A compound modifier for acidified red soil and a method for applying the same

Abstract

The application discloses a compound modifier suitable for acidified red soil and a use method thereof, and the core raw material is oyster shell powder, weathered coal and a biological base material, and the weight ratio is 60-70:25-35:1-3, and auxiliary raw materials such as sodium alginate and polyglutamic acid can be added. The oyster shell powder is calcined at 600-900 DEG C, crushed and sieved to 100 mesh, the weathered coal has a fineness of 60-80 mesh and a humic acid content up to standard. The application amount is 100 kg / hm 2 The application is used in combination with conventional fertilizers and related use taboos, and is suitable for different acidified red soils, has low cost and is easy to use.

Description

Technical Field

[0001] This invention belongs to the field of acidic soil improvement and arable land fertilization technology, specifically involving a composite soil improvement material for acidified red soil in southern China that combines acid reduction, fertilization, low cost, and long-term stable effect, as well as its potted / field application method. Background Technology

[0002] The red soil region in the south is rich in water and heat resources and is an important production base for grain and cash crops in my country. However, long-term high-intensity use and excessive application of chemical fertilizers have led to increasingly prominent soil acidification problems. In some areas, the soil pH has dropped to 4.5-5.5. Accompanied by the accumulation of exchangeable hydrogen and aluminum, soil structure deterioration, and decreased nutrient availability, it seriously restricts crop growth and the improvement of arable land productivity.

[0003] In production, alkaline materials such as quicklime and hydrated lime are commonly used to improve acidified soils. Although they can quickly raise the pH, they have drawbacks such as strong effects, easy soil compaction, short-lasting effects, and the potential to inhibit crop growth if applied in excess. Mineral amendments such as limestone and dolomite have milder effects, but their improvement on severely acidified soils is limited and slow. Organic materials such as biochar, organic fertilizer, and humic acid can increase soil organic matter and nutrient content, but their effect on soil pH improvement is weak when applied alone, making it difficult to meet the rapid acidification requirements of severely acidified red soils. Amendments such as vermiculite, sepiolite, and fly ash have shown inconsistent performance in experiments, with some treatments showing no significant pH increase, and even exhibiting unstable improvement effects and high costs.

[0004] In current research and applications, single soil amendments struggle to simultaneously achieve "rapid acid reduction, stable acid regulation, long-lasting fertilization, and low cost with easy promotion." There is a lack of differentiated, low-cost, and highly efficient compound soil amendments specifically designed for severely acidified (pH 4.7) and moderately acidified (pH 5.3) red soils. Previous pot experiments comparing 17 alkaline materials and organic materials have demonstrated that oyster shell powder and weathered coal consistently improve soil pH and promote maize biomass growth. Furthermore, these materials are widely available, have low application costs, and their overall effects are superior to biochar, peat moss, humic acid, and most commercial organic fertilizers, showing potential for compound development into specialized soil amendments for acidified red soils.

[0005] Currently, there are no publicly reported compound soil conditioners with alkaline materials as the core component, applied at equivalent lime amounts, and adapted to different degrees of acidification in red soils. Furthermore, no standardized application techniques have been developed for these compound conditioners. Therefore, developing a red soil acidification conditioner that offers stable acidification, significant fertilization enhancement, low cost, and convenient application is of great practical significance for the sustainable utilization of acidified red soils in southern China. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, a compound soil conditioner is provided that is suitable for red soils with different degrees of acidification, has stable acid reduction and fertilization effects, is low-cost and easy to apply, and is accompanied by standardized application methods to solve the pain point of difficulty in balancing "effectiveness, cost and long-term effect" in the improvement of acidified red soil.

[0007] A compound soil conditioner adapted to acidified red soil, with oyster shell powder, weathered coal and bio-based materials as the core, in a ratio of 60-70:25-35:1-3; Preferably, the ratio of oyster shell powder, weathered coal, and bio-based materials is 70:28:2; A compound soil conditioner suitable for acidified red soil is made from the following raw materials in the indicated weight ratios: 55-65 parts oyster shell powder, 25-35 parts weathered coal (humic acid powder), 1-3 parts bio-based material, 2-4 parts sodium alginate, 1-2 parts polyglutamic acid (γ-PGA), and 15-20 parts deionized water.

[0008] Preferably, the oyster shell powder is obtained by calcining oyster shells at 600–900℃ and then pulverizing them through a 100-mesh sieve; The weathered coal has a fineness of 60-80 mesh, humic acid (dry basis) ≥40%, and water-soluble humic acid ≥10%. The preferred bio-based material is selected from fermented soybean meal or fermented rapeseed meal.

[0009] Preferably, the application rate is based on 100 kg / hm², and is applied in stages according to the degree of acidification:

[0010] Base fertilizer application: Apply evenly to the entire field 7–15 days before crop sowing / transplanting; Topdressing: For perennial crops (citrus, tea), apply fertilizer along the drip line of the tree canopy after harvesting in autumn each year; Preferably, apply as a base fertilizer once per crop season, and stop applying for one season after two consecutive seasons to avoid excessive alkalinity; This invention also discloses a method for applying an acidified red soil conditioner, the operation steps of which are as follows: 1. Dryland crops (corn, peanuts, rapeseed) Spread the fertilizer evenly across the entire field → Till the soil to a depth of 15–20 cm to mix thoroughly → Irrigate the field (soil moisture content 60%–70%) → Let the soil stand for 7 days before sowing; Do not allow direct contact with seeds; maintain a distance of at least 5 cm to prevent scorching of the buds. 2. Paddy field crops (rice) Apply fertilizer 7–10 days before transplanting → harrow and compact the soil → transplant rice seedlings; Maintain a shallow water layer of 3–5 cm to promote uniform neutralization; 3. Economic forests (citrus, tea) Dig a circular trench 20cm deep and 15cm wide along the drip line of the tree canopy → evenly sprinkle the soil into the trench → cover with soil → water thoroughly to settle the roots, but do not directly contact the soil with the roots to avoid scorching; Preferably, the above-mentioned compound fertilizer should be applied in combination with conventional fertilizers: N 135 kg / hm², P2O5 80 kg / hm², K2O 135 kg / hm², with urea, calcium magnesium phosphate, and potassium chloride applied as base fertilizers. The compound amendment must not be directly mixed with strong acid fertilizers (ammonium sulfate, superphosphate), and should be applied at a 3-day interval; The compound amendment should be used in conjunction with straw return to the field to increase organic carbon accumulation and prolong the duration of the amendment effect; Preferably, the compound modifier is first premixed with the bacterial agent and weathered coal (adsorption carrier), and then mixed with oyster shell powder to avoid the high alkalinity of oyster shell powder directly killing the live bacteria; The compound amendment should be avoided from being mixed with strongly alkaline / acidic pesticides or uncomposted organic fertilizers. The compound improver should be mixed and used immediately. By adopting the above technical solution, the present invention can achieve the following beneficial effects: (I) Core Innovation 1. The ternary synergistic system (oyster shell powder + weathered coal + bio-based materials) solves the pain points of "lowering acidity without improving fertility and improving fertility without stable effect".

[0011] 2. Graded formulation to suit different acidified red soils, achieving precise improvement.

[0012] 3. Standardized application, simple operation, and extended effectiveness when combined with straw return to the field.

[0013] 4. Add auxiliary ingredients to improve the effect without increasing the cost.

[0014] (II) Stabilizing the effect of acid reduction This invention provides precise acid reduction without excessive alkalinity or rebound, and its effects are superior to existing technologies. Furthermore, its effectiveness lasts for ≥8 months, reducing the number of applications and labor costs.

[0015] (III) This invention can improve soil organic matter and beneficial microorganisms, resulting in a significant increase in crop yield and achieving a win-win situation for soil improvement and yield.

[0016] (iv) The raw material cost of this invention is low, 38.5% lower than that of conventional lime, making it affordable for farmers. In addition, its preparation and application are simple, making it suitable for large-scale production in red soil in southern China.

[0017] (v) This invention uses natural raw materials, recycles waste, leaves no chemical residues, and is in line with green agriculture.

[0018] (vi) This invention is adaptable to different acidified red soils, covers a variety of crop scenarios, and is highly practical. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 The effects of different inorganic and organic materials on maize biomass in high-fertility and low-fertility red soils; Figure 2 Cost of different inorganic and organic materials; Detailed Implementation The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0021] The present invention will be further explained below with reference to specific embodiments.

[0022] Example 1 Improvement of mildly acidified red soil (pH 4.9, exchangeable aluminum 1.7 cmol / kg) 1.1 Compound Modifier Formulation (by weight ratio) Oyster shell powder (calcined at 600℃, 100 mesh): weathered coal (70 mesh, 42% humic acid on dry basis, 11% water-soluble humic acid): fermented soybean meal = 65:32:3; auxiliary raw materials: sodium alginate 3 parts, polyglutamic acid 1.5 parts, deionized water 18 parts (based on the total weight of core raw materials).

[0023] 1.2 Preparation method First, premix fermented soybean meal with weathered coal. After it is fully adsorbed, add oyster shell powder and stir evenly. Then, add sodium alginate and polyglutamic acid in sequence, while stirring and adding deionized water. Mix until there are no lumps and the mixture is loose. Use immediately after mixing.

[0024] 1.3 Application Method Application rate: 100 kg / hm 2 As a base fertilizer, apply it evenly across the entire field 10 days before corn sowing, till to a depth of 18 cm to mix, and irrigate until the soil moisture content reaches 65%. Let it stand for 7 days before sowing. After corn harvest, apply it once more using the same method as a peanut base fertilizer, applying it continuously for two seasons, then stopping for one season. Combine with conventional chemical fertilizers (N 135 kg / hm²). 2, P2O580 kg / hm², K2O 135 kg / hm 2 Urea, calcium magnesium phosphate, and potassium chloride should be applied as base fertilizers together; straw should be returned to the field, and direct mixing with strongly acidic fertilizers is prohibited.

[0025] Example 2 Improvement of moderately acidified red soil (pH 4.6, exchangeable aluminum 3.1 cmol / kg, the most common type) 2.1 Compound Improver Formulation (by weight, golden ratio) Oyster shell powder (calcined at 750℃, 100 mesh): weathered coal (70 mesh, 45% humic acid dry basis, 13% water-soluble humic acid): fermented rapeseed meal = 70:28:2; auxiliary materials: sodium alginate 3 parts, polyglutamic acid 1.5 parts, deionized water 18 parts.

[0026] 2.2 Preparation method Similar to Example 1, fermented rapeseed meal and weathered coal are premixed and adsorbed first, and then mixed with oyster shell powder and auxiliary materials, and used immediately after mixing.

[0027] 2.3 Application Method Application rate: 100 kg / hm 2 Apply basal fertilizer (10 days before corn sowing) and topdressing (10 days before sowing) once each, using the same application method as in Example 1; combine with conventional fertilizer application and straw return to the field, and strictly follow the application taboos.

[0028] Example 3 Improvement of severely acidified red soil (pH 4.3, exchangeable aluminum 4.8 cmol / kg, soil compaction and significant aluminum toxicity) 3.1 Compound Modifier Formulation (by weight ratio) Oyster shell powder (calcined at 900℃, 100 mesh): weathered coal (70 mesh, 43% humic acid on dry basis, 12% water-soluble humic acid): fermented rapeseed meal = 75:24:1; auxiliary raw materials: sodium alginate 4 parts, polyglutamic acid 2 parts, deionized water 20 parts (based on the total weight of core raw materials).

[0029] 3.2 Preparation method Similar to Example 1, the mixing time is increased to ensure that the oyster shell powder is fully mixed with the weathered coal and fermented rapeseed meal, thus preventing the microbial agent from being killed by the highly alkaline environment.

[0030] 3.3 Application Method Application rate: 100 kg / hm 2Apply base fertilizer twice (once before corn and once before peanut sowing). When applying, increase the rotary tillage depth to 20cm to ensure that the soil conditioner is fully mixed with the compacted soil. Irrigate the field until the soil moisture content is 70% and extend the resting time to 8 days to avoid aluminum toxicity residue. Apply conventional chemical fertilizers and return straw to the field. Strictly prohibit mixing with strong acid fertilizers or uncomposted organic fertilizers.

[0031] Comparative Example 1 Improvement with single oyster shell powder (Control Example 2, moderately acidified red soil) 1.1 Formulation and Application Oyster shell powder (same as in Example 2) was used at an application rate of 100 kg / hm². 2 The application method is the same as in Example 2, except that no weathered coal, bio-based materials and auxiliary raw materials are added, and all other conditions are the same.

[0032] Comparative Example 2: Oyster shell powder + weathered coal compound (no bio-based materials, control example 2) 2.1 Formulation and Application Formula: Oyster shell powder: weathered coal = 70:30 (same as the raw material standard in Example 2), without adding bio-based materials or auxiliary raw materials, application rate 100 kg / hm. 2 The application method is the same as in Example 2, and all other conditions are the same.

[0033] Comparative Example 3: Conventional lime modification (current mainstream technology, comparative example 2) 3.1 Formulation and Application Use conventional quicklime (crushed to 80 mesh) at a rate of 150 kg / hm². 2 The application method is the same as in Example 2, and all other conditions are the same.

[0034] Comparative Example 4: Improper mixing ratio and non-standard application (Comparative Example 2) 4.1 Formulation and Application The golden ratio compound improver of Example 2 was used, but it was not graded according to the degree of acidification and was applied directly; the application time was changed to broadcasting on the day of sowing, and straw was not returned to the field, while the other conditions were the same.

[0035] Experimental Example 1 Screening of different materials Experimental location: Jiangxi Provincial Red Soil Germplasm Institute, Zhanggong Town, Jinxian County, Nanchang City, Jiangxi Province Trial period: 2023 Experimental Design: Two types of soil were collected: one severely acidified (pH 4.7) and the other moderately acidified (pH 5.3). Thirteen alkaline treatments were administered for each soil type. Pot experiments were conducted, with four pots per treatment, each containing 3 kg of soil. Considering that each treatment needed to be compared with lime, we used the standard lime dosage (100 kg / 667 m³). 2 The standard is 1500 kg / ha, and all other materials are 100 kg / 667m³. 2 .

[0036] Based on the conversion of field fertilizer application to potted plant fertilizer application: 1 hectare of topsoil weight: 1.2 g cm⁻³ × 20 cm × 10000 × 10⁴ cm 2 =24×105 kg, fertilizer requirement for 1 kg soil sample (g) = field application rate / 24×10-5×103 = 0.6 g / kg. Considering that the application rate in pot experiments is generally 3 times that in field experiments, 5 kg of soil is 0.6 g / kg×3×5 = 9 g of alkaline material, which is equivalent to an addition of 0.2%.

[0037] (1) CK1: Control 1, without the addition of chemical fertilizers or alkaline materials; (2) CK2: Control 2, with added fertilizer but no added alkaline materials; All the following treatments were performed with the addition of alkaline materials, based on control 2.

[0038] (3) A1: quicklime CaO (9 g); (4) A2: slaked lime Ca(OH)2 (9 g); (5) A3: Limestone CaCO3 (9 g); (6) A4: Oyster shell powder (9 g); (7) A5: Corn straw biochar (9 g); (8) A6: Bamboo biochar (9 g); (9) A7: Rice biochar (9 g); (10) A8: Vermiculite (9 g); (11) A9: Dolomite (9 g); (12) A10: sepiolite (9 g); (13) A11: Fly ash (9 g); (14) A12: Weathered coal (9 g); (15) A13: Peat moss (9 g); (16) A14: Humic acid (9 g); (17) A15: Fermented soybean meal (9 g); (18) A16: Sesame cake organic fertilizer (9 g); (19) A17: Fermented rapeseed meal (9 g).

[0039] Crop fertilization should follow local conventional fertilization rates and methods: apply N, P2O5, and K2O at 135, 80, and 135 kg / hm2 respectively; and apply all fertilizer as base fertilizer before corn sowing. The types of nitrogen, phosphorus, and potassium fertilizers applied are urea (containing 46% N), calcium magnesium phosphate (containing 12% P2O5), and potassium chloride (containing 60% K2O), respectively. Based on soil weight, the specific fertilizer application rates are 1.8 g of urea, 4 g of calcium magnesium phosphate, and 1.4 g of potassium chloride.

[0040] The corn variety is Zhengdan 958. It is sown in early May, with two seeds sown in each pot. After the seedlings emerge, only one seed needs to be kept.

[0041] Experimental Sampling and Index Evaluation: (1) Material costs: purchase costs, application costs, etc. Fertilizer costs, pesticide costs, seed costs, and labor management costs.

[0042] (2) Basic soil samples and alkaline materials: Before the experiment, soil samples were sieved through a 2 mm mesh and the soil pH, exchangeable hydrogen aluminum content, soil organic carbon, total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus, and available potassium content were measured. The pH and / or organic carbon, nitrogen, phosphorus, and potassium content of alkaline materials were measured.

[0043] (3) Maize samples: Biomass and yield were assessed at the maize maturity stage. The plants were dried and the maize kernels and straw were crushed separately to determine the carbon, nitrogen, phosphorus, and potassium content of the kernels and straw. At the same time, the maize sales price was also calculated.

[0044] (4) Soil samples: After crop harvest, soil samples were collected, passed through a 2 mm mesh sieve, and the soil pH, exchangeable aluminum hydrogen content, soil organic carbon, available nitrogen, available phosphorus and available potassium content were determined.

[0045] Based on pot experiment data, the main types of alkaline materials and organic materials were preliminarily identified. Regarding crop biomass enhancement ( Figure 1 Suitable alkaline materials include quicklime, oyster shell powder, vermiculite, and weathered coal, while suitable organic materials include fermented soybean meal and fermented rapeseed meal. Further analysis of soil pH data (Table 1) shows that all alkaline materials can significantly increase soil pH, but from a cost perspective… Figure 2 From the perspective of price, oyster shell powder, weathered coal, fermented soybean meal, and fermented rapeseed meal have a more obvious price advantage.

[0046] Table 1. Effects of different inorganic and organic materials on pH in high-fertility and low-fertility red soils.

[0047] Application Example 1: Determination of Soil Physicochemical Properties Soil pH was measured using a pH meter (PHSJ-5, Leici, Shanghai).

[0048] Soil organic matter was measured using the potassium dichromate oxidation method.

[0049] Total soil porosity = [1 - (bulk density / specific gravity)] × 100%, where the soil specific gravity is 2.65 g / cm³. Water was used as the control group.

[0050] Yield measurements were conducted in Zhanggong Town, Jinxian County, Nanchang City, Jiangxi Province. The maize variety used was Zhengdan 958, and all fertilizer was applied as basal fertilizer before sowing. The nitrogen, phosphorus, and potassium fertilizers applied were urea (containing 46% N), calcium magnesium phosphate (containing 12% P2O5), and potassium chloride (containing 60% K2O), respectively. The specific fertilizer application rates, calculated based on soil weight, were 1.8 g of urea, 4 g of calcium magnesium phosphate, and 1.4 g of potassium chloride. Yields were measured at maize maturity.

[0051] Exchangeable aluminum content: Take 200 kg of soil sample and determine the exchangeable aluminum content of the soil using potassium chloride exchange-neutralization titration method; The pH values ​​of all examples were significantly increased, with the slightly acidified red soil (Example 1) increasing to 5.95, the moderately acidified red soil (Example 2) increasing to 6.10, and the severely acidified red soil (Example 3) increasing to 6.25. In the comparative examples, the pH value of conventional quicklime (Comparative Example 3) increased to 5.90, while the pH values ​​of oyster shell powder alone (Comparative Example 1), oyster shell powder + weathered coal (Comparative Example 2), and improper application (Comparative Example 4) increased to 5.40, 5.60, and 5.10 respectively, all of which were lower than those of the corresponding examples.

[0052] Soil organic matter: The organic matter content in the examples ranged from 19.3% to 21.5%, increasing slightly with increasing acidification. Among the comparative examples, Comparative Example 2 (18.5%) was higher than Comparative Example 1 (16.8%) and Comparative Example 4 (17.1%), while the conventional quicklime group (Comparative Example 3) had the lowest organic matter content (15.2%).

[0053] Soil porosity and bulk density: The porosity of the example soil was 51.8%~53.4%, and the bulk density was 1.16~1.24 g / cm³, indicating the optimal soil structure. The porosity of the comparative examples was all below 50%, and the bulk density was all above 1.30 g / cm³. Among them, the conventional quicklime group (comparative example 3) had the lowest porosity (46.5%) and the highest bulk density (1.39 g / cm³).

[0054] Maize yield: The yield in the example was 7470.0~7910.0 kg / hm². 2The heavily acidified improved group (Example 3) had the highest yield; the comparative examples all had yields below 7000.0 kg / hm². 2 The conventional quicklime group (Comparative Example 3) had the lowest yield (6510.0 kg / hm). 2 The yield of Comparative Example 4 was 6720.0 kg / hm². 2 .

[0055] Exchangeable aluminum content: The exchangeable aluminum content in the examples was 0.36~1.30 cmol / kg, which was significantly lower than the initial value; among the comparative examples, the aluminum content of Comparative Example 3 (0.41 cmol / kg) was low, but the aluminum content of the other comparative examples was higher than 0.87 cmol / kg, with Comparative Example 4 having the highest (1.27 cmol / kg).

[0056] Table 2 Results of Soil Physicochemical Properties Measurement

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A compound soil conditioner suitable for acidified red soil, characterized in that, The core raw materials are oyster shell powder, weathered coal and bio-based materials, with the weight ratio of oyster shell powder, weathered coal and bio-based materials being 60-70:25-35:1-3.

2. The compound improver according to claim 1, characterized in that, The bio-based material is either fermented soybean meal or fermented rapeseed meal.

3. The compound modifier according to claim 1, characterized in that, It also includes auxiliary materials, which, by weight, include 2-4 parts sodium alginate, 1-2 parts polyglutamic acid, and 15-20 parts deionized water.

4. The compound modifier according to claim 1, characterized in that, The oyster shell powder is obtained by calcining oyster shells at 600–900℃, pulverizing them, and then passing them through a 100-mesh sieve.

5. The compound improver according to claim 1, characterized in that, The weathered coal has a fineness of 60-80 mesh, and contains ≥40% humic acid on a dry basis and ≥10% water-soluble humic acid.

6. A method for applying a compound soil conditioner suitable for acidified red soil, characterized in that, The compound soil conditioner described in claim 1 is applied at a rate of 100 kg / hm², according to the degree of red soil acidification. The specific grading and corresponding formulations are as follows: 。 7. The application method according to claim 6, characterized in that, Application time: Base fertilizer should be applied 7–15 days before crop sowing / transplanting; topdressing should be applied after autumn harvest of perennial crops, along the drip line of the tree canopy; base fertilizer should be applied once per crop season, and application should be stopped for one season after two consecutive seasons.

8. The application method according to claim 6 or 7, characterized in that, The specific application procedures for different crops are as follows: Dryland crops: Apply the compound amendment evenly across the field, till to a depth of 15–20 cm to mix, irrigate the field until the soil moisture content is 60%–70%, let stand for 7 days before sowing, and keep the compound amendment at a distance of ≥5 cm from the seeds. For paddy field crops: Apply compound soil conditioner 7–10 days before transplanting, harrow and compact the soil before transplanting, and maintain a shallow water layer of 3–5 cm. For economic forests: Dig a circular trench 20cm deep and 15cm wide along the drip line of the tree canopy, evenly sprinkle the compound conditioner into the trench, cover with soil, and water thoroughly to settle the roots. The compound conditioner should not come into direct contact with the roots.

9. The application method according to any one of claims 6-8, characterized in that, The compound fertilizer improver is applied in combination with conventional fertilizers. The application rate of conventional fertilizers is 135 kg / hm² of N, 80 kg / hm² of P₂O₅, and 135 kg / hm² of K₂O. The fertilizers selected are urea, calcium magnesium phosphate, and potassium chloride, which are applied together with the compound fertilizer improver as base fertilizers.

10. The application method according to claim 9, characterized in that, The compound amendment must not be directly mixed with strong acid fertilizers and should be applied at an interval of more than 3 days. The compound amendment is used in conjunction with straw return to the field; The compound modifier is prepared by first premixing the bio-based material with weathered coal, and then mixing it with oyster shell powder and auxiliary raw materials. The compound amendment must not be mixed with strongly alkaline / acidic pesticides or uncomposted organic fertilizers. The compound improver is to be mixed and used immediately.

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