Zinc-silicon synergistic soil conditioner as well as preparation method and application thereof

Abstract

The invention relates to the technical field of soil improvement and crop disease prevention and control. The invention provides a zinc-silicon synergistic soil conditioner and a preparation method and application thereof.The zinc-silicon synergistic soil conditioner is prepared from, by mass, 5-8 parts of citric acid chelated zinc, 5-8 parts of citric acid chelated zinc, 5-8 parts of citric acid chelated zinc, 5-8 parts of citric acid chelated zinc, 5-8 parts of citric acid chelated zinc, 5- 25 to 40 parts of potassium silicate; 30 to 45 parts of humic acid; 5 to 10 parts of soluble starch; and the balance of deionized water. According to the zinc-silicon synergistic soil conditioner, the pH and the alkalization degree of soda saline-alkali soil are reduced through humic acid, and the rhizosphere microenvironment is improved; the citric acid chelated zinc provides quick-acting zinc, the potassium silicate continuously releases silicon, and the citric acid chelated zinc and the potassium silicate keep high bioavailability under the protection of humic acid; the soluble starch regulates nutrient release and prevents precipitation and inactivation. Field application shows that the morbidity of the rice red blight in the soda saline-alkali soil can be reduced to 5% or below, and synergistic interaction of soil improvement and disease prevention and control is achieved.

Description

Technical Field

[0001] This application relates to the fields of soil improvement and crop disease control technology, and in particular to a zinc-silicon synergistic soil conditioner, its preparation method and uses. Background Technology

[0002] Soda-saline-alkali soils are characterized by high pH and high alkalinity. In this highly alkaline environment, zinc and silicon in the soil easily transform into insoluble forms; for example, zinc forms zinc hydroxide precipitate, while silicon polymerizes as monosilicic acid to form insoluble silicates or silicon dioxide. Rice, a crop highly sensitive to zinc and silicon nutrients, is prone to typical zinc- and silicon-deficient red wilt disease in such soils because it has difficulty absorbing the fixed micronutrients. Symptoms include reddish-brown spots on leaves during the tillering stage, blackening of the roots, stunted growth, and in severe cases, the entire plant dies. Taking the soda-saline-alkali rice paddies of the Songnen Plain as an example, the incidence of red wilt in the planted rice exceeds 40%, becoming a key bottleneck restricting stable and high yields of rice in the area.

[0003] To address this problem, existing technologies mainly employ two approaches: First, conventional saline-alkali soil conditioners such as gypsum and desulfurized gypsum are applied to soda-alkali paddy fields. Their core function is to reduce soil alkalinity and salinity, but they do not specifically supplement key trace elements such as zinc and silicon, thus failing to effectively control red blight. Second, ordinary zinc or silicon fertilizers are applied alone. However, these fertilizers are easily fixed and rendered ineffective in highly saline-alkali soils, resulting in a significant reduction in the availability of zinc and silicon nutrients. Even after application, the incidence of red blight remains above 15%.

[0004] Therefore, the high incidence of rice blast disease in rice paddy areas with soda saline-alkali soil urgently needs further solutions. Summary of the Invention

[0005] The purpose of this application is to provide a zinc-silicon synergistic soil conditioner, its preparation method and uses, so as to achieve the synergistic supply of zinc and silicon elements while improving soil alkalinity, and solve the technical problem of red blight caused by zinc and silicon deficiency in rice in soda saline-alkali land.

[0006] To address the aforementioned technical problems, this application provides the following technical solutions: The first aspect of this application provides a zinc-silicon synergistic soil conditioner, comprising the following components based on a total mass of 100 parts: Zinc chelate citrate: 5–8 parts; Potassium silicate: 25–40 parts; Humic acid: 30–45 parts; Soluble starch: 5–10 parts; Deionized water: Balance.

[0007] In some modified embodiments of the first aspect of this application, the mass ratio of zinc citrate chelate to potassium silicate is 1:4–1:6.

[0008] In some modified embodiments of the first aspect of this application, the K₂SiO₃ content in the potassium silicate is ≥98%; and / or, The organic matter content of the humic acid is ≥70%.

[0009] The second aspect of this application provides a method for preparing a zinc-silicon synergistic soil conditioner, comprising: Zinc chelate citric acid, potassium silicate, humic acid and soluble starch are mixed for the first time according to the mass ratio described in any one of claims 1-3 to obtain a dry mixture. Deionized water is added to the dry mixture to adjust the solid-liquid mass ratio to 1:1–1:2, and then a second mixing is performed. After mixing, the mixture is homogenized to obtain a homogeneous slurry. The homogeneous slurry is spray-dried to obtain the zinc-silicon synergistic soil conditioner according to any one of claims 1–3.

[0010] In some modified embodiments of the second aspect of this application, the rotational speed of the first mixing is 150–180 r / min, and the time is 15–18 min; and / or, The second mixing is performed at a rotation speed of 800–1000 r / min for a time of 30–40 min; and / or, The inlet air temperature of the spray dryer is 170–190℃, and the outlet air temperature is 75–85℃.

[0011] The third aspect of this application provides the use of the zinc-silicon synergistic soil conditioner described in the first aspect in the control of rice blast disease in soda saline-alkali land.

[0012] In some modified embodiments of the third aspect of this application, the soil pH of the soda saline-alkali land is 8.5–11.0; and / or, The soil alkalinity of the soda saline-alkali land is ≥30%; and / or, The available zinc content in the soil of the soda-saline-alkali land is ≤0.5 mg / kg; and / or, The available silicon content in the soil of the soda saline-alkali land is ≤20 mg / kg.

[0013] In some modified embodiments of the third aspect of this application, the zinc-silicon synergistic soil conditioner is applied 6–8 days after rice transplanting.

[0014] In some modified embodiments of the third aspect of this application, the zinc-silicon synergistic soil conditioner is applied by a combination of basal soil application and foliar spraying, with a total application rate of 15-20 kg per acre; The mass ratio of the zinc-silicon synergistic soil conditioner applied as a soil base to the zinc-silicon synergistic soil conditioner applied as a foliar spray is 2:1–3:1. The soil basal application method is as follows: the zinc-silicon synergistic soil conditioner is mixed with fine soil at a mass ratio of 1:5 and then applied. The foliar spraying method involves diluting the zinc-silicon synergistic soil conditioner with water at a mass ratio of 1:6 before application.

[0015] In some modified embodiments of the third aspect of this application, the water in the soda saline-alkali paddy field is drained one day before the application of the zinc-silicon synergistic soil conditioner, and the paddy field is irrigated within 24 hours after application so that the water depth is 3-5 cm. No artificial drainage is carried out for three consecutive days after the irrigation is completed.

[0016] Compared with existing technologies, the zinc-silicon synergistic soil conditioner, its preparation method, and its uses provided in this application have the advantage that the humic acid in the soil is rich in active functional groups such as carboxyl and phenolic hydroxyl groups, which can effectively complex exchangeable sodium ions in the soil, thereby reducing soil alkalinity. At the same time, the weak acidity of humic acid can buffer the strong alkaline environment, causing the pH of soda saline-alkali soil to decrease significantly after application (the decrease reached 0.8–1.2 units in field trials), thereby improving the rhizosphere microenvironment and creating basic conditions for the availability of zinc and silicon nutrients.

[0017] In this improved microenvironment, humic acid can chelate zinc ions through its functional groups, inhibiting the precipitation of zinc hydroxide; at the same time, its macromolecular network structure can adsorb monosilicic acid, delaying its polymerization into insoluble silicates. This dual effect significantly improves the bioavailability of zinc and silicon in high-pH soils (field measurements show that the absorption efficiency of zinc and silicon by rice has increased to levels equivalent to utilization rates of over 45% and 50%, respectively).

[0018] Citric acid chelated zinc, as a fast-acting zinc source, possesses a stable cyclic chelate structure that fundamentally prevents zinc ions from forming zinc hydroxide precipitates. This ensures rapid zinc absorption during the critical period from rice greening to tillering, effectively alleviating growth inhibition caused by zinc deficiency. Potassium silicate, as a soluble silicon source, continuously releases monosilicic acid in the weakly alkaline microenvironment created by humic acid, meeting the high silicon requirements of rice from jointing to booting stages, promoting silicon deposition in cell walls, and enhancing plant mechanical strength and disease resistance. Zinc participates in auxin synthesis, promoting root development and tillering; silicon strengthens cell wall structure, reducing pathogen infection pathways. Both cover the key nutrient window throughout the entire rice growth cycle and complement each other functionally, thereby targeting and controlling zinc- and silicon-deficient rice wilt disease (field application shows that the incidence of rice wilt disease can be stably controlled below 5%).

[0019] Soluble starch, as a multifunctional adjuvant, not only improves the homogeneity of slurry and the granulation rate of spray drying during formulation preparation, but also forms a hydrophilic slow-release network after being applied to the soil, regulating the release rate of zinc and silicon, avoiding excessive local concentrations that could lead to the precipitation and inactivation of zinc and silicon, and ensuring their long-term synergistic effect.

[0020] This invention significantly improves the bioavailability of zinc and silicon by using humic acid to reduce soil alkalinity and improve soil quality, citric acid to chelate zinc and potassium silicate to provide nutrients in a synergistic manner, and soluble starch to slow-release and stabilize the effect. This reduces the incidence of rice blast disease in soda saline-alkali land to below 5%, achieving a dual breakthrough in soil improvement and disease control. Detailed Implementation

[0021] Exemplary embodiments of this disclosure will now be described in more detail. While exemplary embodiments of this disclosure have been shown, it should be understood that this disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0022] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application pertains.

[0023] The Songnen Plain is the core distribution area of ​​soda-alkali soil in my country. Its soils are generally characterized by high pH (8.5–11.0), high alkalinity (exchangeable sodium percentage ESP ≥ 30%), and extremely low availability of trace elements such as zinc and silicon. Rice cultivation in such soils often leads to severe zinc and silicon deficiency, resulting in physiological diseases primarily characterized by zinc- and silicon-deficient red blight, with field incidence rates exceeding 40%. The root cause is that under strongly alkaline conditions, zinc easily forms zinc hydroxide precipitate, while soluble silicon (mainly monosilicic acid) polymerizes into insoluble silicates or silicon dioxide, making it difficult for rice roots to absorb. This manifests as reduced tillering, reddish-brown spots on leaves, stunted growth, and a decrease in the number of grains per panicle, resulting in yield losses of 20%–40% in severe cases.

[0024] In existing technologies, technicians mainly adopt two measures: one is to apply conventional saline-alkali soil conditioners, but these conditioners focus on reducing soil alkalinity and salinity without simultaneously supplementing key nutrients such as zinc and silicon; the other is to apply ordinary zinc fertilizer or silicon fertilizer alone, which can temporarily supplement nutrients, but is easily fixed and inactivated in high pH and high alkalinity environments, resulting in the incidence of red blight remaining above 15% after application.

[0025] To address the aforementioned problems, this invention provides a zinc-silicon synergistic soil conditioner that combines soil alkalinity improvement, synergistic zinc-silicon supply, and slow-release stability. This conditioner lowers soil pH and alkalinity through humic acid, creating a microenvironment conducive to nutrient activation. Citric acid chelates zinc, and potassium silicate provides highly available zinc and silicon, respectively, within this environment. Soluble starch regulates the nutrient release rate, prevents localized precipitation, and ensures long-term synergistic effects. Field applications show that this conditioner can reduce the incidence of rice blast disease in soda-saline-alkali land to below 5%, achieving a dual breakthrough in soil improvement and disease control.

[0026] The first aspect of this application provides a zinc-silicon synergistic soil conditioner, comprising the following components based on a total mass of 100 parts: Zinc chelate citrate: 5–8 parts; Potassium silicate: 25–40 parts; Humic acid: 30–45 parts; Soluble starch: 5–10 parts; Deionized water: Balance.

[0027] Specifically, citric acid chelated zinc, as an organic chelated zinc fertilizer, can improve the bioavailability and stability of zinc in soda-salt-alkali soils with high pH and high salinity. Its mechanism of action lies in the fact that citric acid, through its multidentate coordination structure, forms a stable cyclic chelate with zinc ions, fundamentally preventing the formation of zinc hydroxide precipitate. This chelated zinc exhibits strong mobility in the soil, efficiently transporting zinc to the crop root zone and releasing absorbable zinc ions through the rhizosphere microenvironment; it can also be directly absorbed and utilized through leaves. Citric acid chelated zinc is also a highly efficient and readily available zinc source, especially during the critical growth period of rice from greening to tillering, rapidly providing effective zinc, alleviating zinc deficiency stress, and effectively inhibiting the occurrence and development of zinc- and silicon-deficient red blight. Furthermore, citric acid itself is a natural organic acid secreted by plant roots and can be degraded by microorganisms, ensuring both rapid effectiveness and a certain degree of sustained zinc supply.

[0028] Potassium silicate, as a soluble silicon fertilizer and a highly efficient slow-release silicon source, can continuously provide plants with usable silicon nutrition in high-pH, high-salt-alkaline soda-alkali soil environments. Its mechanism of action lies in the fact that potassium silicate releases monosilicic acid upon dissolving in water, which is the form of silicon that rice roots can directly absorb. In the weakly alkaline rhizosphere microenvironment created by humic acid, monosilicic acid maintains high solubility and stability, preventing rapid polymerization into insoluble silicates or silica precipitates. This soluble silicon can be efficiently absorbed by rice roots and transported to the stems and leaves, where it deposits in the cell walls to form a silicified layer, significantly enhancing plant mechanical strength, improving photosynthetic structure, and reducing pathogen infection pathways. Especially during the critical growth period from jointing to booting in rice, the demand for silicon increases significantly. Potassium silicate can stably and continuously supply available silicon, effectively alleviating silicon deficiency stress and working synergistically with zinc nutrition to inhibit the development of zinc- and silicon-deficient red blight. In addition, the potassium ions in potassium silicate can partially replace the sodium ions on soil colloids, helping to improve soil structure, while the silicon it releases also has a certain buffering effect on alkalinity in the soil, further optimizing the rhizosphere microenvironment.

[0029] In some embodiments, the potassium silicate contains ≥98% K₂SiO₃. This ensures the stability and water solubility of the formulation, and guarantees the efficient release of monosilicic acid, significantly improving the bioavailability of silicon and the control effect of red blight.

[0030] The amount of zinc citrate chelate in the improver can be 5 parts, 6 parts, 7 parts, 8 parts, etc.

[0031] The amount of potassium silicate in the modifier can be 25 parts, 30 parts, 35 parts, or 40 parts, etc.

[0032] In some embodiments, the mass ratio of zinc citrate chelate to potassium silicate is 1:4–1:6.

[0033] Specifically, the mass ratio of zinc citrate chelate to potassium silicate can be 1:4, 1:5, or 1:6, etc. This range of ratios can balance the rice's immediate zinc requirement with a continuous supply of silicon, achieving synergistic nutrition. Among them, when the mass ratio of zinc citrate chelate to potassium silicate is 1:5, the zinc and silicon supply is most balanced: it meets the critical zinc requirement during the greening-tillering stage and ensures sufficient silicon absorption during the jointing-booting stage, resulting in the best synergistic effect on disease prevention and yield increase.

[0034] Humic acid is a natural organic polymeric weak acid and a core component for in-situ soil improvement and synergistic nutrient activation. Its mechanism of action lies in the fact that the carboxyl and phenolic hydroxyl groups, abundant in humic acid molecules, can effectively complex and replace exchangeable sodium ions adsorbed on soda-saline soil colloids, promoting their leaching and excretion with irrigation water, thereby significantly reducing soil alkalinity. Simultaneously, its weak acidity can neutralize the strongly alkaline soil environment, causing the pH to decrease by 0.8–1.2 units after application, improving soil aggregate structure and permeability, and creating favorable conditions for rice root growth.

[0035] In this improved rhizosphere microenvironment, humic acid can chelate zinc ions through its functional groups, inhibiting zinc hydroxide precipitation, and adsorb monosilicic acid through its macromolecular network, delaying its polymerization and inactivation. This significantly enhances the bioavailability and synergistic supply efficiency of zinc and silicon in high-pH soils, increasing zinc utilization to over 45% and silicon utilization to over 50%. Furthermore, humic acid itself can be slowly degraded by soil microorganisms as a carbon source, continuously releasing active groups and maintaining a prolonged improvement and complexation effect, providing stable support for the long-term utilization of zinc and silicon nutrients.

[0036] In some embodiments, the organic matter content of the humic acid is ≥70%. This enhances its ability to chelate sodium ions and zinc and silicon, effectively reducing soil pH and alkalinity, improving nutrient stability and bioavailability, and ensuring that the soil conditioner exerts a stable synergistic effect of reducing alkalinity and supplying fertilizer in soda saline-alkali land.

[0037] Soluble starch, as a natural hydrophilic polysaccharide, primarily functions as a dispersant and stabilizer, as well as a slow-release regulator. Its mechanism of action is as follows: During formulation preparation, soluble starch dissolves in water to form a homogeneous colloidal system, effectively increasing the viscosity and suspension stability of the slurry. This prevents the sedimentation or aggregation of citric acid-chelated zinc, potassium silicate, and humic acid particles, thus ensuring uniform particle formation and good flowability during spray drying. After application to the soil, soluble starch forms a hydrophilic three-dimensional network structure under the influence of water, slowing down the release rate of zinc and silicon nutrients. This avoids excessively high local concentrations that could lead to the precipitation and inactivation of zinc and silicon, ensuring their long-term synergistic supply in the rhizosphere microenvironment. Furthermore, this starch can be gradually degraded by soil microorganisms, helping to align nutrient release patterns with crop needs, further enhancing the long-term effectiveness and compatibility of the amendment.

[0038] Deionized water is used as a solvent and carrier to adjust the concentration and viscosity of the amendment system, ensuring that the components are uniformly dispersed to meet the process requirements of spray drying granulation, and to facilitate subsequent field spraying and basal application.

[0039] The zinc-silicon synergistic improver provided by this invention is specifically designed to address the core obstacles of high pH, ​​high alkalinity, and low trace element availability in soda-saline-alkali soils such as the Songnen Plain. Its components are all commercially available, common agricultural raw materials, widely and stably sourced, and inexpensive, making it economically feasible for large-scale application.

[0040] Compared with existing technologies, the zinc-silicon synergistic soil conditioner, its preparation method, and its uses provided in this application have the advantage that the humic acid in the soil is rich in active functional groups such as carboxyl and phenolic hydroxyl groups, which can effectively complex exchangeable sodium ions in the soil, thereby reducing soil alkalinity. At the same time, the weak acidity of humic acid can buffer the strong alkaline environment, causing the pH of soda saline-alkali soil to decrease significantly after application (the decrease reached 0.8–1.2 units in field trials), thereby improving the rhizosphere microenvironment and creating basic conditions for the availability of zinc and silicon nutrients.

[0041] In this improved microenvironment, humic acid can chelate zinc ions through its functional groups, inhibiting the precipitation of zinc hydroxide; at the same time, its macromolecular network structure can adsorb monosilicic acid, delaying its polymerization into insoluble silicates. This dual effect significantly improves the bioavailability of zinc and silicon in high-pH soils (field measurements show that the absorption efficiency of zinc and silicon by rice has increased to levels equivalent to utilization rates of over 45% and 50%, respectively).

[0042] Citric acid chelated zinc, as a fast-acting zinc source, possesses a stable cyclic chelate structure that fundamentally prevents zinc ions from forming zinc hydroxide precipitates. This ensures rapid zinc absorption during the critical period from rice greening to tillering, effectively alleviating growth inhibition caused by zinc deficiency. Potassium silicate, as a soluble silicon source, continuously releases monosilicic acid in the weakly alkaline microenvironment created by humic acid, meeting the high silicon requirements of rice from jointing to booting stages, promoting silicon deposition in cell walls, and enhancing plant mechanical strength and disease resistance. Zinc participates in auxin synthesis, promoting root development and tillering; silicon strengthens cell wall structure, reducing pathogen infection pathways. Both cover the key nutrient window throughout the entire rice growth cycle and complement each other functionally, thereby targeting and controlling zinc- and silicon-deficient rice wilt disease (field application shows that the incidence of rice wilt disease can be stably controlled below 5%).

[0043] Soluble starch, as a multifunctional adjuvant, not only improves the homogeneity of slurry and the granulation rate of spray drying during formulation preparation, but also forms a hydrophilic slow-release network after being applied to the soil, regulating the release rate of zinc and silicon, avoiding excessive local concentrations that could lead to the precipitation and inactivation of zinc and silicon, and ensuring their long-term synergistic effect.

[0044] This invention significantly improves the bioavailability of zinc and silicon by using humic acid to reduce soil alkalinity and improve soil quality, citric acid to chelate zinc and potassium silicate to provide nutrients in a synergistic manner, and soluble starch to slow-release and stabilize the effect. This reduces the incidence of rice blast disease in soda saline-alkali land to below 5%, achieving a dual breakthrough in soil improvement and disease control.

[0045] The second aspect of this application provides a method for preparing a zinc-silicon synergistic soil conditioner, including: Zinc chelate citric acid, potassium silicate, humic acid and soluble starch are mixed for the first time according to the mass ratio described in the first aspect to obtain a dry mixture. Specifically, prior to the first mixing, the preparation of zinc citrate chelate may also be included. The preparation of zinc citrate chelate includes the following steps: Chelation reaction: Food-grade zinc sulfate heptahydrate and 8% citric acid solution were mixed at a molar ratio of 1:1.2 and stirred in a constant temperature water bath at 60℃ for 2 hours to obtain the reaction solution; Concentration treatment: The reaction solution is concentrated under vacuum at 50℃ and -0.08 MPa until the system becomes a paste; Drying and pulverizing: The obtained paste was freeze-dried at -40℃, then pulverized and passed through an 80-mesh sieve to obtain zinc citric acid chelate powder.

[0046] According to the mass ratio described in the first aspect, zinc citrate chelate, potassium silicate, humic acid and soluble starch can be added to a stirred tank and mixed for the first time at room temperature. In some embodiments, the rotation speed of the first mixing is 150–180 r / min, for example, the rotation speed can be 150 r / min, 160 r / min, 170 r / min or 180 r / min, etc., and the time is 15–18 min, for example, the time can be 15 min, 16 min, 17 min or 18 min, etc.

[0047] Deionized water is added to the dry mixture to adjust the solid-liquid mass ratio to 1:1–1:2, and then a second mixing is performed. After mixing, the mixture is homogenized to obtain a homogeneous slurry. The solid-liquid mass ratio can be 1:1, 1:1.5, or 1:2, etc. A second mixing is then performed. In some embodiments, the second mixing speed is 800–1000 r / min, for example, 800 r / min, 900 r / min, or 1000 r / min, etc., and the time is 30–40 min; for example, 30 min, 35 min, or 40 min, etc. In some embodiments, the mixed slurry can be homogenized using a colloid mill (grinding gap controlled at 0.05 mm) to fully break up agglomerated particles, ensuring uniform dispersion of each component in the system, improving slurry stability, and laying the foundation for subsequent spray drying to obtain a particulate product with good flowability and uniform composition.

[0048] The homogeneous slurry is spray-dried to obtain the zinc-silicon synergistic soil conditioner of the first aspect. In some embodiments, the inlet air temperature of the spray drying is 170–190°C, for example, 170°C, 180°C, or 190°C, etc., and the outlet air temperature is 75–85°C, for example, 75°C, 80°C, or 85°C, etc. After drying, most of the deionized water is evaporated, and the resulting solid particles contain only a small amount of bound water. This residual water is the final form of "deionized water" in the zinc-silicon synergistic soil conditioner of the first aspect. That is, the "deionized water" in the components of the first aspect of this application refers to the raw material added as a dispersion medium during the preparation process. This water is mostly evaporated and removed during the spray drying step, and ultimately exists in the solid particle product in the form of trace amounts of bound water. Therefore, the final form of the conditioner is dried particles, rather than a liquid or paste-like preparation. The dried granules are sieved and 100–120 mesh particles are collected to obtain the zinc-silicon synergistic soil conditioner of the first aspect of this application.

[0049] The third aspect of this application provides the use of the zinc-silicon synergistic soil conditioner described in the first aspect in the control of rice blast disease in soda saline-alkali land.

[0050] Specifically, in terms of application, this product is easy to use and can be seamlessly integrated into the existing rice planting process. Farmers do not need to purchase complicated special equipment or master difficult operating skills, which greatly reduces the threshold for technology promotion and the cost of use.

[0051] In some embodiments, the soil pH of the soda saline-alkali land is 8.5–11.0; and / or, The soil alkalinity of the soda saline-alkali land is ≥30%; and / or, The available zinc content in the soil of the soda-saline-alkali land is ≤0.5 mg / kg; and / or, The available silicon content in the soil of the soda saline-alkali land is ≤20 mg / kg.

[0052] Specifically, this type of soda saline-alkali land is mainly distributed in the Songnen Plain (such as Daqing in Heilongjiang and Baicheng in Jilin) ​​in my country, and can also be found in the Xiliaohe Plain, the northern part of the Hetao Plain and the southern edge of the Junggar Basin in Xinjiang. Its common characteristics are high sodium ion saturation and low availability of trace elements, making rice cultivation susceptible to zinc and silicon deficiency-type red blight.

[0053] When the zinc-silicon synergistic soil conditioner described in this invention is applied to typical soda-saline-alkali land, the following technical effects can be achieved: Firstly, soil improvement effect: 20 days after application, the soil pH dropped to 7.5–8.5, and the alkalinity decreased by 25%–30%, indicating that humic acid effectively replaced exchangeable sodium ions and had a significant buffering effect on alkalinity. Secondly, nutrient activation effect: the available zinc content in the soil increased to 1.2–1.5 mg / kg, and the available silicon content increased to 40–50 mg / kg, reflecting that citrate chelated zinc and potassium silicate maintain high bioavailability in the improved microenvironment, and that humic acid has a synergistic stabilizing effect on zinc and silicon. Thirdly, the disease control effect: the incidence of zinc and silicon deficiency type red blight in rice was ≤5% throughout the entire growth period, and the disease index was ≤2.0 (investigated according to GB / T 15790-2009 standard), indicating that the synergistic supply of zinc and silicon nutrition effectively alleviated physiological stress. Fourth, environmental safety: The heavy metal content in the obtained amendment meets the requirements of the "Soil Environmental Quality Standard for Agricultural Land Soil Pollution Risk Control (Trial)" (GB 15618–2018), with cadmium (Cd) ≤ 0.5 mg / kg and lead (Pb) ≤ 50 mg / kg; no inhibitory effect on soil microbial community structure and activity was observed in pot and field trials, demonstrating good ecological safety.

[0054] Fifth, it enhances the overall stress resistance of rice: improving tolerance to soda saline-alkali stress and stem mechanical strength, thereby reducing the risk of lodging; at the same time, the deposition of silicon in the leaf cell walls helps improve plant structure and photosynthetic efficiency, and zinc, as an activator of various enzymes, can also promote carbon and nitrogen metabolism. Field trials have shown that after applying this amendment to typical soda saline-alkali land, the thousand-grain weight of rice increased by 5%–8% compared with the control, and the yield per mu increased by 12%–18%; the zinc content in rice increased to 25–30 mg / kg (dry basis), significantly higher than that of ordinary rice (usually <20 mg / kg), and the nutritional quality was significantly improved.

[0055] In some embodiments, the zinc-silicon synergistic soil conditioner is applied 6–8 days after rice transplanting. For example, it can be applied on the 6th, 7th, or 8th day after transplanting. Among these, application on the 7th day after transplanting (the greening stage) is the most effective, as the rice root system begins to expand, resulting in the highest zinc-silicon absorption efficiency and the best control effect against rice blast disease.

[0056] In some embodiments, the zinc-silicon synergistic soil conditioner is applied by a combination of basal soil application and foliar spraying, with a total application rate of 15-20 kg per acre. The mass ratio of the zinc-silicon synergistic soil conditioner applied as a soil base to the zinc-silicon synergistic soil conditioner applied as a foliar spray is 2:1–3:1. The soil basal application method is as follows: the zinc-silicon synergistic soil conditioner is mixed with fine soil at a mass ratio of 1:5 and then applied. The foliar spraying method involves diluting the zinc-silicon synergistic soil conditioner with water at a mass ratio of 1:6 before application.

[0057] Specifically, in soil basal application, 10-15 kg of zinc-silicon synergistic soil conditioner per acre can be mixed with fine soil at a mass ratio of 1:5 and then applied.

[0058] For foliar spraying, 5 kg of zinc-silicon synergistic soil conditioner per acre can be diluted with 30 kg of water and applied. The spraying pressure can be 0.3 MPa, and the droplet size can be 50-80 μm, for example, the droplet size can be 50 μm, 60 μm, 70 μm or 80 μm.

[0059] In some embodiments, the zinc-silicon synergistic soil conditioner can be applied on a sunny day with an air temperature of 15–28°C and no rainfall. The specific application time can be selected from 9:00–11:00 AM or after 4:00 PM to reduce the impact of high-temperature evaporation or strong light degradation on the active ingredients. If rainfall occurs within 4 hours of application, 50% of the original amount of soil conditioner can be applied to compensate for nutrient loss caused by rainwater runoff and ensure the control effect.

[0060] In some embodiments, the water in the soda saline-alkali paddy field is drained one day before the application of the zinc-silicon synergistic soil conditioner, and the paddy field is irrigated within 24 hours after application to make the water depth of the paddy field 3–5 cm. No artificial drainage is carried out for three consecutive days after the irrigation is completed.

[0061] Specifically, the water depth can be 3 cm, 4 cm, or 5 cm. A shallow water layer of 3–5 cm can promote the dissolution and uniform distribution of humic acid, citric acid chelated zinc, and potassium silicate in the soil conditioner. On the other hand, the reducing microenvironment formed by the shallow water layer can inhibit the premature precipitation of zinc and silicon under strong oxidizing conditions, thereby improving their bioavailability. After irrigation, no artificial drainage should be carried out for three consecutive days (i.e., no drainage should be carried out for three days) to prolong the interaction time between the soil conditioner and the rhizosphere soil, ensuring the leaching effect of humic acid on sodium ions and the continuous release and absorption of zinc and silicon nutrients, thereby maximizing the synergistic effect of soil improvement and red blight control.

[0062] Example 1 The test site was a typical soda saline-alkali land in area A. The initial soil pH was 9.8, the soil alkalinity was 35%, the available zinc content was 0.4 mg / kg, and the available silicon content was 18 mg / kg.

[0063] The test site was 30 m 2 The region was divided into multiple experimental areas. There were 7 treatments, and each treatment had 3 independent, randomly arranged experimental areas as biological replicates (i.e., parallel samples). The same rice variety was planted in each experimental area.

[0064] Except for the blank control (CK), treatments 1-6 were all treated with the zinc-silicon synergistic soil conditioner described in this invention. The application methods for treatments 1-6 were identical. Specifically, the zinc-silicon synergistic soil conditioner used in treatments 1-6 contained 6 parts of citric acid-chelated zinc, 38 parts of humic acid, and 8 parts of soluble starch. Different zinc-silicon mass ratios were achieved by adjusting the amount of potassium silicate used in each treatment, with the remainder being deionized water. The specific treatments are as follows: CK: No modifiers applied; Treatment 1: 18 parts potassium silicate, zinc chelate citric acid: potassium silicate = 1:3; Treatment 2: 24 parts potassium silicate, zinc chelate citric acid: potassium silicate = 1:4; Treatment 3: 30 parts potassium silicate, zinc chelate citric acid: potassium silicate = 1:5; Treatment 4: 36 parts potassium silicate, zinc chelate citric acid: potassium silicate = 1:6; Treatment 5: 42 parts potassium silicate, zinc chelate citric acid: potassium silicate = 1:7; Treatment 6: Potassium silicate 54 parts, citric acid chelated zinc: potassium silicate = 1:9; The application time and method are the same for all treatments.

[0065] The test results for CK and treatments 1-6 in Example 1 are shown in Table 1. Table 1. CK and treatments 1-6 of Example 1

[0066] Among them, the incidence and disease index of red blight can be referenced in "GB / T 15790—2023 Rice Blast Monitoring and Survey Specification"; available zinc in the soil is determined by DTPA extraction-atomic absorption method; available silicon in the soil is determined by citric acid extraction-silicon molybdenum blue colorimetric method; the yield is the yield per mu after threshing and air drying in the actual harvest plots, converted to 14% moisture content.

[0067] Results Analysis: Compared with the control group, all application treatments significantly reduced the incidence of rice wilt and increased the content of available zinc and silicon in the soil, as well as rice yield. Among them, treatment 3 (zinc-silicon mass ratio 1:5) showed the best effect: the lowest incidence of rice wilt (3.2%), and the content of available zinc and available silicon synergistically increased to a high level, with a yield of 536 kg / mu, an increase of 18.6% compared with the control group. When the zinc-silicon ratio deviated from 1:5 (such as 1:3 or 1:9), although the content of silicon or zinc as a single nutrient may be higher, the control effect of rice wilt was not good, indicating that there is a synergistic threshold between zinc and silicon in physiological function. The 1:5 ratio best matches the stage-specific demand balance of rice for zinc (greening-tillering stage) and silicon (jointing-booting stage). At the same time, the ratio of 1:4-1:6 also reduced the incidence of rice wilt to 5% and below, and the yield level was close to the optimal ratio, with good control effect, thus achieving the best disease prevention and yield increase effect.

[0068] Example 2 The test site was a typical soda saline-alkali land in area A. The initial soil pH was 9.8, the soil alkalinity was 35%, the available zinc content was 0.4 mg / kg, and the available silicon content was 18 mg / kg.

[0069] The test site was 30 m 2 The region was divided into multiple experimental plots. Four treatments were established, with three independent, randomly arranged experimental plots for each treatment, serving as biological replicates (i.e., parallel samples). The same rice variety was planted in each experimental plot. The specific treatments are as follows: Blank control (CK): No modifier was applied; Control treatment 1: Apply conventional desulfurized gypsum amendment at a rate of 50 kg / mu; Control treatment 2: Apply 1 kg / mu of zinc sulfate and 5 kg / mu of potassium silicate.

[0070] The treatment of this invention is as follows: The zinc-silicon synergistic soil conditioner (zinc-silicon mass ratio 1:5) of treatment 3 in Example 1 is applied at a rate of 18 kg / mu.

[0071] The application time and method are the same for all treatments.

[0072] The test results of CK and each treatment in Example 2 are shown in Table 2. Table 2. Test results of CK and each treatment in Example 2

[0073] Among them, soil pH was measured by collecting soil samples from the 0–20 cm soil layer 20 days after application; the incidence of red blight was investigated at the heading stage (refer to GB / T 15790–2009); the thousand-grain weight was measured by randomly sampling air-dried grains; and the yield increase per mu was calculated as a relative value based on the CK.

[0074] Results Analysis: Although control treatment 1 reduced soil pH (to 8.3), the incidence of red wilt disease remained as high as 35.2% due to the lack of zinc and silicon supplementation, resulting in limited yield increase. Control treatment 2 alleviated some nutrient deficiency symptoms (incidence rate reduced to 16.7%) through inorganic zinc and silicon fertilizer, but the availability of zinc and silicon was low in the high pH environment, and it lacked alkalinity-reducing function, resulting in almost no improvement in soil pH (9.5), limiting its potential for disease prevention and yield increase. In contrast, the zinc-silicon synergistic soil conditioner of this invention has three functions: alkalinity reduction, zinc supply, and silicon supply. It not only effectively reduced soil pH to 8.1 but also efficiently improved the bioavailability of zinc and silicon, significantly reducing the incidence of red wilt disease to 3.2%, with significantly better increases in thousand-grain weight and yield compared to the control treatments. The results indicate that synergistic design of soil improvement and precise nutrient supply can achieve effective control of red wilt disease and stable yield increase in rice in soda-saline-alkali land.

[0075] Example 3 The test site was a typical soda saline-alkali land in area A. The initial soil pH was 9.8, the soil alkalinity was 35%, the available zinc content was 0.4 mg / kg, and the available silicon content was 18 mg / kg.

[0076] The test site was 30 m 2 The region was divided into multiple experimental plots. Four treatments were established, with three independent, randomly arranged experimental plots per treatment as biological replicates (i.e., parallel samples). The same rice variety was planted in each experimental plot. The zinc-silicon synergistic soil conditioner was applied in the same proportions across all treatments: 6 parts citric acid chelated zinc, 38 parts humic acid, 8 parts soluble starch, 30 parts potassium silicate, and the remainder deionized water. The only difference between the treatments was the application time, as detailed below: Treatment 7: Apply on the 3rd day after rice transplanting; Treatment 8: Apply on the 6th day after rice transplanting; Treatment 9: Apply on the 7th day after rice transplanting; Treatment 10: Apply on the 8th day after rice transplanting; Treatment 11: Apply on the 10th day after rice transplanting; Treatment 12: Apply on the 15th day after rice transplanting; The test results for different application times in Example 3 are shown in Table 3. Table 3. Test results of different application times in Example 3

[0077] Among them, the incidence and disease index of rice blast disease can be referenced in "GB / T 15790—2023 Rice Blast Monitoring and Survey Specification"; root absorption efficiency is measured through¹ 5 The yield is estimated using N or Zn isotope tracing (or indirectly characterized by plant zinc and silicon accumulation / application rate × 100%); the yield is the yield per mu (unit of land area) calculated from the actual harvested air-dried grains to a moisture content of 14%.

[0078] Results Analysis: Rice is most sensitive to zinc requirements during the greening-up to early tillering stage (6–8 days after transplanting). Zinc deficiency during this stage easily leads to poor root development, reduced tillering, and subsequently induces red blight. Treatment 8 (applied on the 7th day after transplanting) precisely covered this critical window period, allowing citrate-chelated zinc to be released in a timely manner during the active root growth period, significantly improving zinc absorption efficiency (45.6%). At the same time, humic acid simultaneously improved the rhizosphere microenvironment, promoting effective silicon supply and achieving the best disease prevention effect (disease incidence rate of only 3.2%) and the highest yield (536 kg / mu). When applied too early (treatment 7, day 3), the seedlings had not yet recovered physiological activity, the root absorption capacity was weak, and some nutrients may have been lost with water migration, resulting in poor effects. On the other hand, delayed application (treatments 11 and 12, days 10–15) missed the critical period for zinc nutrition. Although there was still some effect, it could not completely reverse the growth inhibition caused by early zinc deficiency, leading to a rebound in disease incidence and a decrease in absorption efficiency. That is, the preferred application time for the improver of the present invention is 6-8 days after transplanting, and the best application time is 7 days after transplanting. This can match the physiological needs of rice and give full play to the comprehensive effect of zinc-silicon synergy and soil improvement.

[0079] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A zinc-silicon synergistic soil conditioner, characterized in that, Based on a total mass of 100 parts, it contains the following components: Zinc chelate citrate: 5–8 parts; Potassium silicate: 25–40 parts; Humic acid: 30–45 parts; Soluble starch: 5–10 parts; Deionized water: Balance.

2. The zinc-silicon synergistic soil conditioner according to claim 1, characterized in that, The mass ratio of the citric acid chelated zinc to potassium silicate is 1:4–1:

6.

3. The zinc-silicon synergistic soil conditioner according to claim 1, characterized in that, The potassium silicate contains ≥98% K₂SiO₃; and / or, The organic matter content of the humic acid is ≥70%.

4. A method for preparing a zinc-silicon synergistic soil conditioner, characterized in that, include: Zinc chelate citric acid, potassium silicate, humic acid and soluble starch are mixed for the first time according to the mass ratio described in any one of claims 1-3 to obtain a dry mixture. Deionized water is added to the dry mixture to adjust the solid-liquid mass ratio to 1:1–1:2, and then a second mixing is performed. After mixing, the mixture is homogenized to obtain a homogeneous slurry. The homogeneous slurry is spray-dried to obtain the zinc-silicon synergistic soil conditioner according to any one of claims 1–3.

5. The preparation method of the zinc-silicon synergistic soil conditioner according to claim 4, characterized in that, The first mixing is performed at a rotation speed of 150–180 r / min for a time of 15–18 min; and / or, The second mixing is performed at a rotation speed of 800–1000 r / min for a time of 30–40 min; and / or, The inlet air temperature of the spray dryer is 170–190℃, and the outlet air temperature is 75–85℃.

6. The use of the zinc-silicon synergistic soil conditioner according to any one of claims 1–3 in the control of rice blast disease in soda saline-alkali land.

7. The use of the zinc-silicon synergistic soil conditioner according to claim 6, characterized in that, The soil pH of the soda saline-alkali land is 8.5–11.0; and / or, The soil alkalinity of the soda saline-alkali land is ≥30%; and / or, The available zinc content in the soil of the soda-saline-alkali land is ≤0.5 mg / kg; and / or, The available silicon content in the soil of the soda saline-alkali land is ≤20 mg / kg.

8. The use of the zinc-silicon synergistic soil conditioner according to claim 6, characterized in that, The zinc-silicon synergistic soil conditioner was applied 6–8 days after rice transplanting.

9. The use of the zinc-silicon synergistic soil conditioner according to claim 6, characterized in that, The zinc-silicon synergistic soil conditioner is applied by a combination of basal soil application and foliar spraying, with a total application rate of 15-20 kg per acre. The mass ratio of the zinc-silicon synergistic soil conditioner applied as a soil base to the zinc-silicon synergistic soil conditioner applied as a foliar spray is 2:1–3:

1. The soil basal application method is as follows: the zinc-silicon synergistic soil conditioner is mixed with fine soil at a mass ratio of 1:5 and then applied. The foliar spraying method involves diluting the zinc-silicon synergistic soil conditioner with water at a mass ratio of 1:6 before application.

10. The use of the zinc-silicon synergistic soil conditioner according to any one of claims 6-9, characterized in that, One day before applying the zinc-silicon synergistic soil conditioner, drain the water from the soda saline-alkali paddy field. Irrigate within 24 hours after application to make the water depth of the paddy field 3–5 cm. Do not drain the water artificially for 3 consecutive days after irrigation.

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