A method for reducing cadmium in wheat in a medium-light cadmium contaminated soil

Abstract

The application discloses a method for reducing cadmium in wheat in medium and light cadmium contaminated soil, and belongs to the technical field of safe production of crops. In view of the problem that the effect of existing single planting or single cadmium reduction technology is limited and easy to affect the yield of wheat, a four-dimensional combined scheme combining soil passivation, screening of low-cadmium varieties, foliar control and agronomic regulation is adopted, the soil cadmium activity is reduced by applying a composite passivation agent, a low-cadmium high-yield variety is screened, a negative load foliar control agent is sprayed to inhibit the transportation of cadmium to grains, and scientific agronomic management is combined, so that the reduction of cadmium in wheat and high yield are realized. The method is simple in operation, controllable in cost, has a cadmium reduction efficiency of more than 35%, and can reduce the cadmium content in wheat grains to within the national food safety standard, is suitable for the safe production of wheat in medium and light cadmium contaminated farmland, and has good popularization and application value.

Description

Technical Field

[0001] This invention relates to the field of agricultural crop safety production technology, specifically to a combined prevention and control method for reducing cadmium in wheat grown in moderately to slightly cadmium-contaminated soil. Background Technology

[0002] Cadmium is highly toxic and difficult to degrade. Industrial and agricultural development in my country has led to significant cadmium pollution in farmland soils, with moderately to slightly polluted soils accounting for the largest proportion. Wheat has a strong capacity for cadmium accumulation, and cadmium-contaminated wheat threatens food security and human health. Existing single cadmium reduction technologies have obvious limitations, and existing combined cadmium reduction technologies also suffer from problems such as unreasonable combinations and complex operation. Therefore, developing a simple, cost-effective, and high-yield combined control method is of great significance. Summary of the Invention

[0003] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0004] In view of the problems existing in the above and / or existing combined prevention and control methods for reducing cadmium in wheat in moderately to slightly cadmium-contaminated soil, the present invention is proposed.

[0005] Therefore, the purpose of this invention is to provide a combined prevention and control method for wheat cadmium reduction in moderately to mildly cadmium-contaminated soil. This method combines low-cadmium variety selection, soil passivation, foliar inhibition, and agronomic regulation in a four-dimensional approach to achieve cadmium content in wheat grains that meets standards and ensures stable yield. At the same time, it improves the physical and chemical properties of the soil, providing technical support for the safe production of wheat in moderately to mildly cadmium-contaminated soil.

[0006] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0007] A combined method for controlling cadmium levels in wheat grown in moderately to slightly cadmium-contaminated soil includes the following steps: Step 1: Application of soil composite passivating agent; the composite passivating agent is prepared by mixing attapulgite, nano hydroxyapatite, silica sol, and zinc selenite in a weight ratio of 10:0.8:22:0.7; Step 2: Screening and sowing of low-cadmium wheat varieties; The screening criteria for low-cadmium wheat varieties are: planting in moderately to slightly polluted soil with a cadmium content of 0.3-1.0 mg / kg, grain cadmium content ≤0.1 mg / kg, and yield not less than 90% of the average yield of the local main cultivated varieties; Step 3: Foliar spraying of a foliar inhibitor during the wheat growth period; the foliar inhibitor comprises 200-400 mg / L zinc sulfate, 150-250 mg / L sodium selenite, 100-500 mg / L water-soluble silicon, 5-10 g / L chitosan oligosaccharide, 10-20 g / L amino acids, and 5-10 g / L humic acid, with 2-4 g / L sodium citrate added as a surfactant; the dosage of the foliar inhibitor is 1.5-3.0 L / hm² each time. 2 Dilute with water 200 times and spray on the leaves of wheat during its critical growth period; Step 4: Agronomic regulation and management: Apply nitrate nitrogen fertilizer; maintain soil moisture content at 60%-70% of field capacity during the growing season, and control water appropriately during the grain-filling period; remove weeds in a timely manner, prevent and control pests and diseases, and avoid using pesticides and fertilizers containing cadmium.

[0008] The above four steps combine to achieve cadmium reduction and high yield in wheat.

[0009] As a preferred embodiment of the combined method for controlling cadmium pollution in wheat in moderately to slightly cadmium-contaminated soil as described in this invention, in step 1, the composite passivating agent is applied 7-10 days before wheat sowing, at a rate of 1500-2500 kg / hm². 2 After application, till the soil to a depth of 20-30cm to ensure the passivating agent is evenly mixed with the soil.

[0010] As a preferred embodiment of the combined prevention and control method for reducing cadmium in wheat in moderately to slightly cadmium-contaminated soil according to the present invention, in step 1, the silica sol contains 15 wt% silica, the nano-hydroxyapatite has a particle size of 50-100 nm, and 0.3% sodium citrate is added as a dispersant to the composite passivating agent.

[0011] As a preferred embodiment of the combined prevention and control method for reducing cadmium in wheat in moderately to slightly cadmium-contaminated soil according to the present invention, in step 3, the foliar inhibitor is sprayed once each during the wheat jointing stage and the booting stage, and sprayed on cloudy days or in the evening, with the front and back of the leaves being sprayed evenly.

[0012] As a preferred embodiment of the combined prevention and control method for reducing cadmium in wheat in moderately to slightly cadmium-contaminated soil according to the present invention, in step 2, the low-cadmium wheat variety is selected from one or more of Ningmai 11, Xumai 35, and Zhengmai 136.

[0013] As a preferred embodiment of the combined control method for reducing cadmium in wheat in moderately to slightly cadmium-contaminated soil described in this invention, in step 2, seed pretreatment is performed before sowing by soaking the seeds in a 0.1% potassium permanganate solution for 15-20 minutes, drying them, and then sowing them at a rate of 180-225 kg / hm². 2 The sowing depth is 3-5cm.

[0014] As a preferred embodiment of the combined prevention and control method for reducing cadmium in wheat in moderately to slightly cadmium-contaminated soil as described in this invention, in step 4, nitrate nitrogen fertilizer is applied at a rate of 180-225 kg / hm². 2 Apply fertilizer three times: base fertilizer, jointing fertilizer, and heading fertilizer, in a ratio of 5:3:2. Maintain soil moisture content at 60%-70% of field capacity during the growing season, and control watering appropriately during the grain-filling period. Remove weeds in a timely manner, prevent and control pests and diseases, and avoid using pesticides and fertilizers containing cadmium.

[0015] As a preferred embodiment of the combined prevention and control method for reducing cadmium in wheat in moderately to slightly cadmium-contaminated soil as described in this invention, the nitrate nitrogen fertilizer contains ≥11% nitrate nitrogen, is applied as basal fertilizer in conjunction with deep soil tillage, and is applied in strips for jointing and heading fertilizers, followed by soil covering.

[0016] As a preferred embodiment of the combined prevention and control method for reducing cadmium in wheat in moderately to slightly cadmium-contaminated soil described in this invention, the moderately to slightly cadmium-contaminated soil refers to farmland soil with a cadmium content of 0.3-1.0 mg / kg and a soil pH value of 5.5-7.5.

[0017] As a preferred embodiment of the combined control method for reducing cadmium in wheat in moderately to mildly cadmium-contaminated soil described in this invention, after wheat harvest, the straw in the field is removed, crushed, and returned to the field, combined with the application of 50-75 kg / hm² of fertilizer. 2 Compound microbial fertilizer improves soil physical and chemical properties and continuously reduces soil cadmium activity.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention adopts a four-dimensional combination strategy, with each link working synergistically to achieve a cadmium reduction efficiency of over 55%, which can stably reduce the cadmium content of wheat grains to below 0.1 mg / kg, meeting national food safety standards and effectively solving the problem of cadmium contamination in wheat.

[0019] 2. Select low-cadmium, high-yield varieties and combine them with scientific agronomic regulation and fertilizer application to avoid inhibiting wheat growth during the cadmium reduction process. The wheat yield should not be less than 90% of the average yield of the local main varieties, thus achieving the dual goals of cadmium reduction and high yield.

[0020] 3. The raw materials for the composite passivating agent and leaf surface inhibitor used are readily available and simple to prepare. The application method is combined with conventional wheat planting and management, without the need for additional complex equipment. The cost is lower than existing combined cadmium reduction technologies, making it suitable for large-scale promotion and application.

[0021] 4. The application of compound passivating agents and microbial fertilizers can improve the physical and chemical properties of soil, reduce soil cadmium activity, and long-term use can gradually improve soil quality, thus achieving an organic combination of soil pollution control and sustainable agricultural development. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0023] Example 1 This example was conducted in a farmland with moderate to mild cadmium contamination. The soil cadmium content was 0.5 mg / kg, the soil pH was 6.2, the soil type was alluvial soil, and the main wheat variety cultivated locally was Jimai 44, with an average yield of 7500 kg / hm². 2 .

[0024] 1. Application of soil compound passivating agent Preparation of the composite passivating agent: Weigh attapulgite, 80nm nano-hydroxyapatite, silica sol with 15wt% silica content, and zinc selenite in a weight ratio of 10:0.8:22:0.7, add 0.3% sodium citrate as a dispersant, mix thoroughly, and set aside. Eight days before sowing, apply the composite passivating agent at a rate of 2000 kg / hm². 2 Apply the agent evenly to the soil surface, then use a deep tiller to till to a depth of 25cm to ensure the passivating agent is fully mixed with the soil.

[0025] 2. Screening and sowing of low-cadmium wheat varieties Ningmai 11 was selected as a low-cadmium, high-yield variety. When planted in the contaminated soil, this variety had a cadmium content of 0.08 mg / kg in the grains and a yield of 7100 kg / hm². 2 The seeds met the screening criteria. Before sowing, Ningmai 11 seeds were soaked in a 0.1% potassium permanganate solution for 18 minutes, dried, and then sown in mid-October at a sowing rate of 200 kg / hm². 2 Sowing depth is 4cm, and the soil should be compacted after sowing to retain moisture.

[0026] 3. Foliar spraying of inhibitors during wheat growth period Preparation of foliar inhibitor: Mix 200-400 mg / L zinc sulfate, 150-250 mg / L sodium selenite, 100-500 mg / L water-soluble silicon, 5-10 g / L chitosan oligosaccharide, 10-20 g / L amino acids, and 5-10 g / L humic acid, and add 2-4 g / L sodium citrate surfactant. Stir until homogeneous to prepare an aqueous solution. The dosage of the foliar inhibitor is 1.5 L / hm² per application. 2 Dilute with water 200 times and spray once each in mid-March (jointing stage) and mid-April (heading stage) of the following year. Choose to spray in the evening or on a cloudy day to ensure that both sides of the leaves are evenly covered.

[0027] 4. Agronomic regulation and management Fertilization: Use nitrate nitrogen fertilizer with a nitrate nitrogen content of 12%, and apply at a rate of 200 kg / hm².2 Of which, 100 kg / hm² of base fertilizer 2 Combine with deep soil tillage and application; apply 60 kg / hm² of fertilizer during the jointing stage. 2 Apply fertilizer in strips and cover with soil; apply 40 kg / hm² of fertilizer during the heading stage. 2 Apply the fertilizer in strips and cover with soil. Water management: During the growing season, maintain soil moisture content at approximately 65% ​​of field capacity through drip irrigation. During the grain-filling stage, appropriately control watering to maintain soil moisture content at approximately 60%. Field management: Remove weeds promptly, use Trichogramma wasps to control wheat aphids, and avoid using pesticides and fertilizers containing cadmium.

[0028] 5. Harvesting and Testing The wheat was harvested in mid-June of the following year after ripening, and the cadmium content and yield of the wheat grains were measured. The results showed that the cadmium content of the wheat grains was 0.06 mg / kg, the cadmium reduction efficiency was 40%, and the wheat yield was 7200 kg / hm². 2 The yield reached 96% of the average yield of the local main varieties, meeting national food safety standards and high-yield requirements. After wheat harvest, the straw was crushed and returned to the field, with an application rate of 60 kg / hm². 2 Compound microbial fertilizer improves the physical and chemical properties of soil.

[0029] Example 2 This example was conducted in another farmland with moderate to mild cadmium contamination. The soil cadmium content was 0.8 mg / kg, the soil pH was 7.0, the soil type was brown soil, and the main wheat variety cultivated locally was Aikang 58, with an average yield of 7200 kg / hm². 2 .

[0030] 1. Application of soil compound passivating agent Preparation of the composite passivating agent: Weigh attapulgite, 60nm nano-hydroxyapatite, silica sol with 15wt% silica content, and zinc selenite in a weight ratio of 10:0.8:22:0.7, add 0.3% sodium citrate as a dispersant, mix thoroughly, and set aside. Ten days before sowing, apply the composite passivating agent at a rate of 2400 kg / hm². 2 Apply the agent evenly to the soil surface, then plow to a depth of 30cm to ensure the passivating agent is fully mixed with the soil.

[0031] 2. Screening and sowing of low-cadmium wheat varieties Zhengmai 136 was selected as a low-cadmium, high-yield variety. When planted in the contaminated soil, this variety had a cadmium content of 0.09 mg / kg in the grains and a yield of 6800 kg / hm². 2 The seeds met the screening criteria. Before sowing, Zhengmai 136 seeds were soaked in a 0.1% potassium permanganate solution for 15 minutes, dried, and sown in late October at a rate of 220 kg / hm². 2 Sowing depth is 5cm, and the soil should be compacted after sowing to retain moisture.

[0032] 3. Foliar spraying of inhibitors during wheat growth period Preparation of foliar inhibitor: A foliar inhibitor solution was prepared by mixing zinc sulfate (400 mg / L), sodium selenite (250 mg / L), water-soluble silicon (500 mg / L), chitosan oligosaccharide (10 g / L), amino acids (20 g / L), and humic acid (10 g / L), with the surfactant sodium citrate (4 g / L) added. The solution was stirred until homogeneous. The dosage of the foliar inhibitor was 3.0 L / hm² per application. 2 Dilute with water 200 times and spray once each in late March (jointing stage) and late April (heading stage) of the following year. Choose a cloudy day for spraying to ensure even coverage on both sides of the leaves.

[0033] 4. Agronomic regulation and management Fertilization: Select nitrate nitrogen fertilizer with a nitrate nitrogen content of 11%, and apply at a rate of 220 kg / hm². 2 Of which, 110 kg / hm² of base fertilizer 2 Combined with deep soil tillage; apply fertilizer at the jointing stage (66 kg / hm²). 2 Apply fertilizer in strips and cover with soil; apply 44 kg / hm² of fertilizer during the heading stage. 2 Apply the fertilizer in strips and cover with soil. Water management: Maintain soil moisture content at approximately 70% of field capacity during the growing season; control watering appropriately during the grain-filling stage, maintaining soil moisture content at approximately 65%. Field management: Remove weeds promptly, use biological agents to control wheat sheath blight, and avoid using pesticides and fertilizers containing cadmium.

[0034] 5. Harvesting and Testing The wheat was harvested in mid-June of the following year after ripening, and the cadmium content and yield of the wheat grains were measured. The results showed that the cadmium content of the wheat grains was 0.07 mg / kg, the cadmium reduction efficiency was 38.75%, and the wheat yield was 6900 kg / hm². 2 The yield reached 95.8% of the average yield of the local main varieties, meeting national food safety standards and high-yield requirements. After wheat harvest, the straw was crushed and returned to the field, with an application rate of 70 kg / hm². 2 Compound microbial fertilizer continuously improves soil quality.

[0035] Comparative Example In the same experimental field as in Example 1, a single soil passivating agent was applied only to attapulgite soil at a rate of 2000 kg / hm². 2 Treatment and other planting management measures were the same as in Example 1. Post-harvest measurements showed that the cadmium content in wheat grains was 0.28 mg / kg, the cadmium reduction efficiency was 16%, and the wheat yield was 6800 kg / hm². 2 The yield and cadmium reduction effect were lower than those of Example 1, and the cadmium content of the grains did not meet the national food safety standards.

[0036] The above specific embodiments are merely preferred embodiments of the present invention and are not intended to limit the technical solutions of the present invention. Any modifications, equivalent substitutions, improvements, etc., made without departing from the technical principles and inventive concept of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for reducing cadmium in wheat in a medium-lightly cadmium-contaminated soil, comprising the steps of, Includes the following steps: Step 1: Application of soil composite passivating agent; the composite passivating agent is prepared by mixing attapulgite, nano hydroxyapatite, silica sol, and zinc selenite in a weight ratio of 10:0.8:22:0.7; Step 2: Screening and sowing of low-cadmium wheat varieties; The screening criteria for low-cadmium wheat varieties are: planting in moderately to slightly polluted soil with a cadmium content of 0.3-1.0 mg / kg, grain cadmium content ≤0.1 mg / kg, and yield not less than 90% of the average yield of the local main cultivated varieties; Step 3: Foliar spraying of a foliar inhibitor during the wheat growth period; the foliar inhibitor comprises 200-400 mg / L zinc sulfate, 150-250 mg / L sodium selenite, 100-500 mg / L water-soluble silicon, 5-10 g / L chitosan oligosaccharide, 10-20 g / L amino acids, and 5-10 g / L humic acid, with 2-4 g / L sodium citrate added as a surfactant; the dosage of the foliar inhibitor is 1.5-3.0 L / hm² each time. 2 Dilute with water 200 times and spray on the leaves of wheat during its critical growth period; Step 4: Agronomic regulation and management: Apply nitrate nitrogen fertilizer; maintain soil moisture content at 60%-70% of field capacity during the growing season, and control water appropriately during the grain-filling period; remove weeds in a timely manner, prevent and control pests and diseases, and avoid using pesticides and fertilizers containing cadmium.

2. The method according to claim 1, wherein the method is characterized by, In step 1, the composite passivator is applied 7-10 days before wheat sowing at a rate of 1500-2500 kg / hm 2 and is mixed with the soil by ploughing 20-30 cm deep after application.

3. The method according to claim 1, wherein the method is characterized by, In step 1, the silica sol contains 15 wt% silica, the nano-hydroxyapatite has a particle size of 50-100 nm, and 0.3% sodium citrate is added as a dispersant to the composite passivating agent.

4. The method according to claim 1, wherein the method is characterized by, In step 2, the low-cadmium wheat variety is selected from one or more of Ningmai 11, Xumai 35, and Zhengmai 136.

5. The method according to claim 1, wherein the method is characterized by, In Step 2, seed pretreatment is carried out before sowing. The seeds are soaked in 0.1% potassium permanganate solution for 15-20 minutes, then dried and sown. The sowing rate is 180-225 kg / hm 2 , and the sowing depth is 3-5 cm.

6. The method according to claim 1, wherein the method is characterized by, In step 3, the foliar inhibitor is sprayed once each during the wheat jointing stage and the booting stage, on cloudy days or in the evening, and the front and back of the leaves are sprayed evenly.

7. The method according to claim 1, wherein the method is characterized by, In step 4, apply nitrate nitrogen fertilizer at a rate of 180-225 kg / hm². 2 It is applied in three stages: base fertilizer, jointing fertilizer, and heading fertilizer, in a ratio of 5:3:

2.

8. The method according to claim 1, wherein the method is characterized by, The nitrate nitrogen fertilizer contains ≥11% nitrate nitrogen. It is applied as a base fertilizer in conjunction with deep soil tillage, while the jointing fertilizer and heading fertilizer are applied in strips and covered with soil after application.

9. The method according to claim 1, wherein the method is characterized by, The term "moderately cadmium-contaminated soil" refers to farmland soil with a cadmium content of 0.3-1.0 mg / kg and a pH value of 5.5-7.

5.

10. The method according to claim 1, wherein the method is characterized by, After wheat harvest, remove straw from the field, crush the straw and return it to the field, and apply 50-75 kg / hm² of fertilizer. 2 Compound microbial fertilizer improves soil physical and chemical properties and continuously reduces soil cadmium activity.