A fertilizer additive combination for improving the aggregation and potassium availability of red paddy soil

Abstract

The application discloses a fertilizer additive combination for improving red paddy soil aggregate and potassium availability and a method for applying the same, and belongs to the technical field of soil improvement and fertilization. The application realizes the improvement of the physicochemical properties of soil by compounding the fertilizer with functional additives and applying the fertilizer in layers and steps. The application has the characteristics of stable improvement effect, wide application range, simple operation, low cost and the like, and is suitable for the comprehensive improvement and sustainable utilization of the physicochemical properties of red paddy soil.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement and agricultural fertilization technology, specifically relating to a fertilizer additive combination and its application method for improving the aggregates and potassium availability of red paddy soil. It is applicable to the improvement of the physicochemical properties of red paddy soil, the enhancement of soil fertility, and the regulation of sustainable utilization of red paddy soil. Background Technology

[0002] Soil aggregates are the core functional units of soil structure. They are structural units formed by soil particles under the combined action of parent material, microorganisms, plant residues, and secretions. Their quantity, particle size distribution, and water stability directly determine the soil's water and fertilizer retention, aeration, water permeability, and erosion resistance, making them one of the key indicators for measuring soil fertility. Among them, large aggregates with a diameter ≥0.25mm are the core of soil structural stability. The higher their content, the more moderate the soil porosity, and the more coordinated the ratio of water-holding porosity to aeration porosity. This not only reduces surface runoff and prevents soil erosion but also provides a suitable environment for crop root growth and nutrient transport, and is also the main site for soil organic carbon fixation. Conversely, if the number of soil aggregates is insufficient and their stability is poor, it will lead to soil compaction and reduced porosity, thereby exacerbating water and fertilizer leakage and nutrient fixation, severely restricting the productivity of arable land.

[0003] Potassium, an essential macronutrient for crop growth, participates in the transport of photosynthetic products, activation of enzyme systems, stress regulation, and quality formation, making it a core nutrient for ensuring crop yield and quality. The total potassium content in Chinese soils varies significantly by region, generally ranging from 0.3% to 3.6%, with an average of 1% to 2%. However, 90% to 98% of this potassium exists in mineral form (structural potassium) such as potassium feldspar and muscovite, which is ineffective and difficult for crops to directly absorb and utilize. Slow-release potassium (non-exchangeable potassium) accounts for 2% to 8% of the total potassium and is a direct source of readily available potassium, which can be slowly converted into available potassium under certain conditions. The readily available potassium that crops can directly absorb and utilize (water-soluble and exchangeable potassium) accounts for only 0.05% to 2% of the total potassium, and is easily fixed by the lattice of 2:1 clay minerals or leached away in sandy soils by rainwater and irrigation water. This results in a potassium fertilizer utilization rate of only 30% to 40% in the current season, far lower than that of nitrogen and phosphorus, becoming one of the important factors restricting high crop yield and quality.

[0004] Potassium availability in soil is crucial for the growth and development of crops such as rice. However, as one of the main arable land types in the hilly areas of southern my country, red soil paddy soils have significantly lower exchangeable and non-exchangeable potassium contents than other soil types, including dryland red soils under similar climatic conditions, due to the combined effects of desilication and aluminization processes and the scarcity of potassium-containing minerals in clay. This results in a generally low potassium availability in red soil paddy soils, seriously impacting food security and stability in southern my country. However, numerous studies have shown that because the amount of potassium absorbed by crops accumulates in grains at a low rate, and because the potassium activated by fertilization measures, besides meeting crop potassium requirements, is also converted to non-exchangeable potassium and mineral potassium through adsorption and fixation or direct leaching, fertilization measures such as straw return, green manure planting, and organic fertilizer application, while increasing crop potassium uptake, have a weak effect on increasing the exchangeable potassium content of red soil paddy soils. This leads to the false impression in rice production in this region that "increased yield is unrelated to soil potassium fertility" or even "potassium fertilizer does not increase yield." Contrary to the results regarding soil exchangeable potassium, fertilization measures such as straw return to the field, planting green manure, and applying organic fertilizer significantly increased both the organic carbon content and the available nitrogen and phosphorus content in red paddy soils. However, unlike the synergistic increase in carbon and nitrogen / phosphorus, most fertilization measures, except for straw-derived biochar which can significantly increase soil exchangeable potassium content, cannot effectively achieve a synergistic increase in organic carbon and exchangeable potassium in red paddy soils due to insufficient potassium input to meet the potassium requirements of rice and the tendency of exchangeable potassium to transfer to non-exchangeable potassium and mineral potassium. Therefore, given the current shortage of potassium fertilizer resources in my country, it is particularly urgent to improve the efficient utilization of soil potassium resources and achieve a synergistic increase in soil carbon and potassium while enhancing the carbon sequestration capacity of paddy soils.

[0005] To address these issues, various soil conditioners and potassium activators have emerged in existing technologies, but all have significant functional limitations, making it difficult to simultaneously achieve the dual goals of improving soil aggregate structure and potassium availability. While single organic conditioners (such as straw and organic fertilizer) can replenish soil organic matter and improve soil aggregate structure with stable effects, they suffer from drawbacks such as slow onset of action, large dosage requirements, and the potential to carry pathogens and weed seeds, making it difficult to rapidly improve aggregate stability and potassium activation efficiency. Inorganic conditioners (such as gypsum and bentonite) can quickly improve aggregate properties and increase soil permeability, but lack potassium activation function; long-term application can easily lead to soil nutrient imbalance and even secondary compaction. Single microbial agents (such as silicate bacteria) can decompose mineral potassium and promote potassium release, but their effect on improving soil aggregates is limited, and their activity is easily affected by environmental factors such as soil pH, temperature, and humidity, resulting in poor stability and difficulty in maintaining stable performance in different soil types.

[0006] In addition, existing technologies have attempted to simply mix two or more single soil amendments, but due to the differences in the mechanisms of action of different amendments, poor synergy and antagonistic effects are likely to occur after mixing. Therefore, in view of the current problems of soil aggregate structure deterioration, low potassium availability, and the inability of existing amendment technologies to achieve dual improvement goals, poor synergy, and unscientific application, it is necessary to develop a fertilizer additive combination and its application method that can achieve synergistic improvement of soil aggregate structure and potassium availability, is suitable for different soil types, is easy to apply, and has stable effects. This has important practical significance and application value for improving arable land quality, increasing potassium fertilizer utilization, and promoting sustainable agricultural development. Summary of the Invention

[0007] To achieve the above objectives, this invention involves uniformly mixing fertilizer with selected regulatory additives and then employing a "dry mixing + low-temperature activation" treatment. The technical content disclosed in this invention is as follows: This invention provides a fertilizer additive combination that enhances the aggregates and potassium availability of red soil paddy soil. The compound system consists of basic fertilizers, additives, and auxiliary materials. Preferably, the base fertilizer is selected from one or more of NP fertilizer, NPK fertilizer, NPK2 fertilizer, and NPKM; Preferably, the additive is selected from one or more of biochar, straw, and glucose.

[0008] The excipients are selected from one or more of bentonite, zeolite powder, kaolin, potassium silicate, and Bacillus subtilis inoculant.

[0009] Preferably, the method for preparing the biochar is as follows: It is prepared by pyrolyzing wheat straw at 400℃ under anaerobic conditions for 3 hours or by pyrolyzing peanut straw at 380℃ under anaerobic conditions for 2.5 hours.

[0010] The preferred NP fertilizer formulation is as follows: 840-860 parts NP fertilizer + 70-90 parts biochar / 60-80 parts straw / 25-35 parts glucose (select as needed) + mineral conditioner (35-50 parts bentonite, 20-40 parts zeolite powder, 25-45 parts kaolin, 25-35 parts potassium silicate), choose 2-3 types.

[0011] The preferred NPK fertilizer formulation is as follows: 830-850 parts NPK fertilizer + 70-90 parts biochar / 60-80 parts straw (select as needed) + mineral conditioner (35-45 parts bentonite, 30-50 parts zeolite powder, 25-35 parts potassium silicate, 25-30 parts kaolin) of any 2-3 types, and 25-35 parts glucose can be added as needed.

[0012] Preferred NPK2 fertilizer formulation: 820-840 parts NPK2 fertilizer + 80-100 parts biochar / 70-90 parts straw (select as needed) + mineral conditioner (40-50 parts zeolite powder, 40-45 parts bentonite, 25-35 parts kaolin, 25-35 parts potassium silicate) 2-3 types can be selected, and 25-35 parts glucose and 1-3 parts Bacillus subtilis inoculant can be added as needed.

[0013] Preferred NPKM fertilizer formulation: 810-830 parts NPKM fertilizer + 80-100 parts biochar / 70-90 parts straw (select as needed) + mineral conditioner (35-45 parts bentonite, 40-50 parts zeolite powder, 30-40 parts kaolin, 30-40 parts potassium silicate) 2-3 types can be selected, and 25-35 parts glucose and 4-8 parts polyacrylamide water-retaining agent can be added as needed.

[0014] This invention also provides a method for applying fertilizer, which mainly includes the following steps: S1. First, dry mix the solid additive (biochar, etc.) with the fertilizer in proportion for 10-15 minutes to ensure uniform mixing; then add a small amount of water (moisture content controlled at 10%-15%) and activate for 24 hours to fully release the active ingredients of the additive and form a stable combination with the nutrients of the compound fertilizer, thereby improving the regulation effect and fertilizer efficacy. This avoids the additive and fertilizer from separating after application, which would affect the regulation efficiency. It is especially suitable for nutrient activation of slow-release compound fertilizers.

[0015] S2. Spread the 30% fertilizer-additive mixture evenly over the soil layer of 40-50cm (achieved by deep tillage with a deep tiller), and then use a rotary tiller to shallowly till 5-10cm to fully mix the mixture with the bottom soil.

[0016] S3. Spread 40% of the compound fertilizer-additive mixture on the soil layer of 20-40cm (the main root distribution layer of the crop), and use a rotary tiller to till 15-20cm to ensure that the mixture is evenly mixed with the soil.

[0017] S4. Spread the remaining 30% of the compound fertilizer-additive mixture evenly on the top 0-20cm of soil, and shallowly cultivate to 5-10cm to avoid deep cultivation which would cause nutrient loss from the surface.

[0018] Preferably, the activation conditions in step S1 are at 25-30°C.

[0019] Preferably, the fertilizer is applied 7-10 days before sowing for field crops (wheat, corn), 10-15 days before transplanting for greenhouse vegetables, and when applying base fertilizer in autumn (after harvest) or sprouting fertilizer in spring for fruit trees. Application should be avoided on rainy days or when the soil is too wet to prevent additive loss and fertilizer clumping. If the soil is dry, a small amount of water can be applied after application (moisture content controlled at 20%-25%) to promote the dissolution and activation of additives and fertilizers.

[0020] By adopting the above technical solution, the present invention can achieve the following beneficial effects: 1. This invention can synergistically improve the quantity and stability of soil aggregates, improve soil structure, significantly enhance the water stability and porosity of soil aggregates, coordinate the ratio of water-holding pores to air-filling pores, effectively alleviate soil compaction, enhance soil water and fertilizer retention, aeration and water permeability and erosion resistance, provide a suitable environment for crop root growth and nutrient transport, and at the same time promote soil organic carbon fixation and delay soil fertility decline.

[0021] 2. This invention efficiently activates soil potassium and improves potassium fertilizer utilization. This combination can specifically address the problems of soil potassium fixation and leaching. On the one hand, it can promote the decomposition and transformation of mineral potassium (potassium feldspar, muscovite, etc.) in the soil, increase the reserve of slow-release potassium, reduce the leaching loss of available potassium in sandy soil, significantly increase the content of available potassium in the soil, effectively make up for the deficiency of available potassium supply in the soil, reduce the amount of single-element potassium fertilizer input, and reduce agricultural production costs.

[0022] 3. Breaking the vicious cycle of "structural degradation - nutrient inefficiency" and improving arable land quality. This invention simultaneously improves soil aggregate structure and enhances potassium availability, forming a virtuous cycle of "aggregate stabilization - potassium activation - enhanced microbial and root activity - further aggregate formation." This effectively solves problems such as declining soil organic matter, aggregate breakage, and potassium depletion in intensive agricultural production. Long-term application can sustainably improve arable land fertility, achieve a steady improvement in arable land quality, and provide support for the development of green agriculture.

[0023] 4. This invention overcomes the functional limitations of a single soil conditioner by scientifically combining various components to avoid antagonistic effects after mixing different conditioners. It ensures that organic, inorganic, and microbial components work synergistically and is suitable for different types of soil, such as sandy soil and clay soil. It is not significantly affected by environmental factors such as soil pH, temperature, and humidity, and has strong stability, so it can stably improve soil conditions in various types of arable land.

[0024] 5. The application method of this invention is scientific and simple, highly practical, easy to operate, requires no complicated equipment, can be combined with conventional fertilization and tillage measures, and is easy to promote and apply on a large scale. It can not only meet the needs of farmers in the field, but also maximize the improvement effect of the additive combination, taking into account both practicality and economy. Attached Figure Description

[0025] 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.

[0026] Figure 1 The proportion of soil aggregates for each additive under different fertilizers; Figure 2 The proportion of soil aggregates for each fertilizer under different additives; Figure 3 The organic matter content of soil aggregates under different fertilizer additives; Figure 4 The organic matter content of soil aggregates under different fertilizer additives; Figure 5 The total nitrogen content of soil aggregates under different fertilizer additives; Figure 6 The total nitrogen content of soil aggregates under different fertilizer additives; Figure 7 The content of slow-release potassium in soil aggregates under different fertilizer additives; Figure 8 The content of slow-release potassium in soil aggregates under different fertilizer additives; Figure 9 The available potassium content in soil aggregates under different fertilizer additives; Figure 10 The available potassium content in soil aggregates under different fertilizer additives; Figure 11 The organic matter content of the whole soil was determined by different fertilizers and additives. Figure 12 The organic matter content of the whole soil under different fertilizer treatments with different additives; Figure 13 Total nitrogen content in soil under different fertilizer and additive treatments; Figure 14 Total nitrogen content in soil under different fertilizer treatments with different additives; Figure 15 The content of slow-release potassium in the whole soil was determined by different fertilizers and additives. Figure 16 The content of slow-release potassium in the whole soil under different fertilizer treatments with different additives; Figure 17 The available potassium content in the whole soil was determined by different fertilizers and additives. Figure 18 The available potassium content in the whole soil under different fertilizer treatments with different additives; Detailed Implementation The present invention will be further described below with reference to embodiments, but the present invention is not limited thereto.

[0027] All reagents used in the following embodiments of the present invention can be obtained commercially available or in-house. Furthermore, unless otherwise specified, all parts mentioned in the following embodiments are parts by weight.

[0028] Example 1: 845 parts of NP fertilizer, 60 parts of straw, 70 parts of biochar, and 40 parts of bentonite.

[0029] Example 2: 840 parts NPK fertilizer, 25 parts glucose, 75 parts biochar, and 35 parts zeolite powder.

[0030] Example 3 The ingredients are: 835 parts NPK2 fertilizer, 75 parts straw, 35 parts glucose, 2 parts Bacillus subtilis inoculant, and 25 parts kaolin.

[0031] Example 4 815 parts NPKM fertilizer, 85 parts biochar, 75 parts straw, 30 parts glucose, and 6 parts water-retaining agent (polyacrylamide type).

[0032] Example 5 850 parts NP fertilizer, 80 parts biochar, 40 parts bentonite, and 20 parts zeolite powder.

[0033] Example 6 850 parts NP fertilizer, 70 parts straw, 45 parts kaolin, and 25 parts potassium silicate.

[0034] Example 7 860 parts NP fertilizer, 30 parts glucose, 50 parts bentonite, and 40 parts zeolite powder.

[0035] Example 8 840 parts NPK fertilizer, 80 parts biochar, 35 parts bentonite, and 25 parts potassium silicate.

[0036] Example 9 840 parts NPK fertilizer, 70 parts straw, 40 parts zeolite powder, and 30 parts kaolin.

[0037] Example 10 850 parts NPK fertilizer, 30 parts glucose, 40 parts bentonite, and 30 parts potassium silicate.

[0038] Example 11 830 parts NPK2 fertilizer, 90 parts biochar, 40 parts zeolite powder, and 30 parts potassium silicate.

[0039] Example 12 830 parts NPK2 fertilizer, 80 parts straw, 45 parts bentonite, and 25 parts kaolin.

[0040] Example 13 840 parts NPK2 fertilizer, 30 parts glucose, 50 parts zeolite powder, and 30 parts potassium silicate.

[0041] Example 14 820 parts NPKM fertilizer, 90 parts biochar, 35 parts bentonite, and 35 parts kaolin.

[0042] Example 15 820 parts NPKM fertilizer, 80 parts straw, 45 parts zeolite powder, and 35 parts potassium silicate.

[0043] Example 16 830 parts NPKM fertilizer, 30 parts glucose, 40 parts bentonite, and 40 parts zeolite powder.

[0044] Comparative Example 1 830 parts NPKM fertilizer, 40 parts bentonite, and 40 parts zeolite powder.

[0045] Comparative Example 2 830 parts NPK2 fertilizer, 40 parts zeolite powder, and 30 parts potassium silicate.

[0046] Comparative Example 3 840 parts NPK fertilizer, 35 parts bentonite, and 25 parts potassium silicate.

[0047] Comparative Example 4 850 parts NP fertilizer, 40 parts bentonite, and 20 parts zeolite powder.

[0048] Application Example 1 The effects of fertilizers and additives on soil physical and chemical properties Fertilizers tested: Examples 5-16, Comparative Examples 1-4.

[0049] The method of applying fertilizer is as described in the invention: applying fertilizer in layers and steps.

[0050] The test site is Guanshanping, Qiyang City, Yongzhou City, Hunan Province.

[0051] The proportion of soil aggregates was measured by wet sieving; the content of soil organic matter was determined by potassium dichromate titration; the total nitrogen content of soil was determined by Kjeldahl distillation titration; and the contents of available and slow-release potassium in soil were determined according to NY / T 889-2004. 1. The combined effects of fertilizers and additives on the proportion of soil aggregates From Table 1, Figure 1 and Figure 2 The results showed that the proportion of >2 mm aggregates in NP fertilizer was 2.01%, while the addition of biochar reduced it to 1.58%, reflecting that biochar may inhibit the formation of large aggregates. In contrast, the NPK2 fertilizer combination using straw as an additive increased the proportion of >2 mm aggregates to 4.88%. In addition, glucose promoted the formation of 0.25-2 mm aggregates, reaching 80.33%, while no significant difference was observed for fine aggregates.

[0052] Table 1. Results of the two-way ANOVA

[0053] 2. Analysis of the effects of fertilizers and additives on the organic matter content of soils with different particle sizes From Table 2, Figure 3 and Figure 4 It was found that in aggregates >2 mm, the addition of biochar increased the organic matter content from 15 g / kg to 20 g / kg, while the NPKM fertilizer group using straw reached 30 g / kg, significantly higher than other treatments (F value 11.12, p < 0.01), demonstrating the effective enhancement of organic matter levels by straw. In aggregates of 0.25–2 mm, the organic matter content without additives was 10 g / kg, which increased to 15 g / kg after the addition of straw, indicating its good soil amendment effect. In aggregates of 0.053–0.25 mm, the addition of biochar increased the organic matter content to 12 g / kg (F value 14.61, p < 0.001). For aggregates <0.053 mm, the organic matter content of the NP fertilizer group was 5 g / kg, which increased to 7 g / kg after the addition of biochar, demonstrating its enhancing effect in fine-grained soils.

[0054] Table 2. Results of the Two-Way ANOVA

[0055] 3. Analysis of the effects of fertilizers and additives on total nitrogen content in soils with different particle sizes From Table 3, Figure 5 and Figure 6It was found that in aggregates >2 mm, the NPKM fertilizer combination using straw resulted in a total nitrogen content of 1.80 g / kg, significantly higher than the 1.20 g / kg in the group without added NP fertilizer and the 1.40 g / kg in the group with added biochar, indicating a significant enhancement of the nitrogen supply capacity of straw. In aggregates of 0.25–2 mm, the straw and NPK combination increased the total nitrogen content to 1.10 g / kg, showing a good effect on soil nitrogen accumulation, while the effect of glucose was relatively weak, at only 0.75 g / kg. In aggregates of 0.053–0.25 mm, the addition of straw significantly increased the total nitrogen content to 1.30 g / kg. Finally, in aggregates <0.053 mm, the addition of biochar increased the total nitrogen content to 0.70 g / kg, showing its potential to enhance nitrogen retention capacity.

[0056] Table 3. Results of the Two-Way ANOVA

[0057] 4. Analysis of the effects of fertilizers and additives on the content of slow-release potassium in soils with different particle sizes From Table 4 and Figure 7 , Figure 8 The results showed that in aggregates >2 mm, the NPKM fertilizer combination using straw as an additive reached 811.8 mg / kg, significantly higher than other treatments (biochar and NPK combination: 382.7 mg / kg). In aggregates of 0.25–2 mm, the NPK2 combination using straw significantly increased the slow-release potassium content to 654.8 mg / kg. Simultaneously, in aggregates of 0.053–0.25 mm, straw application resulted in a slow-release potassium content of 596.6 mg / kg. In particles <0.053 mm, the slow-release potassium content in the NP treatment was 200.5 mg / kg, which increased to 350.6 mg / kg with the addition of biochar, while the addition of straw yielded 265.2 mg / kg. These results indicate that straw has a significant effect on increasing the slow-release potassium content in soil, providing important evidence for soil management and plant nutrition.

[0058] Table 4. Results of the Two-Way ANOVA

[0059] 5. Analysis of the effects of fertilizers and additives on the available potassium content in soils with different particle sizes From Table 5, Figure 9 and Figure 10It was found that in aggregates >2 mm, the addition of biochar increased the available potassium content from 150 mg / kg to 210 mg / kg, while the NPKM fertilizer combination using straw as an additive significantly increased it to 400 mg / kg, indicating the effective provision of available potassium by straw. In aggregates of 0.25–2 mm, the addition of straw increased the available potassium content to 300 mg / kg, significantly better than the 200 mg / kg in the no-additive treatment, while glucose had a weaker effect, at only 180 mg / kg. In aggregates of 0.053–0.25 mm, the use of straw increased the available potassium content to 280 mg / kg, further confirming the promoting effect of organic matter on the retention of available potassium. In aggregates <0.053 mm, the available potassium in the NP fertilizer treatment was 90 mg / kg, which increased to 150 mg / kg after the addition of biochar, demonstrating the ability of biochar to promote available potassium in fine-grained soils.

[0060] Table 5. Results of the Two-Way ANOVA

[0061] 6. Analysis of the impact of fertilizers and additives on the total soil organic matter content Depend on Figure 11 and Figure 12 The organic matter content was 15 g / kg in the NP fertilizer group, increasing to 30 g / kg in the NPK group with added straw (F value 14.23, p < 0.001), 28 g / kg in the NPK2 group, and reaching 31 g / kg in the NPKM fertilizer group, showing the best improvement effect. The use of straw significantly increased the organic matter content in all fertilizer groups, especially in the NPKM group. In contrast, biochar had a weaker effect, with an organic matter content of approximately 20 g / kg in the NP and NPK groups, failing to achieve the same improvement effect as straw.

[0062] 7. Analysis of the impact of fertilizers and additives on total nitrogen content in soil Depend on Figure 13 and Figure 14 The results showed that the total nitrogen content in the NP fertilizer group was 1.8 g / kg, in the NPK group with added biochar it was 2.1 g / kg, and in the NPKM fertilizer combination it was the highest at 2.6 g / kg (F value 8.24, p < 0.001). Using straw as an additive significantly increased the total nitrogen content of the soil, especially in the NPKM fertilizer, indicating that straw not only increased nitrogen but also improved soil microbial activity. In contrast, the effect of biochar was moderate, failing to significantly increase the total nitrogen content.

[0063] 8. Analysis of the effects of fertilizers and additives on the total soil slow-release potassium content Depend on Figure 15 and Figure 16 The average slow-release potassium content in the NP fertilizer group was 300 mg / kg, while it significantly increased to 740 mg / kg in the NPK fertilizer group with added straw (F value 12.78, p < 0.001), and to 680 mg / kg in the NPK2 combination. Biochar had a relatively weak effect, with slow-release potassium contents of 420 mg / kg and 450 mg / kg in the NP and NPK combinations, respectively.

[0064] 9. Analysis of the effects of fertilizers and additives on the total available potassium content of soil Depend on Figure 17 and Figure 18 The available potassium content in the NP fertilizer group was 120 mg / kg, which significantly increased to 400 mg / kg after the addition of straw (F value 11.62, p < 0.001). The available potassium contents in the NPK and NPK2 combinations were 350 mg / kg and 380 mg / kg, respectively, with the NPKM fertilizer combination reaching 450 mg / kg, demonstrating the best soil improvement effect. When straw was used as an additive, available potassium increased significantly under all fertilizer treatments, with the NPK2 and NPKM combinations showing particularly significant effects. In contrast, the available potassium content was lower with the addition of biochar, especially under NP and NPK conditions.

[0065] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0066] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. Furthermore, various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of the present invention, and should also be regarded as the content disclosed by the present invention.

Claims

1. A fertilizer additive combination that enhances the aggregates and potassium availability of red paddy soil, characterized in that, The compound fertilizer consists of basic fertilizer, additives and auxiliary materials; The basic fertilizer is selected from one or more of NP fertilizer, NPK fertilizer, NPK2 fertilizer, and NPKM; The additive is selected from one or more of biochar, straw, and glucose; The excipients are selected from one or more of bentonite, zeolite powder, kaolin, potassium silicate, and Bacillus subtilis inoculant.

2. The fertilizer additive combination for improving aggregates and potassium availability in red paddy soil according to claim 1, characterized in that, The method for preparing the biochar is as follows: It is prepared by pyrolyzing wheat straw at 400℃ under anaerobic conditions for 3 hours or by pyrolyzing peanut straw at 380℃ under anaerobic conditions for 2.5 hours.

3. The fertilizer additive combination for improving aggregates and potassium availability in red paddy soil according to claim 1, characterized in that, The NP fertilizer formulation is as follows: 840-860 parts NP fertilizer + 70-90 parts biochar / 60-80 parts straw / 25-35 parts glucose + mineral conditioner (35-50 parts bentonite, 20-40 parts zeolite powder, 25-45 parts kaolin, 25-35 parts potassium silicate), choose 2-3 types.

4. The fertilizer additive combination for improving aggregates and potassium availability in red paddy soil according to claim 1, characterized in that, The NPK fertilizer formulation is as follows: 830-850 parts NPK fertilizer + 70-90 parts biochar / 60-80 parts straw + mineral conditioner (35-45 parts bentonite, 30-50 parts zeolite powder, 25-35 parts potassium silicate, 25-30 parts kaolin), choose 2-3 types, and you can add 25-35 parts glucose as needed.

5. The fertilizer additive combination for improving aggregates and potassium availability in red paddy soil according to claim 1, characterized in that, The NPK2 fertilizer formulation is as follows: 820-840 parts NPK2 fertilizer + 80-100 parts biochar / 70-90 parts straw (select as needed) + mineral conditioner (40-50 parts zeolite powder, 40-45 parts bentonite, 25-35 parts kaolin, 25-35 parts potassium silicate) select 2-3 types, and can be mixed with 25-35 parts glucose and 1-3 parts Bacillus subtilis inoculant as needed.

6. The fertilizer additive combination for improving aggregates and potassium availability in red paddy soil according to claim 1, characterized in that, The NPKM fertilizer formulation is as follows: 810-830 parts NPKM fertilizer + 80-100 parts biochar / 70-90 parts straw (select as needed) + mineral conditioner (35-45 parts bentonite, 40-50 parts zeolite powder, 30-40 parts kaolin, 30-40 parts potassium silicate) select 2-3 types, and can be mixed with 25-35 parts glucose and 4-8 parts polyacrylamide water-retaining agent as needed.

7. A method for applying a fertilizer additive combination that enhances the aggregates and potassium availability in red paddy soil, characterized in that, The main steps include: S1. First, dry mix the additives (biochar, etc.) with the fertilizer in proportion for 10-15 minutes to ensure uniform mixing; then add a small amount of water (moisture content controlled at 10%-15%) and place it in an environment of 25-30℃ to activate for 24 hours. S2. Spread 30% of the compound fertilizer-additive mixture evenly on the soil layer of 40-50cm (achieved by deep tillage with a deep tiller), and then use a rotary tiller to shallowly till 5-10cm to fully mix the mixture with the bottom soil. S3. Spread 40% of the compound fertilizer-additive mixture on the soil layer of 20-40cm (the main root distribution layer of the crop), and use a rotary tiller to till 15-20cm to ensure that the mixture is evenly mixed with the soil; S4. Spread the remaining 30% of the compound fertilizer-additive mixture evenly on the top 0-20cm of soil, and shallowly cultivate to 5-10cm to avoid deep cultivation which would cause nutrient loss from the surface.

8. The application method according to claim 7, characterized in that, The activation conditions in step S1 are 25-30℃.

9. The application method according to claim 7, characterized in that, The fertilizer application time is as follows: For field crops (wheat, corn), apply 7-10 days before sowing; Apply fertilizer 10-15 days before transplanting for greenhouse vegetables; Apply fertilizer to fruit trees when applying base fertilizer in autumn (after fruit harvest) or when applying fertilizer for sprouting in spring.

10. The application of the fertilizer additive combination for improving the aggregates and potassium availability of red paddy soil according to any one of claims 1-6 or the application method according to any one of claims 7-9 in regulating soil physicochemical properties.

Images