Method for reducing cadmium content in peanuts

Abstract

According to the method for reducing the cadmium content in the peanuts, the cadmium content in the peanuts is reduced by regulating and controlling the molar ratio of calcium to cadmium in a soil solution, and the molar ratio of calcium to cadmium is 20000-210000. According to the method for reducing the cadmium content in the peanuts by regulating and controlling the calcium-cadmium ratio of the soil solution, the calcium / cadmium molar concentration ratio of the soil solution is regulated and controlled to 20000-210000 by applying the calcium fertilizer, the cadmium content in the peanuts can be effectively reduced, the yield of the peanuts can be increased, the pertinence is high, and the method is scientific and accurate; the technical defect that the application amount of an existing in-situ passivation material is blind is overcome, and the method has wide application prospects in the fields of heavy metal polluted farmland remediation and safety production.

Description

Technical Field

[0001] The invention belongs to the technical field of heavy metal contaminated soil remediation, and in particular relates to a method for regulating the calcium-cadmium ratio of a soil solution to reduce the cadmium content in peanuts. Background Art

[0002] Peanuts are important oil and cash crops in my country, and are an important source of edible vegetable oil and protein for Chinese residents. my country is a major producer and consumer of peanuts in the world, and peanuts are one of the few agricultural products in my country that have obvious competitive advantages and are exported to earn foreign exchange. With the increasing demand for direct consumption and food processing of peanuts, the international community is paying more and more attention to the problem of excessive heavy metals in peanuts. In recent years, food safety issues such as excessive heavy metal content in peanuts, especially cadmium content, have become one of the main constraints on my country's peanut export trade. The survey found that peanuts have a strong ability to accumulate cadmium in the soil. The phenomenon of excessive cadmium in peanuts in some parts of my country is more serious, especially on acidic soils.

[0003] At present, the research on heavy metal pollution control technology at home and abroad is mainly focused on crops such as rice and wheat. There are relatively few studies on the control measures for cadmium migration and transport in the soil-peanut system. They are mainly based on rice, wheat and other crops, and mainly focus on low accumulation variety screening, leaf surface control, in-situ passivation and other aspects. However, the selected varieties often have unstable low accumulation characteristics, and the contradiction between low accumulation and high yield is prominent. In-situ passivation technology has the advantages of high efficiency, rapidity, easy operation, and wide application range. It is more suitable for the requirements of safe utilization of heavy metal polluted farmland in my country. The more commonly used passivation materials include lime, calcium silicon materials, phosphorus-containing materials, clay minerals, organic materials, biochar, etc. However, in actual field application, the above passivation materials lack scientific and precise application amounts for different pollution levels and different soil properties, resulting in blind application. If the amount is too low, the cadmium reduction effect of crops is not obvious, and if the amount is too large, the cost is too high. Long-term, large-scale or high-frequency application is also likely to cause secondary obstacles in the soil. It is urgent to combine the physiological characteristics of peanuts themselves to develop targeted, scientific and precise control technologies.

[0004] Calcium is a necessary secondary element for plant growth and development. It has important physiological functions. It is not only a structural material of cells, but also a second messenger in cells. It plays an important role in the plant's resistance to adversity. Calcium can not only reduce the absorption of cadmium by plants by competing with cadmium for ion channels, but also reduce the transport of cadmium between cells by forming calcium pectinate complexes with pectin in cell walls and participating in regulating the activity of enzymes related to cell wall metabolism, and increase the retention of cadmium in plant roots, thereby reducing the cadmium content in edible parts such as rice, wheat, and sorghum. Peanuts are calcium-loving crops with a large demand for calcium. Calcium is the third essential element after nitrogen and potassium. When peanuts are calcium deficient, seed development is hindered, the shell tissue is loose, and the number of empty, blighted, and rotten fruits increases, and the yield and quality are significantly reduced. Peanut production is mostly fertilized once before sowing, especially calcium fertilizer. At present, the types of calcium fertilizers commonly used for peanuts in the field include lime, gypsum, superphosphate, calcium magnesium phosphate, etc. Lime is often used to supplement calcium sources on acidic soils. Summary of the invention

[0005] Technical problem to be solved: In view of the problems existing in the above background technology, the present invention provides a method for regulating the calcium-cadmium ratio of soil solution to reduce the cadmium content in peanuts; the method of the present invention is highly targeted, scientific and accurate, and overcomes the technical disadvantages of the current blind application of in-situ passivation materials. At the same time, it has a good cadmium reduction efficiency for peanuts and has broad application prospects in the fields of heavy metal contaminated farmland restoration and safe production.

[0006] Technical solution: A method for reducing the cadmium content in peanuts, which reduces the cadmium content in peanuts by regulating the calcium-cadmium molar ratio in the soil solution, wherein the calcium / cadmium molar ratio is 20,000-210,000.

[0007] Preferably, calcium fertilizer is spread into the farmland before peanut sowing, mixed evenly with the tillage layer soil, and combined with conventional peanut planting field management measures; the amount of calcium fertilizer added is such that the calcium / cadmium molar ratio in the soil solution reaches 210,000 after application.

[0008] The calcium fertilizer is any one of lime or chelated calcium.

[0009] The method also includes the following steps: using a soil solution collector to collect soil solution when the field water holding capacity is 70%, determining the calcium and cadmium contents, and calculating the amount of calcium fertilizer required to be added according to the calcium and cadmium concentrations of the background soil solution.

[0010] The soil solution collector is a standard type of Rhizon from the Netherlands, with a sampling head diameter of 2.5 mm, an aperture of 0.15 μM, a length of 10 cm, and an extension tube of 15 cm.

[0011] Spread the calcium fertilizer and base fertilizer on the farmland, mix them evenly with the topsoil, and then sow peanuts. Carry out conventional peanut planting field management measures until the peanuts are mature and harvested.

[0012] Beneficial effect: The method proposed in the present invention is a method for regulating the calcium-cadmium ratio of soil solution to reduce the cadmium content in peanuts. By applying calcium fertilizer to regulate the calcium / cadmium molar concentration ratio of the soil solution to 20,000-210,000, not only can the cadmium content in peanuts be effectively reduced, but also the peanut yield can be increased. It is highly targeted, scientific and accurate, and overcomes the current technical drawback of blind application of in-situ passivation materials. It has broad application prospects in the fields of heavy metal contaminated farmland restoration and safe production.

[0013] Based on the above advantages, the present invention also provides the application of the above technical solution in reducing the cadmium content of peanuts. By applying calcium fertilizer to adjust the calcium / cadmium molar concentration ratio of the soil solution to 20000-210000, the cadmium content in peanuts can be effectively reduced, and the peanut yield can be increased at the same time. Experiments have shown that by adopting the technical solution provided by the present invention, the cadmium content of peanuts planted on acidic cadmium contaminated soil is reduced by 22%-25%, and the peanut yield is increased by 18%-28%. DETAILED DESCRIPTION

[0014] The invention provides a method for regulating the calcium-cadmium ratio of soil solution to reduce the cadmium content in peanuts. The method comprises the following steps: before sowing peanuts, using a soil solution collector (such as a Dutch Rhizon standard type, with a sampling head diameter of 2.5 mm, an aperture of 0.15 μM, a length of 10 cm, and an extension tube of 15 cm) to collect soil solution when the field water holding capacity is maintained at 70%, determining the calcium and cadmium contents, and controlling the amount of calcium fertilizer applied according to the target soil solution calcium / cadmium molar concentration ratio; spreading the calcium fertilizer on farmland, which can be applied simultaneously with base fertilizer, sowing peanuts after being evenly mixed with the tillage layer soil, and carrying out conventional peanut planting field management measures until the peanuts are harvested after maturity.

[0015] The preferred target soil solution calcium / cadmium molar concentration ratio of the present invention is 20,000-210,000.

[0016] The preferred calcium fertilizer of the present invention is any one of lime or chelated calcium.

[0017] To further illustrate the present invention, a method for regulating the calcium-cadmium ratio of soil solution to reduce the cadmium content in peanuts and its application provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0018] Example 1 Effect of applying lime to increase the molar ratio of calcium / cadmium in soil solution on reducing cadmium content in peanuts

[0019] (1) Cadmium-contaminated soil was collected in Shenyang, Liaoning Province. Its basic physical and chemical properties were as follows: pH value 4.52, total cadmium content 0.52 mg / kg, exchangeable calcium content 0.71 g / kg. Before peanut sowing, soil solution was extracted using a soil solution collector (Rhizon standard type in the Netherlands, sampling head diameter 2.5 mm, pore size 0.15 μM, length 10 cm, extension tube 15 cm). ICP-MS was used to measure the cadmium content of the soil solution to be 0.023 mg / L and the calcium content of the soil solution to be 115 mg / L. Based on the soil used in the pot test of 10 kg / pot, the molar concentration ratio of calcium / cadmium in the soil solution was calculated to be 14,000. Applying 150 kg of slaked lime per mu can increase the molar concentration ratio of calcium / cadmium in the soil solution to 210,000.

[0020] (2) Add the slaked lime and base fertilizer calculated in step (1) to the soil and mix well. Sow peanuts one week later and conduct a potted plant experiment. The peanut variety is Luhua No. 8. In conjunction with conventional peanut field pest and water management, the peanuts are harvested and the yield is measured after they mature, and the cadmium content of the peanut kernels is measured by ICP-MS.

[0021] Comparative Example 1

[0022] Except that slaked lime was not applied, the rest was the same as in Example 1.

[0023] Application effect: It can be seen from Table 1 that, compared with the comparative example 1, the peanut yield of the peanuts planted by the above method in Example 1 increased by 27.5%, and the cadmium content of the seeds decreased by 24.7%.

[0024] Table 1 Effects of lime application on increasing the molar ratio of Ca / Cd in soil solution on peanut yield and cadmium content

[0025]

[0026] Example 2 Effect of applying chelated calcium fertilizer to increase the molar concentration ratio of calcium / cadmium in soil solution on reducing cadmium content in peanuts

[0027] (1) Cadmium-contaminated soil was collected in Shenyang, Liaoning Province. Its basic physical and chemical properties were as follows: pH 4.52, total cadmium content 0.52 mg / kg, exchangeable calcium content 0.71 g / kg. Before peanut sowing, soil solution was extracted using a soil solution collector (Rhizon standard type, Netherlands, sampling head diameter 2.5 mm, pore size 0.15 μM, length 10 cm, extension tube 15 cm). ICP-MS was used to determine the cadmium content of the soil solution to be 0.023 mg / L and the calcium content of the soil solution to be 115 mg / L. Based on 10 kg / pot of soil used in the potted plant experiment, the molar concentration ratio of calcium / cadmium in the soil solution was calculated to be 14,000. Applying 41 kg of calcium iminodisuccinate (IDS chelated calcium) per mu can increase the molar concentration ratio of calcium / cadmium in the soil solution to 20,000.

[0028] (2) The IDS chelated calcium and basal fertilizer calculated in step (1) were added to the soil and mixed evenly. One week later, peanuts were sown and potted for testing. The peanut variety was Luhua No. 8. Conventional peanut field pest and water management was combined. The peanuts were harvested and yielded after maturity, and the cadmium content of the peanut kernels was determined by ICP-MS.

[0029] Comparative Example 2

[0030] The process was the same as Example 2 except that IDS chelated calcium was not applied.

[0031] Application effect: It can be seen from Table 2 that, compared with Comparative Example 2, the peanut yield of Example 2 increased by 17.5%, and the cadmium content of the seeds decreased by 22.2%.

[0032] Table 2 Effects of applying IDS chelated calcium to increase the molar ratio of calcium / cadmium in soil solution on peanut yield and cadmium content

[0033]

[0034] Example 3 Effect of applying calcium ammonium nitrate to increase the molar concentration ratio of calcium / cadmium in soil solution on reducing the cadmium content in peanuts

[0035] (1) Cadmium-contaminated soil was collected in Shenyang, Liaoning Province. Its basic physical and chemical properties were as follows: pH 4.52, total cadmium content 0.52 mg / kg, exchangeable calcium content 0.71 g / kg. Before peanut sowing, soil solution was extracted using a soil solution collector (Rhizon standard type, Netherlands, sampling head diameter 2.5 mm, pore size 0.15 μM, length 10 cm, extension tube 15 cm). ICP-MS was used to determine the cadmium content of the soil solution to be 0.023 mg / L and the calcium content of the soil solution to be 115 mg / L. Based on 10 kg / pot of soil for the potted plant experiment, the soil solution calcium / cadmium molar concentration ratio was calculated to be 14000. Applying 25 kg of calcium ammonium nitrate per mu can increase the soil solution calcium / cadmium molar concentration ratio to 16200 (which did not reach the target soil solution calcium / cadmium molar concentration ratio).

[0036] (2) Add the amount of calcium ammonium nitrate and basal fertilizer calculated in step (1) to the soil and mix well. Sow peanuts one week later and conduct a potted plant experiment. The peanut variety is Luhua No. 8. In conjunction with conventional peanut field pest and water management, the peanuts are harvested and the yield is measured after they mature, and the cadmium content of the peanut kernels is measured by ICP-MS.

[0037] Comparative Example 3

[0038] Calcium ammonium nitrate was not added, and urea was used to make up the difference in nitrogen content compared with Example 3. The rest was the same as Example 3.

[0039] Application effect: It can be seen from Table 3 that the peanut yield of Example 3 increased by 9.89% compared with that of Comparative Example 3, and the cadmium content of the seeds was not significantly reduced.

[0040] Table 3 Effects of applying calcium ammonium nitrate to increase the molar ratio of calcium / cadmium in soil solution on peanut yield and cadmium content

[0041]

[0042] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for reducing the cadmium content in peanuts, characterized in that: The cadmium content in peanuts was reduced by regulating the calcium / cadmium molar ratio in the soil solution, wherein the calcium / cadmium molar ratio was 20,000 to 210,000.

2. The method for reducing cadmium content in peanuts according to claim 1, characterized in that: Before sowing peanuts, calcium fertilizer is spread into the farmland and evenly mixed with the tillage layer soil, and conventional peanut planting field management measures are taken in conjunction with the calcium fertilizer. The amount of calcium fertilizer added is such that the calcium / cadmium molar ratio in the soil solution reaches 210,000 after application.

3. The method for reducing cadmium content in peanuts according to claim 2, characterized in that: The calcium fertilizer is any one of lime or chelated calcium.

4. The method for reducing cadmium content in peanuts according to claim 2, characterized in that: The following steps are also included: The soil solution was collected using a soil solution collector when the field water holding capacity was maintained at 70%, and the calcium and cadmium contents were determined. The amount of calcium fertilizer required to be added was calculated based on the background calcium and cadmium concentrations in the soil solution.

5. The method for reducing cadmium content in peanuts according to claim 4, characterized in that: The soil solution collector is a Dutch Rhizon standard model, with a sampling head diameter of 2.5 mm, an aperture of 0.15 μM, a length of 10 cm, and an extension tube of 15 cm.

6. The method for reducing cadmium content in peanuts according to claim 2, characterized in that: The calcium fertilizer and base fertilizer are spread on the farmland, and after being evenly mixed with the tillage layer soil, peanuts are sown, and conventional peanut planting field management measures are carried out until the peanuts are harvested after they are mature.

Images