Root fertilizer mutual feedback green fertilization method for increasing sugarcane yield and fertilizer

Abstract

The invention discloses a root-fertilizer mutual feedback green fertilization method for increasing the yield of sugarcane and a fertilizer, and belongs to the technical field of sugarcane planting. Sugarcane is planted through the steps of field returning before planting, sugarcane fertilizer input optimization, mutual feedback planting, fertilization and the like, and meanwhile the problems that in the current sugarcane planting process, the fertilizer dosage is large, the proportion is not scientific, the cost is high, and the yield is low are solved through matching with a sugarcane compound fertilizer.

Description

Technical Field

[0001] This invention relates to the field of sugarcane planting technology, and in particular to a green fertilization method and fertilizer that promotes root-fertilizer interaction to increase sugarcane yield. Background Technology

[0002] Sugarcane, as one of my country's most important sugar crops, occupies a vital position in the national economy and food industry. Guangxi, as China's largest sugarcane producing area, has an average application rate of 571 kg / hm² for nitrogen, phosphorus, and potassium fertilizers. 2 279kg / hm 2 390kg / hm 2 The sugarcane yield in China is significantly higher than that of major sugarcane-producing countries such as Brazil, the United States, and Australia. Fertilizer input accounts for over 20% of the production cost of sugarcane. However, unscientific fertilization methods, imbalanced nitrogen, phosphorus, and potassium ratios, and neglect of micronutrient supplementation, coupled with frequent continuous cropping of sugarcane, lead to low fertilizer utilization, soil acidification, and a decline in soil quality. This not only restricts the increase in sugarcane yield and sugar content but also causes environmental problems such as nitrate pollution in groundwater and eutrophication of water bodies, seriously affecting the agricultural ecological environment and human health. Furthermore, the increasing contradictions caused by the shortage of agricultural labor and the fragmented operations of small farmers make it difficult for traditional scientific fertilization techniques, which involve complex agronomic processes, to be effective on a regional scale. Currently, my country is striving to promote the mechanization of sugarcane production, but the complex and cumbersome fertilizer combinations are not conducive to mechanized fertilization operations.

[0003] Sugarcane nitrogen fertilizer management needs to balance long-term effectiveness, economic efficiency, adaptability, and environmental friendliness. my country's main sugarcane producing areas are concentrated in the south, where the growing season lasts 10-12 months and is subject to heavy rainfall. Traditional fertilizers, applied only once, cannot continuously meet the nutrient needs of sugarcane throughout its entire growth period. Multiple fertilizations not only significantly increase labor costs but also reduce overall sugarcane production efficiency. Nitrogen management is particularly challenging. Nitrogen is a highly reactive chemical element, and traditional nitrogen fertilizers are easily lost in the field. Over 30% of nitrogen fertilizer is lost as nitrate nitrogen through leaching, about 6% enters the atmosphere as ammonia volatilization, and about 1% is converted into the greenhouse gas nitrous oxide, resulting in a significant reduction in nitrogen fertilizer utilization. Currently, widely used new nitrogen fertilizers mainly include those containing nitrification inhibitors and urease inhibitors. However, practice shows that the effectiveness of nitrification inhibitors and urease inhibitors diminishes significantly or even becomes ineffective after one month of application, making it difficult to meet the nutrient requirements of sugarcane during its long growth period under a single fertilization.

[0004] Traditional high-concentration phosphate fertilizers (such as compound fertilizers and ammonium phosphate) are easily absorbed by crops, but they have obvious drawbacks: First, they are easily adsorbed or precipitated after being applied to the soil, with a fixation rate of 35.8% in 1 day and 46.5% in 7 days, resulting in low utilization rate in the current season; Second, production depends on high-grade phosphate rock, which involves complicated processes and produces a lot of by-products and pollutants.

[0005] Existing sugarcane fertilization technologies and related patents suffer from poor applicability in fertilizer dosage, materials, and ratios. They fail to fully consider the actual soil conditions in sugarcane growing areas and the inherent biological potential of sugarcane, and the greenness of fertilizer raw materials and their effects on ecological environment improvement are unclear. Therefore, sugarcane production in my country has enormous potential for green and efficiency-enhancing effects. Thus, proposing a green fertilization method that promotes root-fertilizer interaction and related fertilizers is essential for advancing the domestic sugarcane industry. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a root-fertilizer feedback green fertilization technology and corresponding fertilizer for increasing sugarcane yield. The technology combines sugarcane compound fertilizer with root-fertilizer feedback green fertilization, taking into account scientificity, universality, ease of use and greenness, thereby increasing yield while reducing fertilizer usage.

[0007] The present invention solves the above-mentioned technical problems by means of the following:

[0008] A green fertilization method for increasing sugarcane yield through root-fertilizer reciprocation, wherein the fertilization method is as follows:

[0009] A. Returning soil to the field before planting

[0010] Crush the sugarcane leaves and return them to the field;

[0011] B. Optimization of Sugarcane Fertilizer Input

[0012] (1) Soil nutrient diagnosis in sugarcane areas: A model was established based on the correlation between annual fertilizer application and yield data in the main sugarcane producing areas of China, and the N, P, and K nutrient application patterns required for high yield in a certain sugarcane producing area were calculated.

[0013] (2) Fertilizer optimization: Based on the N, P, K usage patterns and actual soil conditions, select environmentally friendly nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer and organic fertilizer in proportion;

[0014] (3) Fertilizer granulation: Nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer and organic fertilizer are mixed and granulated to obtain sugarcane compound fertilizer;

[0015] C. Reciprocal planting and fertilization

[0016] (4) Fertilizer management for newly planted sugarcane: Apply sugarcane compound fertilizer once before planting sugarcane. The fertilizer is applied by sowing the seed and fertilizer at the same time, and then covered with soil in the sugarcane furrow. No additional fertilizer is required.

[0017] (5) Fertilization management of ratoon sugarcane: Apply sugarcane compound fertilizer once to ratoon sugarcane, apply fertilizer in strips on both sides of the sugarcane row, and then cover with soil to achieve local regulation in the root zone, thereby realizing mutual feeding of root fertilizer.

[0018] (6) Sugarcane leaves are returned to the field: After the sugarcane is harvested, all sugarcane leaves are returned to the field to complete the mutual feeding of planting and fertilization.

[0019] With the continuous advancement of mechanization in sugarcane production, the remaining leaves after the sugarcane stalks are harvested and exported from the field are crushed and returned to the field by machines. The nutrients contained in the sugarcane leaves can be retained in the field for recycling and can also improve soil organic matter.

[0020] In the reciprocal planting and fertilization process, this invention employs localized root zone fertilization to achieve root-fertilizer reciprocity, further enhancing nutrient utilization efficiency and environmental friendliness. Root zone fertilization precisely applies fertilizer to the 20cm tillage layer where sugarcane roots are concentrated, causing nutrient patches to be concentrated in the active root area, creating a locally optimized nutrient environment, significantly shortening nutrient migration distance, and improving root absorption efficiency. Simultaneously, this model synergizes with the nutrient release characteristics of the fertilizer itself: in the early stages, water-soluble nitrogen and phosphorus nutrients take effect rapidly in the root zone, meeting the urgent nutrient needs of sugarcane seedlings and tillering stages; in the middle and later stages, the continuous release of coated urea and the continuous dissolution of calcium magnesium phosphate fertilizer continuously supply nutrients to the root zone, adapting to the changes in root activity and location during the sugarcane elongation and maturity stages, avoiding nutrient supply and demand mismatches. Furthermore, within the localized root zone, the combined action of diammonium phosphate, organic fertilizer, and calcium magnesium phosphate fertilizer can rapidly improve the acidic soil microenvironment in the root zone, promoting robust root development and enhancing the root system's ability to adsorb and transform nutrients. Simultaneously, applying fertilizer to the root zone reduces ineffective contact between fertilizer and non-root zone soil, decreasing phosphorus fixation and nitrogen loss. This further alleviates environmental pressure and aligns with the core requirement of "one-time fertilization for full-cycle effectiveness" in simplified production, achieving a balance between high yield, high efficiency, and environmental friendliness. Furthermore, the reduced fertilizer usage and the addition of slow-release fertilizers avoid the root and seedling burn problems associated with single-application fertilization.

[0021] Furthermore, the specific selections of the environmentally friendly nitrogen fertilizer, phosphorus fertilizer, and potassium fertilizer are as follows:

[0022] The nitrogen fertilizer is a combination of controlled-release nitrogen and fast-acting nitrogen.

[0023] The phosphate fertilizer is a mixture of water-soluble phosphorus and citrate-soluble phosphorus.

[0024] The potassium fertilizer used is potassium chloride.

[0025] Of course, the organic fertilizer mentioned can be kitchen waste organic fertilizer or other high-carbon organic materials.

[0026] Coated urea can precisely meet the nutrient requirements of different growth stages of plants by regulating the properties of the membrane material. At the same time, combined with the high temperature and heavy rainfall climate characteristics of my country's main sugarcane producing areas and the nutrient requirements of sugarcane during its long growth period, it was finally determined that coated urea with a release cycle of 150 days and an "S"-shaped release curve should be selected. The ratio of nitrogen element of coated urea to ordinary urea in the fertilizer formula was set to 2:1, which not only reduced the cost but also enhanced the nutrient supply effect throughout the entire growth period.

[0027] Citrate-soluble calcium magnesium phosphate fertilizer can utilize low-grade phosphate rock as raw material, producing no solid waste and being cleaner and greener. In terms of compatibility, sugarcane-growing soils are generally acidic, allowing the fertilizer to gradually dissolve with the help of the weak acidity of the soil and root exudates, without rapid fixation issues. After six months, the available phosphorus content in the soil surpasses that of traditional high-concentration phosphate fertilizers. Therefore, this invention determines that water-soluble diammonium phosphate and citrate-soluble calcium magnesium phosphate fertilizer are mixed in a 1:1 ratio with phosphorus, balancing the early-stage demand for readily available phosphorus and the long-term supply in the later stages.

[0028] In addition, calcium magnesium phosphate fertilizer has multiple functions: its alkaline properties can improve acidic soil; it contains 8%~15% magnesium oxide, which enhances photosynthesis and yield formation; it contains 20%~35% silicon dioxide, which improves lodging resistance and virus resistance; it contains 25%~40% calcium oxide, which strengthens cell walls and improves soil structure; it is also rich in trace elements such as iron, copper, zinc, and boron, which can meet the needs of sugarcane without additional addition.

[0029] Organic fertilizers are rich in organic matter, humic acid, and various active substances. They can improve the soil structure and aggregate properties in acidic sugarcane growing areas, activate soil microbial activity, enhance water and fertilizer retention capacity, and alleviate soil degradation caused by continuous cropping. Calcium magnesium phosphate fertilizer is in powder form, which easily generates dust during production and transportation, and its application in the field is uneven, making it difficult to implement. This invention mixes organic fertilizer and calcium magnesium phosphate fertilizer in a 1:1 mass ratio and granulates them. By utilizing the binding properties of organic fertilizer, the granulation effect is improved. The resulting granular fertilizer has high strength and gradually disintegrates in the soil as it is infiltrated by water and decomposed by microorganisms. This ensures a stable supply of nutrients throughout the sugarcane's growth period, solves the practical problems of calcium magnesium phosphate fertilizer, and provides a feasible path for the large-scale resource utilization of organic waste.

[0030] Furthermore, in the soil nutrient diagnosis step of the sugarcane area, a linear plus platform model is used to establish the N, P, K dosage patterns.

[0031] Furthermore, the nitrogen fertilizer uses a nitrogen ratio of 2:1 between controlled-release nitrogen and readily available nitrogen; and the phosphorus fertilizer uses a phosphorus ratio of 1:1 between water-soluble phosphorus and citrate-soluble phosphorus.

[0032] Furthermore, the sugarcane compound fertilizer contains ≥10wt% organic matter and ≥10wt% trace elements: ≥3.3wt% calcium (Ca), ≥1.0wt% magnesium (Mg), and ≥1.5wt% silicon (Si).

[0033] Furthermore, the controlled-release nitrogen is coated urea, the readily available nitrogen is urea and diammonium phosphate; the water-soluble phosphorus is diammonium phosphate, the citrate-soluble phosphorus is calcium magnesium phosphate fertilizer; and the calcium magnesium silicon is derived from calcium magnesium phosphate fertilizer.

[0034] Furthermore, in the step of fertilizing and managing ratoon sugarcane, strip fertilization is carried out at a depth of 20cm at a distance of 30cm from the left and right sides of the sugarcane row.

[0035] When the sugarcane is newly planted, apply the compound sugarcane fertilizer once in the planting furrow along with the sugarcane seed. This improves planting and fertilization efficiency and promotes seed germination and growth. This fertilization technique can be used in conjunction with various agricultural machines, not limited to one. It can be used in conjunction with integrated sowing, fertilization, and mulching machinery to greatly improve planting efficiency. When the sugarcane is ratooned, apply the compound sugarcane fertilizer once during the tillering stage, using a strip-shaped localized application at points 30cm wide and 20cm deep on both sides of the top of the sugarcane ridge.

[0036] Based on the fertilization method disclosed above, the present invention also provides a sugarcane compound fertilizer that promotes root-fertilizer interaction to increase sugarcane yield, wherein the raw materials of the sugarcane compound fertilizer are as follows by weight:

[0037] 9 parts urea, 23.9 parts coated urea, 6.5 parts diammonium phosphate, 17.8 parts calcium magnesium phosphate fertilizer, 17.8 parts organic fertilizer, and 25 parts potassium chloride.

[0038] Furthermore, the application rate of the compound sugarcane fertilizer is 1800 kg / hm² in both the newly planted sugarcane fertilization management and the ratoon sugarcane fertilization management steps. 2 .

[0039] Beneficial effects:

[0040] The sugarcane compound fertilizer and root fertilizer feedback green fertilization method disclosed in this invention can not only significantly reduce fertilizer usage and alleviate soil acidification, but also increase soil organic matter content, maintain soil nutrient stability, and achieve higher nutrient utilization, thereby increasing yield. Furthermore, reducing fertilizer usage not only reduces resource waste and saves costs, but also reduces the potential environmental risks of excessive soil nutrient accumulation, achieving green and sustainable planting development. Attached Figure Description

[0041] Figure 1 : A method of mutual feeding of root fertilizer between newly planted sugarcane and ratooned sugarcane;

[0042] Figure 2 The impact of root-fertilizer reciprocation green fertilization method on the dynamics of annual inorganic nitrogen content in soil;

[0043] Figure 3 The impact of root-fertilizer reciprocation green fertilization methods on the carbon and nitrogen footprint and environmental damage costs of sugarcane production. Detailed Implementation

[0044] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings:

[0045] Example 1: Green fertilization method of root-fertilizer reciprocation and sugarcane compound fertilizer

[0046] A. Returning soil to the field before planting

[0047] After crushing the sugarcane leaves, all of them were returned to the field.

[0048] B. Optimization of Sugarcane Fertilizer Input

[0049] (1) Soil nutrient diagnosis in sugarcane areas: A model was established based on the correlation between annual fertilizer application and yield data in the main sugarcane producing areas of China, and the patterns of N, P, and K nutrient application required for high yield in the sugarcane producing areas of Guangxi were calculated.

[0050] By collecting fertilization and yield data from major sugarcane producing areas in China from 1980 to 2019 from the Chinese Literature Database, and using a linear-plus-platform model, the nutrient requirements for high yields in Guangxi sugarcane areas were preliminarily estimated as follows: N > K > P, with an estimated N, P, and K nutrient input of 270 kg / hm². 2 99kg / hm 2 and 208kg / hm 2 ;

[0051] (2) Fertilizer optimization: Based on the N, P, K usage patterns and actual soil conditions, select environmentally friendly nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer and organic fertilizer in proportion;

[0052] A 2020 field survey and analysis of soil nutrient status in sugarcane-growing areas of Guangxi, my country, revealed that approximately 80% of the soil is acidic, with about 40% being strongly acidic (pH < 4.5). The overall available nitrogen content is at a moderate level, while available phosphorus and potassium are generally abundant. However, organic matter, exchangeable calcium, and magnesium are generally at a low to moderate level. This situation primarily stems from the excessive application of nitrogen, phosphorus, and potassium in traditional fertilization practices, while neglecting the supplementation of micronutrients and organic matter. Furthermore, excessive nitrogen fertilizer further exacerbates soil acidification. This provides a basis for optimizing fertilizer formulations and application rates in the current sugarcane-growing areas of Guangxi.

[0053] Based on the nutrient ranking calculated in step (1) and the actual soil conditions, and referring to the estimated values ​​of N, P, and K nutrient inputs, the N, P, and K nutrient inputs in Guangxi are calculated to be 288 kg / hm². 2 108kg / hm 2 and 270kg / hm 2 ;

[0054] (3) Fertilizer granulation: Nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer and organic fertilizer are mixed and granulated to obtain sugarcane compound fertilizer;

[0055] When selecting nitrogen, phosphorus, potassium, and organic fertilizers, it is necessary to consider both high yield and environmental friendliness. Therefore, the nitrogen fertilizer selected is a combination of controlled-release nitrogen and readily available nitrogen. Specifically, the controlled-release nitrogen is coated urea, and the readily available nitrogen is urea and diammonium phosphate. The nitrogen ratio between the selected controlled-release nitrogen and readily available nitrogen is 2:1. The selected coated urea has a release period of 150 days and exhibits an "S"-shaped release curve.

[0056] The phosphate fertilizer is a combination of water-soluble phosphorus and citrate-soluble phosphorus. Specifically, the water-soluble phosphorus is diammonium phosphate and the citrate-soluble phosphorus is calcium magnesium phosphate. The ratio of phosphorus (P) between the selected water-soluble phosphorus and citrate-soluble phosphorus is 1:1.

[0057] Potassium chloride should be used as the potassium fertilizer, and well-rotted organic fertilizer from kitchen waste should be used as the organic fertilizer.

[0058] Based on the above ratio and dosage, the specific fertilizer mass percentages are as follows:

[0059] The mixture contains 9% urea, 23.9% coated urea, 6.5% diammonium phosphate, 17.8% calcium magnesium phosphate, 17.8% organic fertilizer, and 25% potassium chloride. All fertilizers are mixed thoroughly, and an appropriate amount of water is added before disc granulation to obtain sugarcane compound fertilizer.

[0060] The prepared sugarcane compound fertilizer needs to have an organic matter content of ≥10wt% and a trace element content of: calcium (Ca) ≥3.3wt%, magnesium (Mg) ≥1.0wt%, and silicon (Si) ≥1.5wt%.

[0061] C. Reciprocal planting and fertilization

[0062] (4) Fertilizer management for newly planted sugarcane: Apply compound sugarcane fertilizer once before planting. The fertilizer is applied at the same time as the seed and is placed in the furrow of the sugarcane row and then covered with soil. No topdressing is required. The application rate is 1800 kg / hm. 2 .

[0063] (5) Fertilization management of ratoon sugarcane: Apply compound sugarcane fertilizer once to the ratoon sugarcane, and apply the fertilizer in strips 30cm wide and 20cm deep on both sides of the top of the sugarcane ridge, and then cover with soil to achieve local regulation in the root zone, thereby realizing mutual feedback between roots and fertilizer; the application rate is 1800 kg / hm. 2 .

[0064] The N, P, and K elements in the sugarcane compound fertilizer are 288 kg / hm². 2 108kg / hm 2 and 270kg / hm 2 That is, the NPK ratio is 16:6:15.

[0065] (6) Sugarcane leaves are returned to the field: After the sugarcane is harvested, all sugarcane leaves are returned to the field to complete the mutual feeding of planting and fertilization.

[0066] Example 2:

[0067] The experiment was conducted from March 2023 to January 2025 at the Jinguang Farm in Tanluo Town, Xixiangtang District, Nanning City, Guangxi, and the experimental site in Quli Town, Chongzuo City. The area has a subtropical monsoon climate with hot and rainy summers.

[0068] I. Selection of Experimental Site

[0069] Experimental Site 1:

[0070] The average annual temperatures at the Nanning test site in 2023 and 2024 were 22.8℃ and 22.5℃, respectively, with annual rainfall of 1459 mm and 1874 mm. The tested soil was red soil with a pH of 5.9 (acidic soil), an organic matter content of 20.2 g / kg, total nitrogen of 1.05 g / kg, available nitrogen of 131.7 mg / kg, available phosphorus of 45.6 mg / kg, available potassium of 402.1 mg / kg, and a bulk density of 1.09 g / cm³. 3 .

[0071] Experimental Site 2:

[0072] The average annual temperatures at the Chongzuo test site in 2023 and 2024 were 23.5℃ and 23.1℃, respectively, with annual rainfall of 1293 mm and 1624 mm. The tested soil was red soil with a pH of 4.5 (strongly acidic soil), an organic matter content of 26.1 g / kg, total nitrogen of 1.13 g / kg, available nitrogen of 174.3 mg / kg, available phosphorus of 39.6 mg / kg, available potassium of 331.0 mg / kg, and a bulk density of 1.07 g / cm³. 3 .

[0073] II. Experimental Time and Sugarcane Variety

[0074] The experimental sites used newly planted sugarcane from March 2023 to January 2024 (2023 / 2024) and ratooned sugarcane from February 2024 to January 2025 (2024 / 2025). The sugarcane variety tested at the Nanning experimental site was Liucheng 07-150, and the sugarcane variety tested at the Chongzuo experimental site was Zhongzhe Funong 48. Both are high-yielding, high-sugar, and multi-resistant new sugarcane varieties with strong ratooning ability, high resistance to smut, and suitable for mechanized production.

[0075] III. Experimental Treatment

[0076] The experiment consisted of three treatments, each replicated three times, arranged in a randomized block design, with a total of nine plots, each plot measuring 66.6 m². 2 Both experimental sites maintained consistent management practices, employing the practice of returning sugarcane leaves to the field.

[0077] The experimental treatments were as follows: (1) CK: no fertilizer control; (2) FP: traditional farmer model; (3) RP: root-fertilizer mutual feeding green fertilization technology of the present invention and sugarcane compound fertilizer prepared by Example 1.

[0078] The specific fertilization method is as follows:

[0079] FP treatment: The total annual input of nitrogen, phosphorus and potassium nutrients is 480 kg / hm². 2322.5 kg / hm 2 and 457.5 kg / hm 2 In newly planted sugarcane (2023 / 2024), apply 750 kg / hm² of calcium magnesium phosphate fertilizer as base fertilizer. 2 Sugarcane-specific fertilizer and pesticide 750 kg / hm 2 The fertilization method involves simultaneous sowing of seeds and application of fertilizer in the sugarcane furrows, followed by covering with soil. Topdressing with sugarcane-specific fertilizer and pesticides is applied at a rate of 750 kg / hm². 2 750 kg / hm² of conventional compound fertilizer 2 375 kg / hm of urea 2 Potassium chloride 375 kg / hm 2 The fertilization method is to spread the fertilizer on the top of the sugarcane rows and then cover it with soil. For ratoon sugarcane (2023 / 2024), all the above fertilizers are applied at once, spread on the top of the sugarcane rows and then covered with soil.

[0080] RP treatment: Apply 1800 kg / hm² of organic-inorganic compound fertilizer as base fertilizer in newly planted sugarcane. 2 The fertilization method involves simultaneous sowing of seeds and application of fertilizer in the sugarcane furrows, followed by covering with soil; no additional fertilization is required. For ratoon sugarcane (2024 / 2025), a single application of 1800 kg / hm² of organic-inorganic compound fertilizer is applied. 2 Apply fertilizer in strips at a depth of 20cm, 30cm apart on both sides of the sugarcane row, and then cover with soil.

[0081] Apart from the differences in fertilization-related procedures and techniques, the field management practices remained consistent across all treatments.

[0082] IV. Sample Collection and Measurement

[0083] 1. Plant sampling and measurement: The whole plot was harvested and the yield was measured during the harvest season in January 2024 and January 2025.

[0084] The number of effective stems in the entire plot was investigated, and six representative plants were selected for biomass, nutrient content, and sucrose yield determination. The Kjeldahl method was used to determine the nitrogen (N) content of the plants, and ICP-OES was used to determine the phosphorus (P) and potassium (K) content. The calculation methods for fertilizer nitrogen, phosphorus, and potassium nutrient indicators are consistent; the following example uses nitrogen:

[0085] Nitrogen fertilizer utilization rate (%) = (Average nitrogen accumulation in the aboveground parts of the fertilized area – Average nitrogen accumulation in the aboveground parts of the unfertilized area) / Nitrogen application rate × 100

[0086] 2. Soil sampling and testing: After sugarcane harvest, soil samples from the 0-20 cm soil layer of each plot were collected using a 5 cm diameter soil auger for physicochemical property analysis.

[0087] Soil pH was determined using the water extraction-potential method (water-to-soil ratio 2.5:1); organic carbon was determined using the potassium dichromate oxidation-external heating method; total nitrogen was determined using the Kjeldahl method; alkaline nitrogen was determined using the alkaline hydrolysis-diffusion method; available phosphorus was determined using the Olsen-P method; available potassium was determined using flame photometry; and bulk density was determined using the ring core method. In addition, soil samples from the 0-20 cm layer were taken every 1-2 months after fertilization to determine the dynamics of soil inorganic nitrogen. Inorganic nitrogen in fresh soil was extracted using 1 mol / L potassium chloride and quantified using a flow analyzer. The calculation of soil organic carbon storage and changes in soil organic carbon storage are as follows:

[0088] Soil organic carbon storage (kg / hm) 2 = Organic carbon content × bulk density × depth × 100

[0089] Changes in soil organic carbon storage (kg / hm) 2 ) = (Soil organic carbon storage) 2025 -Soil organic carbon storage 2023 ) / 2

[0090] 3. Reactive Nitrogen Loss and Greenhouse Gas Emissions: The carbon and nitrogen footprint and greenhouse gas emissions of sugarcane were calculated using the Life Cycle Assessment (LCA) method, as shown in the following formula:

[0091] Reactive nitrogen loss (kg / hm) 2 = Ammonia volatilization + nitrous oxide + nitrogen rinsing

[0092] Nitrogen footprint (kg / t) = Loss of reactive nitrogen / Yield

[0093] Nitrous oxide 总排放量 (kg / hm) 2 = Nitrous oxide + 1% × ammonia volatilization （间接） +2.5% nitrogen leaching （间接）

[0094]

[0095] Net greenhouse gas emissions (kg / hm) 2 = Greenhouse gas emissions – Annual soil organic carbon storage × 44 / 12

[0096] Carbon footprint (kg / t) = Net GHG emissions / Production

[0097] Ammonia volatilization, nitrous oxide emissions, and nitrogen leaching losses are calculated by multiplying the amount of fertilizer applied by the corresponding emission coefficient.

[0098] In addition, nitrous oxide 总排放量The emissions consist of both direct and indirect sources, with the indirect nitrous oxide emission coefficients from ammonia volatilization and nitrogen leaching being 1% and 2.5%, respectively. Greenhouse gas emissions include emissions from agricultural input production, transportation, fuel, electricity consumption, and fertilizer application.

[0099] EC i Rᵢ is the emission factor for the i-th agricultural input, based on the IPCC emission factors (greenhouse gas emission equivalents per unit of input) for agricultural production-related inputs, as follows: Nitrogen fertilizer (as N) production and transportation: 8.30 kg CO₂-eq / kg; Coated urea production and transportation: 9.07 kg CO₂-eq / kg; Phosphate fertilizer (as P₂O₅) production and transportation: 0.79 kg CO₂-eq / kg; Potash fertilizer (as K₂O) production and transportation: 0.55 kg CO₂-eq / kg; Diesel fuel: 3.75 kg CO₂-eq / L; Pesticides: 19.10 kg CO₂-eq / kg; Plastic film: 0.10 kg CO₂-eq / kg; Electricity: 0.92 kg CO₂-eq / kWh; Labor: 0.86 kg CO₂-eq / person / day. Rᵢ is the quantity of the i-th agricultural input. The global warming potential is defined as CO2 = 1 and N2O = 273. In the formula, 44 / 28 is the conversion coefficient from N to N2O, and 44 / 12 is the conversion coefficient from C to CO2.

[0100] 4. The net economic benefits and the related indicators of human health and environmental damage costs are calculated as follows:

[0101] Net economic benefits (yuan / hm) 2 = Sugarcane yield × Purchase price per unit – Expenditure cost

[0102] Costs of human health and environmental damage (yuan / hm) 2 = Ammonia volatilization × 37.5 + Nitrogen leaching × 9.3 + Greenhouse gas emissions × 0.1743

[0103] The sugarcane purchase price is set at 550 yuan / ton. Expenditure costs include fertilizer, machinery, labor, mulch film, pesticides, seeds, and land rent. The costs of human health and environmental damage from ammonia volatilization, nitrogen leaching, and greenhouse gas emissions are 37.5 yuan / kg, 9.3 yuan / kg, and 0.1743 yuan / kg, respectively.

[0104] V. Data Analysis

[0105] All data were compiled using Excel; one-way ANOVA was performed using SPSS 27.0 software, and the significance of each indicator was tested using the Duncan method (P<0.05).

[0106] VI. Results and Analysis

[0107] 1. The effects of root-fertilizer reciprocation green fertilization technology on sugarcane yield and sugar production are shown in Table 1:

[0108] Table 1

[0109]

[0110] Results: As shown in Table 1, compared with the FP treatment, the yield and sugar production of the root-fertilizer mutual feeding green fertilization technology of the present invention increased by an average of 4.4% and 6.2%, respectively.

[0111] 2. The effects of root-fertilizer reciprocation green fertilization technology on nutrient uptake and fertilizer utilization rate of sugarcane aboveground parts are shown in Table 2:

[0112] Table 2

[0113]

[0114] Results: As shown in Table 2, compared with the FP treatment, the RP treatment improved nutrient absorption without reducing the number of fertilizations and the amount of fertilizer used, while also significantly reducing fertilization frequency and amount. Furthermore, the utilization rates of nitrogen, phosphorus, and potassium fertilizers increased by an average of 83.1%, 171.7%, and 75.2%, respectively. This indicates that the root-fertilizer feedback green fertilization technology can achieve higher nutrient utilization and reduce fertilizer and resource waste.

[0115] 3. The effects of root-fertilizer reciprocation green fertilization technology on soil physicochemical properties are shown in Table 3:

[0116] Table 3

[0117]

[0118] Note: Organic matter content = Organic carbon content * 1.732

[0119] Results: As shown in Table 3, compared with the CK treatment, the FP treatment significantly reduced soil pH, while the RP treatment had a higher soil pH than the FP treatment, thus alleviating soil acidification. Due to the use of sugarcane leaf return, the soil organic carbon content increased in all treatments, indicating that sugarcane leaf return plays an important role in improving soil organic matter. While significantly reducing fertilizer application, the total nitrogen, available nitrogen, and available potassium contents in the RP treatment were not significantly different from those in the FP treatment. Compared with the FP treatment, RP also reduced the accumulation of available phosphorus in the soil, lowering the risk of phosphorus pollution and maintaining stable available phosphorus content.

[0120] 4. The effects of root-fertilizer reciprocation green fertilization technology on the dynamics of annual soil inorganic nitrogen content are as follows: Figure 2 As shown

[0121] Result: From Figure 2 It can be seen that different treatments at the two experimental sites had a significant impact on the inorganic nitrogen content of the soil. The FP treatment maintained a high level of inorganic nitrogen content throughout the sugarcane growing season, especially in the first 1-2 months after fertilization, followed by a rapid decline during the hot and rainy months of June to September. These nutrients were not absorbed by the sugarcane but were instead lost from the soil into groundwater and air, increasing environmental pollution. In contrast, the RP treatment maintained a relatively stable level of inorganic nitrogen content throughout the growing season. The nitrogen in the coated urea was slowly released after fertilization, resulting in a gradual decrease in soil nitrogen content as the sugarcane grew and absorbed nutrients, eventually stabilizing.

[0122] 5. The impact of root-fertilizer reciprocation green fertilization technology on the carbon and nitrogen footprint and environmental damage costs of sugarcane production: Figure 3 As shown

[0123] Result: From Figure 3 As can be seen (average results from two experimental sites over two years), FP treatment has the highest costs in terms of reactive nitrogen loss, nitrogen footprint, greenhouse gas emissions, carbon footprint, and damage to human health and the environment, averaging 189.8 kg N / hm². 2 ,1.83kg N / t, 9543.2 kg CO2-eq / hm 2 66.18 kg CO2-eq / hm 2 and 4224 yuan / hm 2 In comparison, RP processing reduced the time by 58.2%, 60.1%, 48.1%, 69.4%, and 57.5%, respectively.

[0124] 6. The results of the root-fertilizer reciprocating green fertilization technology on reducing fertilizer use and increasing yield in sugarcane production are shown in Table 4.

[0125] Table 4. Fertilizer application rate and fertilizer reduction effect in different treatment groups

[0126]

[0127] Table 5. Fertilizer and labor input costs for different treatments (yuan / hm²) 2 )

[0128]

[0129] Results: As shown in Tables 4 and 5, the RP treatment can reduce annual weight by 1200 kg / hm² compared with the FP treatment. 2 The reduction in fertilizer use (by 47% of nutrient input) significantly lowered fertilizer costs and labor costs for fertilization during the new sugarcane planting season, resulting in a net profit of 7491 yuan / hm² for newly planted sugarcane. 2 Sugarcane and perennial sugarcane: 9313 yuan / hm 2 Increased income

[0130] In conclusion:

[0131] 1. Compared with the traditional farmers' model, the root-fertilizer mutual feeding green fertilization technology and the disclosed sugarcane compound fertilizer of this invention have achieved five breakthroughs: "reducing fertilizer use, increasing yield, improving quality, increasing efficiency, and protecting the environment", providing a way for the green and sustainable development of the sugarcane industry.

[0132] 2. Based on the publicly disclosed fertilization methods and fertilizers, yield and sugar production steadily increased. The average yield reached 108.24 t / hm². 2 Compared to the FP treatment, it increased yield by 4.4%, maintaining a stable advantage for two consecutive years at the Nanning and Chongzuo pilot sites; the average sugar yield reached 17.46 t / hm. 2 Compared with the FP treatment, the sugar content increased by 6.2%, significantly improving the core value of sugarcane products.

[0133] 3. With the combined application of fertilization technologies, the utilization efficiency of compound fertilizer for sugarcane was significantly optimized. The utilization rates of nitrogen, phosphorus, and potassium fertilizers were significantly higher on average than those of the FP treatment, resulting in a significant increase in the output efficiency per unit of fertilizer input, reducing fertilizer waste, and addressing the pain point of low nutrient utilization in traditional fertilization methods for farmers.

[0134] 4. Continuous improvement in soil quality. It alleviated soil acidification caused by long-term unscientific fertilization while maintaining soil nutrient balance: with a 47% reduction in nutrient input, the contents of total nitrogen, available nitrogen, and available potassium showed no significant difference from FP (potential fertilizer), while reducing the accumulation of available phosphorus and mitigating the risk of phosphorus pollution. Furthermore, soil fertility was significantly improved, and with the return of sugarcane leaves to the field, the soil organic carbon content steadily increased, enhancing the soil's ability to retain and supply nutrients.

[0135] 5. Significantly enhanced environmental friendliness. While maintaining stable inorganic nitrogen content in the soil throughout the entire growth period and reducing nutrient loss due to high temperatures and heavy rainfall 1-2 months after fertilization, the environmental footprint was also reduced. Active nitrogen loss, nitrogen footprint, greenhouse gas emissions, and carbon footprint were all significantly reduced compared to the FP treatment. Furthermore, environmental costs were significantly reduced, with a 57.5% reduction in costs to human health and environmental damage compared to the FP treatment.

[0136] 6. Outstanding economic benefits, achieving a win-win situation of reduced fertilizer use and increased income, significantly reducing costs. Fertilizer use is reduced by 40% (1200 kg / hm²), nutrient input is reduced by 47%, and the income from newly planted sugarcane increases by 7491 yuan / hm². 2 The income from ratooned sugarcane increased by 9,313 yuan / hm² 2 This achieves the dual benefits of cost savings and increased production.

[0137] In summary, the root-fertilizer feedback green fertilization technology of this invention synergistically achieves increased sugarcane yield and quality, efficient nutrient utilization, cost-saving and labor-saving, and environmentally friendly results. It not only solves the problems of labor shortage and low fertilization efficiency in sugarcane production, but also significantly reduces fertilizer usage while ensuring a safe supply of sugarcane, thus promoting green and sustainable agricultural development. It has significant practical significance and application value.

[0138] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. A root fertilizer mutual feeding green fertilization method for improving the yield of sugarcane, characterized by, The fertilization method is as follows: A. Field application before planting The sugarcane leaves are crushed and applied to the field; B. Optimization of sugarcane fertilizer input (1) Soil nutrient diagnosis of sugarcane field: a model is established based on the data of fertilizer application amount and yield in the previous years in the main sugarcane producing areas in China, and the N, P, and K nutrient use amount rules required for high yield in a certain sugarcane producing area are calculated; (2) Fertilizer optimization: based on the N, P, and K use amount rules and the actual soil conditions, environment-friendly nitrogen, phosphorus, and potassium fertilizers and organic fertilizer are selected and matched; (3) Fertilizer granulation: nitrogen, phosphorus, and potassium fertilizers and organic fertilizer are mixed and granulated to obtain sugarcane compound fertilizer; C. Inter-feeding planting and fertilization (4) Fertilization management for newly planted sugarcane: once sugarcane compound fertilizer is applied before the planting of new sugarcane, the fertilization method is to simultaneously sow and fertilize, and the fertilizer is applied in the sugarcane row and then covered with soil, without the need for topdressing; (5) Fertilization management for ratoon sugarcane: once sugarcane compound fertilizer is applied to the ratoon sugarcane, and the fertilizer is applied in the form of strips on both sides of the sugarcane row, and then covered with soil, so as to achieve the local regulation effect of the root zone, thereby realizing root fertilizer inter-feeding; (6) Sugarcane leaf application to the field: after the harvesting of sugarcane, all the sugarcane leaves are applied to the field, and inter-feeding planting and fertilization are completed.

2. A method of increasing the yield of sugar cane by root-fertilizer mutual feeding green fertilization according to claim 1, characterized in that, The environment-friendly nitrogen, phosphorus, and potassium fertilizers are specifically selected as follows: The nitrogen fertilizer is selected to be a combination of controlled-release nitrogen and quick-acting nitrogen; The phosphorus fertilizer is selected to be a combination of water-soluble phosphorus and non-soluble phosphorus; The potassium fertilizer is selected to be potassium chloride.

3. The method for increasing the yield of sugarcane by root fertilizer mutual feeding green fertilization according to claim 1, characterized in that, In the soil nutrient diagnosis step of the sugarcane field, a linear plus platform model is used to establish the N, P, and K use amount rules.

4. The method for increasing the yield of sugarcane by root fertilizer mutual feeding green fertilization according to claim 2, characterized in that, The N element ratio between the controlled-release nitrogen and the quick-acting nitrogen selected for the nitrogen fertilizer is 2:1; the P element ratio between the water-soluble phosphorus and the non-soluble phosphorus selected for the phosphorus fertilizer is 1:

1.

5. The method for increasing the yield of sugarcane by root fertilizer mutual feeding green fertilization according to claim 4, characterized in that, The organic matter content in the sugarcane compound fertilizer is ≥10wt%, and the trace element content is: calcium (Ca) ≥3.3wt%, magnesium (Mg) ≥1.0wt%, and silicon (Si) ≥1.5wt%.

6. The method for increasing the yield of sugarcane by root fertilizer mutual feeding green fertilization according to claim 4, characterized in that, The controlled-release nitrogen is coated urea, the quick-acting nitrogen is urea and diammonium phosphate, the water-soluble phosphorus is diammonium phosphate, the non-soluble phosphorus is calcium-magnesium-phosphorus fertilizer, and the calcium-magnesium-silicon is derived from calcium-magnesium-phosphorus fertilizer.

7. The method for increasing the yield of sugarcane by root fertilizer mutual feeding green fertilization according to claim 4, characterized in that, In the fertilization management step for ratoon sugarcane, the fertilizer is applied in the form of strips at a depth of 20cm and a distance of 30cm on both sides of the sugarcane row.

8. The root fertilizer mutual feeding sugarcane compound fertilizer for increasing the yield of sugarcane according to any one of claims 1-7, characterized in that, The raw material quality parts of the sugarcane compound fertilizer are as follows: urea 9 parts, coated urea 23.9 parts, diammonium phosphate 6.5 parts, calcium-magnesium-phosphorus fertilizer 17.8 parts, organic fertilizer 17.8 parts, and potassium chloride 25 parts.

9. The sugarcane complex fertilizer for root fertilizer mutual feeding for improving the yield of sugarcane according to claim 8, characterized in that, The sugarcane compound fertilizer is applied in the steps of new planting cane fertilization management and ratoon cane fertilization management, and the application amount is 1800 kg / hm 2 .

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