Soil conditioner as well as preparation method and application thereof

Abstract

The invention belongs to the field of quality safety of agricultural products, and particularly relates to a soil conditioner as well as a preparation method and application thereof. The soil conditioner provided by the invention is prepared from slaked lime, calcium hydrogen phosphate, potassium nitrate, urea, calcium silicate, zinc sodium ethylene diamine tetraacetate and sodium selenite. The conditioner formed by reasonably matching different fertilizers is small in application amount, under the synergistic effect of the fertilizers, the content of heavy metal in agricultural products can be remarkably reduced, meanwhile, the selenium content and yield in the agricultural products can be remarkably increased, and the conditioner is suitable for various crop varieties.

Description

Technical Field

[0001] The invention belongs to the field of agricultural product quality safety, and specifically relates to a soil conditioner and a preparation method and application thereof. Background Art

[0002] With the rapid development of industry and the widespread use of pesticides and fertilizers, heavy metal pollution in soil and agricultural products cannot be ignored. Acidic soil, due to its low pH value, is prone to compaction, which affects the absorption and utilization of nutrients by crops. It also intensifies the dissolution and migration of heavy metals in the soil and increases their biological effectiveness. This is also the main reason why the content of heavy metals (such as cadmium) in the soil is not high, while the content of heavy metals in agricultural products is high or even exceeds the standard. Therefore, it is of great significance to take reasonable improvement measures to control the heavy metal hazards in acidic soil from the source of the soil to reduce the content of heavy metals in agricultural products.

[0003] At present, soil conditioners are mainly applied in two ways: soil application and spraying. Foliar spraying of conditioners has obvious disadvantages, such as the need for multiple sprayings, which greatly increases labor costs, and has limitations such as short duration of effect, so soil application is more advantageous. However, existing soil-applied conditioners have problems such as large application amount, small reduction in heavy metal content in agricultural products, low yield increase, single crop suitability, and no increase in selenium content. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of existing soil conditioners, such as large dosage, small reduction in heavy metal content in agricultural products, low yield increase, suitability for a single crop, and no increase in selenium content, and further provide a soil conditioner and its preparation method and application.

[0005] The invention provides a soil conditioner, which comprises slaked lime, calcium hydrogen phosphate, potassium nitrate, urea, calcium silicate, sodium zinc ethylenediaminetetraacetate and sodium selenite.

[0006] Preferably, the soil conditioner comprises, by mass percentage, 30%-38% slaked lime, 20%-25% calcium hydrogen phosphate, 14%-18% potassium nitrate, 10%-15% urea, 9%-12% calcium silicate, 7%-10% sodium zinc ethylenediaminetetraacetic acid, and 0.04%-0.07% sodium selenite.

[0007] The present invention provides a method for applying the soil conditioner described above, comprising the following steps:

[0008] 1) Before planting crops, spread the soil conditioner on the soil surface and turn the soil;

[0009] 2) Planting crops.

[0010] Preferably, in step 1), the soil conditioner is spread on the soil surface and the soil is turned 1-2 weeks before the crops are planted.

[0011] Preferably, the application amount of the soil conditioner in step 1) is adjusted according to the soil pH and cadmium content;

[0012] The ratio of the application rate of soil conditioner per mu to the cadmium content in soil is recorded as A, and A is negatively correlated with soil pH.

[0013] Preferably, in step 1), when the soil pH satisfies 4.5<pH≤5.5, the ratio of the application amount of soil conditioner per mu to the cadmium content in the soil is (350-450):1, in units of kg:(mg / kg);

[0014] Alternatively, when the soil pH satisfies 5.5<pH≤6.5, the ratio of the application amount of soil conditioner per mu to the cadmium content in the soil is (260-340):1, in kg:(mg / kg);

[0015] Alternatively, when the soil pH satisfies 6.5<pH≤7.5, the ratio of the application amount of soil conditioner per mu to the cadmium content in the soil is (180-220):1, in units of kg:(mg / kg).

[0016] Preferably, the depth of turning the soil in step 1) is 20-40 cm.

[0017] Preferably, the crops in step 2) include at least one of pepper, soybean and Stropharia rugosa.

[0018] The present invention provides an application of the above-mentioned soil conditioner or the above-mentioned method for applying the soil conditioner in planting in heavy metal contaminated soil; preferably, the heavy metal includes cadmium and / or lead.

[0019] The present invention provides an application of the soil conditioner or the application method of the soil conditioner in planting in acidic or neutral soil.

[0020] The present invention uses slaked lime as calcium fertilizer, which is a cheap and effective method for regulating soil pH. However, the amount of slaked lime needs to be determined according to the soil pH, because excessive use can easily cause soil compaction or salinization, thereby affecting soil quality and crop growth. Phosphate fertilizers are commonly used in agricultural production and can also increase soil pH, playing an important role in reducing soil heavy metal pollution. However, some phosphate fertilizers have a high content of heavy metals, and excessive application of phosphate fertilizers can lead to excessive accumulation of soil phosphorus, causing secondary environmental problems. Therefore, it is particularly important to select suitable types and amounts of phosphate fertilizers to reduce heavy metal accumulation.

[0021] Zinc is one of the essential trace elements in the growth and development of plants. It plays a variety of important roles in plants. In our previous research, we found that the application of zinc fertilizer in acidic soil has a good cadmium reduction effect. In addition, the combination of various fertilizers in soil conditioners is extremely important. For example, acidic fertilizers should not be mixed with alkaline fertilizers. Therefore, chelated zinc is selected as zinc fertilizer to replace acidic fertilizer zinc sulfate.

[0022] Selenium has the physiological functions of enhancing immunity, anti-oxidation and anti-aging, and is an essential trace element for the human body. 72% of my country's regions are selenium-deficient areas, and about 700 million people have insufficient selenium intake. Studies have shown that selenium has an antagonistic effect on heavy metals, but it is still quite challenging. It is affected by multiple factors such as selenium and cadmium concentration, application method, and soil physical and chemical properties, and sometimes the effect is not obvious. The soil conditioner of the present invention contains selenium fertilizer, which is beneficial to further reduce the content of heavy metals in agricultural products and improve the safety of agricultural products; at the same time, the selenium content of agricultural products is greatly increased, and the nutritional quality of agricultural products is improved, which can be said to kill two birds with one stone.

[0023] The technical solution of the present invention has the following advantages:

[0024] The soil conditioner provided by the present invention comprises slaked lime, calcium hydrogen phosphate, potassium nitrate, urea, calcium silicate, sodium zinc ethylenediaminetetraacetic acid, and sodium selenite. The present invention selects specific chemical substances for combination to give full play to the synergistic effect between the components. For example, calcium fertilizer can improve the utilization rate of fertilizers such as phosphate fertilizer; phosphate fertilizer can promote the absorption and utilization of zinc fertilizer; potash fertilizer can promote the accumulation of zinc fertilizer and selenium fertilizer in plants; zinc fertilizer can promote the absorption and utilization of nutrient elements. In addition, selenium fertilizer can promote the absorption of nitrogen and phosphorus; reasonable nitrogen-phosphorus ratio or balanced application of potassium-magnesium fertilizer can improve the yield and quality of crops; the synergistic effect of the presence of phosphorus and potassium can improve the stress resistance and yield of crops; the synergistic effect of calcium and magnesium can enhance the stress resistance of crops, improve soil structure, and improve the water and fertilizer retention capacity of soil, thereby promoting the growth and development of plants; the synergistic effect of selenium and silicon can significantly reduce the cadmium content in rice. The present invention scientifically and reasonably combines various fertilizers and conditioners in dosage composition, and under the composite synergistic effect, can effectively improve soil pH, reduce the bioavailability of cadmium and lead in the soil, thereby significantly reducing the cadmium and lead content in agricultural products, while significantly increasing their selenium content and yield. The present invention is suitable for a variety of crops and has a small application amount.

[0025] The soil conditioner provided by the present invention comprises, by mass percentage, 30%-40% of slaked lime, 20%-25% of calcium hydrogen phosphate, 14%-18% of potassium nitrate, 10%-15% of urea, 9%-12% of calcium silicate, 7%-10% of sodium zinc ethylenediaminetetraacetate, and 0.04%-0.07% of sodium selenite. The present invention selects specific components with specific contents and further adjusts the synergistic effect between the components, thereby further reducing the cadmium and lead contents in agricultural products and further increasing the selenium content and yield thereof.

[0026] The soil conditioner provided by the present invention has low cost, small dosage, wide application range, significant and lasting effect, is particularly suitable for improving acidic soil, and can sustainably achieve safe and high-quality production of agricultural products.

[0027] The method for applying the soil conditioner provided by the present invention comprises the following steps: 1) before planting crops, spreading the soil conditioner on the soil surface and turning the soil; 2) planting crops. Spreading the specific soil conditioner of the present invention on the soil surface before planting crops and then turning the soil, after planting crops, can significantly reduce the cadmium and lead content in the agricultural products obtained from the final crops, while significantly increasing the selenium content and yield thereof.

[0028] The method for applying a soil conditioner provided by the present invention, the application amount of the soil conditioner in step 1) is adjusted according to the soil pH and cadmium content; the ratio of the application amount of the soil conditioner per mu to the soil cadmium content is recorded as A, and A is negatively correlated with the soil pH. Further, in step 1), when the soil pH satisfies 4.5<pH≤5.5, the ratio of the application amount of the soil conditioner per mu to the soil cadmium content is (350-450):1, in units of kg:(mg / kg); or, when the soil pH satisfies 5.5<pH≤6.5, the ratio of the application amount of the soil conditioner per mu to the soil cadmium content is (260-340):1, in units of kg:(mg / kg); or, when the soil pH satisfies 6.5<pH≤7.5, the ratio of the application amount of the soil conditioner per mu to the soil cadmium content is (180-220):1, in units of kg:(mg / kg). The present invention further ensures that the cadmium and lead contents in agricultural products are reduced, while increasing the selenium content and yield thereof, by precisely controlling the application amount of the soil conditioner. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 Comparison of cadmium content, lead content, selenium content and yield of peppers grown under different conditions in Example 1 of the present invention, Comparative Example 1 and Comparative Example 2;

[0031] Figure 2 Comparison of cadmium content, lead content, selenium content and yield of soybeans grown under different conditions in Example 2 of the present invention, Comparative Example 10 and Comparative Example 11;

[0032] Figure 3 Comparison of cadmium content, lead content, selenium content and yield of Stropharia rugosa grown under different conditions in Example 3 of the present invention, Comparative Example 12 and Comparative Example 13;

[0033] Figure 4 Comparison of cadmium content in peppers grown under different conditions in Example 1 of the present invention and Comparative Examples 1-9;

[0034] Figure 5 Comparison of lead content in peppers grown under different conditions in Example 1 of the present invention and Comparative Examples 1-9;

[0035] Figure 6 Comparison of selenium content of peppers grown under different conditions in Example 1 of the present invention and Comparative Examples 1-9;

[0036] Figure 7 Comparison of pepper yields grown under different conditions in Example 1 of the present invention and Comparative Examples 1-9. DETAILED DESCRIPTION

[0037] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0038] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0039] Example 1

[0040] This example is a field plot experiment, and each field plot has an area of ​​100m 2 , set up 3 replicates. The experimental soil type is paddy soil, the soil pH is 6.59, and the total cadmium content is 0.48 mg / kg.

[0041] This embodiment provides a method for applying a soil conditioner, comprising the following steps:

[0042] 1) Two weeks before pepper planting, evenly spread the conditioner on the soil surface. The conditioner consists of 30.94% slaked lime, 20% calcium hydrogen phosphate, 18% potassium nitrate, 12% urea, 10% calcium silicate, 9% sodium zinc ethylenediaminetetraacetic acid, and 0.06% sodium selenite by mass. The conditioner application rate is 100 kg / mu, and then the soil is turned over to a depth of 25 cm.

[0043] 2) Transplant pepper seedlings according to conventional production methods, carry out conventional field management, and harvest peppers on the 60th day of the pepper fruiting period.

[0044] Example 2

[0045] This example is a field plot experiment, and each field plot has an area of ​​100m 2 , set up 3 replicates. The experimental soil type is red soil, the soil pH is 5.77, and the total cadmium content is 0.53 mg / kg.

[0046] This embodiment provides a method for applying a soil conditioner, comprising the following steps:

[0047] 1) Two weeks before soybean planting, evenly spread the conditioner on the soil surface. The conditioner consists of 36.93% slaked lime, 20% calcium hydrogen phosphate, 14% potassium nitrate, 10% urea, 10% calcium silicate, 9% sodium zinc ethylenediaminetetraacetic acid, and 0.07% sodium selenite by mass. The conditioner application rate is 150 kg / mu, and then the soil is turned over to a depth of 25 cm.

[0048] 2) Sow soybeans according to conventional production methods, carry out conventional field management, and harvest soybeans when the stems and leaves begin to turn yellow and the stalks and pods are dry and dark brown.

[0049] Example 3

[0050] This example is a field plot experiment, and each field plot has an area of ​​100m 2 , set up 3 replicates. The experimental soil type is paddy soil, the soil pH is 4.93, and the total cadmium content is 0.66 mg / kg.

[0051] This embodiment provides a method for applying a soil conditioner, comprising the following steps:

[0052] 1) Two weeks before planting Stropharia rugosa, evenly spread the conditioner on the soil surface. The conditioner consists of 31.94% slaked lime, 25% calcium hydrogen phosphate, 14% potassium nitrate, 10% urea, 9% calcium silicate, 10% sodium zinc ethylenediaminetetraacetic acid, and 0.06% sodium selenite by mass percentage. The conditioner application rate is 250 kg / mu, and then the soil is turned over to a depth of 25 cm.

[0053] 2) Stropharia were sown in a conventional production manner, and conventional field management was performed. The stropharia were harvested on the 45th day of the fruiting period when the edge of the cap rolled inward but had not yet opened.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is that no conditioner is applied before pepper planting, and the rest is the same as Example 1.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that the conditioner is replaced with zinc sulfate in an equal mass ratio of sodium zinc ethylenediaminetetraacetate, and does not contain sodium selenite. The other aspects are the same as those of Example 1.

[0058] Comparative Example 3

[0059] The difference between this comparative example and Example 1 is that zinc sulfate in an equal mass ratio is used to replace sodium zinc ethylenediaminetetraacetate in the conditioner, and the rest is the same as Example 1.

[0060] Comparative Example 4

[0061] The difference between this comparative example and Example 1 is that urea in an equal mass ratio is used to replace sodium selenite in the conditioner, and the rest is the same as Example 1.

[0062] Comparative Example 5

[0063] The difference between this comparative example and Example 1 is that urea in an equal mass ratio is used to replace calcium silicate in the conditioner, and the rest is the same as Example 1.

[0064] Comparative Example 6

[0065] The difference between this comparative example and Example 1 is that calcium hydrogen phosphate is replaced by slaked lime in an equal mass ratio in the conditioner, and the rest is the same as Example 1.

[0066] Comparative Example 7

[0067] The difference between this comparative example and Example 1 is that potassium nitrate is replaced by urea in an equal mass ratio in the conditioning agent, and the rest is the same as Example 1.

[0068] Comparative Example 8

[0069] The difference between this comparative example and Example 1 is that urea is replaced by potassium nitrate in an equal mass ratio in the conditioning agent, and the rest is the same as Example 1.

[0070] Comparative Example 9

[0071] The difference between this comparative example and Example 1 is that calcium hydrogen phosphate is used in an equal mass ratio to replace slaked lime in the conditioner, and the rest is the same as Example 1.

[0072] Comparative Example 10

[0073] The difference between this comparative example and Example 2 is that no conditioner is applied before soybean planting, and the rest is the same as Example 2.

[0074] Comparative Example 11

[0075] The difference between this comparative example and Example 2 is that the conditioner is replaced with zinc calcium magnesium phosphate in an equal mass ratio instead of calcium hydrogen phosphate and sodium zinc ethylenediaminetetraacetate, and the rest is the same as Example 2.

[0076] The zinc-calcium-magnesium-phosphate fertilizer contains, by mass percentage, 0.010% of effective zinc, 25.0% of effective calcium, 5.4% of effective magnesium, 23.7% of effective phosphorus pentoxide, and 22.8% of soluble silicon dioxide.

[0077] Comparative Example 12

[0078] The difference between this comparative example and Example 3 is that no conditioning agent is applied before planting Stropharia officinalis, and the rest is the same as Example 3.

[0079] Comparative Example 13

[0080] The difference between this comparative example and Example 3 is that the slaked lime is replaced by organic fertilizer in an equal mass ratio in the conditioner, and the rest is the same as Example 3.

[0081] The crop yields harvested in Examples 1-3 and Comparative Examples 1-13 were statistically analyzed, wherein peppers and giant puffballs were harvested in multiple batches. The cadmium, lead, and selenium content of the crops was determined. The method for determining the element content was as follows: the harvested crops were dried, crushed, and then subjected to microwave digestion in a nitric acid-hydrogen peroxide system. The cadmium, lead, and selenium content of the crops was then determined using inductively coupled plasma mass spectrometry. The test results of the test examples of the present invention were all averaged over repeated tests. The statistical and measurement results of Example 1 and Comparative Examples 1-9 are shown in Tables 1 and Figure 1 As shown; compared with the peppers in Example 1 without fertilizer application, the reduction in cadmium content, lead content, selenium content, and yield of the peppers in Example 1 and Comparative Examples 2-9 are shown in Table 2. The statistical and measurement results of Example 2 and Comparative Examples 10 and 11 are shown in Tables 3 and Figure 2 As shown; compared with the soybeans in Comparative Example 10 without fertilizer, the cadmium content reduction, lead content reduction, selenium content increase, and yield range of the soybeans in Example 2 and Comparative Example 11 are shown in Table 4. The statistical and measurement results of Example 3 and Comparative Examples 12 and 13 are shown in Tables 5 and Figure 3 As shown in Table 6, the cadmium content reduction, lead content reduction, selenium content increase, and yield range of the stropharia in Example 3 and Comparative Example 13 are compared with the stropharia in Comparative Example 11 without fertilizer application. Figure 4 As shown, the comparison of lead content in peppers of Example 1 and Comparative Examples 1-9 is shown in Figure 5 As shown, the comparison of selenium content in peppers of Example 1 and Comparative Examples 1-9 is shown in Figure 6 As shown, the comparison of pepper yields of Example 1 and Comparative Examples 1-9 is shown in Figure 7 shown.

[0082] As shown in Table 2, compared with Comparative Example 1 (control), the cadmium content in the pepper of Example 1 (the 60th day of the fruiting period) decreased by 45.7%, the lead content decreased by 36.4%, the selenium content increased by 253.8%, and the yield increased by 17.6%. The cadmium content decrease range, the lead content decrease range, the selenium content increase range, and the yield increase range in the peppers of Comparative Examples 2-9 were 11.96-32.61%, 10.91-27.27%, 15.38%-215.38% and 4.40-12.09%, respectively. It can be seen that the cadmium reduction, lead reduction, selenium increase and yield increase effects of Example 1 are significantly better than those of Comparative Examples 1-9, and multiple batches of samples thereof have obvious cadmium reduction, lead reduction and selenium increase effects, indicating that the soil conditioner has a lasting effect.

[0083] As shown in Table 3, compared with Comparative Example 10 (control), the cadmium content in soybeans of Example 3 decreased by 59.68%, the lead content decreased by 32.73%, the selenium content increased by 729.41%, and the yield increased by 14.50%; the cadmium content in soybeans of Comparative Example 11 decreased by 19.59%, the lead content decreased by 16.36%, the selenium content increased by 516.67%, and the yield increased by 3.50%. It can be seen that the effects of reducing cadmium, reducing lead, increasing selenium and increasing yield of Example 3 are significantly better than those of Comparative Examples 10 and 11.

[0084] As shown in Table 4, compared with Comparative Example 12 (control), the cadmium content of the stropharia in Example 3 decreased by 78.10%, the lead content decreased by 64.62%, the selenium content increased by 228.02%, and the yield increased by 18.30%. The cadmium content of the stropharia in Comparative Example 13 decreased by 53.33%, the lead content decreased by 44.62%, the selenium content increased by 157.14%, and the yield increased by 9.25%. It can be seen that the cadmium reduction, lead reduction, selenium increase and yield increase effects of Example 3 are significantly better than those of Comparative Examples 12 and 13, and multiple batches of samples thereof have obvious cadmium reduction, lead reduction and selenium increase effects, indicating that the soil conditioner has a long-lasting effect and is suitable for various types of crops.

[0085] Table 1 Cadmium content, lead content, selenium content and yield of peppers with different treatments

[0086]

[0087]

[0088] Table 2 Changes in cadmium content, lead content, selenium content and yield of peppers under different treatments

[0089] chili Cadmium content reduction (%) Lead content reduction (%) Selenium content increase (%) Output growth (%) Example 1 45.65 36.36 253.85 17.6 Comparative Example 2 31.52 27.27 23.08 12.1 Comparative Example 3 25.00 15.45 15.38 9.9 Comparative Example 4 20.65 20.91 15.38 7.7 Comparative Example 5 15.22 10.91 215.38 5.5 Comparative Example 6 11.96 15.45 192.31 6.6 Comparative Example 7 32.61 14.55 207.69 5.5 Comparative Example 8 27.17 25.45 184.62 4.4 Comparative Example 9 17.39 26.36 169.23 6.6

[0090] Table 3 Cadmium content, lead content, selenium content and yield of soybeans treated with different methods

[0091] Soybean Cadmium content (mg / kg) Lead content (mg / kg) Selenium content (mg / kg) Yield (kg / mu) Example 2 0.175 0.037 0.846 237 Comparative Example 10 0.434 0.055 0.102 207 Comparative Example 11 0.349 0.046 0.629 229

[0092] Table 4 Changes in cadmium content, lead content, selenium content and yield of soybeans under different treatments

[0093] Soybean Cadmium content reduction (%) Lead content reduction (%) Selenium content increase (%) Output growth (%) Example 2 59.68 32.73 729.41 14.49 Comparative Example 11 19.59 16.36 516.67 10.63

[0094] Table 5 Cadmium content, lead content, selenium content and yield of Stropharia officinalis in different treatments

[0095] Stropharia Cadmium content (mg / kg) Lead content (mg / kg) Selenium content (mg / kg) Yield (kg / mu) Example 3 0.023 0.023 0.597 66.5 Comparative Example 12 0.105 0.065 0.182 56.2 Comparative Example 13 0.049 0.036 0.468 61.4

[0096] Table 6 Changes in cadmium, lead, selenium content and yield of Stropharia officinalis under different treatments

[0097] Soybean Cadmium content reduction (%) Lead content reduction (%) Selenium content increase (%) Output growth (%) Example 2 59.68 32.73 729.41 14.49 Comparative Example 11 19.59 16.36 516.67 10.63

[0098] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A soil conditioner, characterized in that: The soil conditioner includes slaked lime, calcium hydrogen phosphate, potassium nitrate, urea, calcium silicate, sodium zinc ethylenediaminetetraacetic acid, and sodium selenite.

2. The soil conditioner according to claim 1, characterized in that The soil conditioner comprises, by mass percentage, 30%-38% slaked lime, 20%-25% calcium hydrogen phosphate, 14%-18% potassium nitrate, 10%-15% urea, 9%-12% calcium silicate, 7%-10% sodium zinc ethylenediaminetetraacetic acid, and 0.04%-0.07% sodium selenite.

3. A method for applying the soil conditioner according to claim 1, characterized in that: The following steps are involved: 1) Before planting crops, spreading the soil conditioner according to claim 1 on the soil surface and turning the soil; 2) Planting crops.

4. The method for applying the soil conditioner according to claim 3, characterized in that: In step 1), 1-2 weeks before planting crops, the soil conditioner according to claim 1 is spread on the soil surface and the soil is turned over.

5. The method for applying the soil conditioner according to claim 3 or 4, characterized in that: The application amount of the soil conditioner in step 1) is adjusted according to the soil pH and cadmium content; The ratio of the application rate of soil conditioner per mu to the cadmium content in soil is recorded as A, and A is negatively correlated with soil pH.

6. The method for applying the soil conditioner according to any one of claims 3 to 5, characterized in that: In step 1), when the soil pH satisfies 4.5<pH≤5.5, the ratio of the application amount of soil conditioner per mu to the cadmium content in the soil is (350-450):1, in units of kg:(mg / kg); Alternatively, when the soil pH satisfies 5.5<pH≤6.5, the ratio of the application amount of soil conditioner per mu to the cadmium content in the soil is (260-340):1, in kg:(mg / kg); Alternatively, when the soil pH satisfies 6.5<pH≤7.5, the ratio of the application amount of soil conditioner per mu to the cadmium content in the soil is (180-220):1, in units of kg:(mg / kg).

7. The method for applying the soil conditioner according to any one of claims 3 to 6, characterized in that: The depth of the soil turning in step 1) is 20-40 cm.

8. The method for applying the soil conditioner according to any one of claims 3 to 7, characterized in that: The crops in step 2) include at least one of pepper, soybean and Stropharia rugosa.

9. Use of the soil conditioner according to claim 1 or 2 or the method for applying the soil conditioner according to any one of claims 3 to 8 in planting in heavy metal contaminated soil; Preferably, the heavy metals include cadmium and / or lead.

10. Use of the soil conditioner according to claim 1 or 2 or the method for applying the soil conditioner according to any one of claims 3 to 8 in planting in acidic or neutral soil.

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