A Composite Cadmium-Reducing Conditioner Based on Kudzu Residue Vermicompost and Its Application Method

Abstract

The present invention discloses a composite cadmium-reducing conditioner based on kudzu residue earthworm manure and an application method thereof. The mass ratio of each component in the cadmium-reducing conditioner is: 35-40 parts of oyster shell powder, 30-45 parts of kudzu residue earthworm manure, 3-5 parts of zinc fulvate, 8-10 parts of sodium sulfide, and 3-5 parts of manganese sulfate; before plowing the paddy field, the cadmium-reducing conditioner is applied to the soil, left standing and then plowed, and then the rice is transplanted; the present invention utilizes earthworm manure to activate the organic matter components in kudzu residue, and uses earthworms to remove cadmium from kudzu residue. The active components in kudzu residue earthworm manure and the active components such as amino acids in oyster shell powder act together with zinc fulvate, manganese fertilizer and sodium sulfide. Coupled with the adsorption and degradation of oyster shell powder and kudzu residue earthworm manure, and the effect of increasing soil organic matter, the cadmium content in brown rice of rice can be synergistically reduced to about 0.1 mg / kg; the operation is simple, and the raw materials are solid wastes and are easily obtained.

Description

Technical Field

[0001] The present invention relates to the field of agricultural technologies, and particularly relates to a composite cadmium-reducing conditioner based on kudzu residue and earthworm manure and an application method thereof. Background Art

[0002] Cadmium in the soil environment exhibits extremely high mobility and bioavailability characteristics, making it extremely easy for crops to absorb and accumulate cadmium during the growth process. Subsequently, through the transfer of the food chain, it ultimately enters the human body, posing a very serious potential hazard to human health.

[0003] Currently, the technical means developed for the treatment of soil cadmium pollution are diverse. However, each type of technology has obvious limitations. Take chemical remediation methods, such as adding chemical amendments to the soil, which can change the occurrence form of cadmium in the soil and thereby reduce its bioavailability. However, long-term reliance on such chemical means is very likely to cause a series of negative effects such as soil acidification and hardening, seriously interfering with the normal activity of soil microorganisms and causing irreversible damage to the balance and stability of the soil ecosystem.

[0004] In the rice planting system, the soil is in a long-term flooded and anaerobic environment. Under this condition, the rapid mineralization and decomposition of soil organic matter lead to a decrease in the adsorption capacity of the soil for cadmium, thereby increasing the bioavailability of cadmium in rice plants and greatly increasing the potential risk of cadmium pollution in rice. Traditional cadmium pollution remediation technologies have limitations in dealing with the complex problem of coexistence of soil organic matter deficiency and cadmium pollution, and it is difficult to achieve ideal results in the treatment of rice planting soil.

[0005] Under this background, the present invention proposes a composite cadmium-reducing conditioner based on kudzu residue and earthworm manure; this conditioner can significantly improve the adsorption and fixation ability of the soil for heavy metal cadmium, inhibit the activity and migration of cadmium from the source, and provide a scientific, efficient and environmentally friendly systematic solution for the treatment of cadmium pollution in rice planting soil. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art, and provide a composite cadmium-reducing conditioner based on kudzu residue earthworm manure and an application method thereof. The mass ratio of each component in the cadmium-reducing conditioner is: 35-40 parts of oyster shell powder, 30-45 parts of kudzu residue earthworm manure, 3-5 parts of zinc fulvate, 8-10 parts of sodium sulfide and 3-5 parts of manganese sulfate; before plowing the paddy field, apply the cadmium-reducing conditioner to the soil, let it stand and then plow, and then transplant the rice; the present invention uses earthworm manure to activate the organic matter components in kudzu residue, and uses earthworms to remove cadmium from kudzu residue. The active components in kudzu residue earthworm manure and the active components such as amino acids in oyster shell powder act together with zinc fulvate, manganese fertilizer and sodium sulfide. Coupled with the adsorption and degradation of oyster shell powder and kudzu residue earthworm manure, and the effect of increasing soil organic matter, the cadmium content in brown rice of paddy rice can be synergistically reduced to 0.1 mg / kg; the operation is simple and the raw materials are easy to obtain.

[0007] To achieve the above technical effects, the following technical solutions are adopted:

[0008] A composite cadmium-reducing conditioner based on kudzu residue earthworm manure, comprising the following components:

[0009] Oyster shell powder, kudzu residue earthworm manure, zinc fulvate, sodium sulfide and manganese sulfate.

[0010] Further, the formula of the composite cadmium-reducing conditioner components is:

[0011] 35-40 parts of oyster shell powder, 30-45 parts of kudzu residue earthworm manure, 3-5 parts of zinc fulvate, 8-10 parts of sodium sulfide and 3-5 parts of manganese sulfate.

[0012] Further, the mesh number of the oyster shell powder is 50-100 meshes.

[0013] Further, the kudzu residue earthworm manure is dried and ground into 80-150 meshes.

[0014] Further, the zinc fulvate, sodium sulfide and manganese sulfate are ground into 80-150 meshes.

[0015] Further, the preparation method of the kudzu residue earthworm manure is specifically as follows:

[0016] Step S1: Take fresh kudzu residue, adjust the moisture content to 60%-70%, stack and ferment for 20-25 days, turn the pile every 5-8 days to control the pile temperature at 50-60 °C;

[0017] Step S2: Place earthworm seeds in the materials obtained by fermentation in Step S1, with a stocking density of 10-15 earthworm seeds per kilogram of dry material, and re-stock once every 20 days, and then separate the earthworms from the earthworm manure to obtain kudzu residue earthworm manure;

[0018] Among them, the survival temperature of the earthworms is set at 25±10°C to ensure the normal reproduction of the earthworms.

[0019] Furthermore, the application method is specifically as follows:

[0020] Before plowing the paddy field, apply the compound cadmium-reducing conditioner to the soil, let it stand and then plow, and then transplant the rice.

[0021] Furthermore, it is applied to the soil 5 - 10 days before plowing the paddy field.

[0022] Furthermore, the dosage of the compound cadmium-reducing conditioner is 150 - 250 kg / mu.

[0023] The beneficial effects of the present invention are as follows:

[0024] The present invention discloses a compound cadmium-reducing conditioner based on kudzu residue earthworm manure and an application method. The mass ratio of each component in the cadmium-reducing conditioner is: 35 - 40 parts of oyster shell powder, 30 - 45 parts of kudzu residue earthworm manure, 3 - 5 parts of zinc fulvate, 8 - 10 parts of sodium sulfide, and 3 - 5 parts of manganese sulfate; apply the cadmium-reducing conditioner to the soil before plowing the paddy field, let it stand and then plow, and then transplant the rice; the present invention utilizes earthworm manure to activate the organic matter components in kudzu residue, and uses earthworms to remove cadmium from kudzu residue. The active components in kudzu residue earthworm manure and the active components such as amino acids in oyster shell powder act together with zinc fulvate, manganese fertilizer, and sodium sulfide. Coupled with the adsorption and degradation of oyster shell powder and kudzu residue earthworm manure, and the effect of increasing soil organic matter, the cadmium content in brown rice of paddy rice can be synergistically reduced, and the cadmium content in brown rice of paddy rice can be reduced to 0.1 mg / kg; the operation is simple and the raw materials are easily available. Specific Embodiments

[0025] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with 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.

[0026] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further descriptions of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0028] The preparation method of kudzu residue earthworm manure in the following examples and comparative examples is specifically as follows:

[0029] Step S1: Take fresh kudzu residue, adjust the moisture content to 65%, stack and ferment for 25 days, turn the pile every 6 days, and control the pile temperature at 55°C;

[0030] Step S2: Place earthworm seeds in the material obtained by fermentation in Step S1, with a stocking density of 12 earthworm seeds per kilogram of dry material, and re-stock once every 20 days. Then separate the earthworms from the earthworm manure to obtain kudzu residue earthworm manure;

[0031] Among them, the survival temperature of the earthworms is set at 28°C to ensure the normal reproduction of the earthworms.

[0032] Example 1:

[0033] Mix 35 parts of oyster shell powder with 100 meshes, 45 parts of kudzu residue earthworm manure with 150 meshes, 3 parts of fulvic acid zinc with 150 meshes, 8 parts of sodium sulfide with 150 meshes, and 5 parts of manganese sulfate with 150 meshes evenly to obtain Compound Cadmium Reduction Conditioner 1.

[0034] Example 2:

[0035] Mix 40 parts of oyster shell powder with 50 meshes, 30 parts of kudzu residue earthworm manure with 80 meshes, 5 parts of fulvic acid zinc with 80 meshes, 10 parts of sodium sulfide with 80 meshes, and 3 parts of manganese sulfate with 80 meshes evenly to obtain Compound Cadmium Reduction Conditioner 2.

[0036] All comparative examples are based on Example 1.

[0037] Comparative Example 1:

[0038] Mix 80 parts of kudzu residue earthworm manure with 150 meshes, 3 parts of fulvic acid zinc with 150 meshes, 8 parts of sodium sulfide with 150 meshes, and 5 parts of manganese sulfate with 150 meshes evenly to obtain Compound Cadmium Reduction Conditioner 3.

[0039] Comparative Example 2:

[0040] Mix 80 parts of oyster shell powder with 100 meshes, 3 parts of fulvic acid zinc with 150 meshes, 8 parts of sodium sulfide with 150 meshes, and 5 parts of manganese sulfate with 150 meshes evenly to obtain Compound Cadmium Reduction Conditioner 4.

[0041] Comparative Example 3:

[0042] Mix 35 parts of oyster shell powder with 100 meshes, 45 parts of kudzu residue earthworm manure with 150 meshes, 8 parts of sodium sulfide with 150 meshes, and 8 parts of manganese sulfate with 150 meshes evenly to obtain Compound Cadmium Reduction Conditioner 5.

[0043] Comparative Example 4:

[0044] Mix 35 parts of oyster shell powder with 100 mesh, 45 parts of kudzu residue vermicompost with 150 mesh, 11 parts of zinc fulvate with 150 mesh, and 5 parts of manganese sulfate with 150 mesh evenly to obtain the composite cadmium-reducing conditioner 6.

[0045] Comparative Example 5:

[0046] Mix 35 parts of oyster shell powder with 100 mesh, 45 parts of kudzu residue vermicompost with 150 mesh, 8 parts of zinc fulvate with 150 mesh, and 8 parts of sodium sulfide with 150 mesh evenly to obtain the composite cadmium-reducing conditioner 7.

[0047] Comparative Example 6:

[0048] Mix 80 parts of kudzu residue vermicompost with 150 mesh, 8 parts of sodium sulfide with 150 mesh, and 8 parts of manganese sulfate with 150 mesh evenly to obtain the composite cadmium-reducing conditioner 8.

[0049] Comparative Example 7:

[0050] Mix 80 parts of kudzu residue vermicompost with 150 mesh, 3 parts of zinc fulvate with 150 mesh, and 13 parts of manganese sulfate with 150 mesh evenly to obtain the composite cadmium-reducing conditioner 9.

[0051] Comparative Example 8:

[0052] Mix 80 parts of kudzu residue vermicompost with 150 mesh, 8 parts of zinc fulvate with 150 mesh, and 8 parts of sodium sulfide with 150 mesh evenly to obtain the composite cadmium-reducing conditioner 10.

[0053] Comparative Example 9:

[0054] Mix 80 parts of oyster shell powder with 100 mesh, 8 parts of sodium sulfide with 150 mesh, and 8 parts of manganese sulfate with 150 mesh evenly to obtain the composite cadmium-reducing conditioner 11.

[0055] Comparative Example 10:

[0056] Mix 80 parts of oyster shell powder with 100 mesh, 3 parts of zinc fulvate with 150 mesh, and 13 parts of manganese sulfate with 150 mesh evenly to obtain the composite cadmium-reducing conditioner 12.

[0057] Comparative Example 11:

[0058] Mix 80 parts of oyster shell powder with 100 mesh, 8 parts of zinc fulvate with 150 mesh, and 8 parts of sodium sulfide with 150 mesh evenly to obtain the composite cadmium-reducing conditioner 13.

[0059] Comparative Example 12:

[0060] Mix 35 parts of oyster shell powder with 100 mesh, 45 parts of kudzu residue vermicompost with 150 mesh, and 16 parts of manganese sulfate with 150 mesh evenly to obtain the composite cadmium-reducing conditioner 14.

[0061] Comparative Example 13:

[0062] Mix 35 parts of oyster shell powder with 100 mesh, 45 parts of kudzu residue vermicompost with 150 mesh, and 16 parts of sodium sulfide with 150 mesh evenly to obtain 15 parts of the composite cadmium-reducing conditioner.

[0063] Comparative Example 14:

[0064] Mix 35 parts of oyster shell powder with 100 mesh, 45 parts of kudzu residue vermicompost with 150 mesh, and 16 parts of zinc fulvate with 150 mesh evenly to obtain 16 parts of the composite cadmium-reducing conditioner.

[0065] Comparative Example 15:

[0066] Mix 80 parts of kudzu residue vermicompost with 150 mesh and 16 parts of manganese sulfate with 150 mesh evenly to obtain 17 parts of the composite cadmium-reducing conditioner.

[0067] Comparative Example 16:

[0068] Mix 80 parts of kudzu residue vermicompost with 150 mesh and 16 parts of sodium sulfide with 150 mesh evenly to obtain 18 parts of the composite cadmium-reducing conditioner.

[0069] Comparative Example 17:

[0070] Mix 80 parts of kudzu residue vermicompost with 150 mesh and 16 parts of zinc fulvate with 150 mesh evenly to obtain 19 parts of the composite cadmium-reducing conditioner.

[0071] Comparative Example 18:

[0072] Mix 80 parts of oyster shell powder with 100 mesh and 16 parts of manganese sulfate with 150 mesh evenly to obtain 20 parts of the composite cadmium-reducing conditioner.

[0073] Comparative Example 19:

[0074] Mix 80 parts of oyster shell powder with 100 mesh and 16 parts of sodium sulfide with 150 mesh evenly to obtain 21 parts of the composite cadmium-reducing conditioner.

[0075] Comparative Example 20:

[0076] Mix 80 parts of oyster shell powder with 100 mesh and 16 parts of zinc fulvate with 150 mesh evenly to obtain 22 parts of the composite cadmium-reducing conditioner.

[0077] Comparative Example 21:

[0078] Mix 96 parts of kudzu residue vermicompost with 150 mesh evenly to obtain 23 parts of the composite cadmium-reducing conditioner.

[0079] Comparative Example 22:

[0080] Mix 96 parts of oyster shell powder with 100 mesh evenly to obtain 24 parts of the composite cadmium-reducing conditioner.

[0081] Comparative Example 23:

[0082] Mix 35 parts of bentonite with 100 mesh, 45 parts of kudzu residue vermicompost with 150 mesh, 3 parts of zinc fulvate with 150 mesh, 8 parts of sodium sulfide with 150 mesh, and 5 parts of manganese sulfate with 150 mesh evenly to obtain Compound Cadmium-removing Conditioner 25.

[0083] Comparative Example 24:

[0084] Mix 35 parts of quicklime with 100 mesh, 45 parts of kudzu residue vermicompost with 150 mesh, 3 parts of zinc fulvate with 150 mesh, 8 parts of sodium sulfide with 150 mesh, and 5 parts of manganese sulfate with 150 mesh evenly to obtain Compound Cadmium-removing Conditioner 26.

[0085] Comparative Example 25:

[0086] Mix 35 parts of attapulgite with 100 mesh, 45 parts of kudzu residue vermicompost with 150 mesh, 3 parts of zinc fulvate with 150 mesh, 8 parts of sodium sulfide with 150 mesh, and 5 parts of manganese sulfate with 150 mesh evenly to obtain Compound Cadmium-removing Conditioner 27.

[0087] Comparative Example 26:

[0088] Mix 35 parts of oyster shell powder with 100 mesh, 45 parts of cow dung with 150 mesh, 3 parts of zinc fulvate with 150 mesh, 8 parts of sodium sulfide with 150 mesh, and 5 parts of manganese sulfate with 150 mesh evenly to obtain Compound Cadmium-removing Conditioner 28.

[0089] Comparative Example 27:

[0090] Mix 35 parts of oyster shell powder with 100 mesh, 45 parts of kudzu residue vermicompost with 150 mesh, 3 parts of zinc sulfate with 150 mesh, 8 parts of sodium sulfide with 150 mesh, and 5 parts of manganese sulfate with 150 mesh evenly to obtain Compound Cadmium-removing Conditioner 29.

[0091] Comparative Example 28:

[0092] Mix 35 parts of oyster shell powder with 100 mesh, 45 parts of kudzu residue, 3 parts of zinc sulfate with 150 mesh, 8 parts of sodium sulfide with 150 mesh, and 5 parts of manganese sulfate with 150 mesh evenly to obtain Compound Cadmium-removing Conditioner 30;

[0093] Preparation method of kudzu residue: Take fresh kudzu residue, adjust the moisture content to 65%, stack and ferment for 25 days, turn the pile every 6 days to control the pile temperature at 55 °C, and dry after fermentation;

[0094] Comparative Example 29:

[0095] Mix 35 parts of oyster shell powder with 100 mesh, 45 parts of sweet potato residue vermicompost with 150 mesh, 3 parts of zinc sulfate with 150 mesh, 8 parts of sodium sulfide with 150 mesh, and 5 parts of manganese sulfate with 150 mesh evenly to obtain the composite cadmium-reducing conditioner 31; the preparation method of sweet potato residue vermicompost is the same as that of kudzu residue vermicompost.

[0096] The following is an evaluation of the composite cadmium-reducing conditioners in Examples 1-2 and Comparative Examples 1-29:

[0097] A field experiment was carried out in a safe utilization area in Xinyu City. The soil pH of the experimental field was 5.42, the total cadmium was 0.85 mg / kg, and the organic matter content was 28.8 g / kg. It was a gleyic paddy soil with medium overall fertility. The entire field was divided into 96 plots, each plot with an area of 20 m 2 , and the field ridges between the plots were cut and covered with plastic film. Each treatment was set with 3 replicates, and there were a total of 32 treatment areas. Treatment area 1 was the blank control group CK (without applying any cadmium-reducing conditioner materials), and treatment areas 2-32 were the composite cadmium-reducing conditioners in Examples 1-2 and Comparative Examples 1-29 in sequence; all plots were planted with the middle-season rice Cenliangyou 1810.

[0098] For rice, field seedling raising was adopted. Three days before rice transplanting, compound fertilizer (total nutrient content 45%, where N-P2O5-K2O = 15-15-15) was applied at 40 kg / mu. The composite cadmium-reducing conditioners described in Examples 1-2 and Comparative Examples 1-29 were applied at 150 kg / mu in different treatment areas simultaneously (the blank control group CK did not apply any cadmium-reducing conditioner materials), and manual tillage was carried out to ensure that the fertilizer and the composite cadmium-reducing conditioner were fully mixed with the soil. The transplanting process was carried out manually. After the rice turned green, urea was topdressed at 10 kg / mu during the tillering stage. Other field water and fertilizer management methods and pest and disease control methods were the same as the traditional methods. After the rice matured, each plot was harvested for yield measurement, and the cadmium content in the brown rice was measured.

[0099] Method for measuring cadmium content in brown rice: Take 0.1 g of brown rice powder sample, add 5 mL of nitric acid and 3.0 mL of hydrogen peroxide solution, cover and digest overnight at low temperature, digest for 2 h using a graphite digestion instrument and volume-fix to 25 mL, and analyze and measure the cadmium concentration in the digestion solution using an inductively coupled plasma mass spectrometer. The test results are shown in Table 1:

[0100] Table 1 Differences in rice yield and cadmium content in brown rice for each treatment

[0101] Treatment area Treatment Rice yield (kg / mu) Cd content in brown rice (mg / kg) 1 Blank control CK 651±20 0.761±0.067 2 Example 1 661±17 0.113±0.012 3 Example 2 663±14 0.108±0.015 4 Comparative example 1 652±16 0.180±0.018 5 Comparative example 2 651±15 0.186±0.015 6 Comparative example 3 654±11 0.169±0.019 7 Comparative example 4 656±13 0.194±0.013 8 Comparative example 5 652±17 0.192±0.020 9 Comparative example 6 647±13 0.237±0.021 10 Comparative example 7 649±12 0.241±0.023 11 Comparative example 8 645±16 0.223±0.021 12 Comparative example 9 651±11 0.239±0.025 13 Comparative example 10 646±12 0.246±0.016 14 Comparative example 11 641±11 0.226±0.019 15 Comparative example 12 643±13 0.235±0.024 16 Comparative example 13 647±17 0.257±0.021 17 Comparative example 14 634±15 0.243±0.023 18 Comparative example 15 636±11 0.356±0.031 19 Comparative example 16 631±12 0.378±0.033 20 Comparative example 17 639±17 0.356±0.030 21 Comparative example 18 643±12 0.361±0.025 22 Comparative example 19 635±16 0.394±0.034 23 Comparative example 20 637±17 0.392±0.032 24 Comparative example 21 629±10 0.449±0.038 25 Comparative example 22 626±12 0.478±0.041 26 Comparative example 23 622±17 0.237±0.016 27 Comparative example 24 632±11 0.229±0.015 28 Comparative example 25 651±11 0.204±0.011 29 Comparative example 26 653±17 0.227±0.015 30 Comparative example 27 650±8 0.201±0.013 31 Comparative example 28 647±12 0.367±0.007 32 Comparative example 29 657±10 0.209±0.011

[0102] Note 1: Except for different treatment methods in each group in the table, other conventional cultivations are the same.

[0103] Note 2: According to the requirements of the "National Food Safety Standard Limits of Contaminants in Foods (GB 2762-2022)", the cadmium content of qualified rice is less than or equal to 0.2 mg / kg.

[0104] According to the experimental results of the above embodiments, the present invention activates the organic matter components in kudzu residue by using earthworm castings, and uses earthworms to remove cadmium from kudzu residue. The active components in kudzu residue earthworm castings and the active components such as amino acids in oyster shell powder act together with zinc fulvate, manganese fertilizer and sodium sulfide. Coupled with the adsorption and degradation of oyster shell powder and kudzu residue earthworm castings, and the effect of increasing soil organic matter, the cadmium content in brown rice of rice is synergistically reduced, and the cadmium content in brown rice of rice can be reduced to 0.1 mg / kg, solving the technical problem in the prior art that rice cannot reduce the cadmium content in brown rice to less than 0.15 mg / kg.

[0105] In summary, the present invention discloses a composite cadmium-reducing conditioner based on kudzu residue earthworm castings and an application method. The mass ratio of each component in the cadmium-reducing conditioner is: 35-40 parts of oyster shell powder, 30-45 parts of kudzu residue earthworm castings, 3-5 parts of zinc fulvate, 8-10 parts of sodium sulfide and 3-5 parts of manganese sulfate; before plowing the rice field, apply the cadmium-reducing conditioner to the soil, let it stand and then plow, and then transplant the rice; the present invention activates the organic matter components in kudzu residue by using earthworm castings, and uses earthworms to remove cadmium from kudzu residue. The active components in kudzu residue earthworm castings and the active components such as amino acids in oyster shell powder act together with zinc fulvate, manganese fertilizer and sodium sulfide. Coupled with the adsorption and degradation of oyster shell powder and kudzu residue earthworm castings, and the effect of increasing soil organic matter, the cadmium content in brown rice of rice is synergistically reduced, and the cadmium content in brown rice of rice can be reduced to 0.1 mg / kg; the operation is simple and the raw materials are easy to obtain.

[0106] At this point, those skilled in the art recognize that although the embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived from the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

Claims

1. A composite cadmium-reducing conditioner based on kudzu residue and earthworm manure, characterized in that, The composite cadmium-reducing conditioner comprises the following components: Oyster shell powder, kudzu residue vermicompost, zinc fulvate, sodium sulfide and manganese sulfate; The formulation of the components of the composite cadmium-reducing conditioner is: 35 - 40 parts of oyster shell powder, 30 - 45 parts of kudzu residue vermicompost, 3 - 5 parts of zinc fulvate, 8 - 10 parts of sodium sulfide and 3 - 5 parts of manganese sulfate; The specific preparation method of the kudzu residue vermicompost is as follows: Step S1: Take fresh kudzu residue, adjust the moisture content to 60% - 70%, stack and ferment for 20 - 25 days, turn the pile every 5 - 8 days to control the temperature of the pile body at 50 - 60 °C; Step S2: Place earthworm seeds in the material obtained by fermentation in Step S1, with a placement density of 10 - 15 earthworm seeds per kilogram of dry material. The earthworm seeds are Eisenia fetida. Re-place them every 20 days, and then separate the earthworms from the vermicompost to obtain kudzu residue vermicompost.

2. The composite cadmium-reducing conditioner based on Pueraria residue and earthworm manure as described in claim 1, characterized in that The mesh number of the oyster shell powder is 50 - 100 mesh.

3. A composite cadmium-reducing conditioner based on kudzu residue and earthworm manure as described in claim 1, characterized in that, The kudzu residue vermicompost is dried and then crushed into 80 - 150 mesh.

4. A composite cadmium-reducing conditioner based on kudzu residue and earthworm manure as described in claim 1, characterized in that, The zinc fulvate, sodium sulfide and manganese sulfate are crushed into 80 - 150 mesh.

5. A composite cadmium-reducing conditioner based on kudzu residue and earthworm manure as described in claim 1, characterized in that, The survival temperature of the earthworms is set at 25 ± 10 °C to ensure the normal reproduction of the earthworms.

6. The application method of a composite cadmium-reducing conditioner based on kudzu residue and earthworm manure as described in claim 1, characterized in that, The specific application method is as follows: Before plowing the paddy field, apply the composite cadmium-reducing conditioner to the soil, let it stand and then plow, and then transplant the rice.

7. The application method of a composite cadmium-reducing conditioner based on kudzu residue and earthworm manure according to claim 6, characterized in that, Apply it to the soil 5 - 10 days before plowing the paddy field.

8. The application method of a composite cadmium-reducing conditioner based on kudzu residue and earthworm manure as described in claim 6, characterized in that The dosage of the composite cadmium-reducing conditioner is 150 - 250 kg / mu.