setting rate by 3.92%, the 100-seed weight by 0.45g, the average yield increase by 5.27g, and the yield increase rate by 16.20%. The testing methods were as follows: pod count per plant was manually counted; pod filling rate = (number of full pods / total number of pods) × 100%; 100-seed weight was calculated using the 1000-seed weight method; and yield was calculated by weighing after drying.

[0052] Comparative Example 1 The difference between this comparative example and Example 1 is that unmodified ordinary inositol phosphate is used. The difference between the preparation method of ordinary inositol phosphate and the preparation method of modified inositol phosphate is that step 3) is omitted, and the graft copolymerization reaction is omitted. That is, after completing the enzymatic hydrolysis in step 2), no initiator and acrylate monomers are added. Instead, the enzymatic hydrolysate is directly concentrated by ultrafiltration and spray-dried to obtain ungrafted inositol phosphate extract.

[0053] Except for the use of ordinary inositol phosphate, the other components in the formula are the same as in Example 1. Potted soybean experiment results: Compared with traditional compound fertilizer, the number of pods per plant increased by only 6.2, the pod filling rate increased by 7.1%, the 100-seed weight increased by 0.21g per plant, and the average yield increase was only 7.3%. This indicates that modified inositol phosphate is a key signaling factor for initiating root meristem production, and the modification treatment significantly improves the bioavailability of inositol phosphate.

[0054] Example 2 This embodiment provides a modified phosphoinositol chitosan organic fertilizer, its preparation method, and its application, including the following steps: First, weigh out the following: 10% modified inositol phosphate; 15% chitosan graft; 22% humic acid (purchased from Guangdong Best Chemical Technology Co., Ltd.); 5% sugar alcohol chelated zinc; 0.3% alginate oligosaccharide (purchased from Hubei Kemaidi Chemical Co., Ltd., molecular weight 2000 Da); 18% bentonite (purchased from Tianjin Damao, 300 mesh, CEC 90 mmol / 100g); and 29.7% mature straw compost (purchased from Gansu Wobao Agricultural Technology Development Co., Ltd., moisture 30%). Mix these ingredients and then extrude and granulate them to produce a powder product. This is used as a top dressing for tomatoes (applied twice, once at the initial flowering stage and once at the fruit setting stage, 5 kg per acre each time, integrated into the drip irrigation system, and consistent with pest and disease control management measures).

[0055] Field tests showed that the average tomato yield in the treatment area of ​​Example 2 reached 1642 catties / mu, an increase of 191 catties / mu (13.2%) compared to the control group of Example 2. Simultaneously, the SOD (superoxide dismutase) activity in the leaves increased by 31%, and the MDA (malondialdehyde) content decreased by 22%, indicating a significant enhancement in stress resistance. SOD activity was detected by the nitroblue tetrazolium (NBT) photoreduction method; MDA content was detected by the thiobarbituric acid (TBA) colorimetric method.

[0056] Comparative Example 2 The difference between this comparative example and Example 2 is that the zinc ion to mannitol molar ratio of 1:1.2 and the chelation rate of only 91.5% in Example 2 are chelated zinc with mannitol.

[0057] Except for the use of sugar alcohol chelated zinc with a low chelation rate, the other components in the formulation were the same as in Example 2. In Comparative Example 2, the average tomato yield per mu (approximately 0.067 hectares) reached 1451 jin (approximately 722.5 catties), and the tomatoes showed slight yellowing. Compared with Example 2, SOD activity decreased, MDA content increased, and drought resistance significantly decreased. This indicates that the synergistic chelation of zinc and AOS can effectively activate the antioxidant system, with an optimal chelation rate of 95.5%.

[0058] Example 3 Rapeseed (Zhongyou 909) was applied as a base fertilizer in Qijiawan, Huangpi District, Wuhan. The organic fertilizer formula was the same as in Example 1.

[0059] Method: One seed dressing plus three sprayings; when dressing the seeds, first dilute the organic fertilizer with water at a ratio of 1:1, then mix the diluted seed dressing agent with the seeds at a ratio of 1:30, ensuring that the seeds have a uniform color.

[0060] For example, 10 grams of organic fertilizer mixed with 10 grams of water makes 20 grams of seed dressing agent, which can be used to dress 600 grams of seeds. If 90 jin (45 catties) of seeds need to be dressed, 750 grams of organic fertilizer can be mixed with an equal amount of water to make about 3 jin (1.5 catties) of seed dressing agent. It is recommended to use mechanical operation when dressing large quantities of seeds. After dressing, let the seeds dry slightly until they are no longer sticky to the touch before sowing. If using a drone for sowing, the seeds can be mixed with granular compound fertilizer or other base fertilizers, and the sowing rate should be set at 30 kg / mu (0.067 hectares). The three sprayings are as follows: the first spray is when the rapeseed seedlings are 15-20 cm tall; the second spray is during the bolting stage; and the third spray is during the pod-setting stage.

[0061] Field observations showed that the average taproot length of the rapeseed in this treatment group was 28.6 cm, an increase of 42.3% compared to control group 3; the number of lateral roots per plant was 47, an increase of 62.1% compared to control group 3; and the average yield of the experimental group was 1876 catties per mu, an increase of 17.4%. This indicates that the fertilizer of this invention significantly promotes rapeseed root development and increases yield, verifying the effectiveness of the "dual-signal driven" system.

[0062] Comparative Example 3 The difference between this comparative example and Example 3 is that ungrafted chitosan was used, that is, commercially available chitosan (purchased from Shanghai Maclean Biochemical Technology Co., Ltd.) was used directly without any treatment.

[0063] Except for the use of ungrafted chitosan, the other components of the formula are the same as in Example 3. However, the ungrafted chitosan has poor binding properties when used as fertilizer, resulting in brittle granules. At the same time, the antibacterial and growth-promoting functions are weakened, and harmful rhizosphere bacteria rebound.

[0064] Field observations showed that the rapeseed taproot length was 20.1 cm, with 29 lateral roots per plant, and an average yield of 1598 jin per mu. This confirms that the absence of chitosan grafting severely affects rapeseed growth, demonstrating the role of chitosan grafts as exogenous excitons in crop growth.

[0065] Example 4 like Figure 3 As shown, the organic fertilizer obtained in Example 1 was added at 10 kg / mu to the seedling substrate of rice experimental field A in Qijiawan, Huangpi District, Wuhan (divided into experimental field A, control field B and experimental field C by drainage ditch). Control field B used traditional compound fertilizer.

[0066] Three days before transplanting, 50 seedlings were randomly selected from each field to measure plant height and stem diameter, and the coefficient of variation (CV%) was calculated. The CV% of plant height in experimental field A decreased from 18.7% in control field B to 10.3%, and the CV% of stem diameter decreased from 22.4% to 13.1%, indicating that the uniformity of seedlings was significantly improved.

[0067] The survival rate was investigated 10 days after transplanting. The average survival rate in experimental field A was 98.3%, while that in control field B was 91.2%. With the unfolding of new leaves as the indicator of seedling establishment, the average establishment time in experimental field A was 4.2 days, which was 4.5 days shorter than that in control field B (8.7 days).

[0068] The results showed that the seedling substrate with the organic fertilizer of this invention significantly improved the quality of seedlings, resulting in uniform growth, well-developed root systems, and strong resistance to adverse conditions, thus achieving a high survival rate and rapid seedling establishment, verifying the root-promoting and seedling-strengthening effect of the fertilizer in the seedling stage.

[0069] Comparative Example 4 The difference between this comparative example and Example 4 is that the formula without added alginate oligosaccharides was used in experimental field C, while the other formula conditions were the same as in Example 4. During the experiment, it was observed that the rice seedlings grew slowly, the leaves were wrinkled, the edges were scorched, and the leaf area was significantly reduced. This indicates that AOS, as a plant elicitor, can induce resistance.

[0070] The embodiments described above are some, but not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A phosphate-inositol chitosan compound organic fertilizer, characterized in that, It includes the following components: modified inositol phosphate, chitosan graft, humic acid, sugar alcohol chelated zinc, alginate oligosaccharide, bentonite, and decomposed organic carrier, wherein the modified inositol phosphate is a graft copolymer of inositol phosphate and acrylate monomers; the chitosan graft is a chitosan-vanillin Schiff base generated by the reaction of chitosan and vanillin; The phosphate inositol chitosan compound organic fertilizer, by total mass percentage (100%), comprises: 8-10% modified phosphate inositol, 12-15% chitosan graft, 18-22% humic acid, 3-5% sugar alcohol chelated zinc, 0.1-0.3% alginate oligosaccharide, 15-18% bentonite, with the remainder being well-rotted organic carrier.

2. The phosphoinositol-chitosan composite organic fertilizer according to claim 1, characterized in that, The modified inositol phosphate is prepared by a method comprising the following steps: S1. After crushing the rice bran, extract it with citric acid solution to obtain an extract containing inositol phosphate esters; S2. Add phytase to the extract for enzymatic hydrolysis; S3. Add an initiator and acrylate monomers to the enzymatically hydrolyzed system to carry out a graft copolymerization reaction; S4. Concentrate and dry the reaction solution to obtain powdered modified inositol phosphate.

3. The phosphoinositol-chitosan composite organic fertilizer according to claim 2, characterized in that, The amount of phytase added is 1500-2500 U / g based on the initial weight of rice bran, and the enzyme activity of the phytase used is not less than 5000 U / mg.

4. The phosphoinositol-chitosan composite organic fertilizer according to claim 1, characterized in that, The preparation method of the chitosan graft includes: dissolving chitosan in an acidic solution, reacting it with vanillin under acidic conditions to generate a Schiff base, and obtaining a chitosan-vanillin Schiff base after precipitation, washing, and drying; wherein the molar ratio of the amino group in the chitosan to the aldehyde group in the vanillin is 1:(1.1-1.3).

5. The phosphoinositol-chitosan composite organic fertilizer according to claim 1, characterized in that, The sugar alcohol chelated zinc is prepared by zinc salt and mannitol; the molar ratio of zinc ions to mannitol in the zinc salt is 1:(1.2-1.8).

6. The phosphoinositol-chitosan composite organic fertilizer according to claim 1, characterized in that, The average molecular weight of the alginate oligosaccharide is 500-2000 Da.

7. The phosphoinositol-chitosan composite organic fertilizer according to claim 1, characterized in that, The bentonite has a particle size of 200-300 mesh and a cation exchange capacity of ≥80 mmol / 100g.

8. The phosphoinositol-chitosan composite organic fertilizer according to claim 1, characterized in that, The decomposed organic carrier is selected from one or more of livestock and poultry manure, straw compost or urban sludge humus, and its decomposition degree is ≥90%.

9. The application of the phosphoinositol chitosan compound organic fertilizer as described in any one of claims 1-8 in agricultural production.

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