Slow-release fertilizer for enhancing stress resistance of crops as well as preparation method and application of slow-release fertilizer

Abstract

The invention discloses a slow-release fertilizer for enhancing crop stress resistance and a preparation method and application thereof. The slow-release fertilizer disclosed by the invention not only has the advantages of improving the nutrient utilization rate and reducing the nutrient loss, but also saves the labor cost while reducing the environmental pollution, and has a remarkable synergistic effect on improving the stress resistance of crops. The product can meet the long-term nutrition and disease and pest resistance requirements of total crops through one-time application, meanwhile, the release efficiency of nutrients is matched with the requirements of the crops, fertilizer supply is stable, soil hardening and salinization are avoided to a great extent through co-application and a synergistic effect, soil microorganism breeding is promoted, the comprehensive fertility of soil is improved, and the yield of the crops is increased. Diseases, weeds and weeds are effectively prevented and treated, the stress resistance of crops is improved, and stable yield, high yield and income increase are ensured.

Description

Technical Field

[0001] The invention relates to the field of agricultural chemistry, and in particular to a slow-release fertilizer for enhancing crop stress resistance, and a preparation method and application thereof. Background Art

[0002] my country is a large agricultural country with a vast territory and rich resources. In the process of agricultural planting and production, in addition to dealing with threats from harmful organisms such as pathogens, pests and weeds, changes in natural geographical conditions and climatic conditions can also cause various adverse effects on the cultivated crops, which sometimes exceed the range that the crops can tolerate for normal growth and development, causing damage to the crops or even death.

[0003] The impact of drought on agricultural production has always been an international issue. With the continuous rise in global temperatures, the meteorological conditions for agricultural production are also deteriorating. In global agricultural production, the cultivated land area with natural precipitation as the main water source accounts for four-fifths, of which more than 30% is in arid and semi-arid areas, covering many countries and regions. In my country, agricultural water accounts for about 62% of the total water resources. Arid areas (including semi-arid areas) account for about half of my country's land area. Humid areas (including semi-humid areas) are often threatened by drought due to climate problems, and form a certain periodic impact. Water retainers have good water absorption and water retention capabilities. They are not easy to evaporate under natural conditions, so they can retain water for a long time and can continuously supply water for plants to use. After the water retainer is applied to the soil to absorb water, it enhances the soil's permeability and aeration, and improves the soil's effective water retention capacity.

[0004] In addition to drought, high temperatures and frost damage often cause serious reductions in the yields of field crops such as wheat, cotton and rice, and cash crops such as grapes, citrus and apples. These environments that harm crops are called adversity or stress. The adaptability and resistance of crops to adverse environments are called stress resistance or stress resistance. Crop stress resistance is the ability of crops to resist adverse external factors, such as drought resistance, salinity resistance, waterlogging resistance, wind resistance, frost resistance, and resistance to diseases and insect pests.

[0005] In order to increase crop yields, fertilizer application has long been widely used in agricultural production. However, due to the particularity of the transformation of nitrogen and phosphorus in the soil, the utilization rate of fertilizers is not high. In order to make up for the low fertilizer utilization rate, people usually can only increase the amount of fertilizer applied, which not only causes a waste of resources and increases agricultural production costs, but also causes serious pollution to the soil and ecological environment. Therefore, it is urgent to find new methods, new technologies and new products with economic efficiency and good environmental compatibility to ensure agricultural production and solve the current environmental pollution and food safety crisis.

[0006] Slow-release fertilizer refers to a new type of fertilizer that can delay or control the release rate of nutrients. It slows down the release rate of nutrients in fertilizers through chemical or biological methods. During release, it is affected by many external factors such as soil pH, microbial activity, and soil moisture content. Unlike traditional instant fertilizers, slow-release fertilizers have the defect of easy loss. The application of slow-release fertilizers can greatly improve the utilization rate of chemical fertilizers, reduce the number of fertilizations, save labor costs, and improve environmental pollution caused by excessive fertilization. In 1961, the United States began to develop slow-release fertilizers with sulfur-coated urea, but because sulfur has weak water resistance and there are holes in the membrane material, the slow-release performance is not stable enough. In 1970, Japan developed encapsulated materials using ethylene-vinyl acetate copolymers, polyvinyl acetate cellulose, thermoplastic polyolefins, etc. as urea fertilizers. The above-mentioned encapsulated materials contain artificially synthesized polymers, which are high in cost, poor in biodegradability, and only have slow-release properties, and do not have the functions of improving soil and enhancing crop resistance. Summary of the invention

[0007] The purpose of the present invention is to provide a slow-release fertilizer for enhancing crop stress resistance, which not only has the advantages of improving nutrient utilization rate and reducing nutrient loss, saving labor costs while reducing environmental pollution, but also has a significant synergistic effect on improving crop stress resistance.

[0008] The invention also provides a preparation method of the slow-release fertilizer and application thereof.

[0009] In order to achieve the purpose of the present invention, in a first aspect, the present invention provides a slow-release fertilizer for enhancing crop stress resistance, the slow-release fertilizer comprising functional particles and a functional layer coated on the outer surface of the functional particles; The functional particles include the following raw materials in parts by weight: 50-80 parts of urea formaldehyde, 100-500 parts of urea, 200-500 parts of monoammonium phosphate, 100-450 parts of potassium chloride, 1-15 parts of ammonium polyphosphate, 8-35 parts of polyglutamic acid and 2-10 parts of EDTA chelated trace elements; The functional layer comprises the following raw materials in parts by weight: 8-25 parts of seaweed extract, 8-20 parts of modified chitosan, 20-45 parts of pyrethrum powder, 8-45 parts of onion peel antibacterial active substances, 8-70 parts of garlic extract and 8-40 parts of brassinolide.

[0010] Preferably, the functional particles include the following raw materials in parts by weight: 60-70 parts of urea formaldehyde, 150-550 parts of urea, 200-400 parts of monoammonium phosphate, 150-350 parts of potassium chloride, 2-10 parts of ammonium polyphosphate, 10-30 parts of polyglutamic acid and 3-7 parts of EDTA chelated trace elements; The functional layer comprises the following raw materials in parts by weight: 10-20 parts of seaweed extract, 10-15 parts of modified chitosan, 25-40 parts of pyrethrum powder, 15-40 parts of onion peel antibacterial active substances, 15-60 parts of garlic extract and 15-30 parts of brassinolide.

[0011] More preferably, the functional particles include the following raw materials in parts by weight: 60 parts of urea formaldehyde, 358 parts of urea, 226 parts of monoammonium phosphate, 242 parts of potassium chloride, 2 parts of ammonium polyphosphate, 10 parts of polyglutamic acid and 3 parts of EDTA chelated trace elements; The functional layer comprises the following raw materials in parts by weight: 10 parts of seaweed extract, 10 parts of modified chitosan, 25 parts of pyrethrum powder, 19 parts of onion peel antibacterial active substances, 20 parts of garlic extract and 15 parts of brassinolide.

[0012] The preparation method of urea formaldehyde comprises: adding urea to a formaldehyde solution with a mass concentration of 35-40% and a temperature of 25-30° C. at a molar ratio of urea:formaldehyde=(1.4-1.6):1, adding an acid catalyst to adjust the pH to 4-6, and reacting to obtain urea formaldehyde.

[0013] Furthermore, the nitrogen content in the urea formaldehyde is 38%-40%, preferably 40%.

[0014] Wherein, the urea is small-particle urea with a particle size of 0.85mm-2.80mm, and a nitrogen content of 45-50 wt%, preferably 46 wt%.

[0015] The acid catalyst is composed of the following components in parts by weight: 4 to 6 parts of 83 to 87 wt% phosphoric acid, 2 to 4 parts of 95 to 99 wt% sulfuric acid, 2 to 4 parts of 13 to 17 wt% oxalic acid and 0.5 to 1.5 parts of 35 to 40 wt% acetic acid, preferably 5 parts of 85 wt% phosphoric acid, 3 parts of 98 wt% sulfuric acid, 3 parts of 15 wt% oxalic acid and 1 part of 38 wt% acetic acid.

[0016] Preferably, the content of phosphorus pentoxide in the monoammonium phosphate is 44 wt %, and the content of nitrogen is 11 wt %.

[0017] Preferably, the content of potassium oxide in the potassium chloride is 62wt%.

[0018] Preferably, the ammonium polyphosphate has a degree of polymerization of 4 to 18, a nitrogen content of 25 wt%, and a phosphorus pentoxide content of 40 wt%.

[0019] Further, the EDTA chelated trace elements include the following components in percentage by mass: 4-6% iron, 3-5% zinc, 4-5% manganese, 1-2% copper, 1.5-2.0% boron and 0.2-0.5% molybdenum; preferably 5.6% iron, 4.7% zinc, 4.7% manganese, 1.7% copper, 1.8% boron and 0.4% molybdenum; Preferably, the seaweed essence contains the following components in percentage by mass: 21% seaweed essence and 20% nitrogen, phosphorus and potassium.

[0020] Furthermore, the preparation method of the modified chitosan comprises: adding citric acid, sodium hypophosphite and chitosan into water, wherein the weight ratio of citric acid, sodium hypophosphite, chitosan and water is (120-140): (0.8-1): (70-80): (3000-3200), starting stirring and controlling the stirring speed to 80-100 rpm, reacting at 80-90°C for 3-3.5 hours, filtering, and drying the filter residue at 105-110°C to obtain the initial chitosan. Primary modified chitosan; add primary modified chitosan, sodium phytate and sodium tripolyphosphate into water, wherein the weight ratio of primary modified chitosan, sodium phytate, sodium tripolyphosphate and water is (100-105): (3-5): (10-12): (2000-2100), start stirring and control the stirring speed to 200-220rpm, react at 80-90℃ for 1.5-2h, filter, and dry the residue at 105-110℃ to obtain modified chitosan.

[0021] Furthermore, the onion peel antimicrobial active substance is added in the form of onion water extract or alcohol extract, and the mass concentration of the onion peel antimicrobial active substance in the onion water extract or alcohol extract is 38-60%, preferably 40-50%, and more preferably 45%.

[0022] For example, the onion water extract or alcohol extract preparation method comprises: The inedible outer skin of white onion or red onion is ground and sieved to obtain onion skin powder, wherein the sieve aperture is preferably 50-80 mesh, more preferably 60-70 mesh, to obtain onion skin powder with uniform particle size; the onion skin powder is mixed with an extraction solvent at a ratio of 1 g:(5-10) mL to obtain an onion powder suspension, wherein the extraction solvent is water or an ethanol solution with a volume concentration of 75-95%, the solid-liquid ratio is more preferably 1 g:8 mL, and the volume concentration of the ethanol solution is preferably 85%-90%; the onion powder suspension is subjected to ultrasonic treatment, the temperature is preferably 40-60°C, more preferably 50°C, the time is preferably 10-30 min, more preferably 20 min, the frequency of the ultrasonic wave is preferably 450w-500w, and the interval time is 5 min. After the ultrasonic treatment, the material after the ultrasonic treatment is centrifuged for solid-liquid separation, and the supernatant is collected to obtain the onion skin antimicrobial active substance, the centrifugation time is preferably 10-30 min, more preferably 20 min, the centrifugation temperature is preferably 20-30° C., more preferably 25° C., and the centrifugation speed is preferably 4000-5000 rpm, more preferably 4500 rpm; the residue obtained by the above centrifugation is mixed with the extraction solvent and then subjected to secondary centrifugation, and the supernatant is combined, the solid-liquid ratio of the residue to the extraction solvent is preferably 1 g: (5-10) mL, more preferably 1 g: 8 mL; the time, temperature and speed of the secondary centrifugation are preferably the same as those of the first centrifugation; the centrifugation process can be repeated 2-3 times, the supernatants are combined, and the onion skin antimicrobial active substance is concentrated by rotary evaporation, the rotary evaporation concentration temperature is preferably 40-60° C., more preferably 45-55° C., most preferably 50° C., and the time is preferably 2-10 h, more preferably 3-8 h; the mass concentration of the concentrated onion skin antimicrobial active substance is preferably 38-60%, more preferably 45%.

[0023] Furthermore, the preparation method of the garlic extract comprises: chopping the garlic, adding deionized water 4.5 to 5.5 times the weight of the garlic, boiling for 14 to 16 minutes under a pressure of 0.5 to 0.7 MPa, and filtering to obtain a filtrate a and a filter residue; mashing the filter residue into a muddy state, and then adding a cellulase solution 4.5 to 5.5 times the weight of the filter residue for hydrolysis for 3.5 to 4.5 hours, using water bath heating and magnetic stirring to assist in the hydrolysis process, the water bath heating temperature is 36 to 38° C., the magnetic stirring speed is 100 to 120 r / min, and filtering again to obtain a filtrate b; boiling the filtrate b to 80 to 89° C., cooling to room temperature, and then combining it with the filtrate a to obtain the garlic extract.

[0024] Furthermore, the mass concentration of allicin in the garlic extract is 1-2%, preferably 1.5%.

[0025] The CAS number of the cellulase is 9012-54-8, and the concentration of the cellulase solution is 0.1%.

[0026] In a second aspect, the present invention provides a method for preparing the slow-release fertilizer, comprising the following steps: (1) weighing the raw materials of the functional particles according to the formula and putting them into a stirring tank for mixing; (2) The mixed raw materials are sent to the crusher by a conveyor belt for crushing, and then sent to the rotary drum granulator. A small amount of steam is sprayed into the granulation drum material through a steam nozzle, and molten urine is sprayed into the granulation drum at the same time to heat the material to 40-50°C, and the granulation drum is continuously rotated to form balls; (3) The pelletized material is sent into a drying drum and dried with hot air. The material outlet temperature of the drying drum is 65-75°C, preferably 70°C; (4) mixing the raw materials of the functional layer to prepare a coating material; (5) The material dried in step (3) is cooled and sieved, and a layer of the coating material prepared in step (4) is sprayed on the surface of the particles to obtain a finished product.

[0027] In a third aspect, the present invention provides use of the slow-release fertilizer in enhancing crop stress resistance.

[0028] The stress resistance includes drought resistance, saline-alkali resistance, waterlogging resistance, wind resistance, frost resistance, disease and pest resistance, etc.

[0029] By means of the above technical solution, the present invention has at least the following advantages and beneficial effects: (I) The present invention adopts the latest scientific formula and is produced by rigorous and scientific methods to produce a slow-release fertilizer that can enhance the stress resistance of crops. The product contains humic acid, which can not only prolong the effective period of nitrogen nutrients and achieve the effects of "nitrogen fixation, phosphorus solubilization, and potassium promotion", but also activate trace nutrients in the soil. It is a new type of fertilizer that can improve environmental conditions, has the advantages of balanced nutrition, strong stress resistance, improved soil, improved quality, etc., and is a typical green and pollution-free fertilizer.

[0030] (ii) The present invention uses activated humic acid as a carrier, adds seaweed extract, polyglutamic acid, modified chitosan, ammonium polyphosphate, pyrethrum powder, onion peel antibacterial active substances, garlic extract, brassinolide, trace elements, etc., organically combines urea-formaldehyde sustained-release technology, plant-derived biological insecticide / antibacterial / water retention and other multifunctional stress resistance technologies, and pays attention to the scientific compatibility of various components to achieve synergistic effects, which is conducive to the transfer and accumulation of nitrogen, phosphorus and potassium elements in crops, is beneficial to increasing crop plant height and stem thickness, further increasing the accumulation of dry matter in crop grains, improving crop quality, increasing production and income, and also increasing the content of effective phosphorus, quick-acting potassium, alkaline nitrogen, total phosphorus, total potassium and total nitrogen in the soil, improving soil fertility, and further improving the utilization rate of fertilizers.

[0031] (III) The present invention adds polyglutamic acid and seaweed extract, among which polyglutamic acid has good buffering capacity for acid and alkali, can effectively balance the soil pH value, and avoid the acidic soil caused by long-term use of chemical fertilizers; the added seaweed extract is a small molecular group of polysaccharide substances, which can stimulate the development of crop roots, and also has the effect of breaking up soil compaction and delaying salinization. Polyglutamic acid can form a protective film on the root system of crops, and synergize with seaweed extract, not only promoting root growth, but also protecting the root system, and jointly improving the drought resistance, cold resistance, and salt-alkali resistance of crops; seaweed extract not only has the effect of swelling when it meets water, but also has a capillary effect, forming a moist capillary channel, which can promote the disintegration of fertilizers after application, promote the absorption of fertilizers by crops, and improve the utilization rate of fertilizers.

[0032] (IV) The product of the present invention can meet the long-term nutritional and pest resistance needs of the total crop through a one-time application, and at the same time, the nutrient release efficiency is matched with the needs of crops, so that the fertilizer supply is stable. Through joint application and synergistic effect, soil compaction and salinization can be avoided to a great extent, soil microbial reproduction can be promoted, the comprehensive fertility of the soil can be improved, pests and diseases can be effectively prevented and controlled, the crop resistance to stress can be improved, and stable production, high yield and increased income can be ensured. DETAILED DESCRIPTION

[0033] In order to achieve the purpose of the present invention, an agricultural service team was specially established, equipped with special agricultural service vehicles and soil rapid testing instruments, and cooperated with 11 soil and fertilizer stations in some provinces and cities across the country, sampled and investigated the soil nutrient status in major grain crop producing areas such as Shandong, Henan, and Northeast China, established a soil nutrient database, and conducted a large number of tests on soil samples.

[0034] Based on the above experiments, the present invention first provides a slow-release fertilizer capable of enhancing crop stress resistance and a preparation method thereof, comprising functional particles and a functional layer coated on the outer surface of the functional particles, specifically comprising the following raw materials in parts by weight:

[0035] As a preferred embodiment, the slow-release fertilizer capable of enhancing crop stress resistance comprises the following components in parts by weight:

[0036] More preferably, the slow-release fertilizer capable of enhancing crop stress resistance comprises the following components in parts by weight:

[0037] Experiments show that the above-mentioned specific formula of slow-release fertilizer can synergistically enhance the disease resistance and insect resistance. At the same time, the addition of urea formaldehyde can enhance the slow-release effect. Especially when urea formaldehyde is added to the functional particles and the functional layer in specific proportions respectively, and arranged in the above-mentioned layers, it is beneficial to make the release efficiency of fertilizers and stress-resistant substances synchronously meet the needs of crops, so as to stabilize the fertilizer supply and thus improve the application effect of the product.

[0038] In order to improve the sustained-release effect, the present invention further optimizes urea formaldehyde. Preferably, the preparation method of the urea formaldehyde is as follows: according to the molar ratio of urea: formaldehyde = (1.4~1.6): 1, urea is added to a formaldehyde solution with a mass concentration of 35~40% and a temperature of 25~30°C, and an acid catalyst is added to adjust the pH to 4-6, and the reaction is obtained. Preferably, the urea is small-particle urea, wherein the nitrogen content is 45~50 wt% and the particle size is 0.85mm-2.80mm; preferably, the acid catalyst is composed of the following components by weight: 83-87 wt% phosphoric acid 4-6 parts; 2-4 parts of 95-99 wt% sulfuric acid; 13~17 wt% oxalic acid 2~4 parts; 35~40 wt% acetic acid 0.5~1.5 parts.

[0039] As a preferred embodiment, the acid catalyst is prepared by mixing 5 parts of phosphoric acid (concentration 85wt%), 3 parts of sulfuric acid (concentration 98wt%), 3 parts of oxalic acid (concentration 15wt%) and 1 part of acetic acid (concentration 38wt%).

[0040] By optimizing the preparation method of urea formaldehyde, its activity index can be increased so that it contains more sustained-release nitrogen, thereby further improving the sustained-release effect.

[0041] 1. Functional particles The functional particles contain urea formaldehyde, urea, monoammonium phosphate, potassium chloride, ammonium polyphosphate, EDTA chelated trace elements, and additives.

[0042] The nitrogen content of the urea formaldehyde is 38%-40%, preferably 40%; the nitrogen content of the urea is 46wt%; the phosphorus pentoxide content of the monoammonium phosphate is 44wt%, and the nitrogen content is 11wt%; the potassium oxide content of the potassium chloride is 62wt%; the degree of polymerization of the ammonium polyphosphate is 4-18, the nitrogen content is 25wt%, and the phosphorus pentoxide content is 40wt%; The EDTA chelated trace elements include the following components in percentage by mass: 4-6% iron, 3-5% zinc, 4-5% manganese, 1-2% copper, 1.5-2.0% boron and 0.2-0.5% molybdenum. More preferably, 5.6% iron, 4.7% zinc, 4.7% manganese, 1.7% copper, 1.8% boron and 0.4% molybdenum. The selection and dosage of the EDTA chelated trace elements can be adjusted according to the needs of crops within the scope of the present invention.

[0043] The present invention adds a specific amount of ammonium polyphosphate to basic nitrogen, phosphorus and potassium fertilizers, which not only has high nutrient content, good solubility, contains polymerized phosphorus, but also is not easy to react with calcium, magnesium, iron, aluminum and other ions in the soil solution to make phosphate ineffective, thereby avoiding phosphorus being fixed by the soil, increasing the moving distance of phosphorus in the soil, nourishing deep root systems, and greatly improving the utilization rate of phosphorus in the current season. In addition, ammonium polyphosphate also has the effect of chelating metal ions, is not easy to be fixed by metal ions such as iron and calcium in the soil, but can form soluble complexes with invalid trace elements in the soil and be absorbed and utilized by plants. At the same time, ammonium polyphosphate is not directly absorbed by plants in the soil, but is gradually hydrolyzed into orthophosphate and utilized by plants, thereby further improving the slow-release effect of fertilizer.

[0044] As a linear polymer, polyglutamic acid has a large number of hydrogen bonds between chains, which allows water molecules to quickly enter the polymer structure, making polyglutamic acid highly water-soluble and water-absorbent. There are a large number of peptide bonds on the main chain of polyglutamic acid, which is susceptible to the action of certain hydrolases in the environment, and degrades to generate non-toxic short peptides or glutamic acid monomers. These substances belong to the human body itself and are non-toxic to the human body, so they have good biodegradability, biocompatibility and safety. Glutamic acid is one of the basic amino acids for nitrogen metabolism in biological organisms, occupies an important position in the protein metabolism process in organisms, and can be directly absorbed and utilized by plants as an amino acid.

[0045] 2. Functional layer The functional layer contains seaweed extract, modified chitosan, pyrethrum powder, onion peel antibacterial active substances, garlic extract, brassinolide, etc.

[0046] The seaweed essence is made from large algae grown in the ocean as raw materials, and through chemical, physical or biological methods, natural nutrients required for crop growth and development are extracted from the seaweed, including a variety of natural plant growth regulators (plant growth hormones, cytokinins, gibberellins, seaweed essence, seaweed polyphenols, protein amino acids, nucleotides, plant stress resistance substances, etc.), and made into fertilizers, which can be used on crops to promote crop growth, increase yields, and improve the quality of agricultural products. Preferably, the seaweed essence contains 21% seaweed essence and 20% nitrogen, phosphorus and potassium.

[0047] The preparation of the modified chitosan comprises adding citric acid, sodium hypophosphite and chitosan into water, wherein the weight ratio of citric acid: sodium hypophosphite: chitosan: water is (120-140): (0.8-1): (70-80): (3000-3200), starting stirring and controlling the stirring speed to 80-100 rpm, reacting at 80-90° C. for 3-3.5 hours, filtering by suction, and drying the filter residue at 105-110° C. to obtain primary modified chitosan. Sugar; add primary modified chitosan, sodium phytate and sodium tripolyphosphate into water, wherein the weight ratio of primary modified chitosan: sodium phytate: sodium tripolyphosphate: water is (100-105): (3-5): (10-12): (2000-2100), start stirring and control the stirring speed to 200-220rpm, react at 80-90℃ for 1.5-2h, filter, and dry the residue at 105-110℃ to obtain modified chitosan.

[0048] The pyrethrum powder is obtained by drying and crushing pyrethrum, which is a plant of the Asteraceae family with both high economic value and ornamental value. Its roots, stems, leaves, flowers, etc. contain toxic insecticidal substances, which can be used to extract raw materials for pyrethrin. Pyrethrin is a broad-spectrum insecticide that can prevent and control a variety of pests. Its insecticidal toxicity is 10 to 100 times higher than that of the older generation of insecticides such as organochlorine, organophosphorus, and carbamate.

[0049] The onion skin antimicrobial active substance is added in the form of a water extract concentrate and / or an alcohol extract concentrate, in which the mass concentration of the onion skin antimicrobial active substance is 38-60%, preferably 40-50%, and more preferably 45%. In some embodiments, the concentrate is a concentrate obtained by water extraction or alcohol extraction, ultrasonic treatment, and separation using discarded onion skin as a raw material. The onion skin antibacterial active substance reacts with the sulfhydryl group in amino acids (such as cysteine) to prevent the formation of corresponding proteins, thereby inhibiting the growth of microorganisms and reducing the occurrence of plant diseases. At the same time, it has insecticidal effects.

[0050] The garlic extract is added in the form of garlic extract, in which the mass concentration of allicin in the garlic extract is 1-2%, preferably 1.5%. The preparation process of the garlic extract is as follows: mince the garlic, add deionized water 4.5-5.5 times the weight of the garlic, boil it under a pressure of 0.5-0.7 MPa for 14-16 minutes, filter to obtain filtrate a and filter residue; mash the filter residue into a mud-like state, then add a cellulase solution (concentration 0.1%) 4.5-5.5 times the weight of the filter residue to hydrolyze for 3.5-4.5 hours, and use water bath heating and magnetic stirring to assist in the hydrolysis process, the water bath heating temperature is 36-38°C, the magnetic stirring speed is 100-120r / min, filter again to obtain filtrate b, boil the filtrate b to 80-89°C, cool it to room temperature, and then combine it with the filtrate a. Allicin can be used for plant protection. Its main component, organic sulfide compounds, have insecticidal, bactericidal and health-care effects on crops. It can effectively improve crop yield and quality after use. Allicin can inhibit a variety of Gram-negative and Gram-positive bacteria, and has a good control effect on tomato early blight, leaf mold, and gray mold. It can effectively inhibit the growth of rapeseed sclerotinia, wheat sheath blight, pepper phytophthora, pepper anthracnose, and rice blast.

[0051] Brassinolide is a new type of green and environmentally friendly plant growth regulator that can promote the growth of vegetables, melons, fruits and other crops, improve quality, increase yield, make the color brighter, and make the leaves thicker. Natural brassinolide can be widely used in various economic crops, generally increasing yield by 5-10%, up to 30%, and significantly improving crop quality. At the same time, it can also improve the drought and cold resistance of crops, and alleviate the symptoms of crops suffering from pests and diseases, pesticide damage, fertilizer damage, frost damage, etc.

[0052] The present invention further provides a method for preparing the slow-release fertilizer capable of enhancing crop stress resistance, comprising: (1) The raw materials of the functional particles are mixed and granulated at 40-50° C., and dried at 65-75° C. to form functional particles; the raw materials of the functional layer are mixed and prepared into a coating material; preferably, the granulation method is spray granulation, wherein molten urine is sprayed into a granulation device, and the raw material mixture is heated to 40-50° C. for granulation; (2) Spraying the coating material onto the surface of the functional particles.

[0053] In some embodiments, the preparation method specifically comprises the following steps: (1) weighing the raw materials of the functional particles according to the formula and putting them into a stirring tank for mixing; (2) The mixed raw materials are sent to the crusher by a conveyor belt for crushing, and then sent to the rotary drum granulator. A small amount of steam is sprayed into the granulation drum material through a steam nozzle, and molten urine is sprayed into the granulation drum at the same time to heat the material to 40-50°C, and the granulation drum is continuously rotated to form balls; (3) The pelletized material is sent into a drying drum and dried with hot air. The material outlet temperature of the drying drum is 65-75°C, preferably 70°C; (4) mixing the raw materials of the functional layer to prepare a coating material; (5) The material dried in step (3) is cooled and sieved again, and a layer of the coating material prepared in step (4) is sprayed on the surface of the particles to obtain a finished product.

[0054] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art, and the raw materials used are all commercially available products.

[0055] The sources of the raw materials used in the following examples are: Urea was purchased from Shandong Xianghe Agricultural Production Materials Co., Ltd.

[0056] Monoammonium phosphate was purchased from Hubei Sanning Agricultural Materials Trading Co., Ltd.

[0057] Potassium chloride was purchased from Meisheng Agricultural Materials (Beijing) Co., Ltd.

[0058] Ammonium polyphosphate was purchased from Shandong Yukang Chemical Co., Ltd.

[0059] Polyglutamic acid was purchased from Shandong Freda Biotechnology Co., Ltd.

[0060] EDTA-chelated trace elements were purchased from Shijiazhuang Jack Chemical Co., Ltd.

[0061] Seaweed extract was purchased from Qingdao Haida Biological Group Co., Ltd.

[0062] Pyrethrum powder was purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0063] Brassinolide was purchased from Shandong Heze Juhe Industrial Co., Ltd.

[0064] In the following embodiments, the preparation method of urea formaldehyde is as follows: urea is added to a formaldehyde solution with a mass concentration of 38% and a temperature of 28°C according to a molar ratio of urea:formaldehyde=1.5:1, an acid catalyst is added to adjust the pH to 5, and the reaction is obtained. The acid catalyst is a mixture of 5 parts of phosphoric acid (concentration 85wt%), 3 parts of sulfuric acid (concentration 98wt%), 3 parts of oxalic acid (concentration 15wt%) and 1 part of acetic acid (concentration 38wt%). The parts are weight parts.

[0065] The onion peel antibacterial active substance is added in the form of an alcohol-extracted concentrated solution, in which the mass concentration of the onion peel antibacterial active substance is 45%.

[0066] The preparation method of the alcohol extraction concentrate is: The inedible outer skin of white onion or red onion is ground and sieved to obtain onion skin powder, wherein the sieve aperture is preferably 50-80 mesh, more preferably 60-70 mesh, to obtain onion skin powder with uniform particle size; the onion skin powder is mixed with an extraction solvent at a ratio of 1 g:(5-10) mL to obtain an onion powder suspension, wherein the extraction solvent is water or an ethanol solution with a volume concentration of 75-95%, the solid-liquid ratio is more preferably 1 g:8 mL, and the volume concentration of the ethanol solution is preferably 85%-90%; the onion powder suspension is subjected to ultrasonic treatment, the temperature is preferably 40-60°C, more preferably 50°C, the time is preferably 10-30 min, more preferably 20 min, the frequency of the ultrasonic wave is preferably 450w-500w, and the interval time is 5 min. After the ultrasonic treatment, the material after the ultrasonic treatment is centrifuged for solid-liquid separation, and the supernatant is collected to obtain the onion skin antimicrobial active substance, the centrifugation time is preferably 10-30 min, more preferably 20 min, the centrifugation temperature is preferably 20-30° C., more preferably 25° C., and the centrifugation speed is preferably 4000-5000 rpm, more preferably 4500 rpm; the residue obtained by the above centrifugation is mixed with the extraction solvent and then subjected to secondary centrifugation, and the supernatant is combined, the material-liquid ratio of the residue to the extraction solvent is preferably 1 g: (5-10) mL, more preferably 1 g: 8 mL, and the time, temperature and speed of the secondary centrifugation are preferably the same as those of the first centrifugation; the centrifugation process can be repeated 2-3 times, the supernatants are combined, and the onion skin antimicrobial active substance is concentrated by rotary evaporation, the rotary evaporation concentration temperature is preferably 40-60° C., more preferably 45-55° C., most preferably 50° C., and the time is preferably 2-10 h, more preferably 3-8 h; the mass concentration of the concentrated onion skin antimicrobial active substance is preferably 38-60%, more preferably 45%.

[0067] The garlic extract is added in the form of garlic extract, in which the mass concentration of the garlic extract is 1.5%. The preparation method of the garlic extract is as follows: chop the garlic, add deionized water 5 times the weight of the garlic, boil it under a pressure of 0.6MPa for 15 minutes, filter to obtain filtrate a, mash the filter residue into a mud, add cellulose hydrolyzate 5 times the weight of the filter residue, and hydrolyze for 4 hours, use water bath heating and magnetic stirring to assist in the hydrolysis process, the water bath heating temperature is 37°C, the speed of the magnetic stirring is 110r / min, filter again to obtain filtrate b, boil the filtrate b to 85°C, cool it to room temperature, and then combine it with the filtrate a; finally, the mass concentration of the garlic extract is controlled to be 1.5%.

[0068] The nitrogen content of the urea is 46 wt %, the phosphorus pentoxide content of the monoammonium phosphate is 44 wt %, and the nitrogen content is 11 wt %; the potassium oxide content of the potassium chloride is 62 wt %.

[0069] The EDTA-chelated trace elements are specifically a mixture of EDTA-chelated zinc, EDTA-chelated magnesium and EDTA-chelated boron in a weight ratio of 1:1:1.

[0070] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0071] Example 1 This embodiment provides a slow-release fertilizer capable of enhancing crop stress resistance, including functional particles and a functional layer coated on the outer surface of the functional particles, and the formula components and contents thereof are as follows:

[0072] This embodiment further provides a method for preparing the slow-release fertilizer capable of enhancing crop stress resistance: (1) weighing the raw materials of the functional particles according to the formula and putting them into a stirring tank for mixing; (2) The mixed raw materials are sent to the crusher by a conveyor belt for crushing, and then sent to the rotary drum granulator. A small amount of steam is sprayed into the granulation drum material through a steam nozzle, and molten urine is sprayed into the granulation drum at the same time. The material is heated to 45°C and formed into balls through the continuous rotation of the granulation drum; (3) The balled material is sent into the drying drum and dried with hot air. The material outlet temperature of the drying drum is 70°C. (4) mixing the raw materials of the functional layer to prepare a coating material; (5) The material dried in step (3) is cooled and sieved again, and a layer of the coating material prepared in step (4) is sprayed on the surface of the particles to obtain a finished product.

[0073] The product obtained has a specification of 21-10-15 and a total nutrient content of 46%, and contains ammonium polyphosphate, EDTA-chelated trace elements, polyglutamic acid, seaweed extract, modified chitosan, pyrethrum powder, onion peel antimicrobial active substances, garlic extract, and brassinolide.

[0074] Example 2 This embodiment provides a slow-release fertilizer capable of enhancing crop stress resistance, including functional particles and a functional layer coated on the outer surface of the functional particles, and the formula components and contents thereof are as follows:

[0075] The preparation method is the same as that of Example 1.

[0076] The resulting product specification is 21-10-15, with a total nutrient content of 46%, and does not contain EDTA-chelated trace elements.

[0077] Example 3 This embodiment provides a slow-release fertilizer capable of enhancing crop stress resistance, which is a functional particle, and its formula components and contents are as follows:

[0078] Among them, the additives are a viscosity reducer and a melting agent in a weight ratio of 1:1; preferably, the viscosity reducer is one or a mixture of ammonium nitrate phosphate, magnesium sulfate, and magnesium sulfate heptahydrate, and more preferably ammonium nitrate phosphate; the melting agent is one or a mixture of ammonium chloride, ammonium sulfate, potassium sulfate, potassium chloride, and potassium nitrate, and more preferably ammonium chloride.

[0079] The preparation method is the same as that of Example 1.

[0080] The product specifications obtained are 21-10-15, total nutrients 46%, and no functional layer.

[0081] Comparative Example 1 This comparative example provides a urea-formaldehyde slow-release fertilizer with a total nutrient content of 46% and a product specification of 21-10-15, containing EDTA-chelated trace elements, wherein the sources of nitrogen, phosphorus and potassium are the same as those in Example 1.

[0082] Comparative Example 2 This comparative example provides a urea-formaldehyde slow-release fertilizer with a total nutrient content of 46% and a product specification of 21-10-15. It does not contain EDTA-chelated trace elements, and the sources of nitrogen, phosphorus and potassium are the same as those in Example 1.

[0083] Experiment 1: Peanut planting comparison experiment The test site was selected in Linshu County, Linyi City, Shandong Province. It is sandy loam. The soil nutrients include 1.2% organic matter, 110 mg / kg nitrate nitrogen, 33 mg / kg available phosphorus, and 116 mg / kg available potassium.

[0084] The test crop is peanut, and the variety is Fenghua No. 1.

[0085] Before sowing, mix the seeds and dry them in a cool and ventilated place. The test site requires fine land preparation before sowing, the ground is flat and there are no clods, the soil moisture content is 60-75% before sowing, and the sowing depth is 3-4 cm.

[0086] Soil information: The test soil is sandy loam, and the soil nutrients include 1.2% organic matter, 110 mg / kg nitrate nitrogen, 30 mg / kg available phosphorus, and 112 mg / kg available potassium.

[0087] Experimental treatment: There are 5 treatments in this experimental example.

[0088] Experimental arrangement: Each experimental plot is 60 square meters, each treatment is repeated 3 times, and random block arrangement is adopted to reduce the experimental error and ensure the consistency of soil fertility in each treatment. Sowing on April 23, 2023, seedling emergence on May 1, flowering on June 10, pod setting on July 11, harvest on September 6, and the growth period is 136 days. Double peanut sowing, 8,000 holes per mu.

[0089] Table 1 Effects of different fertilization treatments on different traits of peanut

[0090] Through the above test comparison, it can be concluded that compared with the comparative example, the number of pods per plant, the fruit yield rate and the weight of 100 fruits in the embodiment are significantly improved. Among them, the peanut yield of Example 1 is the highest at 373.6 kg / mu, which is 5.78% and 7.82% higher than that of Example 2 and Example 3 respectively; it is 9.02% and 16.31% higher than that of Comparative Example 1 and Comparative Example 2 respectively. Therefore, the product of the present invention can not only increase the growth of crops and increase the yield, but also improve the stress resistance of crops, and the effect is significant. Among them, Example 1 has the best effect and is worthy of promotion (Table 1).

[0091] Experiment 2: Rapeseed Planting Comparison Experiment The experiment was conducted in Linyi City, Shandong Province. The soil nutrient content was: 1.19 g / kg nutrient content, 10.3 mg / kg available phosphorus, 92 mg / kg available potassium, and 21.6 g / kg organic matter.

[0092] The test crop was rapeseed, and the variety was Qinyou No. 10.

[0093] Except for the fertilizer being weighed separately according to the requirements of the plan, the basic seedlings, planting density and other agricultural operation procedures and time of each experimental plot are exactly the same.

[0094] According to the experimental design, each plot has 2 beds, each bed is 1.4m wide and 10.7m long, with a planting density of 23×22cm. Each plot has 584 plants, which is equivalent to 13,000 plants per mu. Drainage ditches and irrigation ditches are separated. Seedlings are raised and transplanted. Sowing on September 27, 2023 and harvesting on May 16, 2024.

[0095] Test records, seed testing and yield verification: Test records are made for the fertilizer varieties, quantities, time of fertilization, ratio of base fertilizer to topdressing, and major growth stages of the plants in each plot. When mature, 10 to 20 plants are selected from each plot for seed testing, and the number of pods per plant, the number of grains per pod, and the thousand-grain weight are counted, and seed testing analysis is conducted. When harvesting in each plot, single cutting, single threshing, single drying, single weighing and single packaging are adopted, and internal and external labels are attached, and yields are measured separately.

[0096] The experiment set up 5 treatments, each with 3 replications, and arranged in random blocks. Each plot has an area of ​​30 m2, with protection rows set up around it, and the width of the protection row is not less than 1.5 m.

[0097] After the rapeseed matured, the seeds were tested in time. The results of the rapeseed fertilizer utilization test are shown in Table 2.

[0098] Table 2 Statistics of rapeseed fertilizer utilization rate test

[0099] The test results show that the yield order of each fertilization treatment is: treatment 1 (Example 1) > treatment 2 (Example 2) > treatment 3 (Example 3) > treatment 4 (Comparative Example 1) > treatment 5 (Comparative Example 2), indicating that the addition of ammonium polyphosphate, polyglutamic acid, EDTA chelated trace elements, pyrethrum powder, onion skin antibacterial active substances, garlic extract, brassinolide, etc. has a significant yield-increasing effect on rapeseed. The formula of Example 1 is the most reasonable, and one-time fertilization saves time and effort, can improve crop stress resistance, and has a significant yield-increasing effect.

[0100] Compared with two fertilization methods of applying common fertilizers with the same nutrients, the product of the present invention can effectively increase the number of rapeseed siliques and the thousand-grain weight. Example 1 has the highest yield increase rate. The fertilizer product of the present invention has high nutrient utilization rate, is easy to use, simplifies fertilization procedures, and can be demonstrated and promoted on field crops with a long growth period such as rapeseed.

[0101] Experiment 3: Comparative experiment on Chinese cabbage planting The experiment was set up in Shandong Lanling Modern Demonstration Garden, and the soil nutrient content was: organic matter 1.52%, alkaline nitrogen 116ppm, available phosphorus 28.4ppm, and available potassium 116ppm.

[0102] The test variety was Chinese cabbage. The experiment adopted a randomized block design. Each experiment had 5 treatments, each treatment was repeated 3 times, and the plot area was 20 m 2 The comparison of implementation effects is shown in Table 3.

[0103] Table 3 Effects of different fertilization treatments on the nutritional quality of Chinese cabbage

[0104] It can be seen from the results of the Chinese cabbage test that the yield, vitamin C content and soluble sugar content of Chinese cabbage in all the examples are significantly higher than those in the comparative example, which can increase the cabbage heart (commercial rate) of Chinese cabbage, significantly improve the vitamin C and soluble sugar content, and have a significant yield-increasing effect. Example 3 has no functional layer, resulting in 1% of diseased plants, while Comparative Example 1 and Comparative Example 2 produce 2.03% and 2.04% of diseased plants, respectively. For example, Chinese cabbage has many diseases, and is prone to downy mildew, black spot, white spot, anthracnose, powdery mildew, white rust, sclerotinia, brown spot, brown rot, leaf rot, gray mold, wilt, clubroot, black rot, soft rot, bacterial angular spot, bacterial leaf spot, viral disease, etc., which can easily lead to diseased plants of Chinese cabbage.

[0105] Therefore, the product of the present invention can not only increase the growth of crops, but also better control the development of diseases. Example 1 has the best effect and is worthy of promotion.

[0106] Experiment 4: Rice planting comparison experiment The experiment was conducted in Suihua, Heilongjiang Province. The soil type was black soil, with 153.87 mg / kg of alkaline nitrogen, 39.98 mg / kg of available phosphorus, 172 mg / kg of available potassium, 25.1% of organic matter, and pH 6.30. The rice variety tested was Songjing 9, and the rice seedlings were planted on May 17. There were three treatments, each with 667 m 2 , no repetition. 40kg / mu, applied once. The effects of different fertilizations on the growth and development of rice during the booting stage are shown in Table 4, and the effects on the components of rice yield are shown in Table 5.

[0107] Table 4 Effects of different fertilization on rice growth and development at the booting stage

[0108] The test results show that, at the rice booting stage, the average plant height of Example 1 was the highest, reaching 45.5 cm, and the aboveground fresh weight and dry weight were the largest, which were 45.8 g / hole and 22.9 g / hole, respectively; followed by Example 2, with an average plant height of 44.3 cm, and the aboveground fresh weight and dry weight were 44.3 g / hole and 21.9 g / hole, respectively; the average plant height of Comparative Example 2 was the shortest, at 43.1 cm, and the aboveground fresh weight and dry weight were the smallest, which were 40.2 g / hole and 20.1 g / hole, respectively.

[0109] Table 5 Effects of different fertilizations on rice yield components

[0110] The test results show that the ear length of Example 1 is the same as that of Example 2, with an average ear length of 19.3 cm, 2 cm longer than that of Comparative Example 2; the empty and blight rate of Example 1 is the lowest, with an empty and blight rate of 12.97%, and the empty and blight rate of Comparative Example 2 is the highest, with an empty and blight rate of 25.97%. In terms of the number of grains per ear and the thousand-grain weight, the order of the yield of each fertilization treatment is: Treatment 1 (Example 1) > Treatment 2 (Example 2) > Treatment 3 (Example 3) > Treatment 4 (Comparative Example 1) > Treatment 5 (Comparative Example 2); Example 1 has the highest yield, with an average yield of 684.96 kg per mu, and the yield increase rates of Comparative Example 1 and Comparative Example 2 are 9.32% and 9.68% respectively, and the yield difference reaches a significant level. The second is the treatment of Example 2, with a yield of 678.89 kg / mu, and the yield increase rates of Comparative Example 1 and Comparative Example 2 are 8.35% and 8.71% respectively, and the yield difference reaches a significant level. It is shown that adding ammonium polyphosphate, polyglutamic acid, EDTA chelated trace elements, pyrethrum powder, onion skin antibacterial active substances, garlic extract, brassinolide, etc. has a significant yield-increasing effect on rice. The formula of Example 1 is the most reasonable, and one-time fertilization saves time and labor, can improve crop stress resistance, and has a significant yield-increasing effect.

[0111] Experiment 5: Comparative experiment on blueberry planting The experiment was conducted in Stanley Agricultural Science and Technology Demonstration Park in Linyi City, Shandong Province. The soil of the experimental base is loam, which is loose, has good drainage performance and no pollution history. The soil organic matter content in the 20cm soil layer is 8.5%, total nitrogen is 0.89g / kg, available phosphorus is 19.8mg / kg, and available potassium is 139.6mg / kg. The soil pH is 4.5, the soil fertility is uniform and the terrain is flat.

[0112] The test crop was blueberry, and the variety was "Duke".

[0113] This experiment has 5 treatments, arranged in random blocks, repeated 3 times, and the area of ​​the plot is 300m 2 .

[0114] The test trees in the test site were planted on February 7, 2023. They are 5-year-old northern highbush blueberries with normal growth and similar growth. The spacing between rows and plants is 1.2mx2m, and the average tree height is 1.7m. Fertilization was carried out as required, and the harvest was completed on June 23, 2024.

[0115] During the harvest, the yield was calculated based on the plots, and the yield was the cumulative yield of multiple harvests from February 7 to June 23. Field surveys and seed tests were conducted during the harvest. In addition to the requirements of the plan, other management measures were the same as those for general blueberry fields. The comparison of implementation effects is shown in Table 6.

[0116] Table 6 Effects of different types of fertilizers on blueberry yield

[0117] Note: The data in the table are the average of 3 repetitions.

[0118] As can be seen from Table 6, the average fruit length, number of fruits per plant, yield per plant, and average yield of the embodiments are all better than those of the comparative examples, and the yield of embodiment 1 is the highest. Compared with comparative examples 1 and 2, the yield increase rates are 21.33% and 21.94%, respectively, and the formula is the most reasonable. Therefore, the product of the present invention integrates improving crop stress resistance, increasing crop yield, improving crop quality, and improving soil microecology, and has a high fertilizer utilization rate. The formula of embodiment 1 is the best and is worthy of promotion.

[0119] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A slow-release fertilizer for enhancing crop stress resistance, characterized in that: The slow-release fertilizer comprises functional particles and a functional layer coated on the outer surface of the functional particles; The functional particles include the following raw materials in parts by weight: 50-80 parts of urea formaldehyde, 100-500 parts of urea, 200-500 parts of monoammonium phosphate, 100-450 parts of potassium chloride, 1-15 parts of ammonium polyphosphate, 8-35 parts of polyglutamic acid and 2-10 parts of EDTA chelated trace elements; The functional layer comprises the following raw materials in parts by weight: 8-25 parts of seaweed extract, 8-20 parts of modified chitosan, 20-45 parts of pyrethrum powder, 8-45 parts of onion peel antibacterial active substances, 8-70 parts of garlic extract and 8-40 parts of brassinolide.

2. The slow-release fertilizer according to claim 1, characterized in that The functional particles include the following raw materials in parts by weight: 60-70 parts of urea formaldehyde, 150-550 parts of urea, 200-400 parts of monoammonium phosphate, 150-350 parts of potassium chloride, 2-10 parts of ammonium polyphosphate, 10-30 parts of polyglutamic acid and 3-7 parts of EDTA chelated trace elements; The functional layer comprises the following raw materials in parts by weight: 10-20 parts of seaweed extract, 10-15 parts of modified chitosan, 25-40 parts of pyrethrum powder, 15-40 parts of onion peel antibacterial active substances, 15-60 parts of garlic extract and 15-30 parts of brassinolide.

3. The slow-release fertilizer according to claim 2, characterized in that The functional particles include the following raw materials in parts by weight: 60 parts of urea formaldehyde, 358 parts of urea, 226 parts of monoammonium phosphate, 242 parts of potassium chloride, 2 parts of ammonium polyphosphate, 10 parts of polyglutamic acid and 3 parts of EDTA chelated trace elements; The functional layer comprises the following raw materials in parts by weight: 10 parts of seaweed extract, 10 parts of modified chitosan, 25 parts of pyrethrum powder, 19 parts of onion peel antibacterial active substances, 20 parts of garlic extract and 15 parts of brassinolide.

4. The slow-release fertilizer according to any one of claims 1 to 3, characterized in that: The preparation method of urea formaldehyde comprises: adding urea to a formaldehyde solution having a mass concentration of 35-40% and a temperature of 25-30° C. at a molar ratio of urea:formaldehyde=(1.4-1.6):1, adding an acid catalyst to adjust the pH to 4-6, and reacting to obtain urea formaldehyde; Wherein, the urea is small-particle urea with a particle size of 0.85 mm to 2.80 mm, wherein the nitrogen content is 45 to 50 wt%, preferably 46 wt%; The acid catalyst is composed of the following components in parts by weight: 4 to 6 parts of 83 to 87 wt% phosphoric acid, 2 to 4 parts of 95 to 99 wt% sulfuric acid, 2 to 4 parts of 13 to 17 wt% oxalic acid and 0.5 to 1.5 parts of 35 to 40 wt% acetic acid, preferably 5 parts of 85 wt% phosphoric acid, 3 parts of 98 wt% sulfuric acid, 3 parts of 15 wt% oxalic acid and 1 part of 38 wt% acetic acid.

5. The slow-release fertilizer according to any one of claims 1 to 3, characterized in that: The content of phosphorus pentoxide in the monoammonium phosphate is 44wt%, and the content of nitrogen is 11wt%; The content of potassium oxide in the potassium chloride is 62wt%; The ammonium polyphosphate has a degree of polymerization of 4 to 18, a nitrogen content of 25 wt %, and a phosphorus pentoxide content of 40 wt %; The EDTA chelated trace elements include the following components in percentage by mass: 4-6% iron, 3-5% zinc, 4-5% manganese, 1-2% copper, 1.5-2.0% boron and 0.2-0.5% molybdenum; preferably 5.6% iron, 4.7% zinc, 4.7% manganese, 1.7% copper, 1.8% boron and 0.4% molybdenum; The seaweed essence contains the following components in percentage by mass: 21% of seaweed essence and 20% of nitrogen, phosphorus and potassium.

6. The slow-release fertilizer according to any one of claims 1 to 3, characterized in that: The preparation method of the modified chitosan comprises: adding citric acid, sodium hypophosphite and chitosan into water, wherein the weight ratio of citric acid, sodium hypophosphite, chitosan and water is (120-140): (0.8-1): (70-80): (3000-3200), starting stirring and controlling the stirring speed to 80-100 rpm, reacting at 80-90° C. for 3-3.5 hours, filtering by suction, and drying the filter residue at 105-110° C. to obtain primary modified chitosan. Chitosan; add primary modified chitosan, sodium phytate and sodium tripolyphosphate into water, wherein the weight ratio of primary modified chitosan, sodium phytate, sodium tripolyphosphate and water is (100-105):(3-5):(10-12):(2000-2100), start stirring and control the stirring speed to 200-220rpm, react at 80-90℃ for 1.5-2h, filter and dry the residue at 105-110℃ to obtain modified chitosan.

7. The slow-release fertilizer according to any one of claims 1 to 3, characterized in that: The onion peel antibacterial active substance is added in the form of onion water extract or alcohol extract, and the mass concentration of the onion peel antibacterial active substance in the onion water extract or alcohol extract is 38-60%, preferably 40-50%, and more preferably 45%.

8. The slow-release fertilizer according to any one of claims 1 to 3, characterized in that: The preparation method of the garlic extract comprises: chopping garlic, adding deionized water in an amount of 4.5 to 5.5 times the weight of the garlic, boiling for 14 to 16 minutes under a pressure of 0.5 to 0.7 MPa, and filtering to obtain a filtrate a and a filter residue; mashing the filter residue into a muddy state, and then adding a cellulase solution in an amount of 4.5 to 5.5 times the weight of the filter residue to hydrolyze for 3.5 to 4.5 hours, using water bath heating and magnetic stirring to assist in the hydrolysis process, wherein the water bath heating temperature is 36 to 38° C., and the magnetic stirring speed is 100 to 120 r / min, and filtering again to obtain a filtrate b; boiling the filtrate b to 80 to 89° C., cooling to room temperature, and then combining with the filtrate a to obtain the garlic extract; wherein the concentration of the cellulase solution is 0.1%.

9. The method for preparing the slow-release fertilizer according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) weighing the raw materials of the functional particles according to the formula and putting them into a stirring tank for mixing; (2) The mixed raw materials are sent to the crusher by a conveyor belt for crushing, and then sent to the rotary drum granulator. A small amount of steam is sprayed into the granulation drum material through a steam nozzle, and molten urine is sprayed into the granulation drum at the same time to heat the material to 40-50°C, and the granulation drum is rotated to form balls; (3) The pelletized material is sent into a drying drum and dried with hot air. The material outlet temperature of the drying drum is 65-75°C, preferably 70°C; (4) mixing the raw materials of the functional layer to prepare a coating material; (5) The material dried in step (3) is cooled and sieved, and a layer of the coating material prepared in step (4) is sprayed on the surface of the particles to obtain a finished product.

10. Use of the slow-release fertilizer according to any one of claims 1 to 8 in enhancing crop stress resistance; The stress resistance includes drought resistance, saline-alkali resistance, waterlogging resistance, wind resistance, frost resistance, and disease and insect pest resistance.

Images