Rice selenium enrichment and cadmium reduction synergistic conditioner and use method thereof

Abstract

The invention discloses a rice selenium enrichment and cadmium reduction synergistic conditioner, the conditioner comprises selenide, a nano bamboo charcoal complexing agent, a soil pH regulating agent, an organic material and a root system oxygen secretion accelerant with different contents according to different soil types, and by adding the conditioner into soil, the soil environment is effectively improved, and the soil quality is improved. The soil PH is controlled within the range of 6.0-7.5 suitable for rice planting, the rice cadmium content is reduced, food safety is guaranteed, the rice selenium content is increased, the rice nutritional value is improved, meanwhile, the yield is increased, economic benefits are improved, and the problems that in the prior art, selenium enrichment and cadmium reduction are difficult to cooperate, and the cadmium reduction effect is unstable are solved.

Description

Technical Field

[0001] The invention relates to the technical field of soil improvement, and in particular to a rice selenium-enriched and cadmium-reducing synergistic conditioner and a use method thereof. Background Art

[0002] At present, there are few precise cadmium-blocking conditioners on the market that can adapt to different soil characteristics. my country's paddy field soils are of many types and diverse in nature, and there is an urgent need for precise cadmium-blocking products with strong adaptability. Therefore, it is necessary to modify biochar and scientifically compound it with pH regulators, organic matter and other materials to prepare cadmium-blocking conditioners with excellent effects and for different soil characteristics.

[0003] Foliar cadmium prevention is a method of spraying physiological antagonistic elements or physiologically active substances such as humic acid on the leaves to change the transport and distribution of heavy metals in crops, prevent the transport of heavy metals to edible parts, and improve the safety and quality of agricultural products. Due to its convenient implementation, easy application in large areas of fields, and obvious prevention and control effect, it has become a new direction for the safe use of farmland contaminated by heavy metals. Selenium fertilizer is a common prevention and control material for reducing the accumulation of cadmium in crops. Selenium can promote the formation of antioxidant substances in crops, while promoting selenium-enriched crops and reducing the absorption of heavy metals by crops. However, the cadmium prevention effect of foliar prevention materials often varies with different soils and crops, and there is a synergistic and antagonistic effect between selenium and cadmium in rice absorption. Only when the selenium concentration is low can the absorption of cadmium be reduced and the toxicity of cadmium be alleviated. Excessive selenium concentration will promote cadmium absorption and enhance the biological toxicity of cadmium in soil. Therefore, there is a risk of promoting the absorption of cadmium by crops when selenium-rich foliar fertilizer is applied in cadmium-contaminated rice fields. It is necessary to scientifically compound selenium-rich cadmium-blocking foliar fertilizers for soils of different properties and develop precise selenium-rich foliar fertilizers for different soils.

[0004] In summary, the existing technology still has problems such as difficulty in coordinating selenium-enriched and cadmium-reducing effects and unstable cadmium-reducing effects. Summary of the invention

[0005] The present invention aims to provide a rice selenium-enriched and cadmium-reducing synergistic conditioner and a method of using the same, which is suitable for different soil types and can solve the problems in the prior art that selenium-enriched and cadmium-reducing synergistic effects are difficult to achieve and the cadmium-reducing effect is unstable.

[0006] To achieve the above object, the present invention provides the following technical solutions: According to the characteristics of cadmium-contaminated paddy fields in the south, soil pH was set as low (pH≤5.5), medium (5.5<pH≤6.5) and high (pH>6.5), representing strong acidic, weakly acidic and moderately alkaline soils, respectively. Soil organic matter (SOM) was divided into low (SOM≤15), medium (15<SOM<25) and high (SOM≥25). According to soil pH and soil SOM, soil types were divided into nine types: low pH low SOM, low pH medium SOM, low pH high SOM, medium pH low SOM, medium pH medium SOM, medium pH high SOM, high pH low SOM, high pH medium SOM, and high pH high SOM. A rice selenium-enriched and cadmium-reducing synergistic conditioner comprises the following components: selenide, nano bamboo charcoal composite, soil pH regulator, organic material and root oxygen secretion promoter. The formula ratio of the conditioner is respectively as follows according to the soil type: Low pH and low SOM, selenide 5-10%, nano bamboo charcoal compound 30-40%, soil pH regulator 15-20%, organic material 30-40%, root oxygen secretion promoter 1-2%; SOM in low pH, selenide 5-10%, nano bamboo charcoal compound 35-45%, soil pH regulator 15-20%, organic material 25-35%, root oxygen secretion promoter 1-2%; Low pH and high SOM, selenide 5-10%, nano bamboo charcoal compound 40-50%, soil pH regulator 15-20%, organic material 20-30%, root oxygen secretion promoter 1-2%; Medium pH and low SOM, selenide 5-10%, nano bamboo charcoal compound 35-45%, soil pH regulator 10-15%, organic material 30-40%, root oxygen secretion promoter 1-2%; Medium pH medium SOM, selenide 5-10%, nano bamboo charcoal compound 40-50%, soil pH regulator 10-15%, organic material 25-35%, root oxygen secretion promoter 1-2%; Medium pH and high SOM, selenide 5-10%, nano bamboo charcoal compound 45-55%, soil pH regulator 10-15%, organic material 20-30%, root oxygen secretion promoter 1-2%; High pH and low SOM, selenide 5-10%, nano bamboo charcoal compound 45-55%, soil pH regulator 0%, organic material 30-40%, root oxygen secretion promoter 1-2%; SOM in high pH, ​​selenide 5-10%, nano bamboo charcoal compound 50-60%, soil pH regulator 0%, organic material 25-35%, root oxygen secretion promoter 1-2%; High pH and high SOM, selenide 5-10%, nano bamboo charcoal compound 55-65%, soil pH regulator 0%, organic material 20-30%, root oxygen secretion promoter 1-2%; By adding different proportions of nano-bamboo charcoal compounds, soil pH regulators and organic materials to different types of soil, targeted treatment is carried out on different types of soil to ensure that the formula of the conditioner more accurately meets the needs of different soils, and the soil environment is optimized to be suitable for rice growth, conducive to selenium absorption and weak cadmium absorption. At the same time, the selenium-enriched effect of rice is promoted by adding an appropriate amount of selenide, and the formation of root surface iron film is enhanced by adding a small amount of root oxygen secretion promoter to block the absorption of cadmium, so as to achieve the synergistic effect of selenium-enriched rice and cadmium-reduced, improve the quality and safety of rice, and reduce the impact on the environment.

[0007] Further, the selenide is a water-soluble selenate or selenite, and further, the selenide is sodium selenite; By adding selenides to the soil, the selenium content in rice can be increased, thereby improving the nutritional value of rice. Generally speaking, low concentrations of selenium (such as selenite) can reduce the absorption of cadmium by rice, while high concentrations of selenium may promote the absorption of cadmium. Sodium selenite is a water-soluble selenium source with high biological effectiveness and is easily absorbed and utilized by plant roots.

[0008] Further, the nano bamboo charcoal composite comprises the following components by mass percentage: 70-80% nano bamboo charcoal, 8-12% humic acid, 8-12% zeolite powder, 5-8% weathered coal humic acid, and further, the nano bamboo charcoal is modified titanium dioxide nano bamboo charcoal; Modified titanium dioxide nano-bamboo charcoal combines the strong adsorption of bamboo charcoal and the photocatalytic performance of titanium dioxide. It can adsorb cadmium ions in the soil, reduce its activity and bioavailability in the soil, and promote the reduction and fixation of cadmium under light conditions, thereby reducing the absorption of cadmium by crops and improving the safety of agricultural products. Under the action of photocatalysis, it can also promote the degradation of organic pollutants in the soil and improve the self-purification ability of the soil; humic acid can form stable complexes with heavy metals in the soil, reduce the bioavailability of heavy metals, and humic acid can also improve soil structure, increase the cation exchange capacity of the soil, and improve the soil's adsorption capacity for cadmium; zeolite powder has a unique pore structure and high adsorption, which can adsorb cadmium in the soil. Cadmium ions, reducing their migration and bioavailability, and can also promote the growth of beneficial microorganisms in the soil, improve the soil microecological environment, thereby improving the soil's self-purification ability; weathered coal humic acid has a high organic matter content and a complex molecular structure, which can effectively adsorb and complex heavy metal ions in the soil, reduce their bioavailability, and enhance the soil aggregate structure, improve the soil's water retention and air permeability, thereby improving the soil environment and reducing cadmium migration; nano bamboo charcoal composites can effectively reduce the activity and bioavailability of cadmium in the soil through the synergistic effect of various components, reduce the absorption of cadmium by crops, thereby improving the safety of agricultural products, and at the same time improve the soil environment and improve the soil's self-purification ability.

[0009] Further, the soil pH regulator is an alkaline regulator, and further, the soil pH regulator is calcium carbonate; Calcium carbonate is used to neutralize acidic soil and increase soil pH, adjusting the soil pH to 6.5-7.5, which is a range suitable for rice growth. It promotes rice's absorption and utilization of selenium and has weak absorption of cadmium.

[0010] Further, the organic material is one or more of plant ash, mushroom residue, organic fertilizer, biochar, and peat. Further, the organic material is peat; Organic materials provide the organic carbon source needed for soil improvement, promote soil microbial activity, improve soil structure and increase soil fertility, while increasing the soil's ability to adsorb heavy metals, helping to reduce the cadmium content in rice. Peat is a soil conditioner with a high organic matter content that can improve the soil's ability to retain water and fertilizer.

[0011] Furthermore, the root oxygen secretion promoter comprises the following components in terms of mass percentage: 30-35% iron source, 40-45% calcium peroxide, 10-15% biostimulant, 1-5% surfactant and 10-15% slow-release agent, wherein the iron source is chelated iron, the biostimulant is polypeptide urea, the surfactant is fatty acid glyceride, and the slow-release agent is montmorillonite; Root oxygen secretion promoters can promote oxygen secretion by rice roots, and then strengthen the formation of root surface iron film, so that they can absorb cadmium ions in the soil, play a blocking role in rice cadmium absorption, and reduce rice's absorption of cadmium. Iron sources directly provide iron ions to rice roots and promote the formation of root surface iron film. Chelated iron is easily absorbed and utilized by rice roots and will not have a negative impact on the soil environment. Calcium peroxide can slowly decompose in water to produce oxygen, directly providing oxygen to the roots, promoting root oxygen secretion and respiration. The amount of calcium peroxide added should be moderate. Too much may lead to excessive local oxygen concentration, causing oxidative stress to rice roots; too little may not have obvious effects. Biostimulants can stimulate the physiological activity of rice roots, enhance the metabolic capacity and respiration of root cells, thereby enhancing the root oxygen secretion capacity. The increase in root oxygen secretion helps the formation and stability of root surface iron film. Peptide urea has good biocompatibility. The surfactant can reduce the surface tension of water, enhance the spreading and penetration of the agent in the plant root system and soil, and improve the emulsification and dispersion ability of the agent, ensure the uniform distribution of the active ingredients, and improve the stability and bioavailability of the agent. Among them, fatty acid glyceride is a non-ionic surfactant with good dispersibility and wettability and is environmentally friendly. The sustained-release agent can control the release rate of fertilizers or other active ingredients, so that they are released slowly over a period of time, thereby prolonging their effectiveness, reducing losses caused by rainwater erosion or irrigation, and reducing the impact on the environment. Among them, montmorillonite is a mineral-based sustained-release agent with good environmental friendliness and low cost.

[0012] The method for using the rice selenium-enriched and cadmium-reducing synergistic conditioner comprises the following steps: S1. Determine the type of topsoil: Before paddy field cultivation, use the five-point sampling method to collect 0-20cm deep topsoil from the target field, then mix it and send it to a third-party testing agency to measure the cadmium content, pH and organic matter content of the topsoil; S2, preparation of nano bamboo charcoal composite: nano bamboo charcoal, humic acid, zeolite powder and weathered coal humic acid are mixed evenly using a stirrer according to mass percentage to obtain a nano bamboo charcoal composite; S3. Preparation of root oxygen secretion promoter: mixing the iron source, calcium peroxide, biostimulant, surfactant and slow-release agent uniformly according to mass percentage to obtain root oxygen secretion promoter; S4, conditioning agent preparation: selenide, nano bamboo charcoal composite, soil pH regulator, organic material and root oxygen secretion promoter are mixed evenly according to the formula ratio corresponding to the measured soil type to obtain a rice selenium-enriched and cadmium-reducing synergistic conditioning agent; S5. Preliminary treatment of rice fields to ensure that the field surface is flat and there is a shallow water layer of 1-3 cm in the field, which helps to maintain soil moisture, promote the growth of rice roots and the activity of microorganisms in the soil, and also helps the uniform distribution and action of the conditioner; S6. Application of conditioner: Determine the application amount of conditioner according to the cadmium pollution of the soil. The application amount per mu of paddy fields with mild and moderate cadmium pollution is 80 kg and 120 kg respectively. Mix the conditioner and base fertilizer evenly and apply it to the surface of the field. Then, fully till the soil to make the conditioner, base fertilizer and soil evenly mixed. The tillage depth is preferably 15-20 cm to ensure the consistency of the soil improvement effect. The selection of tillage depth helps the conditioner to act on the main distribution area of ​​the rice root system. S7. Keep the field flooded for 1 month, and then manage it according to the local conventional water management method. Flooding conditions are conducive to the fixation of heavy metal cadmium in the soil and reduce its migration to rice. Continuous water supply is conducive to the chemical reaction in the soil, so that the various components in the conditioner can better interact with the soil and play a synergistic effect of selenium enrichment and cadmium reduction.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The invention provides a rice selenium-enriched and cadmium-reducing synergistic conditioner. The conditioner comprises selenide, a nano bamboo charcoal composite, a soil pH regulator, an organic material and a root oxygen secretion promoter in different contents according to different soil types. By adding the conditioner into the soil, the soil environment is effectively improved, and the soil pH is controlled within a range of 6.0 to 7.5 suitable for rice planting, thereby reducing the cadmium content of the rice and ensuring food safety, increasing the selenium content of the rice and improving the nutritional value of the rice, and increasing the yield, thereby improving the economic benefit, and solving the problems of the prior art that selenium-enriched and cadmium-reducing synergistic effects are difficult and the cadmium-reducing effect is unstable. DETAILED DESCRIPTION

[0014] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Example

[0015] This embodiment is tested in Hongtang Town, Yuanzhou District, Yichun City, Jiangxi Province from mid-June to late October 2023. The background soil of the test site is measured: the cadmium content is 0.65 mg / kg, the pH is 4.87, and the organic matter is 31.51 g / kg. It is known that the soil is slightly contaminated with cadmium (the soil cadmium concentration is between 0.2 mg / kg and 1.0 mg / kg for mild cadmium pollution, and between 1.0 mg / kg and 3.0 mg / kg for moderate cadmium pollution), the soil type is low pH and high SOM, and the formula of the conditioner for rice selenium enrichment and cadmium reduction is determined: 5% selenide, 46.5% nano bamboo charcoal composite, 20% soil pH regulator, 27% organic material, and 1.5% root oxygen secretion promoter; Experimental plot setting: The experimental plot area is 30m 2 (6m×5m), repeated three times, marked as 1# test plot, 2# test plot, and 3# test plot, with a total area of ​​90 m 2 Based on the application amount of 80 kg per mu of rice fields with mild cadmium contamination, a total of 10.8 kg of conditioner is required, and 3.6 kg of conditioner is applied to each experimental plot.

[0016] Preparation before sowing: Use rotary tillage to level the rice field. There should be a shallow water layer 1-3 cm deep in the field. After the mud sinks, build ridges around the plot. The ridges are 30 cm high and 30 cm wide, and covered with film.

[0017] Variety selection: The test variety is a hybrid late rice variety: Yexiang Youfengzhan, which has the characteristics of strong tillering ability, high yield and excellent rice quality.

[0018] Preparation of nano bamboo charcoal composite: 75% by mass of modified titanium dioxide nano bamboo charcoal, 9% by mass of humic acid, 10% by mass of zeolite powder and 6% by mass of weathered coal humic acid were mixed evenly using a stirrer according to a total weight of 5.02 kg (10.8×0.465) to obtain a nano bamboo charcoal composite; Preparation of root oxygen secretion promoter: 33% by mass of chelated iron, 42% by mass of calcium peroxide, 11% by mass of polypeptide urea, 2% by mass of fatty acid glyceride and 12% by mass of montmorillonite are crushed and mixed evenly according to a total weight of 0.16 kg (10.8×0.015) to obtain a root oxygen secretion promoter; Conditioning agent preparation: 5% sodium selenite, 46.5% nano bamboo charcoal compound, 20% calcium carbonate, 27% peat and 1.5% root oxygen secretion promoter are mixed evenly according to a total weight of 10.8 kg to obtain a rice selenium-enriched and cadmium-reducing synergistic conditioning agent; Sowing and transplanting: Late rice was sown on June 25 and transplanted on July 25. The spacing between rows was 13.3 cm × 23.3 cm, and two seedlings were planted in each hole.

[0019] Application of conditioner: Conditioners and base fertilizers were manually spread on July 28, and rotary tillage was performed manually on July 30 with a tillage depth of 15-20 cm to allow the conditioner to be fully mixed with the soil. The soil was then kept flooded until August 30, followed by alternating dry and wet irrigation.

[0020] Late Rice Harvest: Late rice is harvested on October 20th. Example

[0021] This embodiment is substantially the same as the first embodiment, except that the test site is located in Sanyang Town, Yuanzhou District, Yichun City. The background soil of the test site is measured as follows: the total cadmium content is 0.89 mg / kg, the pH is 5.73, and the organic matter is 24.54 g / kg. The soil is slightly contaminated with cadmium, and the soil type is medium pH medium SOM. The formula of the conditioner for rice selenium enrichment and cadmium reduction is determined as follows: 7% selenide, 44.5% nano bamboo charcoal composite, 12% soil pH regulator, 35% organic material, and 1.5% root oxygen secretion promoter; The experimental plot setting area and method were the same as in Example 1, and were repeated three times, marked as 4# experimental plot, 5# experimental plot, and 6# experimental plot, with a total area of ​​90 m 2 Based on the application amount of 80 kg per mu of rice fields with mild cadmium contamination, a total of 10.8 kg of conditioner is required, and 3.6 kg of conditioner is applied to each experimental plot.

[0022] Nano bamboo charcoal compound, root oxygen secretion promoter and conditioner are prepared in sequence according to the formula.

[0023] The methods and date intervals for pre-sowing preparation, variety selection, sowing date, sowing and transplanting, application of conditioner and late rice harvest are substantially the same as those in the first embodiment.

[0024] Comparative Example: The experimental background was the same as that of Example 1, and conventional cultivation treatment was performed. Except for not applying the conditioner, other management measures were consistent with those of Example 1.

[0025] The differences in soil pH and effective cadmium content at different periods in the embodiments and comparative examples are shown in Table 1, the differences in selenium and cadmium content in rice are shown in Table 2, and the rice yield is shown in Table 3.

[0026] Table 1: Comparison of soil pH and available cadmium content at different periods

[0027] Table 2: Comparison of Selenium and Cadmium Contents in Rice

[0028] Table 3: Comparison of rice yield and aboveground biomass

[0029] It can be concluded from Table 1 that the soil environment in Example 1 and Example 2 is effectively improved, the soil pH is controlled within the range of 6.0 to 7.5 suitable for rice cultivation, and the effective cadmium content in the soil is significantly reduced, thereby reducing the cadmium absorption of rice.

[0030] It can be concluded from Table 2 that the selenium content in rice in the experimental plot has increased, and the cadmium content in rice is far lower than the requirement of the national standard GB2762-2017 that the cadmium residue in grains should be less than 0.2 mg / kg.

[0031] It can be concluded from Table 3 that the output of Example 1 and Example 2 is increased.

[0032] In summary, by adding rice selenium-enriching and cadmium-reducing synergistic conditioners to the soil, the soil environment was effectively improved, which not only reduced the cadmium content and ensured food safety, but also increased the selenium content of rice and improved the nutritional value of rice. At the same time, the yield was increased, which improved the economic benefits.

[0033] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A rice selenium-enriched and cadmium-reducing synergistic conditioning agent, characterized in that: The invention comprises the following components: selenide, nano bamboo charcoal compound, soil pH regulator, organic material and root oxygen secretion promoter. The formula ratio of the conditioner is as follows according to the soil type: Low pH and low SOM, selenide 5-10%, nano bamboo charcoal compound 30-40%, soil pH regulator 15-20%, organic material 30-40%, root oxygen secretion promoter 1-2%; SOM in low pH, selenide 5-10%, nano bamboo charcoal compound 35-45%, soil pH regulator 15-20%, organic material 25-35%, root oxygen secretion promoter 1-2%; Low pH and high SOM, selenide 5-10%, nano bamboo charcoal compound 40-50%, soil pH regulator 15-20%, organic material 20-30%, root oxygen secretion promoter 1-2%; Medium pH and low SOM, selenide 5-10%, nano bamboo charcoal compound 35-45%, soil pH regulator 10-15%, organic material 30-40%, root oxygen secretion promoter 1-2%; Medium pH medium SOM, selenide 5-10%, nano bamboo charcoal compound 40-50%, soil pH regulator 10-15%, organic material 25-35%, root oxygen secretion promoter 1-2%; Medium pH and high SOM, selenide 5-10%, nano bamboo charcoal compound 45-55%, soil pH regulator 10-15%, organic material 20-30%, root oxygen secretion promoter 1-2%; High pH and low SOM, selenide 5-10%, nano bamboo charcoal compound 45-55%, soil pH regulator 0%, organic material 30-40%, root oxygen secretion promoter 1-2%; SOM in high pH, ​​selenide 5-10%, nano bamboo charcoal compound 50-60%, soil pH regulator 0%, organic material 25-35%, root oxygen secretion promoter 1-2%; High pH and high SOM, selenide 5-10%, nano bamboo charcoal compound 55-65%, soil pH regulator 0%, organic material 20-30%, root oxygen secretion promoter 1-2%.

2. The rice selenium-enriched and cadmium-reducing synergistic conditioner according to claim 1, characterized in that: The selenide is a water-soluble selenate or selenite. Furthermore, the selenide is sodium selenite.

3. The rice selenium-enriched and cadmium-reducing synergistic conditioner according to claim 1, characterized in that: The nano bamboo charcoal composite comprises the following components in percentage by mass: 70-80% nano bamboo charcoal, 8-12% humic acid, 8-12% zeolite powder, and 5-8% weathered coal humic acid. Furthermore, the nano bamboo charcoal is modified titanium dioxide nano bamboo charcoal.

4. The rice selenium-enriched and cadmium-reducing synergistic conditioning agent according to claim 1, characterized in that: The soil pH regulator is an alkaline regulator. Furthermore, the soil pH regulator is calcium carbonate.

5. The rice selenium-enriched and cadmium-reducing synergistic conditioning agent according to claim 1, characterized in that: The organic material is one or more of wood ash, mushroom residue, organic fertilizer, biochar, and peat. Furthermore, the organic material is peat.

6. The rice selenium-enriched and cadmium-reducing synergistic conditioning agent according to claim 1, characterized in that: The root oxygen secretion promoter comprises the following components in percentage by mass: 30-35% of an iron source, 40-45% of calcium peroxide, 10-15% of a biostimulant, 1-5% of a surfactant and 10-15% of a slow-release agent. The iron source is chelated iron, the biostimulant is polypeptide urea, the surfactant is fatty acid glyceride, and the slow-release agent is montmorillonite.

7. A method for using the rice selenium-enriching and cadmium-reducing synergistic conditioner according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Determine the type of topsoil: Before paddy field cultivation, use the five-point sampling method to collect 0-20cm deep topsoil from the target field, then mix it and send it to a third-party testing agency to measure the cadmium content, pH and organic matter content of the topsoil; S2, preparation of nano bamboo charcoal composite: nano bamboo charcoal, humic acid, zeolite powder and weathered coal humic acid are mixed evenly using a stirrer according to mass percentage to obtain a nano bamboo charcoal composite; S3. Preparation of root oxygen secretion promoter: mixing the iron source, calcium peroxide, biostimulant, surfactant and slow-release agent uniformly according to mass percentage to obtain root oxygen secretion promoter; S4, conditioning agent preparation: selenide, nano bamboo charcoal composite, soil pH regulator, organic material and root oxygen secretion promoter are mixed evenly according to the formula ratio corresponding to the measured soil type to obtain a rice selenium-enriched and cadmium-reducing synergistic conditioning agent; S5. Preliminary treatment of rice fields to ensure that the field surface is flat and there is a shallow water layer of 1-3 cm in the field; S6. Application of conditioner: Determine the application amount of conditioner according to the cadmium pollution in the soil. The application amount per mu of paddy fields with mild and moderate cadmium pollution is 80 kg and 120 kg respectively. Mix the conditioner and base fertilizer evenly and apply it to the surface of the field. Then, fully cultivate the field to make the conditioner, base fertilizer and soil evenly mixed. The cultivation depth is preferably 15-20 cm. S7. Keep the field surface flooded for 1 month, and then manage it according to local conventional water management methods.

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