Precise fertilization method for corn in whole growth period

Abstract

The invention relates to the technical field of corn fertilization, and provides a corn whole growth period precise fertilization method, which comprises the following steps: S1, applying a base fertilizer containing a nitrogen fertilizer, a phosphate fertilizer, a potassium fertilizer, fucoidan, calcium ammonium nitrate, zinc citrate, potassium humate and gamma-polyglutamic acid between corn rows during corn sowing; s2, spraying a leaf fertilizer containing monopotassium phosphate, magnesium sulfate, alginic acid and polyaspartic acid in a corn filling stage; the base fertilizer is a slow-release fertilizer, and is sequentially coated with a polyester composite layer and a wax layer after being mixed and granulated. According to the scheme, the base fertilizer is prepared into double-layer coated slow-release particles and then applied along with sowing, the outer bran wax / microcrystalline wax forms a hydrophobic barrier to inhibit sudden release and salt damage in the seedling stage, and the inner polyester composite layer forms a controllable water channel and is slowly hydrolyzed along with time, so that nutrients enter staged platform type supply in the corn growing period; and precise fertilizer supply and efficient utilization in the whole growth period are achieved.

Description

Technical Field

[0001] This invention relates to the field of corn fertilization technology, and in particular to a method for precise fertilization of corn throughout its entire growth period. Background Technology

[0002] Northwest my country is an important corn-producing region, and its corn production plays a vital role in ensuring national food security. However, due to the region's arid climate, infertile soil, and other natural limitations, improving corn yield and quality faces numerous challenges.

[0003] With the continuous development of agricultural technology, precision fertilization has gradually become an important means to improve crop yield and quality. By applying fertilizers scientifically and rationally, the nutrient needs of crops at different growth stages can be met, fertilizer utilization can be improved, and environmental pollution can be reduced.

[0004] Currently, fertilization techniques for maize in Northwest China still suffer from problems such as inaccurate fertilizer application rates, unreasonable fertilization timing, and a lack of variety in fertilizer types, resulting in low fertilizer utilization and high production costs. Therefore, developing a precise fertilization and nutrition technology program for maize throughout its entire growth cycle in Northwest China is of significant practical importance. Summary of the Invention

[0005] In view of this, the present invention proposes a precise fertilization method for the entire growth period of corn with high fertilizer utilization rate and increased yield and efficiency.

[0006] The technical solution of this invention is implemented as follows: This invention provides a method for precise fertilization throughout the entire growth period of corn, comprising the following steps: S1, Apply a base fertilizer containing nitrogen, phosphorus, potassium, brown algae polysaccharides, calcium ammonium nitrate, zinc citrate, potassium humate and γ-polyglutamic acid between corn rows when planting corn; Through the synergistic effects of nitrogen, phosphorus, and potassium with brown algae polysaccharides, calcium ammonium nitrate, zinc citrate, potassium humate, and γ-polyglutamic acid, the dual goals of nutrient supply and physiological regulation are achieved. Nitrogen, phosphorus, and potassium provide the nutritional foundation for the vegetative and reproductive growth of maize. Brown algae polysaccharides activate rhizosphere microbial activity, promote root hair development, and improve the root system's ability to absorb water and nutrients. Calcium ammonium nitrate (used after drying) provides readily available calcium, preventing leaf edge scorching and stem weakness. Zinc citrate, as an organic zinc source, effectively prevents the common zinc deficiency phenomenon of "white seedlings" in maize. Potassium humate and γ-polyglutamic acid synergistically enhance the soil's water and fertilizer retention capacity, improve the root system's efficiency in capturing nutrients, alleviate drought stress, and ensure full ear development, laying a key structural foundation for high yield.

[0007] S2, foliar fertilizer is sprayed during the corn grain-filling stage. The components of the foliar fertilizer include potassium dihydrogen phosphate, magnesium sulfate, alginic acid and polyaspartic acid. Foliar fertilizer, applied during the grain-filling stage, primarily consists of potassium dihydrogen phosphate and magnesium sulfate, supplemented with alginic acid and polyaspartic acid. Its main functions are rapid nutrient replenishment, delayed senescence, and increased grain weight. Potassium dihydrogen phosphate rapidly replenishes phosphorus and potassium during the critical grain-filling period, promoting the translocation of photosynthetic products to the grains and increasing the thousand-grain weight. Magnesium sulfate corrects magnesium deficiency, which is common in the later stages, maintaining leaf photosynthetic function. Alginic acid and polyaspartic acid, as biostimulants, activate the antioxidant system, enhancing the plant's tolerance to adverse conditions such as high temperature and drought, delaying premature leaf senescence, extending the grain-filling period, and significantly improving grain plumpness and quality, serving as the final guarantee for achieving stable yield and improved quality.

[0008] The base fertilizer is a slow-release fertilizer, which is coated with a polyester composite layer and a wax layer after granulation. The raw materials of the polyester composite layer include polybutylene succinate, betaine and sodium alginate, and the raw materials of the wax layer include rice bran wax, microcrystalline wax, polybutylene adipate / terephthalate and ethyl acetate.

[0009] The inner polyester composite coating structure achieves precise release: using polybutylene succinate (PBS) as a hydrophobic matrix, a continuous and dense membrane is formed, effectively blocking the rapid penetration of water and nutrients and providing a basic slow-release barrier. Within the PBS matrix, hydrophilic microdomains stabilized by sodium alginate and rich in betaine are dispersed through W / O emulsification technology. These microdomains can actively absorb moisture and dissolve under drought conditions, locally increasing osmotic pressure and activating microscale mass transfer channels to achieve "drought-induced release." In humid environments, the density of PBS still limits the overall diffusion rate, maintaining delayed release, thus achieving an intelligent response of "drought-induced release and humid-induced release," matching the peak nutrient demand of corn from the jointing to the tasseling stage.

[0010] The outer wax coating constructs a highly efficient physical protective barrier, enhancing overall weather resistance: the hydrophobic layer composed of rice bran wax and microcrystalline wax provides a hydrophobic, low surface energy protective shell, primarily controlling the initial wetting and ingress rate of water, essentially adding an external flow resistance to the system. Poly(butylene adipate) terephthalate (PAT) serves as a key compatibilizer; its polar groups form a strong interfacial interaction with the inner PBS layer, effectively preventing wax layer detachment and ensuring the integrity of the coating structure.

[0011] Based on the above technical solutions, the preferred method is that in the base fertilizer of step S1, the mass ratio of nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, brown algae polysaccharide, calcium ammonium nitrate, zinc citrate, potassium humate and γ-polyglutamic acid is 5-7.5:1.5-2.5:4-6:0.04-0.1:0.6-1.2:0.08-0.15:0.2-0.5:0.05-0.15, and the fertilizer application rate is 40-60 kg / mu.

[0012] Based on the above technical solutions, preferably, the nitrogen fertilizer is one or two of ammonium bicarbonate and urea, the phosphate fertilizer is one or two of superphosphate and calcium magnesium phosphate, and the potassium fertilizer is one or more of potassium chloride, potassium sulfate and potassium nitrate.

[0013] Based on the above technical solutions, preferably, in step S2, the foliar fertilizer contains 1.0wt%-1.5wt% potassium dihydrogen phosphate, 0.5wt%-1.0wt% magnesium sulfate, 0.05wt%-0.15wt% alginic acid, and 0.05wt%-0.15wt% polyaspartic acid, with water as the solvent.

[0014] Based on the above technical solutions, the preferred method for preparing the polyester composite layer includes the following steps: S11, Organic phase preparation: Polybutylene succinate is dissolved in a mixed solvent of ethyl acetate and ethanol at 50-55℃, and then cooled to 20-30℃ to obtain the oil phase. S12, Aqueous phase preparation: Sodium alginate was dissolved in deionized water, and betaine was added and stirred until clear to obtain an aqueous phase; S13, Mixing: The aqueous phase is slowly added to the organic phase, and after high-speed shearing and filtration, a polyester composite layer mixture is obtained.

[0015] Based on the above technical solutions, preferably, in step S11, the volume ratio of ethyl acetate to ethanol is 15.6-19:1, and the amount of polybutylene succinate is 18wt%-20wt% of the total amount of ethyl acetate and ethanol; in step S12, the mass ratio of polybutylene succinate, sodium alginate, and betaine is 90-100:5-8:1-3.

[0016] Based on the above technical solutions, the preferred method for preparing the wax layer is as follows: heating ethyl acetate to 70-80℃, and then sequentially adding microcrystalline wax, rice bran wax and polybutylene adipate / terephthalate to dissolve and obtain a wax layer mixture.

[0017] Based on the above technical solutions, the preferred mass ratio of rice bran wax, microcrystalline wax, and poly(butylene adipate) terephthalate is 45-60:35-50:5-7, and the amount of ethyl acetate is 2.8-3.3 times the total weight of the three. The amount of ethyl acetate is calculated according to m=ρ×V.

[0018] Based on the above technical solutions, the preferred coating method is as follows: the granulated fertilizer is placed in a fluidized bed coating machine and heated to 40-45℃. Then, the polyester composite layer mixture is sprayed onto the fertilizer surface, with a spraying amount of 5.5%-7.5% of the initial fertilizer mass. After the polyester composite layer dries, the wax layer mixture is sprayed, with a spraying amount of 3%-4.5% of the initial fertilizer mass.

[0019] The method for precise fertilization of maize throughout its entire growth period, as proposed in this invention, has the following advantages over existing technologies: This method involves preparing the base fertilizer into double-coated slow-release granules and applying it during sowing. The outer layer of rice bran wax / microcrystalline wax and the compatible modified poly(adipic acid) / butylene terephthalate form a hydrophobic barrier, which inhibits sudden release and salt damage during the seedling stage. The inner layer of polybutylene succinate, combined with betaine and sodium alginate, constructs a controllable water channel and slow-release network, enabling the release of nitrogen, phosphorus, and potassium as needed from the seedling stage to the jointing stage. Nitrogen drives leaf formation and assimilation, phosphorus ensures root extension and energy metabolism, and potassium enhances drought resistance and promotes osmotic regulation. Calcium ammonium nitrate provides readily available Ca and nitrate N in the early and mid-stages, strengthens cell walls and stem toughness, and reduces leaf edge scorching. Zinc citrate maintains high availability in an organic complex state, continuously preventing zinc deficiency bleaching and promoting meristematic tissue activity. Potassium humate and γ-polyglutamic acid increase soil cation exchange capacity and water and fertilizer retention capacity, enhance the rhizosphere's interception of NPK and micronutrients, and buffer against drought and flood fluctuations. Brown algae polysaccharides and betaine work together as biostimulants to activate rhizosphere microorganisms and root hair differentiation, solidify the early root framework, and improve carbon and nitrogen metabolism efficiency under stress. During the grain-filling stage, potassium dihydrogen phosphate, magnesium sulfate, alginic acid, and polyaspartic acid are used to provide targeted P and Mg to promote grain filling, thereby achieving precise fertilization throughout the entire growth period from seedling emergence to maturity, including low initial release, plateau supply, and late-stage top supplementation. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] The γ-polyglutamic acid (solid) used in this invention was purchased from Shandong Peptide and Biotechnology Co., Ltd., product model 301, with a PGA content ≥30%. Polyaspartic acid (solid) was purchased from Shandong Yuanlian Chemical Co., Ltd., and polybutylene succinate was purchased from Xuke New Materials (Shandong) Co., Ltd. Polybutylene adipate / terephthalate was purchased from Maclean's, model P729139, in powder form.

[0022] This invention first mixes the components of the base fertilizer, then adds 1 wt% binder (sodium lignosulfonate) and 3 wt% bentonite, and mixes and granulates them by machine to form spherical particles with a diameter of 4-6 mm.

[0023] Example 1 The precise fertilization method for the entire growth period of corn in this embodiment includes the following steps: S1. Apply a base fertilizer containing nitrogen (urea), phosphorus (superphosphate), potassium (potassium sulfate), brown algae polysaccharide, calcium ammonium nitrate, zinc citrate, potassium humate, and γ-polyglutamic acid at the time of corn sowing. The mass ratio of nitrogen, phosphorus, potassium, brown algae polysaccharide, calcium ammonium nitrate, zinc citrate, potassium humate, and γ-polyglutamic acid is 6:2:5:0.5:1:0.1:0.3:0.1, with a dosage of 40 kg per mu (approximately 667 square meters), applied together with corn sowing.

[0024] The base fertilizer is a slow-release fertilizer, which is coated with a polyester composite layer and a wax layer after granulation. The preparation method of the slow-release fertilizer is as follows: S11, Preparation of polyester composite layer material: Organic phase preparation: 90g of polybutylene succinate was dissolved in a mixed solvent of 450mL ethyl acetate and 50mL ethanol at 55℃, and then cooled to 25℃ to obtain the oil phase.

[0025] Aqueous phase preparation: Dissolve 7g of sodium alginate in 80mL of deionized water, add 2g of betaine and stir until clear to obtain the aqueous phase.

[0026] Mixing: The aqueous phase is slowly added to the organic phase, and after high-speed shearing at 10,000 rpm, it is filtered through a 20 μm filter membrane to obtain a polyester composite layer mixture.

[0027] S12, Preparation of wax layer material: 300 mL of ethyl acetate was heated to 75 °C, and 45 g of microcrystalline wax, 45 g of rice bran wax and 6.5 g of poly(butylene adipate / terephthalate) were added in sequence to dissolve and obtain the wax layer mixture.

[0028] S13, Coating: Place the granulated base fertilizer in a mixer and heat it to 40°C. Then spray the polyester composite layer mixture onto the fertilizer surface at a rate of 6% of the initial fertilizer mass. After the polyester composite layer dries, spray the wax layer mixture at a rate of 4% of the initial fertilizer mass.

[0029] The method for applying base fertilizer is as follows: apply fertilizer between the rows of corn seeds, with a spacing of 10cm between the fertilizer and the seeds, and a depth of 15-20cm.

[0030] S2, during the corn grain-filling stage, foliar fertilizer was applied using a plant protection drone. The foliar fertilizer consisted of potassium dihydrogen phosphate, magnesium sulfate, alginic acid, and polyaspartic acid. Specifically, potassium dihydrogen phosphate was 1.3 wt%, magnesium sulfate was 0.8 wt%, alginic acid was 0.1 wt%, and polyaspartic acid was 0.1 wt%, with water as the solvent.

[0031] Example 2 The precise fertilization method for the entire growth period of corn in this embodiment includes the following steps: S1. Apply a base fertilizer containing nitrogen fertilizer (ammonium bicarbonate and urea in a 1:3 mass ratio), phosphorus fertilizer (superphosphate and calcium magnesium phosphate in a 1:1 mass ratio), potassium fertilizer (potassium chloride, potassium sulfate, and potassium nitrate in a 1:1:1 mass ratio), brown algae polysaccharide, calcium ammonium nitrate, zinc citrate, potassium humate, and γ-polyglutamic acid at corn sowing. The mass ratio of nitrogen, phosphorus, potassium, brown algae polysaccharide, calcium ammonium nitrate, zinc citrate, potassium humate, and γ-polyglutamic acid is 7.5:2.5:6:0.04:1.2:0.15:0.5:0.15, prepared in 50 kg batches, and applied at a rate of 50 kg per mu (approximately 0.067 hectares) along with corn sowing. The fertilization method is as follows: apply fertilizer between corn rows, 10 cm away from the seeds, at a depth of 15-20 cm.

[0032] S2, during the corn grain-filling stage, foliar fertilizer was applied using a plant protection drone. The foliar fertilizer consisted of potassium dihydrogen phosphate, magnesium sulfate, alginic acid, and polyaspartic acid. The components were: potassium dihydrogen phosphate 1.0 wt%, magnesium sulfate 0.5 wt%, alginic acid 0.05 wt%, and polyaspartic acid 0.05 wt%, with water as the solvent.

[0033] The above-mentioned base fertilizer is a slow-release fertilizer. After granulation, it is sequentially coated with a polyester composite layer and a wax layer. The preparation method of the slow-release fertilizer is as follows: S11, Preparation of polyester composite layer material: Organic phase preparation: 100g of polybutylene succinate was dissolved in a mixed solvent of 475mL ethyl acetate and 25mL ethanol at 50℃, and then cooled to 30℃ to obtain the oil phase.

[0034] Aqueous phase preparation: Dissolve 8g of sodium alginate in 80mL of deionized water, add 3g of betaine and stir until clear to obtain the aqueous phase.

[0035] Mixing: The aqueous phase is slowly added to the organic phase, and after high-speed shearing at 10,000 rpm, it is filtered through a 20 μm filter membrane to obtain a polyester composite layer mixture.

[0036] S12, Preparation of wax layer material: 350 mL of ethyl acetate was heated to 80 °C, and 35 g of microcrystalline wax, 60 g of rice bran wax and 7 g of poly(butylene adipate / terephthalate) were added in sequence to dissolve and obtain wax layer mixture.

[0037] S13, Coating: Place the granulated fertilizer in a mixer and heat it to 45°C. Then spray the polyester composite layer mixture onto the fertilizer surface at a rate of 5.5% of the initial fertilizer mass. After the polyester composite layer dries, spray the wax layer mixture at a rate of 3% of the initial fertilizer mass.

[0038] Example 3 The precise fertilization method for the entire growth period of corn in this embodiment includes the following steps: S1. Apply a base fertilizer containing nitrogen (urea), phosphorus (calcium magnesium phosphate), potassium (potassium chloride), brown algae polysaccharide, calcium ammonium nitrate, zinc citrate, potassium humate, and γ-polyglutamic acid at corn sowing. The mass ratio of nitrogen, phosphorus, potassium, brown algae polysaccharide, calcium ammonium nitrate, zinc citrate, potassium humate, and γ-polyglutamic acid is 5:1.5:4:0.1:0.6:0.08:0.2:0.05, with 60 kg of the mixture prepared. Apply 60 kg per mu (approximately 0.067 hectares) along with the corn at sowing. The fertilization method is to apply the fertilizer between the corn rows, 10 cm away from the seeds, at a depth of 15-20 cm.

[0039] S2, during the corn grain-filling stage, foliar fertilizer was applied using a plant protection drone. The foliar fertilizer consisted of potassium dihydrogen phosphate, magnesium sulfate, alginic acid, and polyaspartic acid. The components were: potassium dihydrogen phosphate 1.5 wt%, magnesium sulfate 1.0 wt%, alginic acid 0.15 wt%, and polyaspartic acid 0.15 wt%, with water as the solvent.

[0040] The above-mentioned base fertilizer is a slow-release fertilizer. After granulation, it is sequentially coated with a polyester composite layer and a wax layer. The preparation method of the slow-release fertilizer is as follows: S11, Preparation of polyester composite layer material Organic phase preparation: 95g of polybutylene succinate was dissolved in a mixed solvent of 460mL ethyl acetate and 40mL ethanol at 55℃, and then cooled to 25-30℃ to obtain the oil phase.

[0041] Aqueous phase preparation: Dissolve 5g of sodium alginate in 80mL of deionized water, add 1g of betaine and stir until clear to obtain the aqueous phase.

[0042] Mixing: The aqueous phase is slowly added to the organic phase, and after high-speed shearing at 10,000 rpm, it is filtered through a 20 μm filter membrane to obtain a polyester composite layer mixture.

[0043] S12, Preparation of wax layer material: 350 mL of ethyl acetate was heated to 70 °C, and 42 g of microcrystalline wax, 50 g of rice bran wax and 5 g of poly(butylene adipate / terephthalate) were added in sequence to dissolve and obtain wax layer mixture.

[0044] S13, Coating: Place the granulated fertilizer in a mixer and heat it to 45°C. Then spray the polyester composite layer mixture onto the fertilizer surface at a rate of 7.5% of the initial fertilizer mass. After the polyester composite layer dries, spray the wax layer mixture at a rate of 4.5% of the initial fertilizer mass.

[0045] Example 4 The precise fertilization method for the entire growth period of corn in this embodiment includes the following steps: S1. Apply a base fertilizer containing nitrogen (ammonium bicarbonate), phosphate (calcium magnesium phosphate), potassium (potassium nitrate), brown algae polysaccharide, calcium ammonium nitrate, zinc citrate, potassium humate, and γ-polyglutamic acid at corn sowing. The mass ratio of nitrogen, phosphate, potassium, brown algae polysaccharide, calcium ammonium nitrate, zinc citrate, potassium humate, and γ-polyglutamic acid is 6:2:3.5:0.1 or 7:2.5:6:0.1:1.2:0.15:0.5:0.15, prepared at 45 kg per mu (approximately 0.067 hectares), applied together with corn sowing. The fertilization method is as follows: apply fertilizer between corn rows, 10 cm away from the seeds, at a depth of 15-20 cm.

[0046] S2, during the corn grain-filling stage, foliar fertilizer was applied using a plant protection drone. The foliar fertilizer consisted of potassium dihydrogen phosphate, magnesium sulfate, alginic acid, and polyaspartic acid. The components were: potassium dihydrogen phosphate 1.0 wt%, magnesium sulfate 1.0 wt%, alginic acid 0.1 wt%, and polyaspartic acid 0.15 wt%, with water as the solvent.

[0047] The above-mentioned base fertilizer is a slow-release fertilizer. After being machine-mixed and granulated (3-5mm in diameter), it is sequentially coated with a polyester composite layer and a wax layer. The preparation method of the slow-release fertilizer is as follows: S11, Preparation of polyester composite layer material: Organic phase preparation: 96g of polybutylene succinate was dissolved in a mixed solvent of 470mL ethyl acetate and 30mL ethanol at 55℃, and then cooled to 30℃ to obtain the oil phase.

[0048] Aqueous phase preparation: Dissolve 6g of sodium alginate in 80mL of deionized water, add 2.5g of betaine and stir until clear to obtain the aqueous phase.

[0049] Mixing: The aqueous phase is slowly added to the organic phase, and after high-speed shearing at 10,000 rpm, it is filtered through a 20 μm filter membrane to obtain a polyester composite layer mixture.

[0050] S12, Preparation of wax layer material: 300 mL of ethyl acetate was heated to 70 °C, and 35 g of microcrystalline wax, 55 g of rice bran wax and 6 g of poly(butylene adipate / terephthalate) were added in sequence to dissolve and obtain wax layer mixture.

[0051] S13, Coating: Place the granulated fertilizer in a mixer and heat it to 45°C. Then spray the polyester composite layer mixture onto the fertilizer surface at a rate of 7% of the initial fertilizer mass. After the polyester composite layer dries, spray the wax layer mixture at a rate of 4% of the initial fertilizer mass.

[0052] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the base fertilizer does not include brown algae polysaccharides, while the rest of the contents are the same as in Example 1.

[0053] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the base fertilizer does not include γ-polyglutamic acid, while the rest is the same as in Example 1.

[0054] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the foliar fertilizer does not include alginic acid and polyaspartic acid, while the rest is the same as in Example 1.

[0055] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the base fertilizer is only granulated and not coated with a polyester composite layer and a wax layer; the rest is the same as in Example 1.

[0056] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the base fertilizer is only coated with a polyester composite layer, while the rest is the same as in Example 1.

[0057] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that the polyester composite layer material does not contain betaine, while the rest is the same as in Example 1.

[0058] Comparative Example 7 The difference between Comparative Example 7 and Example 1 is that the wax layer material does not contain polybutylene adipate / terephthalate, while the rest is the same as in Example 1.

[0059] Comparative Example 8 The difference between Comparative Example 8 and Example 1 is that the content of sodium alginate exceeds the specified range, specifically 14g, while the rest are the same.

[0060] Comparative Example 9 The difference between Comparative Example 9 and Example 1 is that the content of betaine exceeds the specified range, specifically 6g, while the rest are the same.

[0061] Comparative Example 10 The difference between Comparative Example 10 and Example 1 is that the content of poly(butylene adipate / terephthalate) exceeds the specified range, specifically 14g, while the rest are the same.

[0062] The experimental field for this invention was located in Gulang County, Wuwei City, Gansu Province. The soil fertility was uniform, and the maize planted was spring maize, variety Jingke 968. Sowing was done by machine on April 20, 2024, and harvesting was on August 30, 2024. The planting density was 60cm row spacing and 25cm plant spacing. The maize planting area for each embodiment or comparative example was 60m². 2 During the growth period, normal pest control and watering were carried out, and the amount of pesticides sprayed and the amount of water irrigated were almost equal. The field management of the implementation examples and comparative examples was consistent, and external factors were excluded from interference.

[0063] After corn emergence, the emergence rate was measured, and at harvest, the root length and final yield were measured. The method for measuring corn root length was as follows: a five-point method was used, with five points taken in each example and comparative experimental field, and the average value was calculated. The results are shown in Table 1 below.

[0064] Table 1. Maize growth and yield

[0065] Examples 1 and Comparative Examples 1-3 show that the brown algae polysaccharide in the basal fertilizer, the γ-polyglutamic acid in the top dressing, and the alginic acid and polyaspartic acid in the foliar fertilizer all have a significant impact on yield. Among them, the brown algae polysaccharide and γ-polyglutamic acid have the greatest impact.

[0066] Comparative examples 4 and 5 show that without coating or with only a polyester composite layer, fertilizer is released too quickly in the early stage and the fertilizer effect is insufficient in the later stage, which cannot meet the needs of corn growth and thus leads to reduced yield.

[0067] Water resistance test of slow-release fertilizer: Take 20g of slow-release fertilizer prepared in Example 1 and Comparative Examples 5-10 above, soak them in 500g of water, and place them in a constant temperature chamber at 25℃ for 60 days. Then, determine the dissolution rate of urea according to GB / T 23348-2009 slow-release fertilizer standard. The test results are shown in Table 2.

[0068] Table 2 Urea dissolution rate (%)

[0069] Table 2 shows that Comparative Example 5, lacking a hydrophobic wax layer, exhibited rapid initial water absorption and accelerated urea dissolution; Comparative Example 6, lacking betaine, resulted in an unstable emulsion, uneven coating, and rapid water penetration, leading to faster initial dissolution and even faster overall dissolution; Comparative Example 7, lacking poly(adipate-adipate / butylene terephthalate), had poor wax layer adhesion and was prone to detachment, resulting in accelerated urea dissolution; Comparative Example 8, with excessive sodium alginate (hydrophilic phase), resulted in increased porosity and a higher permeability coefficient, leading to accelerated urea dissolution; Comparative Example 9, also with excessive hydrophilic salt (betaine), similarly exhibited a faster urea dissolution rate; Comparative Example 10, with excessive polar grafts (poly(adipate-adipate / butylene terephthalate), altered the wax phase crystal form and brittleness, resulting in accelerated urea dissolution.

[0070] The optimal release window for the double-coating lies in the inner layer of a moderately hydrophilic polyester composite (with sodium alginate and betaine within limited limits) and the outer layer of a wax phase containing a small amount of polybutylene adipate / terephthalate (PBAT), which together achieve low initial release and smooth, long-term release. Any alteration that weakens the outer hydrophobic barrier or disrupts interlayer adhesion will significantly worsen water resistance; similarly, excessive sodium alginate and betaine will lead to over-porosity and premature release. The data from Example 1 represent a good level of water resistance against burst release and full coverage of the growth period, which is more in line with the nutrient requirements of maize from jointing to grain filling in Northwest China.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for precise fertilization throughout the entire growth period of maize, characterized in that, Includes the following steps: S1, When planting corn, apply a base fertilizer containing nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, brown algae polysaccharide, zinc citrate and potassium humate between the corn rows; S2, foliar fertilizer is sprayed during the corn grain-filling stage. The components of the foliar fertilizer include potassium dihydrogen phosphate, magnesium sulfate, alginic acid and polyaspartic acid. The base fertilizer is a slow-release fertilizer, which is coated with a polyester composite layer and a wax layer in sequence after being mixed and granulated. The raw materials for the polyester composite layer include polybutylene succinate, betaine, and sodium alginate, while the raw materials for the wax layer include rice bran wax, microcrystalline wax, polybutylene adipate / terephthalate, and ethyl acetate.

2. The method for precise fertilization of maize throughout its entire growth period as described in claim 1, characterized in that: In step S1, the mass ratio of nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, brown algae polysaccharide, calcium ammonium nitrate, zinc citrate, potassium humate, and γ-polyglutamic acid in the base fertilizer is 5-7.5:1.5-2.5:4-6:0.04-0.1:0.6-1.2:0.08-0.15:0.2-0.5:0.05-0.15, and the fertilizer application rate is 40-60 kg / mu.

3. The method for precise fertilization of maize throughout its entire growth period as described in claim 2, characterized in that: In the foliar fertilizer of step S2, there are 1.0wt%-1.5wt% potassium dihydrogen phosphate, 0.5wt%-1.0wt% magnesium sulfate, 0.05wt%-0.15wt% alginic acid and 0.05wt%-0.15wt% polyaspartic acid, and the solvent is water.

4. The method for precise fertilization of maize throughout its entire growth period as described in claim 1, characterized in that: The method for preparing the polyester composite layer includes the following steps: S11, Organic phase preparation: Polybutylene succinate is dissolved in a mixed solvent of ethyl acetate and ethanol at 50-55℃, and then cooled to 20-30℃ to obtain the oil phase. S12, Aqueous phase preparation: Sodium alginate was dissolved in deionized water, and betaine was added and stirred until clear to obtain an aqueous phase; S13, Mixing: The aqueous phase is slowly added to the organic phase, and after high-speed shearing and filtration, a polyester composite layer mixture is obtained.

5. The method for precise fertilization of maize throughout its entire growth period as described in claim 4, characterized in that: In step S11, the volume ratio of ethyl acetate to ethanol is 15.6-19:1, and the mass of polybutylene succinate is 18wt%-20wt% of the total mass of ethyl acetate and ethanol.

6. The method for precise fertilization of maize throughout its entire growth period as described in claim 4, characterized in that: In step S12, the mass ratio of polybutylene succinate, sodium alginate, and betaine is 90-100:5-8:1-3.

7. The method for precise fertilization of maize throughout its entire growth period as described in claim 4, characterized in that: The wax layer is prepared by heating ethyl acetate to 70-80°C, and then adding microcrystalline wax, rice bran wax and polybutylene adipate / terephthalate in sequence to dissolve and obtain a wax layer mixture.

8. The method for precise fertilization of maize throughout its entire growth period as described in claim 7, characterized in that: The mass ratio of rice bran wax, microcrystalline wax, and poly(butylene adipate) / terephthalate is 45-60:35-50:5-7, and the amount of ethyl acetate is 2.8-3.3 times the total weight of the three.

9. The method for precise fertilization of maize throughout its entire growth period as described in claim 8, characterized in that: The coating method is as follows: the granulated fertilizer is placed in a fluidized bed coating machine and heated to 40-45℃. Then, the polyester composite layer mixture is sprayed onto the fertilizer surface, with a spraying amount of 5.5%-7.5% of the initial fertilizer mass. After the polyester composite layer dries, the wax layer mixture is sprayed, with a spraying amount of 3%-4.5% of the initial fertilizer mass.

10. The method for precise fertilization of maize throughout its entire growth period as described in claim 1, characterized in that: The nitrogen fertilizer is one or two of ammonium bicarbonate and urea, the phosphate fertilizer is one or two of superphosphate and calcium magnesium phosphate, and the potassium fertilizer is one or more of potassium chloride, potassium sulfate and potassium nitrate.

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