A sowing method for controlling crops from absorbing cadmium and arsenic

Abstract

The application provides a sowing method for controlling crops to absorb cadmium and arsenic, a composite adsorbent material is prepared first, then the composite adsorbent material is saturatedly soaked in a selenium working solution or a silicon working solution, effective components of the working solution are sufficiently adsorbed to obtain a supported adsorbent material, the supported adsorbent material is applied to the bottom of a sowing hole to form a cover layer, and then the seeds are sowed and covered with soil, the application changes the traditional one-time seed soaking treatment into a slow-release supply controlled by the adsorbent material, the blocking and controlling effect of silicon / selenium covers the key growth period of crops, and the mode of large-area scattering of soil conditioners is changed, the blocking and controlling material is accurately concentrated around the roots, the amount of the material is small, and the efficiency is high, meanwhile, the composite adsorbent material with a specific ratio produces synergy in physical structure and chemical function, and the comprehensive blocking and controlling effect is better than the simple superposition of single materials or single technologies, the method is easy to combine with existing sowing or transplanting agronomy, does not increase complex procedures, and is convenient for popularization and application in agricultural production.

Description

Technical Field

[0001] This invention belongs to the field of crop cultivation technology, and specifically relates to a sowing method for controlling crop absorption of cadmium and arsenic. Background Technology

[0002] The "National Soil Pollution Status Survey Bulletin" reveals the severe state of soil pollution across the country. Cadmium and arsenic pollution has become one of the most pressing environmental problems. Cadmium levels have risen across the country, with an increase exceeding 50%. Sources of arsenic pollution in soil include both natural factors, such as weathering or geological changes of arsenic-containing rocks and minerals, and human activities, such as industrial emissions, mining, agricultural pollution, and the energy sector. High concentrations of cadmium and arsenic pollution not only adversely affect soil organisms but also accumulate in organisms through the food chain. Long-term accumulation can lead to chronic arsenic poisoning, damaging human tissues and organs, inducing diseases of the nervous, cardiovascular, respiratory, digestive, and reproductive systems, and may even cause cancer.

[0003] Existing technologies, such as CN202310710550.1, involve mixing the soil conditioner with the soil, resulting in poor targeting and large dosage requirements; CN201911268090.1 uses a seed soaking method, which has a short action time and is prone to silicon and selenium loss. Therefore, there is an urgent need for a method that can construct a long-lasting and stable barrier-controlled microenvironment in situ in the rhizosphere. Summary of the Invention

[0004] This invention provides a sowing method for inhibiting crop absorption of cadmium and arsenic by constructing a long-lasting, targeted microenvironment in the rhizosphere of crops to inhibit the absorption of cadmium and arsenic, thereby solving the above-mentioned problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A sowing method for controlling crop absorption of cadmium and arsenic includes the following steps: S1. Preparation of composite adsorbent material: Soil conditioner, volcanic rock and vermiculite are mixed in a specific mass ratio to form a matrix with a porous structure. Preferably, soil conditioner, volcanic rock and vermiculite are mixed uniformly in a mass ratio of 4-6:2-4:1-3. More preferably, soil conditioner, volcanic rock and vermiculite are mixed in a mass ratio of 5:3:2. S2. Preparation of supported adsorbent material: The composite adsorbent material obtained in step S1 is saturated in selenium working solution or silicon working solution to fully adsorb the effective components of the working solution, and then taken out and dried. S3. Co-site sowing: In the sowing operation, the loaded adsorbent material obtained in step S2 is applied to the bottom of the sowing hole to form a covering layer of a certain thickness. Then, the seeds are sown on the covering layer and covered with soil. S4. Seedling Transplanting at Co-location Sites: Place 20g of the loaded adsorbent material obtained in step S2 into a corn fiber tea bag and seal the bag. When manually transplanting rice seedlings, first insert the corn fiber tea bag containing the loaded composite adsorbent material into the paddy field soil to a depth of 3 cm, and then insert the rice seedlings into the corn fiber tea bag in the same location.

[0006] Further, the selenium working solution contains a selenium-containing compound, preferably sodium selenite; the silicon working solution contains a silicon-containing compound, preferably sodium metasilicate; the working solution may also contain auxiliary nutrients, such as EDTA-chelated iron and potassium dihydrogen phosphate. The silicon working solution is prepared in step S2 as follows: by mass, sodium metasilicate (0.13%-0.20%), EDTA-chelated iron (4%-6%), potassium dihydrogen phosphate (10%-20%), and water (73.80%-85.87%). The above substances are mixed evenly to form a solution, which is the silicon working solution. The selenium working solution is prepared as follows: by mass, sodium selenite (0.13%-0.20%), EDTA-chelated iron (4%-6%), potassium dihydrogen phosphate (10%-20%), and water (73.80%-85.87%). The above substances are mixed evenly to form a solution, which is the selenium working solution. This application achieves synergy in physical structure and chemical function through a specific ratio of composite adsorbent materials. Its comprehensive resistance and control effect is superior to the simple superposition of single materials or single technologies (such as seed soaking only), thus achieving a synergistic effect.

[0007] Furthermore, the saturated soaking mentioned in step S2 refers to the amount of adsorption working solution reaching 80%-95% of the saturated adsorption capacity of the composite adsorption material. This application transforms the traditional one-time seed soaking treatment into a slow-release supply controlled by the adsorption material, enabling the inhibition and control effect of silicon / selenium to cover the key growth period of crops, thus having the advantage of long-term inhibition and control.

[0008] Furthermore, in step S3, a covering layer of at least 2 cm thickness is formed at the bottom of the hole; this application changes the mode of large-area application of soil conditioner, and precisely concentrates the control material around the root system, which has the advantages of low dosage, high efficiency and targeted precision.

[0009] Furthermore, the soil conditioner is a material obtained by aerobic composting and fermentation of agricultural and forestry waste.

[0010] Furthermore, the method is applicable to rice sowing or seedling transplanting, enabling targeted application of the loaded adsorbent material to the co-sites of seeds or seedling roots. This method is easily integrated with existing sowing or transplanting agronomy, without adding complex procedures, facilitating its widespread application in agricultural production and making it practical for practical use.

[0011] This invention, through the innovative agronomic operation combining "pre-loading" and "co-site sowing," can construct a stable microenvironment in the rhizosphere region during the early stages of seed germination. This microenvironment simultaneously possesses the following functions: (1) Physical adsorption function: Cadmium and arsenic ions in the rhizosphere soil are directly fixed by porous composite adsorption materials; (2) Chemical passivation function: The loaded material can slowly release silicon or selenium ions, which can inhibit the absorption and transport of cadmium and arsenic by crops in a long-term manner through chemical competition and antagonism. (3) Ecological maintenance function: Provide good water and air conditions for seed germination and seedling growth, and promote root development.

[0012] Compared with the prior art, the present invention has the following advantages: This application provides a sowing method for controlling the absorption of cadmium and arsenic by crops. First, a composite adsorbent material is prepared. Then, the composite adsorbent material is saturated and soaked in a selenium or silicon working solution to fully adsorb the effective components of the working solution, resulting in a loaded adsorbent material. This loaded adsorbent material is applied to the bottom of the sowing hole to form a covering layer. Seeds are then sown and covered with soil. This application transforms the traditional one-time seed soaking treatment into a slow-release supply controlled by the adsorbent material, allowing the control effect of silicon / selenium to cover the critical growth period of the crop. It also changes the traditional method of large-area application of soil conditioners, precisely concentrating the control material around the root system, resulting in lower dosage and higher efficiency. Furthermore, the specific ratio of composite adsorbent materials creates synergy in physical structure and chemical function, resulting in a comprehensive control effect superior to the simple superposition of single materials or technologies. This method is easily integrated with existing sowing or transplanting agronomy, does not add complex procedures, and is convenient for widespread application in agricultural production. Detailed Implementation

[0013] To better understand the technical content of this invention and to provide a clear and complete description of the technical solution, some embodiments of this invention are provided below for further explanation. This should not be construed as limiting the scope of protection of this invention. Non-essential improvements or adjustments made to this invention by those skilled in the art based on these embodiments still fall within the scope of protection of this invention.

[0014] The specific technical solution of the present invention will be described below with reference to specific embodiments 1-2 and the comparative group: Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0015] In this embodiment, the reagent used to inhibit the absorption of cadmium and arsenic by rice is a silicon working solution or a selenium working solution. The soil conditioner is a humus-rich, well-rotted material made from crushed agricultural and forestry waste through aerobic fermentation. Volcanic rock and vermiculite were purchased directly online.

[0016] Example 1 A sowing method for controlling crop absorption of cadmium and arsenic, comprising the following steps: S1. Preparation of composite adsorbent material: The soil conditioner that has been aerobically fermented and decomposed, volcanic rock and vermiculite are mixed evenly in a mass ratio of 5:3:2 to obtain the composite adsorbent material. S2. Preparation of silicon working solution: Sodium metasilicate (0.18%), EDTA chelated iron (5%), potassium dihydrogen phosphate (15%), and water (balance) are mixed evenly to form a solution, which is the silicon working solution. S3. Preparation of silicon-supported adsorbent material: Immerse the above-mentioned composite adsorbent material in the prepared silicon working solution until the working solution reaches at least 80%-95% of its saturated adsorption capacity, i.e., load the composite adsorbent material at a ratio of 8-12 ml of working solution per gram of composite adsorbent material. Remove and air dry. S4. Co-site sowing: Germinated rice seeds are sown at the same site as silicon-supported adsorbent material. Specifically, silicon-supported composite adsorbent material is applied to the sowing holes in the rice nursery, forming a covering layer at least 2 cm thick at the bottom of the hole. Germinated rice seeds are then sown on top of this covering layer, and covered with soil, the thickness of which is 2-3 times the thickness of the seeds. When the rice seedlings are 25-30 days old, they are manually transplanted. S5. Rice Seedling Transplanting Pot Experiment: (This experiment was a verification test conducted in pots simulating heavily polluted farmland. The soil for the pots was ordinary red soil from Lianfeng Mountain in Zhongshan City, Guangdong Province. 25 mL of arsenic standard solution (1000 ug / mL) and 125 mL of cadmium standard solution (0.1 mg / mL) were added to every 25 kg of soil to prepare simulated heavily polluted cadmium and arsenic farmland soil.) 20 g of silicon-supported composite adsorbent material was placed in a corn fiber tea bag and the bag was sealed. When artificially transplanting rice seedlings aged 25-30 days, the corn fiber tea bag containing the silicon-supported composite adsorbent material was first inserted 3 cm into the potting soil, and then the rice seedlings were inserted into the corn fiber tea bag in the same position.

[0017] S6. Field management of potted rice should be carried out according to conventional methods. After the rice is harvested, the cadmium and arsenic content of the rice roots, stems, leaves, and grains should be measured.

[0018] Table 1: Cadmium and arsenic content (mg / kg) in various organs of the Shijiuxiang rice variety under silicon-supported adsorbent treatment conditions.

[0019] Note: Group A: The same composite adsorbent material (5:3:2) without soaking in the working solution during sowing; Group B: Only soak the seeds with the silicon working solution and do not add any adsorbent material during sowing; Group C: The method of the present invention, that is, soaking seeds + treating with pre-loaded adsorbent material at the co-site. Different letters (such as a, b) in the same row indicate significant differences.

[0020] As can be seen from the data in Table 1, under the treatment conditions of the silicon-loaded composite adsorbent material, there are significant differences in the cadmium, arsenic contents and yield of rice among the three treatment groups (Group A: Only apply the unloaded composite adsorbent material; Group B: Only soak the seeds with the silicon working solution; Group C: Soak the seeds in combination with applying the pre-loaded adsorbent material at the co-site).

[0021] Among them, Group C (the method of the present invention) has the most significant effect in reducing the cadmium and arsenic contents of rice and increasing the yield. The specific performance is as follows: (1) Cadmium reduction effect: The cadmium content in rice from low to high is in the order of Group C (1.625 mg / kg) < Group B (1.836 mg / kg) < Group A (3.990 mg / kg). The cadmium content in rice of Group C is significantly lower than that of the other two groups, and it is reduced by 59.3% compared with Group A and 11.5% compared with Group B.

[0022] (2) Arsenic reduction effect: The arsenic content in rice from low to high is in the order of Group C (0.455 mg / kg) < Group B (0.483 mg / kg) < Group A (0.609 mg / kg). The arsenic content in rice of Group C is also the lowest.

[0023] (3) Yield increase effect: The yield of Group C (458.741 kg / mu) is significantly higher than that of Group A (402.548 kg / mu) and Group B (410.741 kg / mu), and the increase rates reach 14.0% and 11.7% respectively.

[0024] The above results show that although Group A (only applying the unloaded adsorbent material) has a certain physical adsorption effect on cadmium, due to the material not being functionally loaded and being mixed and dispersed in the soil, it lacks targeting and chemical passivation ability, and the control effect is limited. Although Group B (only soaking seeds) provides a silicon source for the seeds in the early stage, after the seedlings are transplanted, the continuous supply of silicon is interrupted, resulting in the difficulty of maintaining the control effect for a long time. Group C (the method of the present invention) combines the advantages of "soaking seeds" and "applying pre-loaded materials at the co-site" and produces a synergistic effect.

[0025] External physical adsorption and targeted slow release: The composite adsorbent material pre-loaded with silicon forms a high-concentration "microzone" in the rhizosphere, which can not only physically adsorb and fix cadmium and arsenic, but also slowly release as a "reservoir" of silicon to achieve long-term chemical passivation.

[0026] Internal physiological enhancement: The supply of silicon promotes the development and thickening of root cell walls (manifested as higher fixation of cadmium and arsenic in the roots of groups B and C than in group A), enhancing the root system's internal retention capacity for cadmium and arsenic, forming a dual barrier of "external fixation - internal interception".

[0027] Synergistic effect mechanism: This invention uses "pre-loading-co-site" precision agronomy to organically combine external control (adsorption material) and internal control (silicon-induced physiological barrier) in space and time, thereby achieving continuous and efficient control of cadmium and arsenic absorption, and ultimately resulting in a significant reduction in cadmium and arsenic content in rice and a synergistic increase in yield.

[0028] The results strongly demonstrate that the integrated technical solution of "seed soaking + co-site application of preloaded adsorbent material" proposed in this invention does not simply add up the effects of a single technology (A or B), but produces a synergistic effect of "1+1>2", which has outstanding inventiveness and practicality.

[0029] Example 2 A sowing method for controlling crop absorption of cadmium and arsenic, comprising the following steps: S1. Preparation of composite adsorbent material: The composite adsorbent material is obtained by mixing aerobic fermented and decomposed soil conditioner, volcanic rock and vermiculite in a mass ratio of 5:3:2. S2. Preparation of selenium working solution: Sodium selenite (0.17%), EDTA chelated iron (4.5%), potassium dihydrogen phosphate (18%), and water (balance) are mixed evenly to form a solution, which is the selenium working solution. S3. Preparation of selenium-supported composite adsorbent material: Immerse the above-mentioned composite adsorbent material in the prepared selenium working solution until the working solution reaches at least 80%-95% of its saturated adsorption capacity, i.e., load the composite adsorbent material at a ratio of 8-12 ml of working solution per gram of composite adsorbent material. After immersion and drying, the selenium-supported composite adsorbent material is obtained. S4. Co-site sowing: Germinated rice seeds are sown at the same site as selenium-loaded adsorbent material. Specifically, selenium-loaded composite adsorbent material is applied to the sowing holes in the rice nursery, forming a covering layer at least 2 cm thick at the bottom of the hole. Germinated rice seeds are then sown on top of this covering layer, and covered with soil, the thickness of which is 2-3 times the thickness of the seeds. When the rice seedlings are 25-30 days old, they are manually transplanted. S5. Rice seedling transplanting: Put 20g of selenium-loaded composite adsorbent material into a corn fiber tea bag and seal the bag. When transplanting rice seedlings manually, first insert the corn fiber tea bag containing the selenium-loaded composite adsorbent material into the paddy field soil to a depth of 3 cm, and then insert the rice seedlings into the corn fiber tea bag in the same position. S6. Rice field management shall be carried out according to conventional methods. After rice harvest, the cadmium and arsenic content of rice roots, stems, leaves and grains shall be measured.

[0030] Table 2: Cadmium and arsenic content (mg / kg) in various organs of Guanghei glutinous rice variety under selenium-supported adsorbent treatment conditions.

[0031] Note: Group A: Seeds were sown using the same composite adsorbent material (5:3:2) without soaking in the working solution; Group B: Seeds were soaked only in the selenium working solution, without adding any adsorbent material at the time of sowing; Group C: The method of this invention, i.e., soaking + treatment with pre-loaded adsorbent material at co-sites. Different letters in the same row (e.g., a, b, c) indicate significant differences.

[0032] According to the experimental data in Table 2, under the treatment conditions of selenium-loaded composite adsorbent material, there were significant differences in the cadmium and arsenic content and yield of Guanghei glutinous rice in the three treatment groups (Group A: only unloaded composite adsorbent material was applied; Group B: only seed soaking in selenium working solution was performed; Group C: seed soaking combined with co-site application of pre-loaded adsorbent material). Among them, the method of the present invention (Group C: seed soaking + co-site treatment with pre-loaded adsorbent material) showed significant advantages in controlling cadmium and arsenic absorption in multiple dimensions and with synergistic effects, which are incomparable to those of single technologies.

[0033] 1. Core effect: Improved rice safety and yield (1) Significant reduction in cadmium: The cadmium content in rice of group C (0.961 mg / kg) was significantly lower than that of group A (2.962 mg / kg) and group B (2.150 mg / kg), with reductions of up to 67.6% and 55.3%, respectively. This indicates that the present invention has an extremely outstanding effect on the prevention and control of cadmium pollution in rice.

[0034] (2) High efficiency in reducing arsenic: The arsenic content in group C rice (0.265 mg / kg) was also the lowest among the three groups, significantly lower than that in group A (0.327 mg / kg) and group B (0.311 mg / kg), achieving synergistic control of cadmium and arsenic compound pollution.

[0035] (3) Significant increase in yield: The yield of group C (347.186 kg / mu) was comparable to that of group B, and both were significantly higher than that of group A (311.217 kg / mu), proving that the present invention can maintain or even improve crop productivity while ensuring food safety.

[0036] 2. Mechanism of action: Selenium's dual synergistic effect of "rhizosphere fixation - in vivo barrier" Unlike silicon processing, data from selenium processing reveals its unique and more efficient resistivity mode: (1) Rhizosphere "fixation-passivation" microenvironment: Group C (the present invention) had the highest root arsenic content (8.390 mg / kg), and the root cadmium content was significantly lower than that of Group A. This strongly indicates that the rhizosphere microenvironment created by the method of the present invention can greatly promote the rhizosphere fixation of arsenic by selenium. The pre-loaded selenium is continuously released in the rhizosphere, which may form insoluble compounds with arsenic or compete for adsorption sites, thereby "locking" a large amount of arsenic in the roots and preventing its upward transport.

[0037] (2) In vivo “interception-diversion” transport barrier: The stem arsenic content of group C (0.193 mg / kg) was the lowest among the three groups and significantly lower than that of group B. This reveals the key mechanism: The continuous selenium source provided by this invention can not only fix arsenic in the roots, but also form an efficient interception and diversion of the absorbed arsenic during the transport process of the plant’s vascular bundles, which greatly hinders the migration of arsenic to the grains.

[0038] (3) Synergistic and decoupling of cadmium and arsenic control: For cadmium, Group C achieves the lowest cadmium level through the combined effect of "physical fixation by adsorption materials + physiological barrier of selenium". For arsenic, control is mainly achieved through the dual mechanisms of "rhizosphere fixation" and "in vivo interception" of selenium. This demonstrates the synergistic and targeted control capability of this invention for cadmium and arsenic, two pollutants with different properties.

[0039] 3. Conclusion: The irreplaceable nature of the method of this invention Comprehensive data shows that: (1) Group A (using only adsorption materials) lacks chemical passivation function and has a weak effect on selenium / arsenic complexation.

[0040] (2) Although Group B (seed soaking only) had a certain effect, the short-term supply of selenium could not establish a long-term rhizosphere fixation bank and in vivo interception barrier. Therefore, the arsenic content in rice was higher than that in Group C, and the arsenic content in stems was abnormally high, indicating that the transport of arsenic was not effectively blocked.

[0041] (3) Group C (the present invention) achieves the following through the integrated design of "seed soaking (initial protection) + pre-loaded materials (long-lasting sustained release and rhizosphere construction)": a. Spatial coordination: Establishing control barriers simultaneously in the rhizosphere (external) and vascular bundles (internal).

[0042] b. Time coordination: ensures continuous function throughout the entire growth period from seed germination to crop maturity.

[0043] c. Synergistic Function: It leverages the dual benefits of physical fixation by the adsorbent material and chemical and biological passivation by selenium.

[0044] Therefore, the method of the present invention exhibits the distinct characteristics and outstanding effects of "enriching and fixing arsenic in the rhizosphere and blocking the transport of arsenic in vivo" in terms of selenium-based arsenic control, which fully demonstrates the non-obviousness and prominent substantive features of the present technical solution, which cannot be achieved by simply superimposing existing single technical means.

[0045] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A sowing method for controlling crop absorption of cadmium and arsenic, characterized in that, Includes the following steps: S1. Preparation of composite adsorbent material: Soil conditioner, volcanic rock and vermiculite are mixed uniformly in a mass ratio of 4-6:2-4:1-3; S2. Preparation of supported adsorbent material: The composite adsorbent material obtained in step S1 is saturated in selenium working solution or silicon working solution, then taken out and dried. S3. Co-site sowing: Apply the loaded adsorbent material obtained in step S2 into the sowing hole to form a covering layer at least 2 cm thick at the bottom of the hole, and then sow the seeds on the covering layer and cover with soil.

2. The sowing method for controlling crop absorption of cadmium and arsenic according to claim 1, characterized in that, It also includes the following steps: S4. Seedling transplanting at co-location sites: The loaded adsorbent material obtained in step S2 is placed into a tea bag, the bag is sealed, and the tea bag is inserted into the paddy field soil to a depth of 2-4 cm. When the rice seedlings in step S3 are 25-30 days old, the rice seedlings are inserted into the tea bag in the same location.

3. The sowing method for controlling crop absorption of cadmium and arsenic according to claim 1, characterized in that: Soil conditioner, volcanic rock and vermiculite are mixed in a mass ratio of 5:3:

2.

4. The sowing method for controlling crop absorption of cadmium and arsenic according to claim 1, characterized in that: The selenium working solution in step S2 includes sodium selenite at a mass percentage of 0.13%-0.20%.

5. The sowing method for controlling crop absorption of cadmium and arsenic according to claim 1, characterized in that: The silicon working solution in step S2 includes sodium metasilicate at a mass percentage of 0.13%-0.20%.

6. The sowing method for controlling crop absorption of cadmium and arsenic according to any one of claims 1-5, characterized in that: The selenium working solution or silicon working solution also contains EDTA-chelated iron and potassium dihydrogen phosphate.

7. The sowing method for controlling crop absorption of cadmium and arsenic according to claim 6, characterized in that: In the selenium working solution or silicon working solution, the EDTA chelated iron has a mass percentage of 4%-6%, and the potassium dihydrogen phosphate has a mass percentage of 10%-20%.

8. The sowing method for controlling crop absorption of cadmium and arsenic according to claim 1, characterized in that: The saturated soaking mentioned in step S2 refers to the amount of adsorption working liquid reaching 80%-95% of the saturated adsorption capacity of the composite adsorption material.

9. The sowing method for controlling crop absorption of cadmium and arsenic according to claim 1, characterized in that: The soil conditioner is a material obtained by aerobic composting and fermentation of agricultural and forestry waste.

10. The sowing method for controlling crop absorption of cadmium and arsenic according to claim 1, characterized in that: The crop in question is rice.

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