Method for producing low-cadmium-selenium-rich soybeans from cadmium-contaminated soil and application thereof

Abstract

The present invention belongs to the technical field of agricultural product safety control and quality regulation, and specifically relates to a method for producing low-cadmium, selenium-rich soybeans in cadmium-contaminated soil and its application. The method provided by the present invention for producing low-cadmium, selenium-rich soybeans in cadmium-contaminated soil comprises the following steps: 1) before planting soybeans, spreading calcium hydroxide and zinc-calcium-magnesium-phosphate fertilizers on the soil surface, and then turning the soil; 2) after planting soybeans, spraying a mixed liquid fertilizer of potassium silicate, ammonium molybdate, and sodium selenite on the leaves at the early stage of pod formation. The production method of the present invention can produce soybeans with low cadmium content and high selenium content in cadmium-contaminated soil, while increasing soybean yield, thereby achieving safe, high-quality and high-yield soybeans in cadmium-contaminated acidic soil.

Description

Technical Field

[0001] The present invention belongs to the technical field of agricultural product safety control and quality regulation, and specifically relates to a method for producing low-cadmium and selenium-rich soybeans in cadmium-contaminated soil and an application thereof. Background Art

[0002] Cadmium is a highly toxic heavy metal. Cadmium pollution is insidious, long-lasting, and irreversible. Tens of thousands of tons of cadmium are released into the environment globally each year, the vast majority of which ends up in the soil. Currently, agricultural soils are severely contaminated with cadmium. Cadmium is easily absorbed and concentrated by surrounding crops, and accumulates through the food chain, seriously affecting crop safety, quality, and yield, and further endangering human health. Selenium is a rare element with uneven distribution in nature. It has physiological functions such as enhancing immunity, providing antioxidant and anti-aging benefits, and is an essential trace element for humans and animals. However, 72% of my country is selenium-deficient, and natural foods such as grains contain low levels of selenium. Approximately 700 million people live in these areas.

[0003] Soybeans and their products have become an indispensable food in people's lives. However, soybeans have a strong ability to accumulate cadmium. During the planting process, cadmium is easily absorbed by soybean roots and transferred to the ground, where it is then concentrated in the crop's grains. Soybeans are particularly prone to cadmium exceeding the standard. Even if the cadmium concentration in the soil is low, the cadmium content in soybean grains can reach a high level. Compared with the alkaline soils in the north, the cadmium in the acidic soils of the south is more active and effective, making it more likely to cause cadmium to exceed the standard in soybeans. Currently, soybeans grown and produced in cadmium-contaminated soils have high cadmium levels and low selenium levels, and the soybean yield is also low. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the prior art that soybeans grown and produced in cadmium-contaminated soil have high cadmium content and low selenium content, and at the same time, low soybean yield, thereby providing a method for producing low-cadmium and selenium-rich soybeans in cadmium-contaminated soil and its application.

[0005] The present invention provides a method for producing low-cadmium-selenium-rich soybeans from cadmium-contaminated soil, comprising the following steps:

[0006] 1) Before planting soybeans, spread calcium hydroxide and zinc calcium magnesium phosphate fertilizers on the soil surface and then turn the soil;

[0007] 2) After planting soybeans, spray the leaves with a mixture of potassium silicate, ammonium molybdate and sodium selenite in the early stage of pod setting.

[0008] The early pod-setting period refers to the period after soybean flowering when pods begin to form. The effect of applying selenium during the early pod-setting period is better than applying selenium during other periods (such as the flowering period and the seed-filling period).

[0009] Preferably, in step 1), 2-4 weeks before soybean planting, calcium hydroxide and zinc calcium magnesium phosphate fertilizer are spread on the soil surface, and then the soil is turned over;

[0010] Optionally, the zinc-calcium-magnesium-phosphate fertilizer contains, by mass percentage, effective zinc ≥ 0.010%, effective calcium ≥ 20.0%, effective magnesium ≥ 4.0%, effective phosphorus pentoxide ≥ 12.0%, and soluble silicon dioxide ≥ 20.0%;

[0011] Optionally, the zinc-calcium-magnesium-phosphate fertilizer contains, by mass percentage, 0.014% effective zinc, 23.0% effective calcium, 6.4% effective magnesium, 21.3% effective phosphorus pentoxide, and 24.7% soluble silicon dioxide.

[0012] The available zinc in the present invention refers to the zinc content in 1g of fertilizer that can be extracted by a hydrochloric acid solution (150mL 0.5mol / L); the extraction steps are: weighing 1g of fertilizer sample, adding 150mL of hydrochloric acid solution (0.5mol / L) and shaking on an oscillator at 30°C for 1h.

[0013] The effective calcium in the present invention refers to the calcium content in 1g of fertilizer that can be extracted by hydrochloric acid solution (150mL 0.5mol / L); the extraction steps are: weighing 1g of fertilizer sample, adding 150mL hydrochloric acid solution (0.5mol / L) and shaking on an oscillator at 30°C for 1h.

[0014] The effective magnesium in the present invention refers to the magnesium content in 1g of fertilizer that can be extracted by hydrochloric acid solution (150mL 0.5mol / L); the extraction steps are: weighing 1g of fertilizer sample, adding 150mL hydrochloric acid solution (0.5mol / L) and shaking on an oscillator at 30°C for 1h.

[0015] The available phosphorus pentoxide in the present invention refers to the phosphorus content in 1g of fertilizer that can be extracted by 150mL of 20g / L citric acid solution, and the content is calculated as phosphorus pentoxide. The specific extraction steps are: weigh 1g of fertilizer sample, add 150mL of 20g / L citric acid solution, and shake on an oscillator at 30°C for 1 hour.

[0016] The soluble silicon dioxide in the present invention refers to the silicon content in 1g of fertilizer that can be extracted by a 150mL 0.5mol / L hydrochloric acid solution, where the silicon content is calculated as silicon dioxide. The extraction steps are as follows: weigh 1g of fertilizer sample, add 150mL of a 0.5mol / L hydrochloric acid solution, and shake on an oscillator at 30°C for 1 hour.

[0017] Preferably, the amount of calcium hydroxide applied is negatively correlated with the pH (acidity) of the soil;

[0018] The application amount of the zinc, calcium, magnesium and phosphate fertilizers is positively correlated with the total cadmium content in the soil.

[0019] Preferably, when the pH of the soil satisfies 7.0≥pH>6.5, the application amount of calcium hydroxide is 30-60 kg / mu;

[0020] Alternatively, when the soil pH satisfies 6.5 ≥ pH > 6.0, the application amount of calcium hydroxide is 60-90 kg / mu;

[0021] Alternatively, when the soil pH satisfies 6.0≥pH>5.5, the application amount of calcium hydroxide is 90-120 kg / mu;

[0022] Alternatively, when the soil pH satisfies 5.5 ≥ pH > 5.0, the application amount of calcium hydroxide is 120-150 kg / mu;

[0023] Alternatively, when the pH of the soil satisfies 5.0≥pH>4.5, the application amount of the calcium hydroxide is 150-180 kg / mu.

[0024] It is understandable that the above-mentioned application amount of calcium hydroxide is based on large-scale field planting.

[0025] Preferably, when the total cadmium content of the soil satisfies 0.10 mg / kg<total cadmium≤0.30 mg / kg, the application amount of the zinc calcium magnesium phosphate fertilizer is 20-60 kg / mu;

[0026] Alternatively, when the total cadmium content of the soil satisfies 0.30 mg / kg<total cadmium≤0.40 mg / kg, the application amount of the zinc calcium magnesium phosphate fertilizer is 60-100 kg / mu;

[0027] Alternatively, when the total cadmium content of the soil satisfies 0.40 mg / kg<total cadmium≤0.50 mg / kg, the application amount of the zinc calcium magnesium phosphate fertilizer is 100-140 kg / mu;

[0028] Alternatively, when the total cadmium content of the soil satisfies 0.50 mg / kg<total cadmium≤0.60 mg / kg, the application amount of the zinc calcium magnesium phosphate fertilizer is 140-180 kg / mu.

[0029] It is understandable that the application amount of the above zinc, calcium, magnesium and phosphate fertilizers is based on large-scale per mu of land planting.

[0030] Preferably, when the pH of the soil satisfies 7.0≥pH>6.5, the mass ratio of the calcium hydroxide to the soil is 1:(3000-6000);

[0031] Alternatively, when the pH of the soil satisfies 6.5≥pH>6.0, the mass ratio of the calcium hydroxide to the soil is 1:(2000-3000);

[0032] Alternatively, when the pH of the soil satisfies 6.0≥pH>5.5, the mass ratio of the calcium hydroxide to the soil is 1:(1500-2000);

[0033] Alternatively, when the pH of the soil satisfies 5.5≥pH>5.0, the mass ratio of the calcium hydroxide to the soil is 1:(1200-1500);

[0034] Alternatively, when the pH of the soil satisfies 5.0≥pH>4.5, the mass ratio of the calcium hydroxide to the soil is 1:(1000-1200).

[0035] It is understandable that the above mass ratio of calcium hydroxide to soil is based on small-scale potted planting.

[0036] Preferably, when the total cadmium content of the soil satisfies 0.10 mg / kg<total cadmium≤0.30 mg / kg, the mass ratio of the zinc calcium magnesium phosphate fertilizer to the soil is 1:(3000-9000);

[0037] Alternatively, when the total cadmium content of the soil satisfies 0.30 mg / kg < total cadmium ≤ 0.40 mg / kg, the mass ratio of the zinc calcium magnesium phosphate fertilizer to the soil is 1: (1800-3000);

[0038] Alternatively, when the total cadmium content of the soil satisfies 0.40 mg / kg < total cadmium ≤ 0.50 mg / kg, the mass ratio of the zinc calcium magnesium phosphate fertilizer to the soil is 1: (1300-1800);

[0039] Alternatively, when the total cadmium content of the soil satisfies 0.50 mg / kg<total cadmium≤0.60 mg / kg, the mass ratio of the zinc calcium magnesium phosphate fertilizer to the soil is 1:(1000-1300).

[0040] It can be understood that the above-mentioned mass ratio of zinc, calcium, magnesium and phosphate fertilizers to soil is based on small-scale potted planting.

[0041] Preferably, the mass concentration of potassium silicate in the mixed liquid fertilizer of potassium silicate, ammonium molybdate and sodium selenite in step 2) is 100-200 mg / L;

[0042] The mass concentration of ammonium molybdate in the mixed liquid fertilizer of potassium silicate, ammonium molybdate and sodium selenite is 100-200 mg / L;

[0043] The mass concentration of sodium selenite in the mixed liquid fertilizer of potassium silicate, ammonium molybdate and sodium selenite is 10-20 mg / L.

[0044] Preferably, the depth of the soil turning in step 1) is 20-30 cm;

[0045] The spraying amount of the mixed liquid fertilizer of potassium silicate, ammonium molybdate and sodium selenite in step 2) is 40-50 L / mu;

[0046] Alternatively, the spraying amount of the mixed liquid fertilizer of potassium silicate, ammonium molybdate and sodium selenite in step 2) is 30-40 mL / plant.

[0047] The present invention provides an application of the above-mentioned method for producing low-cadmium and selenium-rich soybeans in cadmium-contaminated soil in soybean cultivation;

[0048] Preferably, the cadmium-contaminated soil is acidic cadmium-contaminated soil.

[0049] The technical solution of the present invention has the following advantages:

[0050] 1. The method for producing low-cadmium and selenium-rich soybeans from cadmium-contaminated soil provided by the present invention comprises the following steps: 1) before planting soybeans, spreading calcium hydroxide and zinc-calcium-magnesium-phosphate fertilizers on the soil surface, and then turning the soil;

[0051] 2) After planting soybeans, spray a mixed liquid fertilizer of potassium silicate, ammonium molybdate, and sodium selenite on the leaves at the early stage of pod formation. The present invention applies calcium hydroxide and zinc calcium magnesium phosphate fertilizers as fertilizer conditioners in the soil, which act synergistically to effectively improve the physical and chemical properties of the soil, so that cadmium undergoes adsorption, complexation, or precipitation reactions in the soil and is then passivated in situ, and the bioavailable form of cadmium in the soil is converted into an inactive form of cadmium, thereby controlling the migration and absorption of cadmium from the soil environment to the crop system, reducing the bioavailable form content and toxicity of cadmium in the soil, and ultimately reducing the absorption and accumulation of cadmium in soybean crops. Calcium hydroxide conditioners increase soil pH and can form carbonate and silicate precipitations with cadmium. For acidic soils in the south, increasing the soil pH is one of the effective ways to reduce the accumulation of cadmium in soybean crops; phosphorus-containing conditioners induce the adsorption of cadmium, and precipitate or adsorb and fix with cadmium particles; zinc-containing soil conditioners have an antagonistic effect with cadmium during the growth of soybean crops, which can significantly reduce the absorption and accumulation of cadmium in soybean crops. The synergistic effect between calcium hydroxide, zinc calcium magnesium phosphate fertilizer, potassium silicate, ammonium molybdate and sodium selenite can significantly reduce the absorption, accumulation, migration and transport of cadmium in soybean crops. The antagonistic effect between selenium and cadmium is affected by the type of crop. In soybean crops, selenium can alleviate heavy metal stress in plants and inhibit the absorption of heavy metals. In addition, selenium has a positive effect on promoting seed germination, crop growth, improving nutritional quality and increasing yield. Calcium, zinc, selenium, silicon, molybdenum and other ions mainly compete with cadmium for absorption through antagonism. The application of these trace elements promotes the absorption of these trace elements by soybean crops, reduces the cadmium content in soybean crops, and increases soybean yield at the same time. The present invention applies calcium hydroxide and zinc calcium magnesium phosphate fertilizer to the soil, and sprays potassium silicate, ammonium molybdate and sodium selenite mixed liquid fertilizer on the leaves. The synergistic effect can produce soybeans with low cadmium content and high selenium content in cadmium-contaminated soil, while increasing soybean yield, and achieving safe, high-quality and high-yield soybeans in cadmium-contaminated acidic soil.

[0052] 2. The method for producing low-cadmium and selenium-rich soybeans from cadmium-contaminated soil provided by the present invention, the mass concentration of potassium silicate in the mixed liquid fertilizer of potassium silicate, ammonium molybdate and sodium selenite in step 2) is 100-200 mg / L; the mass concentration of ammonium molybdate in the mixed liquid fertilizer of potassium silicate, ammonium molybdate and sodium selenite is 100-200 mg / L; the mass concentration of sodium selenite in the mixed liquid fertilizer of potassium silicate, ammonium molybdate and sodium selenite is 10-20 mg / L. When the concentration of trace elements applied is too high, the antagonistic effect is reduced, and the effect of blocking the absorption and transport of cadmium in soybean crops will be affected to a certain extent. Therefore, foliar spraying further selects specific types of fertilizer conditioners and appropriate concentrations, which can further control the absorption and accumulation of heavy metals in soybean crops, further promote the growth of soybean crops, improve quality (low cadmium content, high selenium content) and increase yield.

[0053] 3. The present invention provides a method for producing low-cadmium, selenium-rich soybeans from cadmium-contaminated soil. The zinc-calcium-magnesium-phosphate fertilizer contains, by mass, ≥0.010% available zinc, ≥20.0% available calcium, ≥4.0% available magnesium, ≥12.0% available phosphorus pentoxide, and ≥20.0% soluble silicon dioxide. The silicon contained in the soil conditioner can fix cadmium in the soil and hinder cadmium absorption by crop roots, thereby reducing cadmium content in the crops. According to the invention, when the pH value of the soil satisfies 7.0≥pH>6.5, the application amount of the calcium hydroxide is 30-60 kg / mu; or, when the pH value of the soil satisfies 6.5≥pH>6.0, the application amount of the calcium hydroxide is 60-90 kg / mu; or, when the pH value of the soil satisfies 6.0≥pH>5.5, the application amount of the calcium hydroxide is 90-120 kg / mu; or, when the pH value of the soil satisfies 5.5≥pH>5.0, the application amount of the calcium hydroxide is 120-150 kg / mu; or, when the pH value of the soil satisfies 5.0≥pH>4.5, the application amount of the calcium hydroxide is 150-180 kg / mu. When the total cadmium content of the soil satisfies 0.10 mg / kg<total cadmium≤0.30 mg / kg, the application amount of the zinc calcium magnesium phosphate fertilizer is 20-60 kg / mu; or, when the total cadmium content of the soil satisfies 0.30 mg / kg<total cadmium≤0.40 mg / kg, the application amount of the zinc calcium magnesium phosphate fertilizer is 60-100 kg / mu; or, when the total cadmium content of the soil satisfies 0.40 mg / kg<total cadmium≤0.50 mg / kg, the application amount of the zinc calcium magnesium phosphate fertilizer is 100-140 kg / mu; or, when the total cadmium content of the soil satisfies 0.50 mg / kg<total cadmium≤0.60 mg / kg, the application amount of the zinc calcium magnesium phosphate fertilizer is 140-180 kg / mu.Alternatively, according to small-scale potted planting, when the pH of the soil satisfies 7.0 ≥ pH > 6.5, the mass ratio of the calcium hydroxide to the soil is 1: (3000-6000); or, when the pH of the soil satisfies 6.5 ≥ pH > 6.0, the mass ratio of the calcium hydroxide to the soil is 1: (2000-3000); or, when the pH of the soil satisfies 6.0 ≥ pH > 5.5, the mass ratio of the calcium hydroxide to the soil is 1: (1500-2000); or, when the pH of the soil satisfies 5.5 ≥ pH > 5.0, the mass ratio of the calcium hydroxide to the soil is 1: (1200-1500); or, when the pH of the soil satisfies 5.0 ≥ pH > 4.5, the mass ratio of the calcium hydroxide to the soil is 1: (1000-12 00); when the total cadmium content of the soil satisfies 0.10 mg / kg < total cadmium ≤ 0.30 mg / kg, the mass ratio of the zinc calcium magnesium phosphate fertilizer to the soil is 1: (3000-9000); or, when the total cadmium content of the soil satisfies 0.30 mg / kg < total cadmium ≤ 0.40 mg / kg, the mass ratio of the zinc calcium magnesium phosphate fertilizer to the soil is 1: (1800-3000); or, when the total cadmium content of the soil satisfies 0.40 mg / kg < total cadmium ≤ 0.50 mg / kg, the mass ratio of the zinc calcium magnesium phosphate fertilizer to the soil is 1: (1300-1800); or, when the total cadmium content of the soil satisfies 0.50 mg / kg < total cadmium ≤ 0.60 mg / kg, the mass ratio of the zinc calcium magnesium phosphate fertilizer to the soil is 1: (1000-1300). By further controlling the application amount of soil fertilizer, the present invention can further effectively change the physical and chemical properties of the soil, such as pH, redox potential, etc., further affect the effectiveness of heavy metal cadmium in the soil, and reduce the absorption and accumulation of cadmium in crops. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0055] Figure 1 Comparison of soybean yields of Example 1, Comparative Example 1, and Comparative Example 4 of the present invention;

[0056] Figure 2 Comparison of soybean yields of Example 2, Comparative Example 2, and Comparative Example 5 of the present invention;

[0057] Figure 3 Comparison of soybean yields of Example 3, Comparative Example 3, and Comparative Example 6 of the present invention;

[0058] Figure 4 Comparison of selenium and cadmium contents in soybeans of Example 1, Comparative Example 1, and Comparative Example 4 of the present invention;

[0059] Figure 5 Comparison of selenium and cadmium contents in soybeans of Example 2, Comparative Example 2, and Comparative Example 5 of the present invention;

[0060] Figure 6 Comparison of selenium and cadmium contents in soybeans of Example 3, Comparative Example 3 and Comparative Example 6 of the present invention. DETAILED DESCRIPTION

[0061] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0062] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0063] The zinc-calcium-magnesium-phosphate fertilizer used in the examples and comparative examples of the present invention contains 0.014% of available zinc, 23.0% of available calcium, 6.4% of available magnesium, 21.3% of available phosphorus pentoxide, and 24.7% of soluble silicon dioxide.

[0064] The calcium magnesium phosphate fertilizer used in the comparative example of the present invention contains 23.0% of available calcium, 6.4% of available magnesium, 21.3% of available phosphorus pentoxide, and 24.7% of soluble silicon dioxide.

[0065] Example 1

[0066] This example is a field plot experiment, and each field plot has an area of 100m 2 The experiment was conducted in Nanchang County, Nanchang City, Jiangxi Province, with three replicates. The soil type was paddy soil with a pH of 5.67 and a total cadmium content of 0.54 mg / kg.

[0067] This embodiment provides a method for producing low-cadmium, selenium-rich soybeans from cadmium-contaminated soil, comprising the following steps:

[0068] 1) Three weeks before soybean planting, evenly spread calcium hydroxide and zinc-calcium-magnesium-phosphate fertilizers on the soil surface, then turn the soil to a depth of 25 cm. The application rate of calcium hydroxide is 120 kg / mu, and the application rate of zinc-calcium-magnesium-phosphate fertilizer is 150 kg / mu.

[0069] 2) After planting soybeans, spray a mixed liquid fertilizer of potassium silicate, ammonium molybdate, and sodium selenite on the leaves at the early stage of soybean pod setting. The spraying rate of the mixed liquid fertilizer of potassium silicate, ammonium molybdate, and sodium selenite is 50 L / mu; the mass concentration of potassium silicate in the mixed liquid fertilizer of potassium silicate, ammonium molybdate, and sodium selenite is 200 mg / L; the mass concentration of ammonium molybdate in the mixed liquid fertilizer of potassium silicate, ammonium molybdate, and sodium selenite is 200 mg / L; the mass concentration of sodium selenite in the mixed liquid fertilizer of potassium silicate, ammonium molybdate, and sodium selenite is 20 mg / L.

[0070] During the soybean growth process, field management was carried out according to conventional production methods. Soybeans were harvested when the stems and leaves began to turn yellow and the stalks and pods were dry and dark brown.

[0071] Example 2

[0072] This example is a field plot experiment, and each field plot has an area of 100m 2 Three replicates were set up in Gao'an, Yichun, Jiangxi Province. The experimental soil type was red loam, with a soil pH of 4.56 and a total cadmium content of 0.46 mg / kg.

[0073] This embodiment provides a method for producing low-cadmium, selenium-rich soybeans from cadmium-contaminated soil, comprising the following steps:

[0074] 1) Three weeks before soybean planting, evenly spread calcium hydroxide and zinc calcium magnesium phosphate fertilizer on the soil surface, then turn the soil to a depth of 30 cm; the application rate of calcium hydroxide is 180 kg / mu, and the application rate of zinc calcium magnesium phosphate is 120 kg / mu.

[0075] 2) After planting soybeans, spray a mixed liquid fertilizer of potassium silicate, ammonium molybdate, and sodium selenite on the leaves at the early stage of soybean pod setting. The spraying rate of the mixed liquid fertilizer of potassium silicate, ammonium molybdate, and sodium selenite is 50 L / mu; the mass concentration of potassium silicate in the mixed liquid fertilizer of potassium silicate, ammonium molybdate, and sodium selenite is 150 mg / L; the mass concentration of ammonium molybdate in the mixed liquid fertilizer of potassium silicate, ammonium molybdate, and sodium selenite is 150 mg / L; the mass concentration of sodium selenite in the mixed liquid fertilizer of potassium silicate, ammonium molybdate, and sodium selenite is 15 mg / L.

[0076] During the soybean growth process, field management was carried out according to conventional production methods. Soybeans were harvested when the stems and leaves began to turn yellow and the stalks and pods were dry and dark brown.

[0077] Example 3

[0078] This example is a potted experiment with six replicates in Gao'an, Yichun, Jiangxi Province. The test soil type is yellow loam, with a soil pH of 5.25 and a total cadmium content of 0.33 mg / kg. Each pot is filled with 10 kg of dry fine soil (4 mm sieved).

[0079] This embodiment provides a method for producing low-cadmium, selenium-rich soybeans from cadmium-contaminated soil, comprising the following steps:

[0080] 1) Three weeks before soybean planting, mix 8.0g of calcium hydroxide and 4.0g of zinc-calcium-magnesium-phosphate fertilizer with 10.0kg of soil and place them in a pot, keeping the soil depth at 30cm.

[0081] 2) After planting soybeans, thinning is carried out according to the growth of seedlings, and 2 seedlings are finally set per pot. At the early stage of soybean pod setting, potassium silicate, ammonium molybdate, and sodium selenite mixed liquid fertilizer is sprayed on the leaves. The spraying rate of potassium silicate, ammonium molybdate, and sodium selenite mixed liquid fertilizer is 40 mL / plant; the mass concentration of potassium silicate in the potassium silicate, ammonium molybdate, and sodium selenite mixed liquid fertilizer is 150 mg / L; the mass concentration of ammonium molybdate in the potassium silicate, ammonium molybdate, and sodium selenite mixed liquid fertilizer is 150 mg / L; the mass concentration of sodium selenite in the potassium silicate, ammonium molybdate, and sodium selenite mixed liquid fertilizer is 10 mg / L.

[0082] During the soybean growth process, manage the soybeans according to conventional production methods. Harvest soybeans when the stems and leaves begin to turn yellow and the stalks and pods are dry and dark brown.

[0083] Comparative Example 1

[0084] This comparative example provides a method for producing low-cadmium and selenium-rich soybeans from cadmium-contaminated soil, which differs from Example 1 in that zinc-calcium-magnesium-phosphate fertilizer is replaced with calcium-magnesium-phosphate fertilizer of equal mass in step 1).

[0085] Comparative Example 2

[0086] This comparative example is a field plot test, with each plot having an area of 100m 2 Three replicates were set up in Gao'an, Yichun, Jiangxi Province. The experimental soil type was red loam, with a soil pH of 4.56 and a total cadmium content of 0.46 mg / kg.

[0087] This comparative example provides a method for producing low-cadmium-selenium-rich soybeans from cadmium-contaminated soil, comprising the following steps:

[0088] 1) Three weeks before soybean planting, evenly spread zinc, calcium, magnesium and phosphate fertilizers on the soil surface, then turn the soil to a depth of 30 cm; the application rate of zinc, calcium, magnesium and phosphate fertilizers is 120 kg / mu.

[0089] 2) After planting soybeans, spray a mixed liquid fertilizer of potassium silicate and ammonium molybdate on the leaves at the early stage of soybean pod formation. The spraying rate of the mixed liquid fertilizer of potassium silicate and ammonium molybdate is 50 L / mu; the mass concentration of potassium silicate in the mixed liquid fertilizer of potassium silicate and ammonium molybdate is 150 mg / L; the mass concentration of ammonium molybdate in the mixed liquid fertilizer of potassium silicate and ammonium molybdate is 150 mg / L.

[0090] During the soybean growth process, field management was carried out according to conventional production methods. Soybeans were harvested when the stems and leaves began to turn yellow and the stalks and pods were dry and dark brown.

[0091] Comparative Example 3

[0092] This comparative example provides a method for producing low-cadmium, selenium-rich soybeans from cadmium-contaminated soil, which differs from Example 3 in that zinc, calcium, magnesium and phosphate fertilizers are not used in step 1).

[0093] Comparative Example 4

[0094] This comparative example provides a method for producing low-cadmium, selenium-rich soybeans from cadmium-contaminated soil. Compared to Example 1, this method does not use any fertilizer or calcium hydroxide. During soybean growth, field management is performed according to conventional production methods. The soybeans are harvested when their stems and leaves begin to yellow and their stalks and pods are dry and dark brown.

[0095] Comparative Example 5

[0096] This comparative example provides a method for producing low-cadmium, selenium-rich soybeans from cadmium-contaminated soil. Compared to Example 2, this method does not use any fertilizer or calcium hydroxide. During soybean growth, field management is performed according to conventional production methods. The soybeans are harvested when their stems and leaves begin to yellow and their stalks and pods are dry and dark brown.

[0097] Comparative Example 6

[0098] This comparative example provides a method for producing low-cadmium, selenium-rich soybeans from cadmium-contaminated soil. This method differs from Example 3 in that no fertilizer or calcium hydroxide is used, and the soybeans are managed according to conventional production methods during their growth. The soybeans are harvested when their stems and leaves begin to yellow and their stalks and pods are dry and dark brown.

[0099] Comparative Example 7

[0100] This comparative example provides a method for producing low-cadmium and selenium-rich soybeans in cadmium-contaminated soil. The difference between the method and Example 2 is that after planting soybeans in step 2), a mixed liquid fertilizer of ammonium molybdate and sodium selenite is sprayed on the leaves at the early stage of soybean pod formation, and the spraying rate of the mixed liquid fertilizer of ammonium molybdate and sodium selenite is 50 L / mu; the mass concentration of ammonium molybdate in the mixed liquid fertilizer of ammonium molybdate and sodium selenite is 150 mg / L; the mass concentration of sodium selenite in the mixed liquid fertilizer of ammonium molybdate and sodium selenite is 15 mg / L.

[0101] Test Case

[0102] The soybean yields of Examples 1-3 and Comparative Examples 1-6 were statistically analyzed, and the statistical results are shown in Table 1. Figure 1-Figure 3 The soybeans harvested from Examples 1-3 and Comparative Examples 1-6 were dried and crushed, and the samples were digested by microwave using a nitric acid-hydrogen peroxide system. The selenium and cadmium contents in the soybeans were then determined using inductively coupled plasma mass spectrometry (ICP-MS). The test results are shown in Table 1. Figure 4-Figure 6 The test results of the test examples of the present invention are all average values of repeated tests.

[0103] Table 1

[0104]

[0105]

[0106] From Table 1, Figure 1 and Figure 4 It can be seen that compared with Comparative Example 4 (the blank control of Example 1), the cadmium content in the soybeans harvested in Example 1 was significantly reduced by 68.8%; the selenium content was significantly increased by 1514%; and the yield was significantly increased by 9.6%. Compared with Comparative Example 4, the cadmium content in the soybeans harvested in Comparative Example 1 was reduced by 34.2%; the selenium content was increased by 1286%; and the yield was increased by 5.6%. It can be seen that the cadmium reduction, selenium enrichment, and yield increase effects of Example 1 are all extremely significant and significantly superior to Comparative Example 1.

[0107] From Table 1, Figure 2 and Figure 5 It can be seen that compared with Comparative Example 5 (the blank control of Example 2), the cadmium content in the soybeans of Example 2 was significantly reduced by 69.4%; the selenium content was significantly increased by 859%; and the yield was significantly increased by 11.4%. Compared with Comparative Example 5, the cadmium content in the soybeans of Comparative Example 2 was reduced by 15.5%. It can be seen that the cadmium reduction, selenium enrichment and yield increase effect of Example 2 are significantly better than those of Comparative Examples 2 and Comparative Examples 7.

[0108] From Table 1, Figure 5 and Figure 6 As can be seen, compared with Comparative Example 6 (the blank control of Example 3), the cadmium content in the soybeans of Example 3 was significantly reduced by 66.5%, the selenium content was significantly increased by 687%, and the yield was significantly increased by 12.1%. Compared with Comparative Example 6, the cadmium content in the soybeans of Comparative Example 3 was reduced by 16.4%, the selenium content was increased by 289%, and the yield was increased by 3.8%. It can be seen that the effect of Example 3 is significantly better than that of Comparative Example 3.

[0109] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for producing low-cadmium-selenium-rich soybeans from cadmium-contaminated soil, characterized in that: The following steps are involved: 1) Before planting soybeans, calcium hydroxide and zinc-calcium-magnesium-phosphate fertilizer are spread on the soil surface, and then the soil is turned over; the zinc-calcium-magnesium-phosphate fertilizer contains, by mass percentage, available zinc ≥ 0.010%, available calcium ≥ 20.0%, available magnesium ≥ 4.0%, available phosphorus pentoxide ≥ 12.0%, and soluble silicon dioxide ≥ 20.0%; 2) After planting soybeans, spraying a mixed liquid fertilizer of potassium silicate, ammonium molybdate, and sodium selenite on the leaves at the early stage of pod setting; the mass concentration of potassium silicate in the mixed liquid fertilizer is 100-200 mg / L; the mass concentration of ammonium molybdate in the mixed liquid fertilizer is 100-200 mg / L; the mass concentration of sodium selenite in the mixed liquid fertilizer is 100-200 mg / L.

2. The method for producing low-cadmium and selenium-rich soybeans from cadmium-contaminated soil according to claim 1, characterized in that: Step 1) 2-4 weeks before planting soybeans, spread calcium hydroxide and zinc calcium magnesium phosphate fertilizers on the soil surface and then turn the soil.

3. The method for producing low-cadmium and selenium-rich soybeans from cadmium-contaminated soil according to claim 1 or 2, characterized in that: The zinc-calcium-magnesium-phosphate fertilizer contains, by mass percentage, 0.014% effective zinc, 23.0% effective calcium, 6.4% effective magnesium, 21.3% effective phosphorus pentoxide, and 24.7% soluble silicon dioxide.

4. The method for producing low-cadmium and selenium-rich soybeans from cadmium-contaminated soil according to claim 1 or 2, characterized in that: The amount of calcium hydroxide applied is negatively correlated with the pH of the soil; The application amount of the zinc, calcium, magnesium and phosphate fertilizers is positively correlated with the total cadmium content in the soil.

5. The method for producing low-cadmium and selenium-rich soybeans from cadmium-contaminated soil according to claim 1 or 2, characterized in that: When the soil pH satisfies 7.0≥pH>6.5, the application amount of calcium hydroxide is 30-60 kg / mu; Alternatively, when the soil pH satisfies 6.5≥pH>6.0, the application amount of calcium hydroxide is 60-90 kg / mu; Alternatively, when the soil pH satisfies 6.0≥pH>5.5, the application amount of calcium hydroxide is 90-120 kg / mu; Alternatively, when the soil pH satisfies 5.5 ≥ pH > 5.0, the application amount of calcium hydroxide is 120-150 kg / mu; Alternatively, when the pH of the soil satisfies 5.0≥pH>4.5, the application amount of the calcium hydroxide is 150-180 kg / mu.

6. The method for producing low-cadmium and selenium-rich soybeans from cadmium-contaminated soil according to claim 1 or 2, characterized in that: When the total cadmium content of the soil satisfies 0.10 mg / kg<total cadmium≤0.30 mg / kg, the application amount of the zinc calcium magnesium phosphate fertilizer is 20-60 kg / mu; Alternatively, when the total cadmium content of the soil satisfies 0.30 mg / kg<total cadmium≤0.40 mg / kg, the application amount of the zinc, calcium, magnesium and phosphate fertilizer is 60-100 kg / mu; Alternatively, when the total cadmium content of the soil satisfies 0.40 mg / kg<total cadmium≤0.50 mg / kg, the application amount of the zinc calcium magnesium phosphate fertilizer is 100-140 kg / mu; Alternatively, when the total cadmium content of the soil satisfies 0.50 mg / kg<total cadmium≤0.60 mg / kg, the application amount of the zinc, calcium, magnesium and phosphate fertilizer is 140-180 kg / mu.

7. The method for producing low-cadmium and selenium-rich soybeans from cadmium-contaminated soil according to claim 1 or 2, characterized in that: When the pH of the soil satisfies 7.0≥pH>6.5, the mass ratio of the calcium hydroxide to the soil is 1:(3000-6000); Alternatively, when the pH of the soil satisfies 6.5 ≥ pH > 6.0, the mass ratio of the calcium hydroxide to the soil is 1: (2000-3000); Alternatively, when the pH of the soil satisfies 6.0≥pH>5.5, the mass ratio of the calcium hydroxide to the soil is 1:(1500-2000); Alternatively, when the pH of the soil satisfies 5.5 ≥ pH > 5.0, the mass ratio of the calcium hydroxide to the soil is 1: (1200-1500); Alternatively, when the pH of the soil satisfies 5.0≥pH>4.5, the mass ratio of the calcium hydroxide to the soil is 1:(1000-1200).

8. The method for producing low-cadmium and selenium-rich soybeans from cadmium-contaminated soil according to claim 7, characterized in that: When the total cadmium content of the soil satisfies 0.10 mg / kg<total cadmium≤0.30 mg / kg, the mass ratio of the zinc calcium magnesium phosphate fertilizer to the soil is 1:(3000-9000); Alternatively, when the total cadmium content of the soil satisfies 0.30 mg / kg<total cadmium≤0.40 mg / kg, the mass ratio of the zinc calcium magnesium phosphate fertilizer to the soil is 1:(1800-3000); Alternatively, when the total cadmium content of the soil satisfies 0.40 mg / kg<total cadmium≤0.50 mg / kg, the mass ratio of the zinc calcium magnesium phosphate fertilizer to the soil is 1:(1300-1800); Alternatively, when the total cadmium content of the soil satisfies 0.50 mg / kg<total cadmium≤0.60 mg / kg, the mass ratio of the zinc calcium magnesium phosphate fertilizer to the soil is 1:(1000-1300).

9. The method for producing low-cadmium and selenium-rich soybeans from cadmium-contaminated soil according to claim 1 or 2, characterized in that: The depth of the soil turned in step 1) is 20-30 cm; The spraying rate of the mixed liquid fertilizer of potassium silicate, ammonium molybdate and sodium selenite in step 2) is 40-50 L / mu; Alternatively, the spraying amount of the mixed liquid fertilizer of potassium silicate, ammonium molybdate and sodium selenite in step 2) is 30-40 mL / plant.

10. Use of the method for producing low-cadmium and selenium-rich soybeans from cadmium-contaminated soil according to any one of claims 1 to 9 in soybean cultivation in cadmium-contaminated soil.

11. Use of the method for producing low-cadmium and selenium-rich soybeans from cadmium-contaminated soil according to claim 10 in soybean cultivation in cadmium-contaminated soil, wherein the cadmium-contaminated soil is acidic cadmium-contaminated soil.

Images