A method for soil improvement in an acidic sugarcane zone and a carbon-based slow-release fertilizer composition

Abstract

The present application relates to the technical field of agricultural fertilizer, in particular to a soil improvement method for acid sugarcane area and a carbon-based slow-release fertilizer composition. The specific technical scheme is as follows: a soil improvement method for acid sugarcane area, comprising the following steps: S1, base application stage: deep ploughing and soil preparation 7-15 days before sugarcane planting, uniformly applying root area long-acting module at 120-180 kg per mu, and rotary ploughing into 0-25 cm plough layer; S2, spraying at tillering peak: 45-60 days after sugarcane planting, spraying leaf surface with resistance photosynthesis module diluted by 500-800 times, using 60-75 L of diluted solution per mu; S3, spraying at initial stage of sugar accumulation: 60-90 days before harvesting, spraying leaf surface with sugar-increasing induction module diluted by 600-900 times, using 60-75 L of diluted solution per mu. The present application solves the problems of single function and insufficient system in the prior art.

Description

Technical Field

[0001] This invention relates to the field of agricultural fertilizer technology, specifically to a method for soil improvement in acidic sugarcane areas and a carbon-based slow-release fertilizer composition. Background Technology

[0002] Sugarcane, an important sugar crop, is mainly distributed in acidic soil regions of southern China. Taking Guangxi Zhuang Autonomous Region as an example, the soils in major sugarcane-producing areas generally suffer from low pH, high exchangeable aluminum content, leaching of basic ions, and insufficient available potassium. Under strongly acidic conditions, a large amount of solid aluminum dissolves from the soil, leading to Al... 3+ Aluminum toxicity affects sugarcane roots, inhibiting root tip cell division and elongation, leading to short, thick roots, root hair degeneration, and severely weakened nutrient absorption capacity. Conventional fast-acting fertilizers are rapidly lost and severely fixed in acidic environments, resulting in low nutrient utilization rates during the current season. As a typical C4 high-photosynthetic crop, sugarcane's biomass yield and sucrose accumulation directly depend on root absorption capacity, leaf photosynthetic capacity, and late-stage source-sink regulation capacity.

[0003] Existing technologies often focus on single problems. For example, soil conditioners emphasize acid-base neutralization, slow-release fertilizers focus on extending the fertilization cycle, and biostimulant products focus on short-term stress relief. While existing biochar-coated slow-release fertilizers can improve nutrient release, they are generally not integrated into a comprehensive, time-series approach that addresses aluminum toxicity in acidic sugarcane growing areas, stress resistance and photosynthetic regulation during tillering, and source-sink translocation regulation during sugar accumulation. Current technologies lack a comprehensive, phased application plan that can simultaneously achieve acidic soil mitigation, long-term high-nitrogen and high-potassium fertilization, improved leaf photosynthetic efficiency, and targeted sugar accumulation regulation. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a soil improvement method for acidic sugarcane growing areas and a carbon-based slow-release fertilizer composition, solving the problems of single function and insufficient system integration in existing technologies. This fertilizer composition integrates acidic soil improvement, high-nitrogen and high-potassium slow-release fertilization, enhanced leaf photosynthesis, and targeted sugar accumulation regulation, along with a phased application method. Through the spatiotemporal synergistic effect of these three modules, sugarcane yield and sugar content are simultaneously increased, while improving the soil quality of the sugarcane fields.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention discloses a method for soil improvement in acidic sugarcane areas, comprising the following steps: S1. Base application stage: 7-15 days before sugarcane planting, deep plow and prepare the land, and evenly spread the long-acting modules in the root zone at 120-180 kg / mu, and rotary till into the 0-25cm tillage layer. S2. Spraying during the peak tillering period: 45-60 days after sugarcane planting, dilute the stress-resistant photosynthetic module 500-800 times and spray it on the leaves, using 60-75L of diluted solution per mu; S3. Spraying at the initial stage of sugar accumulation: 60 to 90 days before harvest, dilute the sugar-inducing module 600 to 900 times and spray it on the leaves. Use 60 to 75 L of diluted solution per mu.

[0006] Preferably, in step S1, the root zone long-acting module comprises 45-60 parts of alkaline mineral conditioning particles, with the remainder being high-nitrogen, high-potassium carbon-based slow-release fertilizer core particles, based on a mass of 100 parts.

[0007] Preferably, by weight, the alkaline mineral conditioning particles comprise 30-50 parts of mineral-derived potassium humate, 20-35 parts of silicon-calcium-magnesium mineral powder, 10-20 parts of bentonite, 3-8 parts of alginate, and 2-5 parts of polyglutamic acid. The potassium fulvic acid from the mineral source has a dry basis fulvic acid content of ≥50% and a pH value of 8.0-10.5 in a 1% aqueous solution; the silicon-calcium-magnesium mineral powder is obtained by calcining limestone, dolomite and wollastonite at 1100-1300℃ and then grinding them to a fineness of ≥200 mesh, with a soluble SiO2 content of ≥25%, an effective CaO content of ≥35%, and an effective MgO content of ≥2%.

[0008] Preferably, the high-nitrogen, high-potassium carbon-based slow-release fertilizer core particles comprise a nitrogen-potassium composite granule fertilizer core and a polymer-carbon composite coating layer covering the surface of the nitrogen-potassium composite granule fertilizer core; based on 100 parts of the uncoated nitrogen-potassium composite granule fertilizer core, the cured mass of the polymer-carbon composite coating layer is 8 to 15 parts; in the nitrogen-potassium composite granule fertilizer core, the mass ratio of N to K2O is 1.5:1 to 1:1.2, the K2O content is ≥22%, and the N content is ≥26%.

[0009] Preferably, the polymer-carbon composite coating layer is formed by spraying a mixture of the following raw materials onto the surface of the nitrogen-potassium composite granular fertilizer core and then curing it. By weight, the polymer-carbon composite coating layer comprises 40-55 parts of bagasse liquefaction products, 8-15 parts of bagasse-based biochar, 5-10 parts of nano-carbon powder, 25-35 parts of polyisocyanate, 0.5-1.5 parts of organotin catalyst, 3-8 parts of silicate, and 2-5 parts of nano-magnesium oxide.

[0010] The bagasse-based biochar is dispersed in the polymer-carbon composite coating layer, with a specific surface area ≥80m². 2 / g, pH value is 7.0~10.5.

[0011] Preferably, in step S2, the anti-stress photosynthetic module comprises, by weight, 20-35 parts of seaweed extract, 15-25 parts of complex amino acids, 8-15 parts of chitosan oligosaccharide, 3-6 parts of abscisic acid, 15-25 parts of 5-aminolevulinic acid or its agriculturally acceptable salt, 10-20 parts of anhydrous magnesium sulfate, and 5-20 parts of trace element chelates.

[0012] Preferably, the composite amino acid is any one of the following: a combination of proline and glutamic acid, a combination of proline, glutamic acid, and glycine, or a combination of proline, glutamic acid, and arginine; wherein the proline content is ≥40% and the glutamic acid content is ≥25%; The abscisic acid is natural abscisic acid or its agriculturally acceptable salt or ester; the trace element chelate is at least one of chelated zinc, chelated manganese, and chelated iron.

[0013] Preferably, in step S3, the sugar-inducing module comprises, by weight, 30-50 parts potassium phosphite, 8-15 parts 5-aminolevulinic acid or its agriculturally acceptable salt, 0.1-0.8 parts brassinolide, 5-10 parts chelated boron, 3-8 parts organosilicon penetrant, and 5-10 parts anhydrous magnesium sulfate.

[0014] Preferably, the brassinolide is one or more of 28-homobrassinolide, 24-epibrassinolide, and 28-epibrassinolide.

[0015] Correspondingly, a soil-improving carbon-based slow-release fertilizer composition for acidic sugarcane areas includes a root zone long-acting module, a stress-resistant photosynthetic module, and a sugar-inducing module; Based on a mass of 100 parts, the root zone long-acting module includes 45-60 parts of alkaline mineral conditioning particles, with the remainder being high-nitrogen, high-potassium carbon-based slow-release fertilizer core particles. By weight, the anti-stress photosynthetic module comprises 20-35 parts of seaweed extract, 15-25 parts of complex amino acids, 8-15 parts of chitosan oligosaccharide, 3-6 parts of abscisic acid, 15-25 parts of 5-aminolevulinic acid or its agriculturally acceptable salt, 10-20 parts of anhydrous magnesium sulfate, and 5-20 parts of trace element chelate. By weight, the sugar-inducing module comprises 30-50 parts potassium phosphite, 8-15 parts 5-aminolevulinic acid or its agriculturally acceptable salt, 0.1-0.8 parts brassinolide, 5-10 parts chelated boron, 3-8 parts organosilicon penetrant, and 5-10 parts anhydrous magnesium sulfate.

[0016] The present invention has the following beneficial effects: (1) This invention addresses the obstacles to sugarcane production in acidic sugarcane areas by designing a complete set of products that include soil improvement and aluminum reduction in the root zone, carbon-based slow-release fertilizer supply, stress resistance and photosynthetic repair during the tillering stage, and sugar accumulation induction during the sugar accumulation stage, all packaged independently and applied in stages. The products have been proven to have synergistic effects through component reduction tests.

[0017] (2) The present invention adopts a three-module synergistic effect system, which integrates root zone soil improvement and aluminum reduction, carbon-based high nitrogen and high potassium slow release, leaf surface anti-stress photosynthesis and late-stage targeted sugar increase into a complete set of products for phased application.

[0018] (3) Under the field trial conditions of the example, the sugarcane stalk yield of the complete three-module scheme increased by 34.4% and the sugarcane juice hardness increased by 3.3 percentage points compared with conventional fertilization.

[0019] (4) Soil quality has been significantly improved. The pH of the topsoil has increased from 4.62 to 5.35, and the exchangeable aluminum content has decreased from 3.92 cmol / kg to 1.52 cmol / kg.

[0020] (5) Fertilizer utilization rate is improved. Under the conditions of the example, the nitrogen fertilizer utilization rate is increased to 45.3% and the potassium fertilizer utilization rate is increased to 50.8%.

[0021] (6) Biochar and liquefied coating products are prepared using sugarcane bagasse, a by-product of the sugar industry, as the main raw material, so as to realize the high-value utilization of sugar industry waste. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the individual packaging for the three-module combination product; Figure 2 A schematic diagram of the cross-sectional structure of high-nitrogen, high-potassium carbon-based slow-release fertilizer core particles; Figure 3 This is a schematic diagram of the phased application process of the fertilizer composition in the field. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Unless otherwise specified, the technical means used in the implementation examples are conventional means well known to those skilled in the art.

[0025] This invention discloses a soil-improving carbon-based slow-release fertilizer composition for acidic sugarcane growing areas, comprising a complete product consisting of a root zone long-acting module, a stress-resistant photosynthetic module, and a sugar-inducing module; the three modules are individually packaged and are respectively used for basal application before sugarcane planting, foliar spraying during the tillering peak period, and foliar spraying at the early stage of sugar accumulation; wherein: The root zone long-acting module is in solid granular form. Based on a mass of 100 parts, the root zone long-acting module includes 45-60 parts of alkaline mineral conditioning particles, with the remainder being high-nitrogen, high-potassium carbon-based slow-release fertilizer core particles. The alkaline mineral conditioning particles and the high-nitrogen, high-potassium carbon-based slow-release fertilizer core particles in the root zone long-acting module are granulated separately and then mixed together, and applied together during basal application.

[0026] The anti-stress photosynthetic module is a soluble preparation, comprising, by weight, 20-35 parts of seaweed extract, 15-25 parts of complex amino acids, 8-15 parts of chitosan oligosaccharide, 3-6 parts of abscisic acid, 15-25 parts of 5-aminolevulinic acid or its agriculturally acceptable salt, 10-20 parts of anhydrous magnesium sulfate, and 5-20 parts of trace element chelates; wherein, the effective content of the seaweed extract, calculated as seaweed polysaccharide, is ≥20%; the effective content of the complex amino acids, calculated as total free amino acids, is ≥80%; the effective content of the chitosan oligosaccharide is ≥90% and has a degree of polymerization of 2-10; the effective content of the abscisic acid is ≥90%; the effective content of 5-aminolevulinic acid or its agriculturally acceptable salt, is ≥98%; and the effective content of the trace element chelates, calculated as chelated trace elements, is ≥15%.

[0027] The sugar-inducing module is a liquid preparation, comprising, by weight, 30-50 parts potassium phosphite, 8-15 parts 5-aminolevulinic acid or its agriculturally acceptable salt, 0.1-0.8 parts brassinolide, 5-10 parts chelated boron, 3-8 parts organosilicon penetrant, and 5-10 parts anhydrous magnesium sulfate.

[0028] Further, by weight, the alkaline mineral conditioning particles comprise 30-50 parts of mineral-derived potassium humate, 20-35 parts of silica-calcium-magnesium mineral powder, 10-20 parts of bentonite, 3-8 parts of alginate, and 2-5 parts of polyglutamic acid; wherein the potassium humate has a dry basis fulvic acid content ≥50% and a 1% aqueous solution pH value of 8.0-10.5; the silica-calcium-magnesium mineral powder is obtained by calcining limestone, dolomite, and wollastonite at 1100-1300℃ for 1-4 hours and then grinding it to a fineness of 200 mesh or higher, with a soluble SiO2 content ≥25%, an effective CaO content ≥35%, and an effective MgO content ≥2%. The mass ratio of limestone, dolomite, and wollastonite is 4-6:3-4:1-3. The polyglutamic acid has an effective content ≥90% and a molecular weight of 500,000-2,000,000 Da.

[0029] Furthermore, the high-nitrogen, high-potassium carbon-based slow-release fertilizer core particles comprise a nitrogen-potassium composite granule fertilizer core and a polymer-carbon composite coating layer covering the surface of the nitrogen-potassium composite granule fertilizer core; based on 100 parts by weight of the uncoated nitrogen-potassium composite granule fertilizer core, the cured mass of the polymer-carbon composite coating layer is 8-15 parts; in the nitrogen-potassium composite granule fertilizer core, the mass ratio of N to K2O is 1.5:1 to 1:1.2, the K2O content is ≥22%, and the N content is ≥26%. The specific structural composition is as follows... Figure 2 As shown.

[0030] Furthermore, the preparation of the high-nitrogen and high-potassium carbon-based slow-release fertilizer core granules includes the following steps: sugarcane bagasse is carbonized at 300-450℃ for 60-120 min under oxygen-limited conditions to obtain sugarcane bagasse-based biochar; urea and potassium sulfate are mixed and granulated at a N:K2O mass ratio of 1.5:1 to 1:1.2 to obtain nitrogen-potassium composite granular fertilizer core.

[0031] Furthermore, the polymer-carbon composite coating layer is a ternary carbon composite coating layer, which is formed by spraying a mixture of the following raw materials onto the surface of the nitrogen-potassium composite granular fertilizer core and curing it. By weight, the polymer-carbon composite coating layer comprises 40-55 parts of bagasse liquefaction products, 8-15 parts of bagasse-based biochar, 5-10 parts of nano-carbon powder, 25-35 parts of polyisocyanate, 0.5-1.5 parts of organotin catalyst, 3-8 parts of silicate, and 2-5 parts of nano-magnesium oxide. The bagasse-based biochar is dispersed within the polymer-carbon composite coating layer and has a specific surface area ≥80 m². 2 / g, pH value 7.0–10.5. The polyisocyanate is one or more of polymethylene polyphenyl polyisocyanate (PAPI), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), methylcyclohexyl diisocyanate (HTDI), or tetramethylphenyl dimethylene diisocyanate (TMXDI), and the organotin catalyst is one or more of dibutyltin dilaurate, stannous octanoate, dibutyltin diacetate, or dibutyltin dilaurate.

[0032] Furthermore, the complex amino acid contains at least proline and glutamic acid, and may further contain glycine and / or arginine; wherein the proline content is ≥40% and the glutamic acid content is ≥25%; the abscisic acid substance is natural abscisic acid or its agriculturally acceptable salt or ester; the trace element chelate is at least one of chelated zinc, chelated manganese and chelated iron.

[0033] Furthermore, the brassinolide is one or more of 28-homobrassinolide, 24-epibrassinolide, and 28-epibrassinolide.

[0034] like Figure 3 As shown, the present invention provides a method for soil improvement in acidic sugarcane areas, comprising the following steps: S1. Base application stage: 7-15 days before sugarcane planting, deep plow and prepare the land to a depth of 30-40cm. Spread the long-acting modules in the root zone evenly on the surface at a rate of 120-180kg / mu. Rotary tillage to fully mix the fertilizer with the 0-25cm topsoil layer. S2. Spraying during the peak tillering period: 45 to 60 days after sugarcane planting, dilute the stress-resistant photosynthetic module 500 to 800 times and spray it on the leaves at a rate of 60 to 75 L of diluted solution per acre. S3. Spraying at the initial stage of sugar accumulation: 60 to 90 days before harvest, dilute the sugar-inducing module 600 to 900 times and spray it on the leaves at a rate of 60 to 75 L of diluted solution per acre. In particular, the spraying in steps S2 and S3 is carried out in the evening on a windless and sunny day, focusing on spraying the front and back of the upper and middle functional leaves of the sugarcane.

[0035] In this invention, alkaline mineral conditioning granules neutralize acidity, passivate active aluminum, improve the microstructure of the root zone, and promote root growth, thereby raising the pH level in the root zone and bringing it closer to the suitable range for sugarcane, reducing acid damage and aluminum toxicity. The high-nitrogen, high-potassium carbon-based slow-release fertilizer core utilizes a dual controlled-release mechanism of biochar physical adsorption and polymer membrane chemical cross-linking, extending the nitrogen and potassium nutrient release cycle to 90-120 days, reducing nutrient leaching and fixation under acidic conditions. The stress-resistant photosynthetic module promotes photosynthetic system repair and chlorophyll synthesis during the tillering peak, enhancing stress tolerance; the sugar-inducing module promotes the transport and unloading of photosynthetic products to the sucrose storage tank in the stem nodes during the early stages of sugar accumulation. These three modules form a sequential, progressive technology chain of "root zone improvement - long-term fertilization - photosynthetic enhancement - targeted sugar induction." See [link to relevant documentation]. Figure 1 As shown.

[0036] The present invention will be further described below with reference to specific embodiments.

[0037] Example 1: Preparation of a long-lasting module in the root region (1) Limestone, dolomite and wollastonite are mixed in a mass ratio of 5:3:2, calcined at 1200℃ for 2 hours, cooled and ground to 250 mesh to obtain silicon-calcium-magnesium mineral powder.

[0038] (2) Take sugarcane bagasse, wash, dry and crush it, heat it to 380°C at 8°C / min under nitrogen protection, carbonize it at a constant temperature for 90 minutes, cool it and grind it through a 200-mesh sieve to obtain sugarcane bagasse-based biochar.

[0039] (3) Weigh 430 parts of urea and 370 parts of potassium sulfate, mix and granulate, sieve 2.5-3.5 mm particles and dry them to obtain nitrogen-potassium composite granular fertilizer core.

[0040] (4) Mix 50 parts of sugarcane bagasse liquefaction product, 12 parts of sugarcane bagasse-based biochar, 8 parts of nano-carbon powder, 30 parts of polymethylene polyphenyl polyisocyanate, 1.0 part of dibutyltin dilaurate, 6 parts of tetraethyl orthosilicate, and 3 parts of nano-magnesium oxide to prepare a polymer-carbon composite coating solution. Spray the coating solution onto the surface of nitrogen-potassium composite granular fertilizer core through a fluidized bed. The coating layer accounts for 12% of the mass of the uncoated fertilizer core, thus obtaining high-nitrogen and high-potassium carbon-based slow-release fertilizer core granules.

[0041] (5) Take 40 parts of potassium humate, 28 parts of silicon-calcium-magnesium mineral powder, 16 parts of bentonite, 5 parts of sodium alginate, and 4 parts of polyglutamic acid, mix and granulate to obtain alkaline mineral conditioning granules. Finally, mix the alkaline mineral conditioning granules with high-nitrogen and high-potassium carbon-based slow-release fertilizer core granules at a mass ratio of 55:45 to obtain a long-lasting module for the root zone.

[0042] Example 2: Preparation of Anti-Resistant Photosynthesis Module Weigh out 30 parts by weight of seaweed extract powder, 12 parts of proline, 8 parts of glutamic acid, 12 parts of chitosan oligosaccharide, 4.5 parts of natural abscisic acid, 20 parts of 5-aminolevulinate, 15 parts of anhydrous magnesium sulfate, 3.5 parts of chelated zinc, and 2.5 parts of chelated manganese. Add all components to a V-type mixer and mix under closed conditions for 30 minutes until homogeneous. Grind the mixture to 150 mesh using an air jet mill to obtain a soluble powder form of the anti-stress photosynthetic module. The total amount of complex amino acids (20 parts) and trace element chelates (6 parts) falls within the specified range.

[0043] Example 3: Preparation of a sugar-inducing module Add an appropriate amount of deionized water to a stirred tank, heat to 40°C and stir. Add 40 parts potassium phosphite (calculated as K₂HPO₃), 10 parts 5-aminolevulinate, 8 parts anhydrous magnesium sulfate, and 5 parts chelated boron sequentially, stirring until completely dissolved. Dissolve 0.5 parts 28-homobrassinolide in 3 parts anhydrous ethanol, and slowly add it to the tank along with 3 parts organosilicon penetrant. Add deionized water to a final volume of 1000 parts, adjust the pH to 6.2 ± 0.2, filter, and fill to obtain the liquid formulation of the saccharification induction module.

[0044] Example 4: Field Application Effect Verification The experiment was conducted at a sugarcane planting base in acidic red soil in Laibin City, Guangxi Zhuang Autonomous Region. The basic physicochemical properties of the topsoil were as follows: pH 4.62, organic matter 15.8 g / kg, available nitrogen 72 mg / kg, available phosphorus 4.8 mg / kg, available potassium 56 mg / kg, and exchangeable aluminum 3.92 cmol / kg. The tested sugarcane variety was Guitang 42. The experiment included six treatments, each with three replicates, using a completely randomized block design. The plot area was 667 m². 2 .

[0045] Treatment I (CK, conventional fertilization): Apply 50 kg / mu of compound fertilizer (15-15-15) as basal fertilizer, apply 15 kg / mu of urea + 10 kg / mu of potassium chloride as top dressing during the tillering stage, and apply 20 kg / mu of urea + 15 kg / mu of potassium chloride as top dressing during the elongation stage.

[0046] Treatment II (commercially available slow-release fertilizer control): Apply 60 kg / mu of commercially available resin-coated slow-release compound fertilizer (produced by Shandong Kingenta Ecological Engineering Group Co., Ltd., with N-P2O5-K2O ratio of 26-10-12, total nutrients ≥48%, and controlled release period of 90 days) as base fertilizer, and do not apply topdressing.

[0047] Treatment III (long-acting module in the root zone only): 10 days before sugarcane planting, apply the long-acting module in the root zone evenly at a rate of 150 kg / mu and then rotary till it into the 0-25 cm tillage layer. Do not spray the stress-resistant photosynthesis module or the sugar-inducing module.

[0048] Treatment IV (Complete three-module program: root zone long-acting module + stress-resistant photosynthesis module + sugar-inducing module): 10 days before sugarcane planting, evenly spread the root zone long-acting module at 150 kg / mu and then rotary till it into the 0-25 cm topsoil layer; 50 days after sugarcane planting, dilute the stress-resistant photosynthesis module 600 times and apply it as a foliar spray at a rate of 65 L / mu; 75 days before harvest, dilute the sugar-inducing module 750 times and apply it as a foliar spray at a rate of 65 L / mu.

[0049] Treatment V (root zone long-acting module + sugar-inducing module): The root zone long-acting module is applied as a base treatment to Treatment IV, but the stress-resistant photosynthesis module is not sprayed. The sugar-inducing module is sprayed as a base treatment to Treatment IV.

[0050] Treatment VI (root zone long-term module + stress-resistant photosynthesis module): The root zone long-term module is applied as a base treatment in the same way as Treatment IV, the stress-resistant photosynthesis module is sprayed with the same way as Treatment IV, and the sugar-inducing module is not sprayed.

[0051] Among them, the basal application of the root zone long-term module for treatments IV, V, and VI was completed 10 days before sugarcane planting; the spraying of the stress-resistant photosynthesis module was carried out on a windless, sunny evening 50 days after sugarcane planting, focusing on spraying the front and back of the upper and middle functional leaves of sugarcane; the spraying of the sugar-inducing module was carried out on a windless, sunny evening 75 days before harvest, focusing on spraying the front and back of the upper and middle functional leaves of sugarcane.

[0052] Yield, sugarcane juice hardness, and soil parameters were measured at harvest. Data are expressed as mean ± standard deviation. One-way ANOVA and Duncan's multiple comparisons were used. Different lowercase letters indicate significant differences between treatments. P <0.05). The results are shown in Tables 1-3.

[0053] Table 1. Sugarcane yield and quality indicators under different treatments (mean ± SD, n=3)

[0054] Table 2 Soil properties of the 0–20 cm topsoil layer after harvest under different treatments (mean ± SD, n=3)

[0055] Table 3 Results of the synergistic validation experiment for component reduction (mean ± SD, n=3)

[0056] Using conventional fertilization as the baseline and the root zone long-acting module treatment as an intermediate reference, the marginal increments of the stress-resistant photosynthetic module and the sugar-inducing module relative to the root zone long-acting module were calculated. For example, yield: E (complete three-module scheme) = 6880 - 5120 = 1760 kg / mu; E (root zone long-acting module increment) = 6220 - 5120 = 1100 kg / mu; E (marginal increment of stress-resistant photosynthetic module) = 6510 - 6220 = 290 kg / mu; E (marginal increment of sugar-inducing module) = 6430 - 6220 = 210 kg / mu; Synergy index SI (yield) = 1760 / (1100 + 290 + 210) = 1.10 > 1. For example, for sugarcane juice saturation, SI (saturation) = 3.3 / (1.6 + 0.1 + 1.0) = 1.22 > 1. The above results show that the overall effect of the complete three-module scheme is higher than the simple sum of the increments of each module, indicating a positive synergistic effect. The results are shown in Table 4 below.

[0057] Table 4 Summary Table of Synergy Index Calculation

[0058] Example 5: Determination of Nutrient Release Characteristics of Slow-Release Fertilizer Cores 10.00 g of the high-nitrogen, high-potassium carbon-based slow-release fertilizer core granules prepared in Example 1 were weighed and placed into a 100-mesh nylon mesh bag and sealed. The mesh bag was immersed in a 250 mL Erlenmeyer flask containing 200 mL of deionized water and placed in a constant temperature incubator at 25 ± 1 °C. The mesh bag was removed at 1, 7, 28, 60, 90, 120, and 180 days after immersion, and the total nitrogen and K2O concentrations in the leachate were measured to calculate the cumulative nutrient release rate. Fresh deionized water was used after each sampling, and the experiment was repeated three times. The results are shown in Table 5.

[0059] Table 5. Cumulative nutrient release rate of high-nitrogen, high-potassium carbon-based slow-release fertilizer core in still water at 25℃ (mean ± SD, n=3)

[0060] Example 6: Fertilizer utilization rate determination Based on the field trial in Example 4, sugarcane plant samples were collected at harvest time for each treatment, and the nitrogen and potassium uptake in the aboveground parts of the plants was measured. Fertilizer utilization rate was calculated using the following formula: Fertilizer utilization rate (%) = (Nutrient uptake in the fertilized area - Nutrient uptake in the blank area without corresponding nutrient application) / Amount of applied nutrients × 100%. The blank area was only used for utilization rate calculation and was not included in the yield comparison in Tables 1 to 3. For Treatment I, conventional fertilization was calculated based on basal compound fertilizer, topdressing during the tillering and elongation stages, and the N and K2O applied were converted. For Treatment II, the nutrient content was calculated based on the label of commercially available slow-release fertilizer. For Treatments III and IV, the nutrient content was calculated based on the proportion of high-nitrogen, high-potassium carbon-based slow-release fertilizer core particles in the long-acting module of the root zone and the measured N and K2O content of the fertilizer core. The results are shown in Tables 6 and 7.

[0061] Table 6. Results of fertilizer utilization rate measurement (mean ± SD, n=3)

[0062] Table 7. Basic data for fertilizer utilization rate calculation (mean, kg / mu, n=3)

[0063] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for soil improvement in acidic sugarcane growing areas, characterized in that: Includes the following steps: S1. Base application stage: 7-15 days before sugarcane planting, deep plow and prepare the land, and evenly spread the long-acting modules in the root zone at 120-180 kg / mu, and rotary till into the 0-25cm tillage layer. S2. Spraying during the peak tillering period: 45-60 days after sugarcane planting, dilute the stress-resistant photosynthetic module 500-800 times and spray it on the leaves, using 60-75L of diluted solution per mu; S3. Spraying at the initial stage of sugar accumulation: 60 to 90 days before harvest, dilute the sugar-inducing module 600 to 900 times and spray it on the leaves. Use 60 to 75 L of diluted solution per mu.

2. The method for soil improvement in acidic sugarcane areas according to claim 1, characterized in that: In step S1, based on a mass of 100 parts, the root zone long-acting module includes 45-60 parts of alkaline mineral conditioning particles, with the remainder being high-nitrogen, high-potassium carbon-based slow-release fertilizer core particles.

3. The method for soil improvement in acidic sugarcane areas according to claim 2, characterized in that: By weight, the alkaline mineral conditioning particles comprise 30-50 parts of mineral-derived potassium humate, 20-35 parts of silicon-calcium-magnesium mineral powder, 10-20 parts of bentonite, 3-8 parts of alginate, and 2-5 parts of polyglutamic acid. The potassium fulvic acid from the mineral source has a dry basis fulvic acid content of ≥50% and a pH value of 8.0-10.5 in a 1% aqueous solution; the silicon-calcium-magnesium mineral powder is obtained by calcining limestone, dolomite and wollastonite at 1100-1300℃ and then grinding them to a fineness of ≥200 mesh, with a soluble SiO2 content of ≥25%, an effective CaO content of ≥35%, and an effective MgO content of ≥2%.

4. A method for soil improvement in acidic sugarcane areas according to claim 2 or 3, characterized in that: The high-nitrogen, high-potassium carbon-based slow-release fertilizer core particles include a nitrogen-potassium composite granule fertilizer core and a polymer-carbon composite coating layer covering the surface of the nitrogen-potassium composite granule fertilizer core; based on 100 parts of the uncoated nitrogen-potassium composite granule fertilizer core, the cured mass of the polymer-carbon composite coating layer is 8 to 15 parts; in the nitrogen-potassium composite granule fertilizer core, the mass ratio of N to K2O is 1.5:1 to 1:1.2, the K2O content is ≥22%, and the N content is ≥26%.

5. A method for soil improvement in acidic sugarcane areas according to claim 4, characterized in that: The polymer-carbon composite coating layer is formed by spraying a mixture of the following raw materials onto the surface of the nitrogen-potassium composite granular fertilizer core and then curing it. By weight, the polymer-carbon composite coating layer comprises 40-55 parts of bagasse liquefaction products, 8-15 parts of bagasse-based biochar, 5-10 parts of nano-carbon powder, 25-35 parts of polyisocyanate, 0.5-1.5 parts of organotin catalyst, 3-8 parts of silicate, and 2-5 parts of nano-magnesium oxide.

6. A method for soil improvement in acidic sugarcane areas according to any one of claims 1-5, characterized in that: In step S2, by weight, the anti-stress photosynthesis module includes 20-35 parts of seaweed extract, 15-25 parts of complex amino acids, 8-15 parts of chitosan oligosaccharide, 3-6 parts of abscisic acid, 15-25 parts of 5-aminolevulinic acid or its agriculturally acceptable salt, 10-20 parts of anhydrous magnesium sulfate, and 5-20 parts of trace element chelates.

7. A method for soil improvement in acidic sugarcane areas according to claim 6, characterized in that: The compound amino acid is any one of the following: a combination of proline and glutamic acid, a combination of proline, glutamic acid, and glycine, or a combination of proline, glutamic acid, and arginine; wherein the proline content is ≥40% and the glutamic acid content is ≥25%; The abscisic acid is natural abscisic acid or its agriculturally acceptable salt or ester; the trace element chelate is at least one of chelated zinc, chelated manganese, and chelated iron.

8. A method for soil improvement in acidic sugarcane areas according to claim 6, characterized in that: In step S3, by weight, the sugar-inducing module comprises 30-50 parts of potassium phosphite, 8-15 parts of 5-aminolevulinic acid or its agriculturally acceptable salt, 0.1-0.8 parts of brassinolide, 5-10 parts of chelated boron, 3-8 parts of organosilicon penetrant, and 5-10 parts of anhydrous magnesium sulfate.

9. A method for soil improvement in acidic sugarcane areas according to claim 8, characterized in that: The brassinolides are one or more of 28-homobrassinolide, 24-epibrassinolide, and 28-epibrassinolide.

10. A soil-improving carbon-based slow-release fertilizer composition for acidic sugarcane growing areas, characterized in that: Includes the root zone long-acting module, the stress-resistant photosynthesis module, and the sugar-inducing module as described in any one of claims 1, 3-5, 7, and 9; Based on a mass of 100 parts, the root zone long-acting module includes 45-60 parts of alkaline mineral conditioning particles, with the remainder being high-nitrogen, high-potassium carbon-based slow-release fertilizer core particles. By weight, the anti-stress photosynthetic module comprises 20-35 parts of seaweed extract, 15-25 parts of complex amino acids, 8-15 parts of chitosan oligosaccharide, 3-6 parts of abscisic acid, 15-25 parts of 5-aminolevulinic acid or its agriculturally acceptable salt, 10-20 parts of anhydrous magnesium sulfate, and 5-20 parts of trace element chelate. By weight, the sugar-inducing module comprises 30-50 parts potassium phosphite, 8-15 parts 5-aminolevulinic acid or its agriculturally acceptable salt, 0.1-0.8 parts brassinolide, 5-10 parts chelated boron, 3-8 parts organosilicon penetrant, and 5-10 parts anhydrous magnesium sulfate.

Images