Rice cadmium reducing agent based on synergy of red mud and cysteine and use method of rice cadmium reducing agent

Abstract

The invention discloses a rice cadmium reducing agent based on red mud and cysteine synergism and a use method thereof. The application amount of each component in the cadmium reducing agent is as follows: 30-50g / m < 2 > of red mud and 10-20g / m < 2 > of cysteine. The cadmium reducing agent is applied to soil with sufficient water before plowing of rice, the soil is uniformly plowing after standing, and then the rice is transplanted; the synergistic effect of a very small amount of red mud and a small amount of cysteine in soil is utilized; the cadmium content in the brown rice is reduced by about 95%, and is reduced to about 0.04 mg / kg under a specific rice variety; the operation is simple, the raw materials are solid wastes, the waste pollution risk of the soil is reduced under the condition of extremely small dosage, the raw materials are easy to obtain, the cost is extremely low, and the method has extremely good popularization and application prospects.

Description

Technical Field

[0001] This invention relates to the field of agricultural soil cadmium reduction and conditioning technology, specifically to a rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine, and its application method. Background Technology

[0002] Cadmium constitutes 15-30% of the soil environment in its water-soluble form, and its absorption efficiency by crops is 3-5 times higher than that of lead, making it highly susceptible to bioaccumulation in crops and entry into the food chain. Epidemiological studies show that for every 0.1 mg / kg increase in cadmium content in rice, the corresponding 8.7% increase in urinary cadmium levels in humans, causing irreversible damage to the kidneys and skeletal system.

[0003] Existing chemical passivation methods, such as phosphate amendments, can reduce available cadmium by 40-60%, but long-term use leads to a decrease in soil pH by 0.8-1.5 units, causing secondary acidification. Biochar adsorption can fix cadmium up to 70%, but its carbon skeleton undergoes oxidative decomposition under flooded conditions, with a half-life of only 2-3 seasons, which actually promotes cadmium reactivation. Microbial remediation: the survival rate of functional strains in organic matter soils with OM < 1.5% is less than 20%, and the remediation effect is unstable.

[0004] When soil is in a flooded anaerobic environment for a long time, the redox potential (Eh) drops to -150~-200mV, which promotes the dissolution of iron and manganese oxides and releases bound cadmium. The rate of organic matter mineralization is accelerated by 60-80%, which reduces the soil cation exchange capacity by more than 30% and seriously weakens the soil's ability to fix cadmium.

[0005] To address the aforementioned problems, this invention utilizes the synergistic effect of a very small amount of red mud and a small amount of cysteine ​​in the soil to significantly reduce the cadmium content in brown rice, demonstrating excellent prospects for widespread application. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine, and its application method. The application amount of each component in this cadmium-reducing agent is: red mud 30-50 g / m³. 2 Cysteine ​​10-20g / m 2 The cadmium-reducing agent is applied to moist soil before rice cultivation, allowed to stand, and then evenly cultivated before transplanting. This invention utilizes the synergistic effect of a very small amount of red mud and a small amount of cysteine ​​in the soil to reduce the cadmium content in brown rice by about 95%, and as low as about 0.04 mg / kg for certain rice varieties. The operation is simple, the raw material is solid waste, and the amount used reduces the risk of soil waste pollution. The raw materials are readily available and the cost is extremely low, making it a promising candidate for widespread application.

[0007] To achieve the above technical effects, the following technical solution is adopted: A rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine, the components of which are: red mud and cysteine; The dosage of each component is as follows: Red mud 30-50g / m 2 Cysteine ​​10-20g / m 2 .

[0008] Furthermore, the red mud 40g / m 2 Cysteine ​​20g / m 2 .

[0009] Furthermore, the red mud needs to be obtained by calcination, specifically: Uncalcined red mud is calcined at 600-1000 ℃ for 4-8 h, then ground and sieved to make its particle size less than 100 μm.

[0010] Furthermore, based on a total weight percentage of 100%, the mass percentages of each major component in the red mud are as follows: SiO2 40%~45%, Al2O3 25%~35%, Fe2O3 20%~25%, K2O 1%~5%, TiO2 1%~5%, CaO 0.5%~1%, MgO 0.1%~0.5%, and its loss on ignition is 0.5%~5%.

[0011] A method for applying a rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine ​​is as follows: Before rice cultivation, apply the rice cadmium-reducing agent to the soil, let it stand, then cultivate it evenly before transplanting the rice.

[0012] Furthermore, the soil moisture content is greater than 30%.

[0013] Furthermore, when using the rice cadmium-reducing agent, first apply red mud into the soil according to the mass ratio, till it evenly, then apply cysteine ​​according to the mass ratio, till it evenly, and then transplant rice seedlings.

[0014] Furthermore, after the red mud is applied, it is tilled evenly and then left to stand for 7-15 days.

[0015] Furthermore, after applying cysteine ​​and tilling the soil evenly, the rice seedlings are transplanted after standing for 5-10 days.

[0016] The beneficial effects of this invention are as follows: This invention discloses a rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine, and its application method. The application amount of each component in the cadmium-reducing agent is: red mud 30-50 g / m³. 2 Cysteine ​​10-20g / m 2The cadmium-reducing agent is applied to moist soil before rice cultivation, allowed to stand, and then evenly cultivated before transplanting. This invention utilizes the synergistic effect of a very small amount of red mud and a small amount of cysteine ​​in the soil to reduce the cadmium content in brown rice by about 95%, and as low as about 0.04 mg / kg for certain rice varieties. The operation is simple, the raw material is solid waste, and the amount used reduces the risk of soil waste pollution. The raw materials are readily available and the cost is extremely low, making it a promising candidate for widespread application. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0018] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0020] The preparation method of the red mud in the following examples and comparative examples is as follows: Red clay needs to be obtained through calcination, specifically: Uncalcined red mud was calcined at 800°C for 6 hours, then ground and sieved to reduce its particle size to less than 100 μm.

[0021] Based on a total weight percentage of 100%, the mass percentages of the main components in red mud are as follows: SiO2 40%~45%, Al2O3 25%~35%, Fe2O3 20%~25%, K2O 1%~5%, TiO2 1%~5%, CaO 0.5%~1%, MgO 0.1%~0.5%, and its loss on ignition is 0.5%~5%.

[0022] Example 1: A rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine: Red mud dosage is 30g / m³ 2 The dosage of cysteine ​​is 10g / m². 2 Instructions for use are provided below.

[0023] Example 2: A rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine: Red mud dosage is 50 g / m³ 2 The dosage of cysteine ​​is 20g / m². 2 Instructions for use are provided below.

[0024] Example 3: A rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine: Red mud dosage is 40g / m³ 2 The dosage of cysteine ​​is 20g / m². 2 Instructions for use are provided below.

[0025] All comparative examples are based on Example 3.

[0026] Comparative Example 1: Cadmium-reducing agent for rice: Red mud dosage is 60g / m³ 2 Instructions for use are provided below.

[0027] Comparative Example 2: Rice cadmium-lowering agent: Cysteine ​​dosage is 60g / m³ 2 Instructions for use are provided below.

[0028] Comparative Example 3: No cadmium-reducing agent was added to the rice; it was used directly as a control group.

[0029] The cadmium-reducing agents in Examples 1-3 and Comparative Examples 1-3 are evaluated below: A field trial was conducted in a safe utilization area in Xinyu City. The soil in the experimental field had a pH of 5.44, total cadmium of 0.87 mg / kg, and organic matter content of 29.1 g / kg, classifying it as gleyed paddy soil with moderate overall fertility. The entire field was divided into 18 plots, each with an area of ​​20 m². 2 The field ridges were cut in half and covered with mulch. Each treatment area was set up with 3 replicate plots, for a total of 6 treatment areas. Treatment area 1 was the blank control group CK (no cadmium-reducing agent was applied, i.e., comparative example 3). Treatment areas 2-6 were the cadmium-reducing agents in Examples 1-3 and Comparative Examples 1-2, respectively. All plots were planted with Zhongdao Cenliangyou 1810.

[0030] Different treatment zones were simultaneously treated with the cadmium-reducing agents described in Examples 1-3 and Comparative Examples 1-3 (the blank control group CK was not treated with any cadmium-reducing conditioner material), and the soil was manually tilled to ensure that the fertilizer and cadmium-reducing agent were fully mixed with the soil.

[0031] The specific usage method is as follows: Before rice cultivation, the soil moisture content needs to be greater than 30%. First, apply red mud into the soil according to the mass ratio, cultivate it evenly, and let it stand for 10 days. Then, apply cysteine ​​according to the mass ratio, cultivate it evenly, and let it stand for 7 days before transplanting rice seedlings.

[0032] Rice seedlings are raised in the field. Three days before transplanting, apply 40 kg / mu of compound fertilizer (total nutrient content 45%, of which N-P2O5-K2O=15-15-15).

[0033] The transplanting process was carried out manually. After the rice turned green, 10 kg / mu of urea was applied as topdressing during the tillering stage. Other field water and fertilizer management methods and pest and disease control methods were consistent with the traditional methods. After the rice matured, the yield of each plot was measured and the cadmium content in the brown rice was determined. Soil samples were collected from each plot. The collection method was as follows: each plot was divided into 9 square grids, and 500g of soil was taken from the center of each square grid. All the soil samples from each plot were mixed evenly, and a small amount was taken for testing. The test was repeated 10 times, and the average value was taken to determine the available cadmium in the soil (DTPA extractable state, i.e., the standard test method of GB / T 23739-2009). The cadmium passivation rate of the soil was calculated. The test results are shown in Table 2.

[0034] The method for determining the cadmium content in brown rice was as follows: 0.1 g of brown rice powder sample was taken, 5 mL of nitric acid and 3.0 mL of hydrogen peroxide solution were added, the mixture was capped and allowed to cold digest overnight. Digestion was then performed using a graphite digester for 2 hours, and the volume was adjusted to 25 mL. The cadmium concentration in the digest was analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The experimental results are shown in Table 1. Table 1. Differences in rice yield and cadmium content in brown rice among treatments.

[0035] Note 1: Except for the treatment method, all other conventional cultivation methods are the same for the groups in the table.

[0036] Note 2: According to the requirements of GB 2762-2022 National Food Safety Standard for Limits of Contaminants in Food, the cadmium content of qualified rice is less than or equal to 0.2 mg / kg.

[0037] Table 2. Differences in available cadmium in soil among different treatments

[0038] Based on the experimental results of the above embodiments, this invention utilizes the synergistic effect of a very small amount of red mud and a small amount of cysteine ​​in the soil to reduce the available cadmium in the soil by about 75% and the cadmium content in brown rice by about 95%, down to about 0.04 mg / kg for specific rice varieties. The operation is simple, the raw material is solid waste, and the use of very small amounts reduces the risk of soil pollution from waste materials. This solves the technical problem in existing technologies where soil cadmium-reducing conditioners alone cannot significantly reduce the cadmium content in brown rice.

[0039] In summary, this invention discloses a rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine, and its application method. The dosage of each component in this cadmium-reducing agent is: red mud 30-50 g / m³. 2 Cysteine ​​10-20g / m 2 The cadmium-reducing agent is applied to well-moistened soil before rice cultivation. After settling, it is tilled evenly before transplanting the rice. This invention utilizes the synergistic effect of a very small amount of red mud and a small amount of cysteine ​​in the soil to reduce the available cadmium in the soil by about 75% and the cadmium content in brown rice by about 95%, down to about 0.04 mg / kg for certain rice varieties. The operation is simple, the raw material is solid waste, and the use of very small amounts reduces the risk of soil waste pollution. The raw materials are readily available and the cost is extremely low, making it a promising candidate for widespread application.

[0040] Therefore, those skilled in the art will recognize that although embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should be understood and recognized as covering all such other variations or modifications.

Claims

1. A rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine, characterized in that, The components of the rice cadmium-reducing agent are: red mud and cysteine; The dosage of each component is as follows: Red mud 30-50g / m 2 Cysteine ​​10-20g / m 2 .

2. The rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine ​​as described in claim 1, characterized in that, The red mud 40g / m 2 Cysteine ​​20g / m 2 .

3. The rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine ​​as described in claim 1, characterized in that, The red mud needs to be obtained by calcination, specifically: Uncalcined red mud is calcined at 600-1000 ℃ for 4-8 h, then ground and sieved to make its particle size less than 100 μm.

4. The rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine ​​as described in claim 1, characterized in that, Based on a total weight percentage of 100%, the mass percentages of the main components in the red mud are as follows: SiO2 40%~45%, Al2O3 25%~35%, Fe2O3 20%~25%, K2O 1%~5%, TiO2 1%~5%, CaO 0.5%~1%, MgO 0.1%~0.5%, and its loss on ignition is 0.5%~5%.

5. The method of using a rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine ​​as described in claim 1, characterized in that, The specific usage method is as follows: Before rice cultivation, apply the rice cadmium-reducing agent to the soil, let it stand, then cultivate it evenly before transplanting the rice.

6. The method of using a rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine ​​as described in claim 5, characterized in that, The soil moisture content is greater than 30%.

7. The method of using a rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine ​​as described in claim 5, characterized in that, When using the rice cadmium-reducing agent, first apply red mud into the soil according to the mass ratio, till it evenly, then apply cysteine ​​according to the mass ratio, till it evenly, and then transplant rice seedlings.

8. The method of using a rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine ​​as described in claim 5, characterized in that, After the red mud is applied, it is tilled evenly and then left to stand for 7-15 days.

9. The method of using a rice cadmium-reducing agent based on the synergistic effect of red mud and cysteine ​​as described in claim 5, characterized in that, After applying cysteine ​​and tilling the soil evenly, the rice seedlings are transplanted after standing for 5-10 days.

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