Method for improving and fertilizing acid paddy field soil by organic and inorganic compound

Abstract

This invention discloses an organic-inorganic compound method for acidification and fertilization of acidic paddy soil, belonging to the field of soil improvement technology. 15-30 days before rice planting, after the first application of chemical fertilizer as base fertilizer to the surface of the acidic paddy soil, organic fertilizer and a highly oxidizing alkaline material, calcium peroxide, are applied in combination. The organic fertilizer is applied evenly at a rate of 300-500 kg / mu, and the calcium peroxide product at a rate of 30-120 kg / mu, onto the surface of the acidic paddy soil, followed by tilling and covering with soil. In this invention, the organic fertilizer replenishes soil organic matter while increasing the soil's acid-base buffering capacity, and the calcium peroxide neutralizes the soil's H₂. + By rapidly increasing pH and inhibiting potential pathogens, the two work synergistically to steadily increase soil pH and cation exchange capacity, improve soil quality, enhance fungal community diversity, and reduce the abundance of potential pathogens, thereby increasing rice yield.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement technology, specifically relating to an organic-inorganic composite method for acidification and fertilization of acidic paddy soil. Background Technology

[0003] Currently, the main measures for improving acidic soils include applying inorganic conditioners such as lime and limestone powder, as well as increasing the application of organic fertilizers. Lime-based substances can increase soil pH in the short term, but their effect is singular, easily leading to soil compaction and nutrient imbalance, and their improvement on the microbial environment is limited. Although organic fertilizers can increase soil organic matter content and improve structure, their acidity adjustment is slow and cannot significantly alleviate soil acidification in the short term.

[0004] In recent years, some studies have attempted to combine different types of amendments, but most of them focus on the combination of lime and organic fertilizer, which has problems such as slow reaction and unstable regulation effect. There is still a lack of efficient methods that can combine rapid acidification and continuous fertilization.

[0005] Calcium peroxide, as a strong oxidizing inorganic alkaline material with oxygen-releasing properties, releases hydroxide ions in the soil, rapidly neutralizing the acidic environment. Simultaneously, the released reactive oxygen species inhibit or kill some harmful pathogens in the soil, thus improving the rhizosphere microecological environment and reducing the number of pathogenic fungi. However, existing research mainly focuses on the water remediation or oxygen supply applications of calcium peroxide, and there is a lack of systematic research on the combined application of organic fertilizer and calcium peroxide in acidic paddy soils in South China.

[0006] Therefore, developing an organic-inorganic composite improvement method that can rapidly reduce soil acidity, improve soil fertility, and enhance the physical, chemical, and biological properties of soil is of significant technical value and promotional importance for improving the efficiency of acidic paddy field soil improvement and extending the duration of its effects. Summary of the Invention

[0007] Purpose of the invention: The purpose of this invention is to provide an organic-inorganic compound method for improving acidic paddy soil. This method utilizes the rational application of organic fertilizer and calcium peroxide to improve acidic paddy soil. By combining organic materials and calcium peroxide, it improves soil quality, replenishes soil base ions, inhibits or kills potential soil pathogens, increases the content of available nutrients in the soil, and enhances the functional effectiveness and stability of the organic-inorganic compound improvement, thereby fundamentally improving acidified soil and promoting sustainable agricultural production.

[0008] Technical solution: The objective of this invention is achieved through the following technical solution: This invention provides a method for organic-inorganic compound acidification and fertilization of acidic paddy soil. The method is as follows: 15-30 days before rice planting, chemical fertilizer is applied as base fertilizer to the surface of the acidic paddy soil for the first time, followed by the application of organic fertilizer and calcium peroxide product, a strong oxidizing alkaline material. The organic fertilizer is applied evenly at a rate of 300-500 kg / mu and the calcium peroxide product at a rate of 30-120 kg / mu on the surface of the acidic paddy soil, and then the soil is tilled and covered.

[0009] This invention increases the content of available nutrients in the soil by supplementing it with organic fertilizer, while calcium peroxide raises the soil pH and inhibits or kills soil pathogens. This invention fully utilizes the properties of calcium peroxide, combined with the rational application of organic fertilizer, to enhance soil organic matter and fertility while simultaneously improving acid-base buffering capacity, achieving a synergistic effect of rapid soil acidity regulation, nutrient enhancement, and increased cation exchange capacity.

[0010] Preferably, the chemical fertilizer and organic fertilizer are applied in a ratio of 1:1 to 2:1 based on their total nitrogen, phosphorus, and potassium content.

[0011] More preferably, the chemical fertilizer and organic fertilizer are applied in a ratio of 1.3:1 based on their total nitrogen, phosphorus, and potassium content.

[0012] In this invention, the amount of chemical fertilizer used remains fixed based on local fertilizer usage, while the application rates of organic fertilizer and chemical fertilizer are determined according to the ratio of their total nitrogen, phosphorus, and potassium content. Typically, the amount of organic fertilizer used is 300-500 kg / mu. In a specific embodiment of this invention, the amount of organic fertilizer used is 400 kg / mu.

[0013] Preferably, the organic fertilizer is applied at a rate of 400 kg / mu, and the calcium peroxide product is applied at a rate of 30-60 kg / mu.

[0014] More preferably, the organic fertilizer is applied at a rate of 400 kg / mu, and the calcium peroxide product is applied at a rate of 60 kg / mu.

[0015] Preferably, the organic fertilizer is made from agricultural waste through decomposition, with an organic matter content of ≥30% and a total nitrogen, phosphorus, and potassium nutrient content of ≥4%.

[0016] Furthermore, the agricultural waste is sourced from sugarcane and rice, the main crops grown in Guangxi, and primarily includes sugarcane filter mud and rice bran. These raw materials are locally available, widely sourced, and inexpensive, enabling the resource-based recycling of agricultural waste. Using them in the soil improvement method of this invention not only reduces environmental pollution but also significantly lowers the material input costs for acidic paddy soils, achieving both good fertilization and acidification effects as well as ecological and economic benefits.

[0017] Preferably, the calcium peroxide product has a calcium peroxide content of ≥50%, and the excipient is calcium carbonate.

[0018] Preferably, the tillage depth is 15-30cm.

[0019] Preferably, the method is applicable to moderately acidic soils in South China where double-cropping rice is grown, with a background pH of 5.5-6.0.

[0020] In one specific embodiment of the present invention, the initial pH value of the acidic paddy soil is 5.80. Beneficial effects

[0021] (1) The method of the present invention makes full use of the fertilization, acid reduction and bactericidal effects of organic fertilizer and calcium peroxide to quickly neutralize soil H. + This invention improves the content of available nutrients in the soil. The method of this invention was applied to moderately acidic soils (background pH 5.5-6.0) used for double-cropping rice cultivation in South China. After treatment, the soil pH increased from 5.80 to 6.17-6.71, CEC increased to 9.39-10.7 cmol / kg, available phosphorus increased to 37.2-58.7 mg / kg, rice yield increased by 7.49%-16.0%, and the relative abundance of potential plant pathogens in the soil decreased by 92.3%-135%.

[0022] (2) The method of this invention can maintain its effectiveness in improving acidity and fertilizing acidic soils even after two or four consecutive seasons of application, demonstrating good stability. Its advantages lie in the synergistic effect of organic materials and calcium peroxide, which improves soil pH, enhances soil quality, replenishes basic ions, inhibits or kills potential soil pathogens, and increases the content of available nutrients in the soil. This enhances the effectiveness and stability of the organic-inorganic composite soil improvement, fundamentally improving acidified soils and promoting sustainable agricultural production. This method provides an efficient solution for the treatment of acidic paddy field soils in South my country. Detailed Implementation

[0023] The technical solution of the present invention will be described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0024] The experimental materials used in the embodiments of this invention are all conventional experimental materials in the art and can be purchased through commercial channels. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art. Specific determination methods not specified in the experiments all adopted the determination methods described in "Soil Agricultural Chemical Analysis Methods" and "Principles and Methods of Soil Microbiology Research".

[0025] Chemical fertilizers: compound fertilizer (N-P2O5-K2O = 15%-15%-15%), nitrogen fertilizer is urea (N 46%), and potassium fertilizer is potassium chloride (K2O 60%). Organic fertilizer: made from sugarcane filter mud and rice bran from local Guangxi production, purchased from Guangxi Woze Biotechnology Co., Ltd., with an organic matter content of [missing information]. 30%, nitrogen, phosphorus, potassium (N-P2O5-K2O) Total nutrient content (1%-2%-1%) 4%; Calcium peroxide product: Purchased from Guangzhou Hongyin Biotechnology Co., Ltd., calcium peroxide content 50%, with calcium carbonate as an auxiliary material.

[0026] The rice variety tested was Xiangya Xiangzhan, a temperature-sensitive conventional indica rice variety, which is the main variety cultivated in South China.

[0027] Example 1: Calcium peroxide-modified culture experiment Soil improvement cultivation experiment location: Laboratory of Nanjing Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province.

[0028] This experiment determined the appropriate dosage of calcium peroxide during the improvement of acidic soil by setting up a calcium peroxide gradient dosage test. Paddy soil from Fumian District, Yulin City, Guangxi Province was used. The soil type was red paddy soil, which was moderately acidic soil with long-term continuous double-cropping of rice. The initial pH value of the soil was 5.80.

[0029] Trial period: February 2024 - March 2024.

[0030] The specific steps of the experiment are as follows: Weigh multiple 200g portions of air-dried paddy soil into 250ml glass culture bottles. Add 0.02, 0.04, 0.06, 0.08, 0.1, 0.16, 0.2, 0.3, and 0.4g of calcium peroxide product at concentrations of 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.08%, 0.1%, 0.15%, and 0.2%, respectively. Mix well and then add 200ml of pure water to submerge the soil. Incubate at 25℃ in the dark for 30 days. After incubation, allow the soil to air dry naturally, pulverize it, and pass it through a 20-mesh sieve. Determine the soil pH according to the "Methods for Soil Agricultural Chemical Analysis".

[0031] The soil pH results for each treatment in the cultivation experiment are shown in Table 1.

[0032] Table 1. Soil pH under different treatments in the calcium peroxide-modified culture experiment.

[0033]

[0034] Experimental results: Calcium peroxide products have a significant effect on raising the pH of acidic soils. An addition of 0.01%-0.2% calcium peroxide can increase the initial soil pH from 5.80 to 6.03-6.91. Calcium peroxide treatment can rapidly increase soil pH. Considering the soil disturbance impact in practical agricultural production applications, the recommended dosages for field soil improvement are 0.02%, 0.04%, and 0.08% calcium peroxide, i.e., 30, 60, and 120 kg / mu, respectively. These dosages can increase the soil pH by 0.28, 0.41, and 0.56 units, respectively.

[0035] Example 2: Rice field plot experiment Field trial location for soil improvement: South China.

[0036] This experiment was conducted in paddy fields in Fumian District, Yulin City, Guangxi Province. The soil type was red paddy soil, a moderately acidic soil that had been continuously used for double-cropping rice for a long time. Before the start of the experiment (i.e., before the planting of early rice in April 2024), the initial pH value of the topsoil layer (0-20cm) was 5.80, the cation exchange capacity (CEC) was 8.83 cmol / kg, the soil organic carbon (SOC) content was 23.2 g / kg, the alkaline nitrogen (AN) content was 233 mg / kg, and the available phosphorus (AP) content was 32.6 mg / kg.

[0037] Trial period: April 2024 - December 2024.

[0038] The specific steps of the experiment are as follows: Treatments were administered 15 days before planting each rice crop. The field trial included five treatments, each replicated three times, with each plot measuring 300 m². 2 A randomized block design was used. Rice was planted as the crop during the experiment, and all treatments maintained consistent practices in fertilization, planting, and other field management.

[0039] The five treatments in the field trial were: CK: Conventional fertilizer application treatment, with a total fertilizer input of 20.75 kg / mu (20.75 kg / mu for nitrogen, phosphorus and potassium), including 20 kg / mu of compound fertilizer as base fertilizer, 7.5 kg / mu of urea and 2.5 kg / mu of potassium chloride as topdressing (tillering fertilizer), and 5 kg / mu of urea and 7.5 kg / mu of potassium chloride as topdressing (earing fertilizer).

[0040] OM: Conventional application of chemical fertilizer (same as CK group treatment) combined with organic fertilizer application, the total nutrient ratio of chemical fertilizer to organic fertilizer was 1.3:1, and the application rate of organic fertilizer was 400 kg / mu.

[0041] OMC1: Conventional application of chemical fertilizers combined with organic fertilizers (same as OM group treatment) and low-dose calcium peroxide product treatment, with a calcium peroxide product application rate of 30 kg / mu.

[0042] OMC2: Conventional application of chemical fertilizers combined with organic fertilizers (same as OM group treatment) and medium amount of calcium peroxide product treatment, with the calcium peroxide product application rate being 60 kg / mu.

[0043] OMC3: Conventional application of chemical fertilizers combined with organic fertilizers (same as OM group treatment) and high-volume calcium peroxide product treatment, with a calcium peroxide application rate of 120 kg / mu.

[0044] Fifteen days before rice planting, apply chemical fertilizer (compound fertilizer) to the soil surface as base fertilizer for the first time, followed by organic fertilizer and calcium peroxide products. Spread the fertilizer evenly on the soil surface, then plow and cover with soil. The soil plowing depth is 15-30cm.

[0045] Fertilization and rice planting were carried out according to local conventional methods. After two consecutive seasons, following the late rice harvest in December 2024, the soil physicochemical properties and fungal community diversity were determined with reference to "Soil Agricultural Chemical Analysis Methods" and "Soil Microbiology Research Principles and Methods," and the yield of each treatment was statistically analyzed.

[0046] Table 2 shows the soil pH and other physicochemical properties and rice yield at the rice harvest time for each treatment in the field. Table 3 shows the soil fungal diversity and the relative abundance of saprophytic bacteria and potential plant pathogens. Among them, different lowercase letters represent significant differences (p < 0.05), and the same lowercase letters represent no significant differences (p > 0.05).

[0047] Table 2. Soil physicochemical properties and rice yield at the late rice harvest period in 2024 in paddy field plots.

[0048]

[0049] Table 3. Soil fungal community diversity, saprophytic fungi, and potential plant pathogens during the late rice harvest period in 2024.

[0050]

[0051] Compared with conventional fertilizer application (CK), conventional fertilizer application combined with organic fertilizer and low to medium calcium peroxide treatments (OMC1, OMC2) significantly increased soil pH by 0.21-0.52 units, increased soil cation exchange capacity from 8.22 cmol / kg to 9.39-9.79 cmol / kg, and increased rice yield by 7.66%-15.0%. Conventional fertilizer application combined with organic fertilizer and medium calcium peroxide treatment (OMC2) significantly increased soil fungal community diversity (Chao1 index) by 12.7% and significantly reduced the relative abundance of potential plant pathogens by 92.3%.

[0052] Experimental results: After two consecutive seasons of application, conventional application of chemical fertilizers combined with organic fertilizers and low to medium amounts of calcium peroxide can neutralize soil H+.+ It also replenishes soil base ions, thereby increasing cation exchange capacity. The input of organic materials and the improvement of soil physicochemical properties are more conducive to the survival of fungal communities, thus fundamentally improving or solving the problem of soil acidification. Example 3

[0053] This experiment was conducted in paddy fields in Fumian District, Yulin City, Guangxi Province. The soil type was red paddy soil, a moderately acidic soil that had been continuously used for double-cropping rice for a long time. Before the start of the experiment (i.e., before the planting of early rice in April 2024), the initial pH value of the topsoil layer (0-20cm) was 5.80, the cation exchange capacity (CEC) was 8.83 cmol / kg, the soil organic carbon (SOC) content was 23.2 g / kg, the alkaline nitrogen (AN) content was 233 mg / kg, and the available phosphorus (AP) content was 32.6 mg / kg.

[0054] Trial period: April 2024 - December 2025.

[0055] The specific steps of the experiment are as follows: Treatments were administered 15 days before planting each rice crop. The field trial included five treatments, each replicated three times, with each plot measuring 300 m². 2 A randomized block design was used. Rice was planted as the crop during the experiment, and all treatments maintained consistent practices in fertilization, planting, and other field management.

[0056] The five treatments in the field trial were: CK: Conventional fertilizer application treatment, with a total fertilizer input of 20.75 kg / mu (20.75 kg / mu for nitrogen, phosphorus and potassium), including 20 kg / mu of compound fertilizer as base fertilizer, 7.5 kg / mu of urea and 2.5 kg / mu of potassium chloride as topdressing (tillering fertilizer), and 5 kg / mu of urea and 7.5 kg / mu of potassium chloride as topdressing (earing fertilizer).

[0057] OM: Conventional application of chemical fertilizer (same as CK group treatment) combined with organic fertilizer application, the total nutrient ratio of chemical fertilizer to organic fertilizer was 1.3:1, and the application rate of organic fertilizer was 400 kg / mu.

[0058] OMC1: Conventional application of chemical fertilizers combined with organic fertilizers (same as OM group treatment) and low-dose calcium peroxide product treatment, with a calcium peroxide product application rate of 30 kg / mu.

[0059] OMC2: Conventional application of chemical fertilizers combined with organic fertilizers (same as OM group treatment) and medium amount of calcium peroxide product treatment, with the calcium peroxide product application rate being 60 kg / mu.

[0060] OMC3: Conventional application of chemical fertilizers combined with organic fertilizers (same as OM group treatment) and high-volume calcium peroxide product treatment, with a calcium peroxide application rate of 120 kg / mu.

[0061] Fifteen days before rice planting, apply chemical fertilizer (compound fertilizer) to the soil surface as base fertilizer for the first time, followed by organic fertilizer and calcium peroxide products. Spread the fertilizer evenly on the soil surface, then plow and cover with soil. The soil plowing depth is 15-30cm.

[0062] Fertilization and rice planting were carried out according to local conventional methods. After four consecutive seasons, soil physicochemical properties and fungal community diversity were measured after the late rice harvest in December 2025, and the yield of each treatment was calculated.

[0063] Table 4 shows the results of soil pH and other physicochemical properties and rice yield at the rice harvest time for each treatment in the field. Table 5 shows the soil fungal diversity and the relative abundance of saprophytic bacteria and potential plant pathogens.

[0064] Table 4. Soil physicochemical properties and rice yield at the late rice harvest period in 2025 in paddy field plots.

[0065]

[0066] Table 5. Soil fungal community diversity, saprophytic fungi, and potential plant pathogens during the late rice harvest period in 2025.

[0067]

[0068] Compared with conventional fertilizer application (CK), conventional fertilizer application combined with organic fertilizer and low to medium calcium peroxide treatments (OMC1, OMC2) significantly increased soil pH by 0.42-0.91 units, soil cation exchange capacity from 9.40 cmol / kg to 10.2-10.7 cmol / kg, and available phosphorus from 38.8 mg / kg to 58.0-58.7 mg / kg. Conventional fertilizer application combined with organic fertilizer and medium calcium peroxide treatment (OMC2) significantly increased rice yield by 16.0%, significantly increased soil fungal diversity indices Chao and Shannon by 26.6% and 10.2%, respectively, and significantly reduced the relative abundance of potential plant pathogens by 135%.

[0069] Experimental results: After four consecutive seasons of application, the combination of conventional chemical fertilizers with organic fertilizers and low to medium amounts of calcium peroxide can neutralize the soil and replenish soil base ions and nutrients, thereby increasing cation exchange capacity and available nutrient content. The input of organic materials and the improvement of soil physicochemical properties are more conducive to the survival of fungal communities, thus fundamentally improving or solving the problem of soil acidification.

[0070] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for organic-inorganic composite acidification and fertilization of acidic paddy soil, characterized in that, The method is as follows: 15-30 days before rice planting, apply chemical fertilizer as base fertilizer to the surface of acidic paddy soil for the first time, followed by the application of organic fertilizer and calcium peroxide product, a strong oxidizing alkaline material; the organic fertilizer is applied evenly at a rate of 300-500 kg / mu and the calcium peroxide product at a rate of 30-120 kg / mu on the surface of acidic paddy soil, and then the soil is turned over and covered.

2. The method according to claim 1, characterized in that, The chemical fertilizer and organic fertilizer are applied in a ratio of 1:1 to 2:1 based on their total nitrogen, phosphorus, and potassium content.

3. The method according to claim 2, characterized in that, The chemical fertilizer and organic fertilizer are applied in a ratio of 1.3:1 based on the total nitrogen, phosphorus and potassium content of the two.

4. The method according to claim 1, characterized in that, The organic fertilizer is applied at a rate of 400 kg / mu, and the calcium peroxide product is applied at a rate of 30-60 kg / mu.

5. The method according to claim 4, characterized in that, The organic fertilizer is applied at a rate of 400 kg / mu, and the calcium peroxide product is applied at a rate of 60 kg / mu.

6. The method according to claim 1, characterized in that, The organic fertilizer is made from agricultural waste through decomposition, with an organic matter content of ≥30% and a total nitrogen, phosphorus, and potassium nutrient content of ≥4%.

7. The method according to claim 1, characterized in that, The calcium peroxide product has a calcium peroxide content of ≥50%, and the excipient is calcium carbonate.

8. The method according to claim 1, characterized in that, The tillage depth is 15-30cm.

9. The method according to claim 1, characterized in that, The method is applicable to moderately acidic soils in South China where double-cropping rice is grown, with a background pH of 5.5-6.

0.

10. The method according to claim 1, characterized in that, The initial pH value of the acidic paddy soil was 5.80.

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