Stable fertilizer for preventing and treating peanut root rot and preparation method thereof

Abstract

The invention relates to the field of fertilizers, in particular to a stable fertilizer for preventing and treating peanut root rot and a preparation method thereof, and the fertilizer comprises a fertilizer inner core layer, a nano microbial metabolite layer and a microbial protective layer from inside to outside. According to the stable fertilizer for preventing and treating peanut rhizome rot, the capsule embedding inhibitor made of humic acid and the trichoderma aureoviride metabolite are adopted to construct a dual nitrification inhibition system, and the capsule embedding inhibitor and the trichoderma aureoviride metabolite have a synergistic effect, so that the nitrification effect is reduced, the nitrogen fertilizer utilization rate is increased, and non-point source pollution is reduced.

Description

Technical Field

[0001] The invention relates to the field of fertilizers, and in particular to a stable fertilizer for preventing and treating peanut root and stem rot and a preparation method thereof. Background Art

[0002] Peanuts are an important oilseed crop in my country, second only to soybeans and rapeseed, and are crucial to national economic development and food and oil security. According to statistics, in 2023, my country's peanut planting area was approximately 71.97 million mu (approximately 1.6 million hectares), with a yield of 19.231 million tons, accounting for 49.8% of total oilseed crop production. However, in recent years, my country's edible oil self-sufficiency rate has only been 34%, exacerbating the imbalance between oilseed supply and demand. To ensure food and oil security, increase agricultural efficiency, and increase farmers' incomes, improving peanut kernel yield and quality has become a key approach to addressing this issue. Fertilizer application is a key factor influencing peanut yield and quality, but farmers often overuse chemical fertilizers in pursuit of higher yields. Excessive fertilizer application stimulates microbial nitrification, which not only reduces nitrogen use efficiency in farmland soils but also increases farmers' economic burden and environmental pollution. Nitrification is the primary cause of nitrogen loss from soil ecosystems. Leaching of nitrate nitrogen contributes to groundwater and surface water pollution and increases emissions of nitrous oxide (NO), one of the three major greenhouse gases. In existing technologies, nitrification inhibitors are often used to inhibit the activity of soil nitrifying microorganisms, thereby slowing nitrification in the soil. These inhibitors include hydrocarbons and their derivatives, sulfur-containing compounds, nitrogen-containing heterocyclic compounds, cyanamides, acetylene (C2H2), 2-chloro-6-trichloromethylpyridine (Nitrapyrin), 3,4-methylpyrazole phosphate (DMPP), and dicyandiamide (DCD). Although nitrification inhibitors can effectively improve fertilizer efficiency and reduce nitrogen loss from nitrate and nitrite leaching and denitrification, existing technologies are limited by high costs, unstable effects due to inhibitor inactivation, and environmental pollution. Peanut root and stem rot is a common fungal disease in peanut fields. Peanut root rot is caused by Fusarium solani, Fusarium oxysporum, Fusarium pinkum, Fusarium trilineum, and Fusarium moniliforme. Peanut stem rot is caused by Diplodia gossypii. Both diseases are soil-borne and seed-borne. The pathogens mainly overwinter in the soil, on diseased and damaged soil stalks, or on seeds as hyphae or conidia, and have strong survival ability, becoming the source of infection the following year. The disease causes plant death, missing seedlings and broken ridges, rotten seeds, and rotten fruits, resulting in reduced peanut production and quality. The application of pesticides is considered one of the most convenient and effective methods to prevent and control peanut root and stem rot. However, excessive use of pesticides may cause serious environmental pollution, including soil degradation, water pollution, and air pollution, while also endangering human health, leading to acute poisoning, and even an increased risk of cancer. In addition, excessive use of pesticides can damage the ecosystem, cause pests to develop resistance, and reduce biodiversity. Summary of the Invention

[0003] To address the high cost and unstable effectiveness of chemical nitrification inhibitors, as well as the environmental pollution and impacts on the sustainable development of farmland ecosystems caused by their application, the present invention provides a stable fertilizer for controlling peanut root and stem rot and its preparation method. This dual nitrification inhibition system utilizes encapsulated humic acid inhibitors and Trichoderma chrysogenum metabolites, achieving a stable increase in soil nitrogen utilization. Furthermore, the combination of microbial solidification microsphere technology improves the effectiveness of peanut root and stem rot control.

[0004] To achieve the above object, the present invention provides the following technical solutions: In a first aspect, the present invention provides a stable fertilizer for preventing and treating peanut root and stem rot, wherein the fertilizer comprises, from the inside out, a fertilizer inner core layer, a nano-microbial metabolite layer, and a microbial protective layer.

[0005] Preferably, the raw materials of the inner core layer of the fertilizer include, in parts by weight: 80-120 parts of humic acid inhibitor capsules, 180-380 parts of urea, 150-340 parts of monoammonium phosphate, 220-320 parts of potassium sulfate, 20-80 parts of calcium nitrate, 6-25 parts of magnesium sulfate, 6-25 parts of sulfur powder, 0.6-1.2 parts of sodium borate, 0.1-0.3 parts of ammonium molybdate, and 100-160 parts of decomposed peanut shells.

[0006] Preferably, the humic acid inhibitor capsule comprises humic acid, sodium alginate, maleopimaric anhydride, an inhibitor, and a curing agent; wherein the mass ratio of humic acid to sodium alginate is 3:1, the mass proportion of the inhibitor is 5%-15%, and the curing agent is a CaCl2 solution.

[0007] Preferably, the raw materials of the nano-microbial metabolic layer include, by weight: 20-30 parts of Trichoderma aureoviride fermentation liquid, 1-1.5 parts of nano silicon dioxide and 0.02-0.03 parts of sodium polyacrylate.

[0008] Preferably, the particle size of nano-silica is 20-50 nm.

[0009] Preferably, the raw materials of the microbial protection layer include, by weight: 20-50 parts of microbial solidified microspheres and 1-2.5 parts of adhesive.

[0010] Preferably, the microbial solidified microspheres include Trichoderma harzianum fermentation broth, Bacillus subtilis fermentation broth, trehalose, and sodium alginate, wherein the viable cell count of the Trichoderma harzianum fermentation broth is (1×10 8 CFU / g), the number of viable bacteria in the fermentation broth of Bacillus subtilis BS-5 was (5×10 8 CFU / g).

[0011] Preferably, the binder is polyvinyl alcohol, and the molecular weight of the polyvinyl alcohol is in the range of 0.5K-10K.

[0012] Preferably, the preparation method of the humic acid inhibitor capsules comprises the following steps: S1: Mix 3g humic acid and 1g sodium alginate, add 100mL deionized water, and stir at pH = 6.5-7.0 until completely dissolved to obtain a colloidal solution; S2: Maleopimaric anhydride (MPA) is gradually added to the colloidal solution in an amount of 2%-4% of the mass of the colloidal solution, and the pH of the solution is adjusted to 8.0-10.0, followed by stirring in the dark for 15-30 hours. After the reaction is complete, the solution is dialyzed in a dialysis bag with a molecular weight cutoff of 15-18 kDa in clean water. After dialysis for 5-7 days, the solution is vacuum dried to obtain a gel matrix, which is then prepared with deionized water to prepare a gel matrix solution; S3: Add the inhibitor to the gel matrix solution, stir evenly, drop 20 mL of 0.1 mol / L CaCl2 solution into the solution for cross-linking and curing, and react at 23-27°C for 25-40 min to obtain a gel microsphere suspension. S4: Humic acid inhibitor capsules are obtained after spray drying.

[0013] Preferably, the inhibitor comprises dicyandiamide (DCD) and / or nitration inhibitor DMPP, and the particle size of the inhibitor powder is 40-60 μm.

[0014] Preferably, the humic acid is one of weathered coal humic acid and lignite humic acid.

[0015] Preferably, the inlet air temperature of the spray drying is 70-80°C, and the outlet air temperature is 40-45°C.

[0016] Preferably, the diameter of the humic acid inhibitor capsule is 0.5-1.2 mm.

[0017] Preferably, the method for preparing the microbial solidified microspheres comprises the following steps: P1: Trichoderma harzianum spore suspension and Bacillus subtilis fermentation broth were mixed in a ratio of 2:1, and 5% of the system weight of trehalose freeze-drying protective agent was added to obtain a mixed bacterial solution; P2: The mixed bacterial liquid was evenly mixed with a 2 wt% sodium alginate solution, and then sprayed into a 0.3 mol / L CaCl2 solution using an electrostatic atomizer. The mixture was reacted at 23-27°C for 20-30 minutes to obtain a suspension of microbial solidified microspheres. P3: Drying at a temperature below 40°C to obtain microbial solidified microspheres.

[0018] In a second aspect, the present invention provides a method for preparing the stable fertilizer, comprising the following steps: Step (1): Calcium nitrate, magnesium sulfate, and sulfur powder are mixed evenly to obtain a calcium-magnesium-sulfur complex, and then urea, monoammonium phosphate, potassium sulfate, decomposed peanut shell powder, and humic acid inhibitor capsules are added and mixed evenly, and polyaspartic acid is added as a binder, and granulation is performed to obtain a fertilizer inner core layer; Step (2): mixing the sodium alginate solution and the chitosan solution, adding glycerol and stirring until there are no bubbles to form a membrane liquid, spraying it on the surface of the fertilizer inner core layer to form a thin film, spraying the CaCl2 solution, and standing to solidify to obtain biofilm-pre-wrapped fertilizer particles; Step (3): preparing a mixture of nano-silica and sodium polyacrylate to obtain a nano-silica suspension, immersing the biofilm pre-coated fertilizer particles in the nano-silica suspension, stirring, removing, and naturally draining to obtain fertilizer particles loaded with silica; Step (4): centrifuge and concentrate the fermentation liquid of Trichoderma aureogreenum, add β-cyclodextrin and mix evenly, immerse the fertilizer particles loaded with silica therein, shake, remove and drain, and solidify to obtain fertilizer particles coated with a nano-microbial metabolite layer.

[0019] Step (5): mixing the microbial solidified microspheres with the polyvinyl alcohol solution, spraying the mixture onto the particle surface to form a microbial coating, and drying the particles until the moisture content is less than 5%; Step (6): irradiating the surface of the particles with an ultraviolet lamp to kill the surface bacteria, and drying at low temperature to obtain the stable fertilizer for preventing and treating peanut root rot.

[0020] Preferably, the wavelength of the UV lamp is 254 nm, the dose is 30 mJ / cm², and the irradiation time is 20-30 seconds.

[0021] The beneficial effects of the present invention are: 1. The stable fertilizer for preventing and controlling peanut root rot provided by the present invention uses a capsule-embedded inhibitor made of humic acid material and a metabolite of Trichoderma chrysogenum to construct a dual nitrification inhibition system. The two act synergistically to reduce nitrification, improve nitrogen fertilizer utilization, and reduce non-point source pollution.

[0022] 2. Microbial microspheres form an outer protective layer on the surface of the fertilizer particles. Trichoderma harzianum and Bacillus subtilis not only effectively inhibit the growth of root rot pathogens, but also induce plant immune responses, enhancing peanut disease resistance. Furthermore, these functional microorganisms promote peanut root development by secreting plant hormones, thereby improving peanut yield and quality.

[0023] 3. This invention incorporates humic acid inhibitor capsules within the core. These capsules utilize the synergistic effect of humic acid and bio-inhibitors to improve fertilizer utilization. The capsules are made from humic acid and sodium alginate. The hydroxyl groups (-OH) in the humic acid and sodium alginate combine with the anhydride groups (-O-CO-O-) of maleopimaric anhydride to form a gel matrix. This is then cured with calcium chloride to create a stable three-dimensional network gel structure.

[0024] 4. Maleopimaric anhydride, a rosin derivative, acts as a ternary crosslinker, connecting sodium alginate molecular chains via ester bonds to form a crosslinked three-dimensional network structure. This crosslinking enhances the stability and water resistance of the capsule material while retaining the pH sensitivity of sodium alginate, imparting enhanced swelling-contraction behavior to the capsule material, thereby achieving better controlled-release properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative effort.

[0026] Figure 1 The dynamic changes of ammonium nitrogen content in the soil of peanuts in the late growth period were observed after the fertilizers prepared in Examples 1-3 and Comparative Examples 1-3 were used to treat the peanuts. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0028] Trichoderma aureoviride and Trichoderma harzianum were purchased from Ningbo Mingzhou Biotechnology Co., Ltd., and Bacillus subtilis was purchased from Beijing Solable Biotechnology Co., Ltd.

[0029] The present invention will be further described below with reference to the following examples.

[0030] Example 1 A stable fertilizer for preventing and treating peanut root and stem rot comprises, from the inside out, a fertilizer inner core layer, a nano-microorganism metabolite layer and a microorganism protection layer.

[0031] The raw materials of the inner core layer of the fertilizer include, by weight: 100 parts of humic acid inhibitor capsules, 180 parts of urea, 300 parts of monoammonium phosphate, 270 parts of potassium sulfate, 30 parts of calcium nitrate, 10 parts of magnesium sulfate, 10 parts of sulfur powder, 0.6 parts of sodium borate, 0.1 parts of ammonium molybdate, and 100 parts of decomposed peanut shells.

[0032] The raw materials of the nano-microbial metabolic layer include, by weight: 20 parts of Trichoderma aureoviride fermentation liquid, 1 part of nano silicon dioxide and 0.02 parts of sodium polyacrylate.

[0033] The raw materials of the microbial protection layer, in parts by weight, include: 20 parts of microbial solidified microspheres and 1 part of polyvinyl alcohol.

[0034] The preparation method of humic acid inhibitor capsules includes: S1: Mix 3 g of weathered coal humic acid and 1 g of sodium alginate, add 100 mL of deionized water, and stir at pH 7.0 until completely dissolved to obtain a colloidal solution; S2: Maleopimaric anhydride (MPA) was gradually added to the colloidal solution in an amount of 3% by mass of the colloidal solution. The pH of the solution was adjusted to 9.0, and then stirred in the dark for 25 hours. After the reaction, the solution was dialyzed in clean water in a dialysis bag with a molecular weight cutoff of 16 kDa. After dialysis for 7 days, the solution was vacuum dried to obtain a gel matrix, which was then prepared with deionized water to prepare a 5 wt% gel matrix solution. S3: Add the inhibitor DCD with a particle size of 60 μm to the gel matrix solution, stir evenly, drop 20 mL of 0.1 mol / L CaCl2 solution into it for cross-linking and curing, and react at 25°C for 30 min to obtain a gel microsphere suspension; S4: spray drying at an inlet air temperature of 75°C and an outlet air temperature of 40°C to obtain humic acid inhibitor capsules; the total mass fraction of DCD in the humic acid inhibitor capsules is 10%.

[0035] The preparation method of microbial solidified microspheres includes: P1: The viable cell count is 1×10 8 CFU / g of Trichoderma harzianum spore suspension and the number of viable bacteria was 5×10 8 CFU / g Bacillus subtilis fermentation broth was mixed in a ratio of 2:1, and 5 wt% trehalose was added as a protective agent to obtain a mixed bacterial solution; P2: The mixed bacterial liquid was evenly mixed with 2 wt% sodium alginate solution, and then sprayed into 0.3 mol / L CaCl2 solution through an electrostatic atomizer. The mixture was reacted at 25°C for 25 min to obtain a suspension of microbial solidified microspheres. P3: Dry at 38°C to obtain microbial solidified microspheres.

[0036] The preparation method of the above-mentioned stable fertilizer for preventing and treating peanut root rot comprises: Step (1): 30 parts of calcium nitrate, 10 parts of magnesium sulfate, and 10 parts of sulfur powder are mixed, and then 180 parts of urea, 300 parts of monoammonium phosphate, 270 parts of potassium sulfate, 100 parts of decomposed peanut shell powder, 80 parts of humic acid inhibitor capsules, 0.6 parts of sodium borate, and 0.1 parts of ammonium molybdate are added and mixed evenly, 0.5 wt% of polyaspartic acid is added as a binder, the moisture content is 12-14%, and granulation is performed at a temperature below 45° C. to obtain a fertilizer inner core layer; Step (2): 2 wt% sodium alginate solution and 1 wt% chitosan solution were mixed, 0.5 wt% glycerol was added and stirred until there were no bubbles to form a membrane liquid, which was sprayed on the surface of the inner layer of the fertilizer to form a thin film, and 2% CaCl2 solution was sprayed and allowed to stand for 10 minutes to solidify, thereby obtaining biofilm-pre-wrapped fertilizer particles; Step (3): preparing a mixture of 5 wt% nano-silica and 0.1 wt% sodium polyacrylate to obtain a nano-silica suspension, immersing the biofilm pre-coated fertilizer particles in the nano-silica suspension, stirring at 40° C. for 30 minutes, removing the particles, and naturally draining for 30 minutes to obtain fertilizer particles loaded with silica; Step (4): Ferment the cultured Trichoderma aureoviride in PD culture medium for 4 days to obtain a spore concentration of 1×10 8 CFU / g of Trichoderma yellow green fermentation broth; take the Trichoderma yellow green fermentation broth and centrifuge it at 5000rpm for 20 minutes at 4℃, take the supernatant and concentrate it to 50g / L, add 0.5wt% β-cyclodextrin and mix evenly, immerse the fertilizer particles loaded with silica in it, shake it at room temperature for 1 hour, remove it and drain it, and solidify it at room temperature to obtain fertilizer particles wrapped with nano-microbial metabolite layer; Studies have shown that Trichoderma yellow green prefers ammonium nitrogen sources, which can slow down nitrification to produce NO3 - It can produce a large number of active secondary metabolites, effectively reducing the abundance of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in the soil, thereby inhibiting the soil nitrification process; Step (5): 20 parts of the microbial solidified microspheres were mixed with 5 wt% polyvinyl alcohol (1K) solution and sprayed onto the particle surface to form a microbial coating; Step (6): Irradiate the particle surface with a 254 nm wavelength UV lamp, 30 mJ / cm 2Under the dosage, irradiate for 20 seconds to kill the surface bacteria, and dry at low temperature to obtain fertilizer.

[0037] Example 2 A stable fertilizer for preventing and treating peanut root and stem rot comprises, from the inside out, a fertilizer inner core layer, a nano-microorganism metabolite layer and a microorganism protection layer.

[0038] The raw materials of the inner core layer of the fertilizer include, by weight: 100 parts of humic acid inhibitor capsules, 320 parts of urea, 180 parts of monoammonium phosphate, 230 parts of potassium sulfate, 24 parts of calcium nitrate, 8 parts of magnesium sulfate, 8 parts of sulfur powder, 0.8 parts of sodium borate, 0.2 parts of ammonium molybdate, and 100 parts of decomposed peanut shells.

[0039] The raw materials of the nano-microbial metabolic layer include, by weight: 25 parts of Trichoderma aureoviride fermentation liquid, 1.25 parts of nano silicon dioxide and 0.025 parts of sodium polyacrylate.

[0040] The raw materials of the microbial protection layer, in parts by weight, include: 30 parts of microbial solidified microspheres and 1.5 parts of polyvinyl alcohol.

[0041] The preparation method of humic acid inhibitor capsules includes: S1: Mix 3 g of lignite humic acid and 1 g of sodium alginate, add 100 mL of deionized water, and stir at pH 7.0 until completely dissolved to obtain a colloidal solution; S2: Maleopimaric anhydride (MPA) was gradually added to the colloidal solution in an amount of 3% by mass of the colloidal solution. The pH of the solution was adjusted to 9.0, and then stirred in the dark for 25 hours. After the reaction, the solution was dialyzed in clean water in a dialysis bag with a molecular weight cutoff of 16 kDa. After dialysis for 7 days, the solution was vacuum dried to obtain a gel matrix, which was then prepared with deionized water to prepare a 5 wt% gel matrix solution. S3: Add DMPP with a particle size of 60 μm to the gel matrix solution, stir evenly, drop 20 mL of 0.1 mol / L CaCl2 solution into it for cross-linking and curing, and react at 23°C for 25 min to obtain a gel microsphere suspension; S4: spray drying at an inlet air temperature of 70°C and an outlet air temperature of 40°C to obtain humic acid inhibitor capsules; the total mass fraction of DMPP in the humic acid inhibitor capsules is 5%.

[0042] The preparation method of microbial solidified microspheres includes: P1: The viable cell count is 1×10 8 CFU / g of Trichoderma harzianum spore suspension and the number of viable bacteria was 5×108 CFU / g Bacillus subtilis fermentation broth was mixed in a ratio of 2:1, and 5% trehalose protective agent was added to obtain a mixed bacterial solution; P2: The mixed bacterial liquid was evenly mixed with 2% sodium alginate solution, and then sprayed into 0.3 mol / L CaCl2 solution through an electrostatic atomizer. The mixture was reacted at 27°C for 20 min to obtain a suspension of microbial solidified microspheres. P3: Dry at room temperature to obtain microbial solidified microspheres.

[0043] The preparation method of the above-mentioned stable fertilizer for preventing and treating peanut root rot comprises: Step (1): 30 parts of calcium nitrate, 10 parts of magnesium sulfate, and 10 parts of sulfur powder are mixed evenly, and then 200 parts of urea, 300 parts of monoammonium phosphate, 300 parts of potassium sulfate, 100 parts of decomposed peanut shell powder, 80 parts of humic acid microcapsules, 0.8 parts of sodium borate, and 0.1 parts of ammonium molybdate are added and mixed evenly, 0.5% of polyaspartic acid is added as a binder, the moisture content is 12-14%, and granulation is carried out at 45°C to obtain a fertilizer inner core layer; Step (2): 2% sodium alginate solution and 1% chitosan solution were mixed, 0.5% glycerol was added and stirred until there were no bubbles to form a membrane liquid, which was sprayed on the surface of the inner core layer of the fertilizer to form a thin film, and 2% CaCl2 solution was sprayed and allowed to stand for 10 minutes to solidify, thereby obtaining biofilm-pre-wrapped fertilizer particles; Step (3): preparing a mixture of 5% nano-silica and 0.1% sodium polyacrylate to obtain a nano-silica suspension, immersing the biofilm pre-coated fertilizer particles in the nano-silica suspension, stirring at 40°C for 30 minutes, removing the particles, and naturally draining for 30 minutes to obtain fertilizer particles loaded with silica; Step (4): 25 portions of Trichoderma aureogreen fermentation broth were centrifuged at 8000 rpm for 20 min at 4°C, the supernatant was concentrated to 50 g / L, 0.5% β-cyclodextrin was added and mixed evenly, the silica-loaded fertilizer particles were immersed therein, shaken at room temperature for 1 hour, removed and drained, and solidified at room temperature to obtain fertilizer particles coated with a nano-microbial metabolite layer; Step (5): 30 parts of microbial solidified microspheres were mixed with 5% polyvinyl alcohol (1K) and sprayed onto the surface of the particles to form a microbial coating; Step (6): Use 254nm wavelength ultraviolet light to irradiate the surface of the particles at a dose of 30mJ / cm² for 20s to kill surface bacteria, and then dry at low temperature to obtain fertilizer.

[0044] Example 3 A stable fertilizer for preventing and treating peanut root and stem rot comprises, from the inside out, a fertilizer inner core layer, a nano-microorganism metabolite layer and a microorganism protection layer.

[0045] The raw materials of the inner core layer of the fertilizer include, by weight: 80 parts of humic acid inhibitor capsules, 200 parts of urea, 300 parts of monoammonium phosphate, 300 parts of potassium sulfate, 30 parts of calcium nitrate, 10 parts of magnesium sulfate, 10 parts of sulfur powder, 1 part of sodium borate, 0.1 part of ammonium molybdate, and 100 parts of decomposed peanut shells.

[0046] The raw materials of the nano-microbial metabolic layer include, by weight: 30 parts of Trichoderma aureoviride fermentation liquid, 1.5 parts of nano silicon dioxide and 0.03 parts of sodium polyacrylate.

[0047] The raw materials of the microbial protection layer, in parts by weight, include: 50 parts of microbial solidified microspheres and 2.5 parts of polyvinyl alcohol.

[0048] The preparation method of humic acid inhibitor capsules includes: S1: Mix 3g of weathered coal humic acid and 1g of sodium alginate, add 100mL of deionized water, and stir at pH=6.5 until completely dissolved to obtain a colloidal solution; S2: Maleopimaric anhydride (MPA) was gradually added to the colloidal solution in an amount of 3% by mass of the colloidal solution. The pH of the solution was adjusted to 9.0, and then stirred in the dark for 25 hours. After the reaction, the solution was dialyzed in clean water in a dialysis bag with a molecular weight cutoff of 16 kDa. After dialysis for 7 days, the solution was vacuum dried to obtain a gel matrix, which was then prepared with deionized water to prepare a 5 wt% gel matrix solution. S3: DMPP and DCD with a particle size of 60 μm were added to the gel matrix solution, stirred evenly, and 20 mL of 0.1 mol / L CaCl2 solution was added dropwise for cross-linking and curing. The reaction was carried out at 27°C for 30 min to obtain a gel microsphere suspension. S4: spray drying at an inlet air temperature of 75°C and an outlet air temperature of 40°C to obtain humic acid inhibitor capsules; in the humic acid inhibitor capsules, the total mass fraction of DMPP and DCD is 8%, and the mass ratio of DMPP to DCD is 1:1.

[0049] The preparation method of microbial solidified microspheres includes: P1: The viable cell count is 1×10 8 CFU / g of Trichoderma harzianum spore suspension and the number of viable bacteria was 5×10 8 CFU / g Bacillus subtilis fermentation broth was mixed in a ratio of 2:1, and 5% trehalose protective agent was added to obtain a mixed bacterial solution; P2: The mixed bacterial liquid was evenly mixed with 2% sodium alginate solution, and then sprayed into 0.3 mol / L CaCl2 solution through an electrostatic atomizer. The mixture was reacted at 25°C for 25 minutes to obtain a suspension of microbial solidified microspheres. P3: Dry at room temperature to obtain microbial solidified microspheres.

[0050] The preparation method of the above-mentioned stable fertilizer for preventing and treating peanut root rot comprises: Step (1): 30 parts of calcium nitrate, 10 parts of magnesium sulfate, and 10 parts of sulfur powder are mixed evenly, and then 200 parts of urea, 300 parts of monoammonium phosphate, 300 parts of potassium sulfate, 100 parts of decomposed peanut shell powder, 80 parts of humic acid microcapsules, 1 part of sodium borate, and 0.1 part of ammonium molybdate are added and mixed evenly, 0.5% of polyaspartic acid is added as a binder, the moisture content is 12-14%, and granulation is carried out at 45°C to obtain a fertilizer inner core layer; Step (2): 2% sodium alginate solution and 1% chitosan solution were mixed, 0.5% glycerol was added and stirred until there were no bubbles to form a membrane liquid, which was sprayed on the surface of the inner core layer of the fertilizer to form a thin film, and 2% CaCl2 solution was sprayed and allowed to stand for 10 minutes to solidify, thereby obtaining biofilm-pre-wrapped fertilizer particles; Step (3): preparing a mixture of 5% nano-silica and 0.1% sodium polyacrylate to obtain a nano-silica suspension, immersing the biofilm pre-coated fertilizer particles in the nano-silica suspension, stirring at 40°C for 30 minutes, removing the particles, and naturally draining for 30 minutes to obtain fertilizer particles loaded with silica; Step (4): 30 portions of Trichoderma aureogreen fermentation broth were centrifuged at 5000 rpm for 20 min at 4°C, the supernatant was concentrated to 50 g / L, 0.5% β-cyclodextrin was added and mixed evenly, the silica-loaded fertilizer particles were immersed therein, shaken at room temperature for 1 hour, removed and drained, and solidified at room temperature to obtain fertilizer particles coated with a nano-microbial metabolite layer; Step (5): 50 parts of microbial solidified microspheres were mixed with 5% polyvinyl alcohol (1K) and sprayed onto the surface of the particles to form a microbial coating; Step (6): Irradiate the particle surface with a 254 nm wavelength UV lamp, 30 mJ / cm 2 Under the dosage, irradiate for 20 seconds to kill the surface bacteria, and dry at low temperature to obtain fertilizer.

[0051] Comparative Example 1 A stable fertilizer for preventing and treating peanut root rot, which differs from Example 2 in that the fertilizer comprises a fertilizer inner core layer and a microbial protection layer from the inside out, no nano-microbial metabolite layer is introduced, and no humic acid inhibitor capsules are added to the fertilizer inner core layer.

[0052] The raw materials of the inner core layer of the fertilizer, in parts by weight, include: 320 parts of urea, 180 parts of monoammonium phosphate, 230 parts of potassium sulfate, 24 parts of calcium nitrate, 8 parts of magnesium sulfate, 8 parts of sulfur powder, 0.8 parts of sodium borate, 0.2 parts of ammonium molybdate, and 100 parts of decomposed peanut shells.

[0053] Comparative Example 2 A stable fertilizer for preventing and treating peanut root rot is provided. The difference from Example 2 is that the preparation method of the humic acid inhibitor capsule in the inner core layer of the fertilizer is different. Other aspects are the same as Example 2.

[0054] The preparation method of humic acid inhibitor capsules comprises: S1: Mix 3 g of lignite humic acid and 1 g of sodium alginate, add 100 mL of deionized water, and stir at pH 7.0 until completely dissolved to obtain a colloidal solution; S2: Add DMPP with a particle size of 60 μm to the colloidal solution, stir evenly, drop 20 mL of 0.1 mol / L CaCl2 solution into the solution for cross-linking and curing, and react at 23°C for 25 min to obtain a gel microsphere suspension. S3: spray drying at an inlet air temperature of 70°C and an outlet air temperature of 40°C to obtain humic acid inhibitor capsules; the total mass fraction of DMPP in the humic acid inhibitor capsules is 5%.

[0055] Comparative Example 3 Commercially available potassium sulfate compound fertilizer (total nutrients 45%, N:P2O5:K2O is 15:15:15).

[0056] Experimental example Experimental location: Zhengyang County, Zhumadian City, Henan Province The nutrient content of the test soil is: organic matter 1.2%, alkaline nitrogen 157 mg / kg, available phosphorus (P2O5) 21 mg / kg, available potassium (K2O) 149 mg / kg, soil pH is 6.5, and the soil is yellow-brown soil.

[0057] Peanut variety tested: Yuanza 9102 Experimental design: This experiment has 6 treatments, each treatment is repeated 3 times, and the experimental area is 111m 2 All fertilizers were applied as base fertilizer at a rate of 50 kg / mu, broadcast before peanut sowing and then tilled into the ground. Single seed sowing was adopted, with a plant spacing of 10-11 cm. Ridges were formed with film covering, with two rows per ridge, a ridge length of 30 m, and a ridge width of 85 cm, for a total of four ridges. Sowing was carried out on May 8, 2024, and harvesting was carried out on September 8. Other management measures were carried out according to conventional field management methods.

[0058] Soil samples were collected at the seedling stage, needle stage, pod stage and maturity stage of peanuts to analyze the soil ammonium nitrogen content. At harvest time, 2 m3 of soil was collected from each plot.2 , record the number of plants, pick all the pods, weigh them after drying, and calculate the yield. Count the number of full fruits, the number of empty fruits, the weight of 100 fruits, the weight of 100 kernels, the incidence of root rot and stem rot, and get the results as follows Figure 1 and Table 1.

[0059] Table 1 Peanut yield and root rot incidence of Examples 1-3 and Comparative Examples 1-3

[0060] Depend on Figure 1 It can be seen that compared with comparative examples 1-3, the ammonium nitrogen content in the peanut soil treated with the fertilizer of Examples 1-3 in the late growth period is higher than that of the other treatments, indicating that Examples 1-3 have a good inhibitory effect on the process of converting soil ammonium nitrogen into nitrate nitrogen.

[0061] As can be seen from Table 1, Examples 1-3 increased peanut yield by 10.4%-14.5%, had a root rot incidence of 2%-4%, and a stem rot incidence of 2%-5%. Their effects of increasing yield and preventing and controlling peanut root and stem rot were better than those of Comparative Examples 1-2.

[0062] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A stable fertilizer for preventing and treating peanut root rot, characterized in that: The fertilizer comprises, from the inside out, a fertilizer inner core layer, a nano-microorganism metabolite layer and a microorganism protection layer; The raw materials of the inner core layer of the fertilizer include, by weight: 80-120 parts of humic acid inhibitor capsules, 180-380 parts of urea, 150-340 parts of monoammonium phosphate, 220-320 parts of potassium sulfate, 20-80 parts of calcium nitrate, 6-25 parts of magnesium sulfate, 6-25 parts of sulfur powder, 0.6-1.2 parts of sodium borate, 0.1-0.3 parts of ammonium molybdate, and 100-160 parts of decomposed peanut shells.

2. The stable fertilizer for preventing and treating peanut root rot according to claim 1, characterized in that: The humic acid inhibitor capsule comprises humic acid, sodium alginate, maleopimaric anhydride, an inhibitor, and a curing agent; wherein the mass ratio of humic acid to sodium alginate is 3:1, the mass proportion of the inhibitor is 5%-15%, and the curing agent is a CaCl2 solution.

3. The stable fertilizer for preventing and treating peanut root rot according to claim 1, characterized in that: The raw materials of the microbial protection layer, in parts by weight, include: 20-50 parts of microbial solidified microspheres and 1-2.5 parts of adhesive.

4. The stable fertilizer for preventing and treating peanut root rot according to claim 3, characterized in that: The microbial solidified microspheres include Trichoderma harzianum fermentation broth, Bacillus subtilis fermentation broth, trehalose, and sodium alginate; wherein the number of viable bacteria in the Trichoderma harzianum fermentation broth is 1×10 8 CFU / g, the number of viable bacteria in the Bacillus subtilis fermentation broth is 5×10 8 CFU / g.

5. The stable fertilizer for preventing and treating peanut root rot according to claim 3, characterized in that: The adhesive is polyvinyl alcohol, and the molecular weight of the polyvinyl alcohol is in the range of 0.5K-10K.

6. The stable fertilizer for preventing and treating peanut root rot according to claim 1, characterized in that: The preparation method of the humic acid inhibitor capsule comprises the following steps: S1: Mix 3g humic acid and 1g sodium alginate, add 100mL deionized water, and stir at pH = 6.5-7.0 until completely dissolved to obtain a colloidal solution; S2: Maleopimaric anhydride is gradually added to the colloidal solution in an amount of 2%-4% of the mass of the colloidal solution, and the pH of the solution is adjusted to 8.0-10.0, followed by stirring in the dark for 15-30 hours. After the reaction is complete, the solution is dialyzed in a dialysis bag with a molecular weight cutoff of 15-18 kDa in clean water. After dialysis for 5-7 days, the solution is vacuum dried to obtain a gel matrix, which is then prepared with deionized water to prepare a gel matrix solution; S3: Add the inhibitor to the gel matrix solution, stir evenly, drop 20 mL of 0.1 mol / L CaCl2 solution into the solution for cross-linking and curing, and react at 23-27°C for 25-40 min to obtain a gel microsphere suspension. S4: Humic acid inhibitor capsules are obtained after spray drying.

7. The stable fertilizer for preventing and treating peanut root rot according to claim 6, characterized in that: The inhibitor includes dicyandiamide (DCD) and / or nitration inhibitor DMPP, and the particle size of the inhibitor powder is 40-60 μm.

8. The stable fertilizer for preventing and treating peanut root rot according to claim 6, characterized in that: Humic acid is a type of weathered coal humic acid and lignite humic acid.

9. The stable fertilizer for preventing and treating peanut root rot according to claim 1, characterized in that: The preparation method of the microbial solidified microspheres comprises the following steps: P1: Trichoderma harzianum spore suspension and Bacillus subtilis fermentation broth were mixed in a ratio of 2:1, and 5% of the system weight of trehalose freeze-drying protective agent was added to obtain a mixed bacterial solution; P2: The mixed bacterial liquid was evenly mixed with a 2 wt% sodium alginate solution, and then sprayed into a 0.3 mol / L CaCl2 solution through an electrostatic atomizer. The mixture was reacted at 23-27°C for 20-30 minutes to obtain a suspension of microbial solidified microspheres. P3: Drying at a temperature below 40°C to obtain microbial solidified microspheres.

10. A method for preparing the stable fertilizer according to claim 1, characterized in that: The steps include: Step (1): Calcium nitrate, magnesium sulfate, and sulfur powder are mixed evenly to obtain a calcium-magnesium-sulfur complex, and then urea, monoammonium phosphate, potassium sulfate, decomposed peanut shell powder, and humic acid inhibitor capsules are added and mixed evenly, and polyaspartic acid is added as a binder, and granulation is performed to obtain a fertilizer inner core layer; Step (2): mixing the sodium alginate solution and the chitosan solution, adding glycerol and stirring until there are no bubbles to form a membrane liquid, spraying it on the surface of the fertilizer inner core layer to form a thin film, spraying the CaCl2 solution, and standing to solidify to obtain biofilm-pre-wrapped fertilizer particles; Step (3): preparing a mixture of nano-silica and sodium polyacrylate to obtain a nano-silica suspension, immersing the biofilm pre-coated fertilizer particles in the nano-silica suspension, stirring, removing, and naturally draining to obtain fertilizer particles loaded with silica; Step (4): centrifuging and concentrating the fermentation broth of Trichoderma aureogreenii, adding β-cyclodextrin and mixing evenly, immersing the fertilizer particles loaded with silica therein, shaking, removing and draining, and solidifying to obtain fertilizer particles coated with a nano-microbial metabolite layer; Step (5): mixing the microbial solidified microspheres with the polyvinyl alcohol solution, spraying the mixture onto the particle surface to form a microbial coating, and drying the particles until the moisture content is less than 5%; Step (6): Irradiate the surface of the particles with ultraviolet light to kill surface bacteria, and dry at low temperature to obtain a stable fertilizer for preventing and treating peanut root rot.

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