Special high-yield disease-resistant controlled-release fertilizer for potatoes and application thereof

Abstract

The invention discloses a potato high-yield disease-resistant controlled-release special fertilizer and application thereof, and relates to the technical field of fertilizer production. The high-yield disease-resistant controlled-release fertilizer special for the potatoes is prepared by adopting synergistic controlled-release urea coated with double-layer microbial agents and a controlled-release potassium-magnesium fertilizer as raw materials, wherein the synergistic controlled-release urea coated with the double-layer microbial agents is prepared by performing double-layer coating on urea through a micro-capsule loaded microbial agent. The fertilizer prepared by the invention has an optimized nutrient proportion of high potassium, medium and high nitrogen and low phosphorus, and the nutrient type and dosage accord with the nutrient requirement rule of the potatoes on macroelements. Meanwhile, the controlled release effect is realized by adopting a modified sulfur coating technology, so that the nutrient requirements of the potatoes in the key growth period are met. Through the comprehensive nutrient controlled release and inner and outer film layer fungicide loading technology, the nutrient utilization efficiency can be greatly improved, the potassium and magnesium absorption rate and the plant resistance of the potatoes are improved, diseases are reduced, the yield of the potatoes per unit area is remarkably improved, and the fertilization amount and the fertilization frequency can be reduced.

Description

Technical Field

[0001] This invention relates to the field of fertilizer production technology, and in particular to a high-yield, disease-resistant controlled-release fertilizer for potatoes and its application. Background Technology

[0002] potato( Solanum tuberosum L. As the world's fourth largest food crop, potatoes hold irreplaceable strategic value for ensuring food security. They are characterized by strong adaptability, a short growing season, balanced nutrition, drought resistance, cold resistance, and tolerance to poor soil conditions, enabling stable yields even in barren land and cool climates. In the context of today's scarce arable land resources and intensifying climate change, potatoes have become a key crop for filling the staple food gap, and achieving high potato yields is of great significance for ensuring national food security.

[0003] In terms of nutrient requirements, potatoes require the most potassium, followed by nitrogen, and less phosphorus. Producing one ton of potato tubers requires the absorption of 2-6 kg of nitrogen (N), 1-3 kg of phosphorus (P2O5), and 7-13 kg of potassium (K2O). However, commercially available potato fertilizers are often high in nitrogen. This unreasonable nutrient ratio only inhibits potassium and magnesium absorption (K⁺ / Mg²⁺ antagonism), causing excessive vegetative growth, hindered tuber enlargement, reduced starch accumulation, and also leading to resource waste and increased costs for farmers. Secondly, micronutrients are also essential for potato growth and development. A deficiency in micronutrients will result in a lack of micronutrients in the soil, thus limiting crop yield, stress resistance, and quality improvement. As a crop with a high magnesium requirement, potatoes, if not replenished in time, will exhibit interveinal yellowing in older leaves (magnesium deficiency), thereby reducing photosynthetic efficiency and tuber yield.

[0004] From a temporal perspective, potatoes exhibit unique growth characteristics. The entire growth cycle, from sowing to emergence, lasts approximately 20-30 days, relying entirely on nutrients stored within the seed tuber without external absorption. During the seedling stage, only a small amount of nutrients are absorbed, with a significant increase in nutrient absorption beginning during tuber formation. The peak nutrient requirement is reached during tuber enlargement, after which the need for fertilizer decreases. Throughout its growth cycle, NPK absorption exhibits an "S-shaped" single-peak curve, with the peak concentrated during the tuber formation to enlargement stage (40-75 days after emergence). During this stage, absorption accounts for over 70% of the total, making it crucial to maintain an adequate nutrient supply during this critical period. Existing potato-specific fertilizer technologies typically involve the application of large amounts of fast-acting nitrogen fertilizer in the early stages. However, traditional nitrogen fertilizers are highly water-soluble. When the soil temperature is 10℃, urea can be completely converted into ammonium nitrogen in just 7-10 days, and the conversion is faster at higher temperatures and moisture levels. The portion that is not absorbed and utilized by the plant will be lost through ammonia volatilization, leaching, and nitrification / denitrification. The large amount of nitrogen used in the early stages will lead to nutrient waste and will be difficult to meet the nitrogen requirements of potato tubers during the tuber enlargement period.

[0005] In addition, due to the physiological fragility of the tuber organ, the high specificity of nutrient demand, and the weak rhizosphere micro-ecological defense, potatoes are more susceptible to disease caused by nutrient imbalance than other crops due to their unique physiological structure, nutrient demand characteristics, and cultivation environment. The tuber, as a storage organ, needs to complete the swelling in the soil, and since its surface has no cutin layer protection, it is more susceptible to direct infection by soil-borne pathogens (such as Streptomyces scabies and Fusarium). Therefore, when pursuing high potato yields, it is necessary to strictly regulate the precision of nutrient supply and enhance the disease prevention of potatoes through safe and ecological microbial interactions.

[0006] In the prior art, CN 119954570A discloses a special fertilizer for potatoes, which comprises biochar, calcium-magnesium phosphate fertilizer and compound fertilizer (N:P2O5:K2O=12:15:15). The NPK nutrients of the special fertilizer for potatoes are all available nutrients, which are difficult to meet the nutrient supply of potatoes in the middle and late stages. In addition, the phosphorus content in the fertilizer is too high, causing resource waste; the magnesium source is a poor-soluble magnesium, the magnesium content is low, and the release period is as long as 6-12 months, the magnesium supply is slow in the early stage, it is not suitable for the soil with high pH in the north, the nutrient utilization rate is low, and the supply precision is low. CN 109651000A discloses a bio-agent synergistic slow-release fertilizer, which comprises a granular slow-release chemical fertilizer core and an outer coating layer, wherein the outer coating layer comprises a bacterial liquid coating layer (inner layer) and an anti-caking agent coating layer (outer layer), and the bacterial liquid coating layer comprises a microbial agent and an organic additive (amino acid, γ-polyglutamic acid and fulvic acid). The patent directly takes the slow-release coated fertilizer as the core, and further coats the bacterial liquid and the anti-caking agent on the basis. The bacterial liquid is not protected, and it is easy to be inactivated when it contacts with the anti-caking agent and the soil environment, thereby reducing the survival rate and effectiveness. In terms of the release characteristics of the bacterial agent, since the anti-caking agent does not have a slow-release effect, the microorganisms adhering to the surface of the granular slow-release chemical fertilizer directly enter the soil environment, on the one hand, they are difficult to colonize and are easily disturbed by indigenous microorganisms, and on the other hand, their action period is in the early growth stage of crops, and it is difficult to maintain their effectiveness in the soil for a long time. Therefore, the microbial loading rate, survival rate and plant utilization rate of the synergistic slow-release fertilizer prepared by the process are all low. CN 115819145A discloses a special controlled-release fertilizer for potatoes, which comprises controlled-release urea, urea, diammonium phosphate, potassium sulfate, trace elements and 15-15-15 general-purpose compound fertilizer. The polyurethane coated controlled-release fertilizer has a non-degradable film material, and long-term application of the film material is easy to cause film residue. Moreover, the invention only controls the release of nitrogen, and it is difficult to meet the high demand for potassium in the middle and late stages of potatoes. CN 109369273A discloses a long-acting slow-release special fertilizer for potatoes, and the preparation method is as follows: mixing base fertilizer, trace elements, humic acid, clay and borax to granulate, then spraying trichoderma preparation to the surface of the granules, and finally spraying anti-caking agent, forming agent and slow-release coating liquid to prepare the special fertilizer. All nutrients, humic acid and trichoderma preparation are controlled release, and there is a lack of available nutrients in the early stage. Moreover, the trichoderma preparation is wrapped in the film, and it is released late, which is difficult to play a role in the seedling stage, and is easy to affect the growth in the seedling stage, thereby being difficult to achieve the effect of increasing yield and resisting disease. In addition, the use amount of the non-effective film material is increased, and the coating cost is increased. Moreover, due to the large difference in particle size and poor compatibility of the granulation materials, the product has poor controlled-release performance and short controlled-release period, and it is difficult to meet the demand for key nutrients such as nitrogen and potassium in the middle and late stages of potatoes, and the nutrient supply for potato growth has poor pertinence.

[0007] Therefore, based on the key nutrient requirement characteristics and unique growth characteristics of potatoes, it is particularly necessary to develop a potato high-yield disease-resistant controlled-release special fertilizer to solve the problems of unreasonable nutrient allocation ratio, disconnection between nutrient release and growth period demand, and inability to effectively prevent and control potato diseases in the prior art, so as to realize the improvement of potato yield and quality. SUMMARY

[0008] In view of the above prior art, the purpose of the present application is to provide a potato special high-yield disease-resistant controlled-release fertilizer and a preparation method and application thereof. The potato special high-yield disease-resistant controlled-release fertilizer is prepared by using double-layer bacteria agent coated synergistic controlled-release urea and controlled-release potassium-magnesium fertilizer as raw materials. In terms of potato nutrient supply, the precise supply of three key nutrients, nitrogen, potassium and magnesium, in the key period of potato tuber formation and bulking can be realized, thereby improving the yield and quality of potatoes; in terms of potato disease prevention and control, the bacteria agent load inside and outside the film can regulate the potato tuber microecology during the seed potato planting period and the middle period, thereby reducing the incidence, and based on the above technology, the high yield, disease resistance and green and sustainable planting of potatoes can be realized. In addition, the potato special high-yield disease-resistant controlled-release fertilizer prepared by the present application improves the utilization rate of potassium mineral resources at the production end, optimizes the film material composition compared with the existing coated controlled-release fertilizer production technology, improves the film material degradation rate, improves the characteristics of traditional sulfur coated fertilizer blasting release, solves the problem of difficult degradation of the existing polyurethane film material, and realizes the stable "S" type supply of nutrients.

[0009] To achieve the above purpose, the technical scheme adopted by the present application is as follows: In a first aspect, the present application provides a potato high-yield disease-resistant controlled-release special fertilizer, comprising double-layer bacteria agent coated synergistic controlled-release urea and controlled-release potassium-magnesium fertilizer; the mass ratio of the double-layer bacteria agent coated synergistic controlled-release urea and the controlled-release potassium-magnesium fertilizer is (141-418):(90-600); The double-layer bacteria agent coated synergistic controlled-release urea is prepared by the following method: (1) mixing a bacteria suspension, a sodium alginate solution and a CaCl2 solution to obtain a microcapsule loaded bacteria agent; (2) spraying a dispersing agent and the microcapsule loaded bacteria agent onto the surface of preheated urea particles in sequence to obtain synergistic urea particles; (3) taking the synergistic urea particles as a fertilizer core, and coating the fertilizer core with sulfur to obtain modified sulfur coated synergistic controlled-release urea; (4) spraying the microcapsule loaded bacteria agent onto the surface of the modified sulfur coated synergistic controlled-release urea and drying to obtain double-layer bacteria agent coated synergistic controlled-release urea.

[0010] As a preferred, in step (1), the bacteria suspension is prepared by the following method: placing a bacterial strain in a culture medium and culturing at 25-35℃ and 150-350rpm until OD 6000.7-0.9, centrifuging the bacterial cells and then dispersing them in water to obtain a bacterial suspension; the bacterial strain is one or more of Bacillus atrophaie, Bacillus subtilis, Bacillus mycoides, Bacillus megaterium, Streptomyces microflavus, Trichoderma harzianum; the concentration of the bacterial suspension is 3.0x10 6 -9.0x10 6 cfu / mL.

[0011] Preferably, in step (1), the concentration of the sodium alginate solution is 0.5-5% (w / v), and the concentration of the CaCl2 solution is 2-15% (w / v); the mass ratio of the bacterial suspension, the sodium alginate solution and the CaCl2 solution is (0.1-10):(10-25):1.

[0012] Preferably, in step (2), the dispersant is one or more of lauryl polyoxyethylene ether, alkyl glycoside, sorbitan fatty acid ester, polyoxyethylene ether.

[0013] Preferably, in step (2), the mass ratio of the dispersant, the microencapsulated bacterial agent and the urea particles is (0.001-0.05):(0.05-5):100.

[0014] Preferably, in step (2), the temperature of the preheated urea particles is 40-55°C; the microencapsulated bacterial agent is sprayed on the urea particles and allowed to react for 1-3 minutes.

[0015] Preferably, in step (4), the mass ratio of the microencapsulated bacterial agent and the modified sulfur-coated urea is (0.05-5):(100-110).

[0016] Preferably, in step (4), the microencapsulated bacterial agent is sprayed on the urea particles and allowed to react for 1-3 minutes.

[0017] Preferably, in step (3), the sulfur is mixed with a polyol to obtain a premix, and the premix is mixed with a curing agent and then sprayed on the surface of the preheated fertilizer core to form a modified sulfur coating layer, which is then dried.

[0018] Further, the polyol is one or more of polyester polyol, polycaprolactone polyol, castor oil polyol, soybean oil polyol, palm oil polyol; the curing agent is one or more of toluene diisocyanate, 4,4'-diphenyl methane diisocyanate, IPDI (isophorone diisocyanate), hexamethylene diisocyanate, 1,12-dodecane diisocyanate.

[0019] Further, the mass ratio of the sulfur, the polyol and the curing agent is (1-5):(0.4-12.5):(0.1-6). ​

[0020] Further, in the spraying process, the total amount of the premix and the curing agent sprayed each time is 1-3% of the mass of the fertilizer core, and the spraying is performed 2-3 times, and the reaction is performed for 5-10 minutes after each spraying.

[0021] Further, the mass of the modified sulfur coating layer accounts for 1.5-5% of the mass of the coated fertilizer.

[0022] As preferred, the controlled-release potassium-magnesium fertilizer is prepared by the following method: (a) mixing (K 1-n ,NH 4n )2SO4·MgSO4·6H2O complex salt and water, and then performing extrusion granulation to obtain mother granules; alternately adding potassium-magnesium salt composite fine powder and a high-molecular binder solution to the surface of the mother granules in batches, and then performing drum granulation to obtain potassium-magnesium salt granules; (b) alternately adding modified fine powder and a high-molecular binder solution to the surface of the potassium-magnesium salt granules in batches, and then performing centrifugal polishing to obtain potassium-magnesium salt composite granules; (c) spraying atomized surface micropore filling agent to the surface of the potassium-magnesium salt composite granules in batches, and then performing centrifugal polishing to obtain modified potassium-magnesium salt composite granules; (d) taking the modified potassium-magnesium salt composite granules as a fertilizer core, and performing sulfur coating treatment on the fertilizer core to obtain the controlled-release potassium-magnesium fertilizer.

[0023] Further, in step (a), the water content in the (K 1-n ,NH 4n )2SO4·MgSO4·6H2O complex salt after mixing with water is 0.5%-5%.

[0024] Further, in step (a), the high-molecular binder solution is prepared by mixing a high-molecular binder and water in a mass ratio of (1-10):(100-500), and then stirring at 40-65°C; the high-molecular binder is one or more of oxidized starch, esterified starch, ethyl cellulose, soybean protein glue, and cellulose acetate. Further, in step (a), the addition amount of the potassium-magnesium salt composite fine powder each time is 1%-5% of the mass of the mother granules, and the addition amount of the high-molecular binder solution each time is 0.5%-2.4% of the mass of the mother granules; the particle size of the potassium-magnesium fertilizer granules is 2-3 mm, and the temperature of the preheated potassium-magnesium fertilizer granules is 40-55°C.

[0025] Further, in step (b), the modified fine powder is one or more of starch, gypsum powder, bentonite, superphosphoric acid calcium, and calcium-magnesium phosphate, and has a diameter of 80-200 mesh.

[0026] Further, in step (b), the modified fine powder is added in an amount of 1-20% of the mass of the potash-magnesium salt particles each time, and the high polymer binder solution is added in an amount of 0.01-5% of the mass of the potash-magnesium salt particles each time; the particle size of the potash-magnesium salt composite particles is 2.5-5.0 mm.

[0027] Further, in step (c), the surface micropore filling agent is one or more of silane coupling agent, polyvinyl alcohol, paraffin wax and mineral oil; and the surface micropore filling agent is subjected to atomization treatment at 0.2-0.5 MPa.

[0028] Further, in step (c), the atomized surface micropore filling agent is added in an amount of 0.2-1.0% of the mass of the potash-magnesium salt composite particles each time.

[0029] Further, in step (c), the centrifugal polishing process is performed at a rotation speed of 1200-2900 rpm; and the modified potash-magnesium salt composite particles have a particle size of 3-5 mm.

[0030] As a preferred, the potato high-yield disease-resistant controlled-release special fertilizer further comprises a base fertilizer, the base fertilizer is composed of organic fertilizer, phosphorus fertilizer and urea; the organic fertilizer is one or more of chicken manure, cow dung, sheep manure, crop straw and commercial organic fertilizer; the phosphorus fertilizer is one or more of superphosphate, triple superphosphate, calcium-magnesium phosphate, phosphate rock powder, monoammonium phosphate and diammonium phosphate. The mass ratio of the phosphorus fertilizer, urea, the synergistic controlled-release urea coated with double-layer bacterial agent and the controlled-release potash-magnesium fertilizer is (100-910):(67-310):(141-418):(90-600); the ratio of the mass of the organic fertilizer to the total mass of the phosphorus fertilizer, urea, the synergistic controlled-release urea coated with double-layer bacterial agent and the controlled-release potash-magnesium fertilizer is (870-3500):50.

[0031] In the second aspect of the present application, the potato high-yield disease-resistant controlled-release special fertilizer is applied in potato planting.

[0032] As a preferred, the specific operation is as follows: the potato high-yield disease-resistant controlled-release special fertilizer is used as the base fertilizer and is once applied into the potato seed side or directly below 5-7 cm by using mechanical deep fertilization technology, and no topdressing is needed during the whole growth period.

[0033] The present application has the following advantages: 1. The present application is based on the nutrient absorption and high-yield response characteristics of potato in the key period, and a special fertilizer meeting the nutrient demand of potato is prepared by using modified sulfur-coated synergistic controlled-release urea and controlled-release potash-magnesium fertilizer raw materials. The fertilizer adopts an optimized nutrient ratio of high potassium, medium-high nitrogen and low phosphorus, and meets the nutrient demand law of potato for macronutrients in terms of nutrient type and amount. In addition, the present application realizes the controlled-release effect by using the modified sulfur-coated technology, so as to meet the nutrient demand of potato in the key growth period.

[0034] The present application can greatly improve nutrient utilization efficiency, improve the potassium and magnesium absorption rate of potatoes and plant resistance, reduce disease occurrence, significantly improve the yield per unit area of potatoes, and also reduce the amount and frequency of fertilization, save labor costs, and improve labor productivity.

[0035] 2. The present application innovates the controlled release film material of traditional commercially available coated fertilizers, further optimizes the mainstream polyurethane film material in the market, and uses polyol modified sulfur as the coating material. The film material optimizes the nutrient release characteristics of the traditional sulfur-coated fertilizer, the modified film material is more in line with the nutrient demand of potatoes, and the degradation performance is improved compared with the existing polyurethane film material. The sulfur used can provide sulfur for potatoes, and is safer for soil and crops. The modified sulfur-coated efficiency controlled release urea prepared by using the innovative film material has a controlled release period of 90-120 days, which avoids excessive nitrogen supply in the early stage, makes nitrogen supply accurate and sufficient during potato tuber formation, tuber swelling and maturation period, avoids additional nitrogen nutrients entering the soil environment to damage the soil ecology, and is particularly suitable for one-time fertilization in northern regions.

[0036] 3. The present application adopts the film inner and outer double-layer loading precision enhancement technology of gel preservative bacteria agent, and sprays microcapsule loaded bacteria agent, modified sulfur coating liquid and microcapsule loaded bacteria agent on urea particles in sequence to prepare modified sulfur-coated efficiency controlled release urea. Specifically, on the one hand, the bacteria agent is protected by seaweed gel to avoid external environmental interference affecting its activity, which is beneficial to the preservation and colonization of the bacteria agent. On the other hand, the preservative bacteria agent is loaded in the controlled release fertilizer film inside and outside. The outer layer loaded bacteria agent can be released in the potato seedling stage to resist the initial infection of pathogenic bacteria carried by the seed potato itself and transmitted through the seed potato wound, improve the survival rate of seedlings, and the inner layer loaded bacteria agent can be released in the middle and late stages to make beneficial bacteria colonize in the key period of high temperature and rainfall, which is prone to late blight, and play a role in the development of crop roots and tuber formation, improving the disease resistance of tubers. In the prior art, the bacteria agent is usually sprayed on the surface of compound fertilizer or the bacteria agent is granulated with compound fertilizer, which may cause some problems such as direct contact of some strains with high-salt fertilizer, rapid decomposition of the bacteria agent by indigenous microorganisms in the soil, and short or unstable effect, the present application reduces the amount of bacteria agent and avoids the inactivation of the bacteria agent caused by environmental changes, greatly improving the activity and utilization efficiency of the bacteria agent.

[0037] 4. The controlled release potassium and magnesium fertilizer prepared by the present application can continuously supply potassium in the middle and late stages of potato (tuber formation and swelling period), improve the tuber formation rate, promote the growth of crops, make the stems hard and strong, enhance the resistance to diseases and pests and lodging, drive the generation and transportation of sugar and starch, and promote tuber swelling, which is of great significance to improve the quality of potatoes.

[0038] 5. The present application realizes the resource utilization of associated magnesium ore by directly granulating potassium ore, reduces the problems of cost increase and waste production caused by separation and purification, and the magnesium source associated with potassium ore is more easily absorbed and utilized by plants than the citric-soluble magnesium such as calcium-magnesium phosphate fertilizer, and the ionic radius of magnesium is significantly lower than that of potassium, so that magnesium can be released earlier than potassium after coating, realizing the directional supply of magnesium before the formation period of potato blocks, improving photosynthetic capacity, and promoting the formation and early enlargement of tubers. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 : Nitrogen supply-demand matching characteristic graph of modified sulfur coated synergistic controlled-release urea prepared in Example 1; Figure 2 : Potassium supply-demand matching characteristic graph of controlled-release potassium-magnesium fertilizer prepared in Example 1; Figure 3 : Magnesium supply-demand matching characteristic graph of controlled-release potassium-magnesium fertilizer prepared in Example 1; Figure 4 : Potato emergence rate result graph; Figure 5 : Potato leaf SPAD value result graph in tuber enlargement period; Figure 6 : Potato tuber number per plant graph; Figure 7 : Potato yield graph; Figure 8 : Potato incidence graph; Figure 9 : Potato starch content graph; Figure 10 : Nutrient release situation graph of controlled-release urea with different coating materials; Figure 11 : Degradation rate graph of different coating materials. DETAILED DESCRIPTION

[0040] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0041] Potatoes from sowing to emergence lasts about 20-30 days, which depends entirely on the storage nutrients in the seed potatoes, without external absorption, and only a small amount of nutrients is absorbed during the seedling stage, a large amount of nutrients is absorbed from the tuber formation stage, and the tuber bulking stage reaches the peak of fertilizer demand, and then the demand for fertilizer decreases. The peak of NPK is concentrated in the tuber formation to bulking stage (40-75 days after emergence), and the amount of absorption during this stage accounts for more than 70% of the total amount. The stem block bulking stage is the potassium demand peak of potatoes, and the demand for potassium is more than 50%, and lack of potassium during this period will hinder tuber bulking, reduce plant disease resistance, and thus reduce yield, and make the tuber susceptible to pathogenic bacteria. After the potassium fertilizer is applied to the soil, it is quickly dissociated into potassium ions, and the fertilizer efficiency period is about 25 days, and the part not absorbed and utilized by plants will be fixed into non-exchangeable potassium through clay, and it is easy to be lost with rainfall and irrigation in sandy soil in the north, so the traditional available potassium fertilizer is difficult to meet the nutrient demand of potato tuber bulking stage. In addition, potato is a crop that requires a lot of magnesium, and research shows that potatoes need to absorb 3.56 kg of magnesium per 1000 kg of tubers produced on average. About 45-100 kg of magnesium (MgO) is taken away per hectare per year in medium and high yield fields, and if it is not replenished in time, yellowing between old leaf veins (magnesium deficiency) can reduce photosynthetic efficiency and reduce tuber yield. The maximum absorption rate of magnesium by potatoes occurs during the tuber formation stage (30-40 days after emergence), so precise supply of magnesium nutrition during this period is of great significance to promote photosynthesis, synthesis, transportation and storage of starch and sugar during the tuber bulking and maturation stages of potatoes.

[0042] In the prior art, a large amount of nitrogen fertilizer is often used in the traditional potato planting habit to increase yield, and excessive nitrogen fertilizer promotes the rapid growth of potato stems and leaves above ground, resulting in vigorous growth of plants, dark green leaves, slender stems, thin cell walls, easy lodging or breaking, on the one hand, leading to tender tubers and plant tissues, easy to be attacked by late blight, aphids and other diseases; on the other hand, high-nitrogen environment delays tuber differentiation and bulking, leading to delayed tuber formation, reduced tuber quantity and smaller tuber size. In addition, unreasonable fertilization will accelerate soil acidification, destroy soil aggregate structure, inhibit microbial activity, and cause soil ecological environment disorder.

[0043] Based on this, the application provides a potato high-yield disease-resistant controlled-release special fertilizer, which comprises a controlled-release potassium-magnesium fertilizer, modified sulfur-coated synergistic controlled-release urea. The application adjusts the NPK ratio and supplements trace elements by optimizing fertilization, improves the absorption rate of potatoes to nutrients, promotes the transportation of photosynthetic products to tubers, improves root development and enhances plant resistance; at the same time, the soil ecology is adjusted by optimizing the fertilization formula, the soil pH value is increased, the soil particle organic matter is increased, the abundance and diversity of beneficial microorganisms are improved, and the abundance of pathogenic bacteria in the soil is reduced, so as to reduce the incidence.

[0044] Controlled-release potassium-magnesium fertilizers can achieve full resource utilization of nutrients. After removing some heavy metals from potassium mines, the original elements beneficial to plant nutrition, such as magnesium, boron, and zinc, are retained. Furthermore, potassium can increase fruit set rate in the mid-to-late stages of tuber formation, promoting robust crop growth, thicker stems, and enhanced resistance to pests, diseases, and lodging; it also promotes sugar and starch production. Therefore, compared to fast-acting potassium basal application, it provides a higher intensity of supply in the later stages, and is more beneficial for increasing potato yield and improving sugar and starch accumulation.

[0045] The modified sulfur-coated controlled-release urea of ​​this invention utilizes microbial agents loaded both inside and outside the membrane. These microbial agents promote sugar metabolism and enrich beneficial microorganisms, playing a crucial role in controlling potato blight. However, once applied to the soil, these agents are easily affected by the native soil flora, hindering their effectiveness. Therefore, this invention employs gel preservation and controlled-release fertilizer-loaded microbial agent technology, enabling the biocontrol bacteria to be released slowly along with nutrients, forming a localized microecological environment with a certain concentration in the potato rhizosphere, thus facilitating their functional expression.

[0046] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0047] The experimental materials used in the embodiments of this invention are all conventional experimental materials in the art and can be purchased through commercial channels.

[0048] In this invention, (K) 1-n ,NH 4n The 2SO4·MgSO4·6H2O double salt was prepared by sun-drying carnallite and ammonium sulfate using the isothermal dissolution equilibrium method described in "Phase Equilibrium Study on the Preparation of Chlorine-Free Potassium Fertilizer by Reaction of Carnallite and Ammonium Sulfate" (Xue Chunyan, Hebei University of Technology). Bacillus atrophus was purchased from the China Agricultural Microbial Culture Collection Center, with accession number CGMCC No. 32577.

[0049] Example 1: The potato high-yield and disease-resistant controlled-release fertilizer in this embodiment includes a double-layer microbial agent-coated synergistic controlled-release urea and a controlled-release potassium-magnesium fertilizer; the mass ratio of the double-layer microbial agent-coated synergistic controlled-release urea and the controlled-release potassium-magnesium fertilizer is 221:540.

[0050] The enhanced controlled-release urea coated with a double-layer bacterial agent was prepared by the following method: (1) Place Bacillus atrophus in LB medium and incubate at 32°C and 300 rpm until OD. 600 The concentration was 0.8. After centrifugation to collect the bacterial cells, they were redispersed in water to obtain a concentration of 6.0 × 10⁸. 6A bacterial suspension of cfu / mL; the bacterial suspension, 3% (w / v) ammonium alginate solution and 2% (w / v) CaCl2 solution were mixed at a mass ratio of 1:15:1 to obtain microcapsule loaded bacterial agent; (2) After preheating the urea granules to 45°C, lauryl polyoxyethylene ether and microcapsule-loaded bacterial agent are sprayed onto the surface of the urea granules in sequence and reacted for 3 minutes to obtain enhanced urea granules; wherein, the mass ratio of lauryl polyoxyethylene ether, urea granules and microcapsule-loaded bacterial agent is 0.025:100:0.5. (3) After mixing polycaprolactone polyol and sulfur, a premix is ​​obtained; the enhanced urea particles are preheated to 45°C, and then the premix and toluene diisocyanate are mixed and sprayed onto the surface of the enhanced urea particles to form a modified sulfur film layer. After drying, the modified sulfur-coated enhanced controlled-release urea is obtained. The mass ratio of polycaprolactone polyol, sulfur, and toluene diisocyanate is 1:1:0.4. During the spraying process, the total amount of premix and curing agent sprayed each time is 2% of the mass of the enhanced urea particles, and a total of 2 sprays are applied. After each spraying, the reaction time is 10 minutes. The mass ratio of the modified sulfur coating layer in the modified sulfur-coated enhanced controlled-release urea is 3.5%. (4) After spraying the microcapsule-loaded bacterial agent onto the surface of the modified sulfur-coated enhanced controlled-release urea again, the reaction time is 3 minutes. The mass ratio of the microcapsule-loaded bacterial agent to the modified sulfur-coated enhanced controlled-release urea is 0.1:100. After drying, the enhanced controlled-release urea (CZU) with double-layer bacterial agent coating is obtained.

[0051] Controlled-release potassium-magnesium fertilizer is prepared by the following method: (a) will (K) 1-n ,NH 4n After the double salt 2SO4·MgSO4·6H2O is mixed with water, (K) 1-n ,NH 4n The water content on the surface of the double salt 2SO4·MgSO4·6H2O is 3%, and then extrusion granulation is performed to obtain masterbatch; Ethyl cellulose and water were mixed at a mass ratio of 5:300 and stirred at 55°C to obtain a polymer binder solution; potassium chloride and magnesium chloride were mixed at a mass ratio of 10:5 to obtain potassium-magnesium salt composite fine powder; the magnesium salt composite fine powder and polymer binder solution were alternately added to the surface of the masterbatch and granulated by roller granulation at 15 r / min to obtain potassium-magnesium salt particles with a particle size of 2.5 mm. The amount of potassium magnesium salt composite fine powder added each time is 3% of the masterbatch mass, and the amount of polymer binder solution added each time is 1.5% of the masterbatch mass. (b) Using superphosphate with a particle size of 150 mesh as the modified fine powder, the modified fine powder and polymer binder solution were added alternately to the surface of potassium-magnesium salt particles in several batches. After centrifugal polishing, potassium-magnesium salt composite particles with a particle size of 4 mm were obtained. The modified fine powder is added at a rate of 10% of the mass of the potassium magnesium salt particles each time, and the polymer binder solution is added at a rate of 2.5% of the mass of the potassium magnesium salt particles each time. (c) Polyacrylol was used as a surface micropore filler and atomized under a pressure of 0.35 MPa. The atomized surface micropore filler was sprayed onto the surface of potassium magnesium salt composite particles in multiple times. The amount of each spray was 0.6% of the mass of the potassium magnesium salt composite particles. The particles were centrifuged and polished at a speed of 2000 rpm to obtain modified potassium magnesium salt composite particles with a particle size of 4.5 mm. (d) Castor oil polyol and sulfur were mixed to obtain a premix; potassium magnesium fertilizer granules were preheated to 45°C, and the premix and toluene diisocyanate were mixed and sprayed onto the surface of the potassium magnesium fertilizer granules to form a modified sulfur coating layer. After drying, controlled-release potassium magnesium fertilizer (CKM) was obtained. The mass percentage of the modified sulfur coating layer in the controlled-release potassium magnesium fertilizer was 4%. The mass ratio of castor oil polyol, sulfur and toluene diisocyanate is 1:1:0.4. The total amount of premix and curing agent sprayed each time is 2% of the mass of potassium magnesium fertilizer. A total of 3 sprays are applied, and the reaction time is 10 minutes after each spray.

[0052] Comparative Example 1: The difference between this comparative example and Example 1 is that neither the double-layer microbial agent-coated synergistic urea nor the potassium-magnesium fertilizer is coated. That is, the potato high-yield, disease-resistant, controlled-release fertilizer includes double-layer microbial agent-coated synergistic urea (ZU) and potassium-magnesium fertilizer granules (KM).

[0053] The enhanced urea coated with a double-layer microbial agent was prepared by the following method: After preparing enhanced urea particles according to the method in Example 1, microcapsule-loaded microbial agent was sprayed again onto the surface of the enhanced urea particles, reacted for 3 minutes, and then dried to obtain the enhanced urea coated with a double-layer microbial agent. The mass ratio of the microcapsule-loaded microbial agent to the enhanced urea particles was 0.1:100.

[0054] Potassium magnesium fertilizer is prepared by the following method: a polymer binder solution is prepared according to the method of Example 1; it is then sprayed onto (K) 1-n ,NH 4n Potassium magnesium fertilizer granules are obtained by extrusion granulation of the double salt surface of 2SO4·MgSO4·6H2O; wherein, the polymer binder solution accounts for (K 1-n ,NH 4n )2SO4·MgSO4·6H2O double salt mass 3%.

[0055] Comparative Example 2: The difference between this comparative example and Example 1 is that the enhanced urea coated with the double-layer microbial agent is coated, while the potassium-magnesium fertilizer is not coated. That is, the potato high-yield, disease-resistant, controlled-release fertilizer includes enhanced controlled-release urea (CZU) coated with the double-layer microbial agent and potassium-magnesium fertilizer granules (KM).

[0056] The preparation method of the double-layer bacterial agent-coated synergistic controlled-release urea is the same as in Example 1. The potassium-magnesium fertilizer granules are prepared by the following method: a polymer binder solution is prepared according to the method in Example 1, and then it is sprayed onto (K 1-n ,NH 4n Potassium magnesium fertilizer granules are obtained by extrusion granulation of the double salt surface of 2SO4·MgSO4·6H2O; wherein, the polymer binder solution accounts for (K 1-n ,NH 4n )2SO4·MgSO4·6H2O double salt mass 3%.

[0057] Comparative Example 3: The difference between this comparative example and Example 1 is that the enhanced urea coated with the double-layer microbial agent is not coated, while the potassium-magnesium fertilizer is coated. That is, the potato high-yield, disease-resistant, controlled-release fertilizer includes enhanced urea coated with the double-layer microbial agent and controlled-release potassium-magnesium fertilizer granules.

[0058] The controlled-release potassium-magnesium fertilizer granules were prepared using the same method as in Example 1. The enhanced urea coated with a double-layer microbial agent was prepared as follows: After preparing the enhanced urea granules according to the method in Example 1, the microcapsule-loaded microbial agent was sprayed again onto the surface of the enhanced urea granules and reacted for 3 minutes, followed by drying to obtain the enhanced urea coated with a double-layer microbial agent. The mass ratio of the microcapsule-loaded microbial agent to the enhanced urea granules was 0.1:100.

[0059] Comparative Example 4: The difference between this comparative example and Example 1 is that the urea coated with the double-layer microbial agent is not modified with a dispersant for enhanced efficacy, and the potassium-magnesium fertilizer is coated. That is, the potato high-yield, disease-resistant, controlled-release fertilizer consists of controlled-release urea (CRU) coated with a double-layer microbial agent and controlled-release potassium-magnesium fertilizer (CKM).

[0060] The controlled-release potassium magnesium fertilizer was prepared using the same method as in Example 1, and the controlled-release urea coated with a double-layer bacterial agent was prepared using the following method: (1) Prepare microcapsule-loaded bacterial agent according to the method of Example 1; spray the microcapsule-loaded bacterial agent onto the surface of urea particles in sequence and react for 3 min to obtain urea particles coated with microcapsule bacterial agent; wherein, the mass ratio of urea particles to microcapsule-loaded bacterial agent is 100:0.5; (2) After mixing polycaprolactone polyol and sulfur, a premix is ​​obtained; the urea particles coated with microcapsule agent are preheated to 45°C, and then the premix and toluene diisocyanate are mixed and sprayed onto the surface of the urea particles coated with microcapsule agent to form a modified sulfur film layer. After drying, modified sulfur-coated controlled-release urea is obtained. The mass ratio of polycaprolactone polyol, sulfur, and toluene diisocyanate is 1:1:0.4. During the spraying process, the total amount of premix and curing agent sprayed each time is 2% of the mass of the urea particles coated with microcapsule agent. A total of 2 sprays are applied, and the reaction time is 10 minutes after each spray. The mass ratio of the modified sulfur coating layer in the modified sulfur-coated controlled-release urea is 3.5%. (3) After spraying the microcapsule-loaded bacterial agent onto the surface of the modified sulfur-coated enhanced controlled-release urea again, the reaction time is 3 minutes. The mass ratio of the microcapsule-loaded bacterial agent to the modified sulfur-coated enhanced controlled-release urea is 0.1:100. After drying, the enhanced controlled-release urea (CRU) with double-layer bacterial agent coating is obtained.

[0061] Experimental Example 1: Nutrient Release Rate 1. The nitrogen nutrient release of the modified sulfur-coated synergistic controlled-release urea prepared in Example 1, and the potassium and magnesium nutrient release of the controlled-release potassium-magnesium fertilizer prepared in Example 1 were tested according to the methods in GB / T 23348-2009 Slow-Release Fertilizers. The results are as follows: Figures 1-3 As shown.

[0062] Depend on Figure 1 It can be seen that the nutrient release rate of the potato-specific high-yield and disease-resistant controlled-release fertilizer prepared by this invention is highly matched with the nutrient accumulation rate of potatoes. This avoids the damage to the soil ecology caused by a one-time input of a large amount of nitrogen and potassium nutrients into the soil environment, greatly improves nutrient utilization efficiency, avoids excessive plant growth caused by excessive nitrogen supply in the early stage, and keeps nitrogen in a good and balanced supply state throughout the entire growth period.

[0063] Depend on Figure 2 It can be seen that the potassium release rate of the controlled-release potassium-magnesium fertilizer in the potato-specific high-yield and disease-resistant controlled-release fertilizer prepared by this invention is highly matched with the potassium accumulation rate of potatoes. The peak period of potassium accumulation in potatoes is 80 days after emergence, while the controlled-release potassium-magnesium fertilizer begins to release potassium in large quantities continuously before the accumulation of potassium nutrients in potatoes (50-80 days), which is conducive to sufficient potassium supply during tuber formation and expansion, thereby improving the stress resistance of potatoes.

[0064] Depend on Figure 3It can be seen that the controlled-release potassium-magnesium fertilizer in the potato high-yield and disease-resistant controlled-release fertilizer prepared by this invention rapidly releases magnesium nutrients within 30-50 days. This stage is the rapid accumulation stage of Mg in potatoes, which is conducive to the absorption of magnesium by potatoes, thereby promoting photosynthesis in the later stages of potato growth (tuber enlargement and maturity), and promoting the storage and transport of starch and sugars. In addition, there is an antagonistic effect between K⁺ and Mg²⁺ when plants absorb nutrients, thereby inhibiting the absorption of one ion. The controlled-release potassium-magnesium fertilizer prepared by this invention can release magnesium first and then potassium, realizing the staggered release of the two ions, which is conducive to the efficient absorption of both nutrients.

[0065] Experimental Example 2: Field Experiment The experiment consisted of 6 treatments, each replicated 3 times, in a randomized block design, with each plot measuring 30 m². 2 Each plot is separated by a 50cm protective row, with double-row raised beds (80cm wide, 35cm plant spacing), and a seeding rate of 4500 plants per acre. Sowing is done manually in furrows, with fertilizer applied into the furrows and covered with 10cm of soil.

[0066] The specific operations for each process are as follows: Treatment 1: Farmers' usual fertilization method (FP), apply 26-6-8 compound fertilizer as basal fertilizer at a rate of 65 kg / mu, and apply urea at a rate of 5 kg / mu during the seedling stage (4-5 leaves); Treatment 2: The high-yield, disease-resistant, controlled-release fertilizer for potatoes prepared in Example 1 was used; Treatment 3: The potato high-yield and disease-resistant controlled-release fertilizer prepared in Comparative Example 1 was used; Treatment 4: The potato high-yield and disease-resistant controlled-release fertilizer prepared in Comparative Example 2 was used; Treatment 5: Potato high-yield and disease-resistant controlled-release fertilizer prepared using Comparative Example 3; Treatment 6: Potato high-yield, disease-resistant, controlled-release fertilizer prepared using Comparative Example 4.

[0067] Treatments 2-6 also included basal fertilizer, which was a mixture of organic fertilizer, phosphate fertilizer, and urea in a mass ratio of 2000:172:75. The organic fertilizer was sheep manure. The mass ratio of the basal fertilizer to the potato high-yield and disease-resistant controlled-release fertilizer was 2247:761. The specific operating steps were as follows: After mixing the basal fertilizer and the potato high-yield and disease-resistant controlled-release fertilizer, the mixed fertilizer was applied in one go to the side or directly below the potato seed at a depth of 6 cm using mechanical deep fertilization technology. No topdressing was required during the entire growth period, and the application rate was 65 kg / mu.

[0068] During the budding stage, the number of seedlings is counted, and the emergence rate is calculated. The formula for the emergence rate is: Emergence rate (%) = Number of seedlings / (Number of seedlings / Number of seeds sown) × 100%. The results are as follows: Figure 4 As shown.

[0069] The SPAD value of potato leaves was measured using a chlorophyll meter during the tuber enlargement period, and the results are as follows: Figure 5 As shown.

[0070] At harvest, 10 plants were randomly selected from each plot, and the number of tubers per plant was counted. Potatoes were harvested simultaneously by plot, and the yield of potatoes in each plot was calculated. The results are as follows: Figure 6 and Figure 7 As shown.

[0071] The potato disease index was calculated according to the screening test for the most suitable inducing agent for potato scab by Wang Hongqiu et al., as shown in the literature. Figure 8 As shown.

[0072] The starch content in potatoes was determined according to the method in GB / T 5009.9—2016 Determination of Starch in Food. The results are as follows: Figure 9 As shown.

[0073] Depend on Figure 4 It can be seen that the potato seedling emergence rate obtained by the high-yield and disease-resistant controlled-release fertilizer for potatoes prepared in this invention (Example 1) was the highest, followed by Example 2, with no significant difference between the two. This is because both added modified sulfur-coated synergistic controlled-release urea, and the release and colonization of the microbial agent on its surface improved the micro-ecosystem near the potato tubers, thereby reducing the early-stage pathogen attack on potatoes. Comparative Examples 1 and 3 also had high seedling emergence rates, but significantly lower than Example 1. This is because Comparative Examples 1 and 3 loaded the same amount of microbial agent onto the urea surface, which may have resulted in a lower survival rate of the strains on the fertilizer and soil, reducing the effectiveness of the microbial agent. FP and Comparative Example 4 did not add any microbial agent, therefore their seedling emergence rates were significantly reduced.

[0074] Depend on Figure 5 It can be seen that the SPAD value of the leaves during the tuber enlargement period of potatoes treated with the high-yield and disease-resistant controlled-release fertilizer for potatoes prepared in this invention (Example 1) is higher than that of Comparative Example 4, with no significant difference between the two, but higher than Comparative Example 1 and FP, indicating that controlled-release nitrogen and controlled-release potassium and magnesium can significantly improve plant photosynthesis.

[0075] Depend on Figure 6 It can be seen that the potato tuber count obtained by the high-yield and disease-resistant controlled-release fertilizer for potatoes prepared in this invention (Example 1) was the highest, followed by Comparative Example 2 and Comparative Example 4, while the tuber count of the uncontrolled-release treatment in Comparative Example 1 was the lowest, which is comparable to the treatment that farmers usually apply fertilizer to.

[0076] Depend on Figure 7It can be seen that the potato yield obtained by the high-yield and disease-resistant controlled-release fertilizer prepared in this invention is the highest, indicating that the three technologies of controlled-release potassium magnesium, modified sulfur-coated controlled-release urea, and the use of microbial agents can synergistically and significantly increase potato yield. Secondly, the yield of Comparative Example 4 is significantly higher than that of Comparative Example 2, indicating that modified sulfur-coated controlled-release urea has a significant effect on increasing potato yield; the yield of Comparative Example 3 is significantly higher than that of Example 1, indicating that controlled-release potassium magnesium also has the effect of increasing yield compared with ordinary potassium magnesium fertilizer.

[0077] Depend on Figure 8 It can be seen that the FP treatment had the highest incidence rate. This is because nutritional imbalance led to an excessive supply of readily available nitrogen in the early stage, resulting in excessive vegetative growth, while potassium supply was insufficient during the tuber formation stage, resulting in poor plant disease resistance. Although Comparative Example 1 balanced nutrients and added microbial agents, the release of readily available nutrients did not significantly improve the incidence rate due to the mismatch between the plant's needs and the supply of readily available nutrients. Comparative Example 2 delayed the supply of controlled-release nitrogen, reducing excessive vegetative growth in the early stage. The microbial agents it carried could inhibit disease in the middle and late stages, but its potassium supply was insufficient in the later stages, so its disease resistance still had certain limitations. The potato high-yield and disease-resistant controlled-release fertilizer prepared in this invention (Example 1) controlled-release nitrogen through modified sulfur coating, inhibiting excessive seedling growth and reducing spore spread. The controlled-release potassium and magnesium can continuously supply potassium and magnesium during the tuber formation stage, enhancing cell wall strength and photosynthesis, thereby enhancing plant disease resistance. By continuously maintaining the beneficial microecology of the tuber through the microbial agents loaded inside and outside the membrane, the incidence rate was significantly reduced.

[0078] Depend on Figure 9 It can be seen that the potato starch content obtained by treatment with the high-yield, disease-resistant, controlled-release fertilizer for potatoes prepared in this invention (Example 1) is higher than that of Comparative Example 4, indicating that the inoculant has a relatively small impact on potato starch accumulation. The starch content of Comparative Example 1 is significantly lower than that of Example 1, indicating that readily available nitrogen and potassium limit starch accumulation during tuber enlargement. FP has the lowest starch content, which is due to excessive supply of readily available nitrogen in the early stage, leading to excessive vegetative growth and reduced allocation of photosynthetic products to tubers. The systemic action of controlled-release potassium and magnesium, controlled-release nitrogen, inoculant, and modified sulfur film material in Example 1 promotes starch synthesis.

[0079] Experimental Example 3: Membrane Material Release Rate and Degradation Performance The nutrient release and degradation of the modified sulfur-coated enhanced controlled-release urea, pure sulfur-coated urea, and pure polymer-coated urea prepared in Example 1 were tested, and the results are as follows: Figure 10 and Figure 11 As shown. Among them, Preparation method of pure sulfur-coated urea: Prepare enhanced urea particles according to the method in Example 1, preheat them to 45°C, then heat the sulfur to a molten state and spray it onto the surface of the enhanced urea particles. The amount of sulfur used each time is 2% of the mass of the enhanced urea particles, and a total of 2 sprays are applied. After each spraying, react for 10 minutes and dry to obtain pure sulfur-coated enhanced controlled-release urea. Preparation method of pure polymer-coated urea: Enhanced urea particles were prepared according to the method in Example 1 and preheated to 45°C. Polycaprolactone polyol and toluene diisocyanate were simultaneously sprayed onto the surface of the enhanced urea particles at a mass ratio of 2.5:1. The reaction was carried out after each spraying, and the particles were dried to obtain pure polymer-coated enhanced controlled-release urea. The total amount of polycaprolactone polyol and toluene diisocyanate sprayed each time was 2% of the enhanced urea particles, and a total of two sprayings were performed. The reaction time was 10 min after each spraying. The corresponding steps for degradation are as follows: Each controlled-release fertilizer sample was weighed 100.0 g and placed in a 200-mesh nylon mesh bag to prevent fragment loss during degradation. The samples were buried 20 cm below the soil surface, with each bag approximately 10 cm apart. Samples were taken before degradation, and on days 30, 60, 90, and 120 to determine the mass of the membrane shell and calculate the degradation rate (%). The formula for calculating the degradation rate is: Degradation rate (%) = [(Weight of membrane shell before degradation - Weight of membrane shell after degradation) / Weight of membrane shell before degradation] × 100% Depend on Figure 10 It can be seen that the nutrient release rate of modified sulfur-coated urea is more consistent with the nutrient accumulation characteristics of potatoes, while the 60-day fertilizer polymer-coated urea and sulfur-coated urea release nutrients faster in the early stages, making it difficult to meet the nitrogen supply needs of potatoes in the later stages. Figure 11 It can be seen that the degradation rate of traditional polymer membranes is very slow, while pure sulfur membranes degrade rapidly in the early stage. Modified sulfur membranes control the degradation rate in the first 90 days. Compared with polymer membranes, its degradation mode is particulate disintegration degradation, which does not affect the nutrient controlled release performance.

[0080] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A controlled-release fertilizer specifically for high-yield, disease-resistant potatoes, characterized in that, Including double-layer microbial agent-coated enhanced controlled-release urea and controlled-release potassium-magnesium fertilizer, the mass ratio of double-layer microbial agent-coated enhanced controlled-release urea and controlled-release potassium-magnesium fertilizer is (141-418):(90-600). The enhanced controlled-release urea coated with the double-layer bacterial agent is prepared by the following method: (1) After mixing the bacterial suspension, sodium alginate solution and CaCl2 solution, microcapsule-loaded bacterial agent is obtained; (2) The dispersant and microcapsule-loaded bacterial agent are sprayed sequentially onto the surface of the preheated urea granules to obtain enhanced urea granules; (3) Using the enhanced urea granules as the fertilizer core, sulfur is used to coat them to obtain modified sulfur-coated enhanced controlled-release urea. (4) Spray the microcapsule-loaded bacterial agent onto the surface of the modified sulfur-coated enhanced controlled-release urea and dry it to obtain enhanced controlled-release urea with double-layer bacterial agent coating.

2. The potato high-yield, disease-resistant, controlled-release fertilizer as described in claim 1, characterized in that, In step (1), the bacterial suspension is prepared by the following method: the bacterial strain is placed in a culture medium and cultured at 25-35℃ and 150-350 rpm until OD reaches 100%. 600 The concentration was 0.7-0.

9. After centrifugation to collect the bacterial cells, they were redispersed in water to obtain a bacterial suspension. The bacterial strain is one or more of the following: Bacillus atrophus, Bacillus subtilis, Bacillus mucilaginosus, Bacillus megaterium, Streptomyces flavus, and Trichoderma harzianum; the concentration of the bacterial suspension is 3.0 × 10⁻⁶. 6 -9.0×10 6 cfu / mL; The mass ratio of bacterial suspension, sodium alginate solution and CaCl2 solution was (0.1-10):(10-25):

1.

3. The potato high-yield, disease-resistant, controlled-release fertilizer as described in claim 1, characterized in that, In step (2), the dispersant is one or more of lauryl polyoxyethylene ether, alkyl glycoside, sorbitan fatty acid ester, and polyoxyethylene ether; the mass ratio of dispersant, microcapsule-loaded bacterial agent and urea particles is (0.001-0.05):(0.05-5):100; the reaction is carried out for 1-3 minutes after spraying the microcapsule-loaded bacterial agent; In step (4), the mass ratio of microcapsule-loaded bacterial agent to modified sulfur-coated synergistic controlled-release urea is (0.05-5):(100-110); the reaction time is 1-3 min after spraying the microcapsule-loaded bacterial agent.

4. The potato high-yield, disease-resistant, controlled-release fertilizer as described in claim 1, characterized in that, Controlled-release potassium-magnesium fertilizer is prepared by the following method: (a) will (K) 1-n ,NH 4n The double salt 2SO4·MgSO4·6H2O is mixed with water and then extruded and granulated to obtain masterbatch; potassium magnesium salt composite fine powder and polymer binder solution are added alternately to the surface of the masterbatch in several batches, and then granulated by roller to obtain potassium magnesium salt particles. (b) The modified fine powder and polymer binder solution were added alternately to the surface of potassium magnesium salt particles in several batches, and then centrifuged and polished to obtain potassium magnesium salt composite particles. (c) The atomized surface micropore filler is sprayed onto the surface of potassium magnesium salt composite particles in multiple layers, and then polished by centrifugation to obtain modified potassium magnesium salt composite particles. (d) Modified potassium magnesium salt composite particles are used as fertilizer cores and coated with sulfur to obtain controlled-release potassium magnesium fertilizer.

5. The potato high-yield, disease-resistant, controlled-release fertilizer as described in claim 1, characterized in that, The specific steps for coating with sulfur are as follows: Sulfur is mixed with polyol to obtain a premix. The premix and curing agent are then sprayed sequentially onto the surface of the preheated fertilizer core to form a modified sulfur coating layer, and then dried. The polyol is one or more of polyester polyol, polycaprolactone polyol, castor oil polyol, soybean oil polyol, and palm oil polyol; the curing agent is one or more of toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, IPDI (isophorone diisocyanate), hexamethylene diisocyanate, and 1,12-dodecane diisocyanate; the mass ratio of sulfur, polyol, and curing agent is (1-5):(0.4-12.5):(0.1-6). During the spraying process, the total amount of premix and curing agent sprayed each time is 1-3% of the fertilizer core mass, and a total of 2-3 sprays are applied. After each spraying, the reaction time is 5-10 minutes. The mass of the modified sulfur coating layer accounts for 1.5-5% of the mass of the coated fertilizer.

6. The potato high-yield, disease-resistant, controlled-release fertilizer as described in claim 4, characterized in that, In step (a), the potassium-magnesium salt composite fine powder is made by mixing potassium salt and magnesium salt in a mass ratio of 10:(1-10), wherein the potassium salt is potassium chloride and / or potassium sulfate, and the magnesium salt is magnesium chloride and / or magnesium sulfate. The polymer binder solution is prepared by mixing polymer binder and water at a mass ratio of (1-10):(100-500) and stirring at 40-65℃; the polymer binder is one or more of oxidized starch, esterified starch, ethyl cellulose, soybean protein gum, and cellulose acetate. The masterbatch has a particle size of 0.5-1.0 mm, and the potassium magnesium salt particles have a particle size of 1.5-3.0 mm. The amount of potassium magnesium salt composite fine powder added each time is 1%-5% of the mass of the masterbatch, and the amount of polymer binder solution added each time is 0.5%-2.4% of the mass of the masterbatch.

7. The potato high-yield, disease-resistant, controlled-release fertilizer as described in claim 4, characterized in that, In step (b), the modified fine powder is one or more of starch, gypsum powder, bentonite, superphosphate, and calcium magnesium phosphate fertilizer; the amount of modified fine powder added each time is 1%-20% of the mass of potassium magnesium salt particles, and the amount of polymer binder solution added each time is 0.01%-5% of the mass of potassium magnesium salt particles; the particle size of potassium magnesium salt composite particles is 2.5-5.0 mm.

8. The potato high-yield, disease-resistant, controlled-release fertilizer as described in claim 4, characterized in that, In step (c), the surface micropore filler is one or more of silane coupling agent, polyvinyl alcohol, paraffin, and mineral oil. The amount of surface micropore filler added each time after atomization is 0.2%-1.0% of the mass of potassium magnesium salt composite particles. During centrifugal polishing, the rotation speed is 1200-2900 rpm. The particle size of the modified potassium magnesium salt composite particles is 3-5 mm.

9. The potato high-yield, disease-resistant, controlled-release fertilizer as described in claim 1, characterized in that, The potato high-yield and disease-resistant controlled-release fertilizer also includes a base fertilizer, which is composed of organic fertilizer, phosphate fertilizer and urea; the organic fertilizer is one or more of chicken manure, cow manure, sheep manure, crop straw and commercial organic fertilizer; the phosphate fertilizer is one or more of superphosphate, triple superphosphate, calcium magnesium phosphate, phosphate rock powder, monoammonium phosphate and diammonium phosphate. The mass ratio of phosphate fertilizer, urea, double-layer microbial agent-coated enhanced controlled-release urea and controlled-release potassium magnesium fertilizer is (100-910): (67-310): (141-418): (90-600); the mass ratio of organic fertilizer to the total mass of phosphate fertilizer, urea, double-layer microbial agent-coated enhanced controlled-release urea and controlled-release potassium magnesium fertilizer is (870-3500):

50.

10. The application of the potato high-yield and disease-resistant controlled-release fertilizer according to any one of claims 1-9 in potato cultivation.

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