CN111250531A

CN111250531A - Repairing agent, preparation method thereof and method for repairing crop root system

Info

Publication number: CN111250531A
Application number: CN202010078943.1A
Authority: CN
Inventors: 姚伦广; 段鹏飞; 李亚东; 倪红; 汤行春; 杨升; 廖卫芳; 王友平; 汪华; 陈勋
Original assignee: Hubei University; Nanyang Normal University; Institute of Plant Protection and Soil Fertilizer of Hubei Academy of Agricultural Science
Current assignee: Hubei University; Nanyang Normal University; Institute of Plant Protection and Soil Fertilizer of Hubei Academy of Agricultural Science
Priority date: 2020-02-03
Filing date: 2020-02-03
Publication date: 2020-06-09

Abstract

The invention provides a repairing agent, a preparation method thereof and a method for repairing crop roots. The repairing agent is applied to cadmium-polluted acid soil, and the preparation method of the repairing agent comprises the following steps: mixing a calcium source raw material and a solvent to obtain calcium-containing emulsion; mixing the protein raw material with the calcium-containing emulsion, and uniformly stirring to obtain a mixed solution; and (3) reacting the mixed solution under a heating condition, filtering to obtain a filtrate after the reaction is finished, and concentrating the filtrate to a concentrated solution with the concentration of 20-30%. The repairing agent provided by the invention is applied to cadmium-polluted acid soil, can obviously repair roots, promote the growth of crop roots, promote the absorption of crops on nutrient substances, prolong the growth life of crops and improve the survival rate of crops.

Description

Repairing agent, preparation method thereof and method for repairing crop root system

Technical Field

The invention relates to the technical field of polluted soil treatment, in particular to a repairing agent, a preparation method thereof and a method for repairing crop roots.

Background

With the rapid development of modern industry and agriculture, the situation of heavy metal pollution of soil is more and more severe, the heavy metal pollution event in China is entering a high-rise period, and the heavy metal pollution is a prominent problem in a plurality of polluted sites. In 2014, "national soil pollution condition survey bulletin" issued by the ministry of environmental protection and the ministry of land resources shows that the point standard exceeding rate of 8 inorganic pollutants of cadmium, mercury, arsenic, copper, lead, chromium, zinc and nickel is respectively 7.0%, 1.6%, 2.7%, 2.1%, 1.5%, 1.1%, 0.9% and 4.8%, wherein cadmium pollution is the most prominent.

Heavy metal pollution of soil is mainly caused by three reasons:

1) the sewage irrigation refers to the irrigation with the sewage which is treated and meets the requirement of irrigation water quality standard as a water source. The sewage irrigation is a double-edged sword, although urban sewage is not only an important fertilizer source but also an important water source for agricultural crops in suburbs, the sewage contains a large amount of heavy metal elements which are not beneficial to the growth of the agricultural crops, and particularly in industrial sewage, a lot of environmental problems can be caused. China is a big agricultural country, and large-area cultivated land and suburb land in cities are polluted by heavy metals to a greater or lesser extent. Moreover, with the rapid development of the industry in China, a large amount of industrial sewage is discharged into a sewer and mixed with domestic sewage without diversion and purification treatment, so that a large amount of heavy metals enter soil in a farmland irrigation area, and serious heavy metal pollution of the soil is caused. According to statistics, the heavy metal pollution area of cultivated land in China accounts for more than 16% of the total cultivated land area, the heavy metal polluted grain reaches astonishing 1200 ten thousand tons every year, the yield of grain is reduced to 1000 ten thousand tons, and the problem is urgently solved.

2) Secondly, China is a big agricultural country and uses a large amount of pesticides and fertilizers every year to promote the rapid development of agriculture. However, fertilizers generally contain a certain amount of heavy metals, and excessive use of fertilizers and pesticides results in an increase in the heavy metal content of soil.

3) Industrial activities such as energy exploitation, metal smelting, fuel burning and the like discharge a large amount of waste gas, the waste gas contains a large amount of heavy metals, most of the heavy metals enter the atmosphere in the state of aerosol, and enter the soil through a series of natural sedimentation and precipitation, and statistics show that when fossil fuels are burned, 10% -30% of the heavy metals naturally settle within 10km of the emission source, and enter the atmosphere along with smoke dust and finally enter the soil.

The existing research shows that the cadmium resolution rate of acid soil types such as red soil, yellow soil and the like at different temperatures is over 15 percent and is obviously higher than that of alkaline soil types such as grey desert soil, chestnut calcium soil and the like (less than 10 percent). In addition, according to the test data statistical analysis of 902 ten thousand soil samples of the soil testing formula fertilization in 2005-2011, compared with the second soil general investigation before 30 years, the soil pH of cultivated land in China is reduced by 0.13-1.3, the average reduction is 0.8, and 40% of cultivated land soil in China is below pH 6.5.

In addition, in cadmium-polluted acid soil, not only the yield and the quality of crops grown cannot be guaranteed, but also the crops planted in the soil can frequently suffer from root rot, and the death rate of the crops is very high; in addition, it has been found that the root system of some crops is too short, resulting in the root system not being able to absorb sufficient nutrients. This means that the yield and quality of the crops are improved and finally the crops are subjected to a bottleneck. At present, no effective method is provided for solving the problem of root system damage of crops in cadmium-polluted acid soil.

Therefore, in acid soil polluted by cadmium, the root system of crops is repaired, which is a very practical problem.

Disclosure of Invention

The invention mainly aims to make up the defects of the prior art and provides a repairing agent, a preparation method and a method for repairing crop roots.

The invention provides an application of a repairing agent in repairing crop root systems, wherein the repairing agent is applied to acid soil; the preparation method of the repairing agent comprises the following steps: mixing a calcium source raw material and a solvent to obtain calcium-containing emulsion; mixing the protein raw material with the calcium-containing emulsion, and uniformly stirring to obtain a mixed solution; and (3) reacting the mixed solution under a heating condition, filtering to obtain a filtrate after the reaction is finished, and concentrating the filtrate to a concentrated solution with the concentration of 20-30%.

In the above applications, the crop may be selected from wheat.

In the above application, the calcium source material may be one or a mixture of not less than two selected from quicklime, calcium oxide and hydrated lime, preferably quicklime; the solvent may be one or a mixture of not less than two selected from purified water, ultrapure water, distilled water, tap water and deionized water, preferably tap water.

In the above application, the protein material may be selected from protein waste, and the protein waste may be selected from one or a mixture of at least two of plant protein waste, microbial thallus, sludge, animal hair, animal hoof and horn, and blood.

In the application, the mass ratio of the calcium source raw material, the solvent and the protein raw material is (10-70): (80-1400): 100.

In the application, the heating temperature is 100-200 ℃, preferably 110-180 ℃, and more preferably 120-160 ℃; the reaction time is 1-8 h, preferably 1.5-6 h, and more preferably 2-5 h.

In the above application, the concentration method is evaporation by using a multi-effect evaporator; the pH value of the concentrated solution is 10-14, preferably 11-13.

In the above application, an alternative repairing agent is prepared as follows: mixing quicklime and water to obtain calcium-containing emulsion; mixing rapeseed cakes with the calcium-containing emulsion, wherein the mass ratio of the quick lime to the water to the rapeseed cakes is 11:100:50, and uniformly stirring to obtain a mixed solution; and reacting the mixed solution at 137 ℃ for 3 hours, filtering to obtain filtrate after the reaction is finished, and evaporating the filtrate by using a multi-effect evaporator to obtain a concentrated solution with the pH value of 12-13 and the concentration of 25-30%.

In the application, the concentration of cadmium in the acid soil can be 1-3 mg/kg.

In the application, the concentration of cadmium in the acid soil can be 1.8-2.2 mg/kg.

The repairing agent provided by the invention is applied to cadmium-polluted acid soil, can obviously repair roots, promote the growth of crop roots, promote the absorption of crops on nutrient substances, prolong the growth life of crops and improve the survival rate of crops.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below, and it should be apparent that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

The invention provides a preparation method of a repairing agent, which comprises the following steps:

step 1: mixing the calcium source material and the solvent to obtain the calcium-containing emulsion.

In step 1, the calcium source material may be one or a mixture of not less than two selected from quicklime, calcium oxide and slaked lime, and is preferably quicklime.

In step 1, the solvent may be one or a mixture of not less than two selected from the group consisting of purified water, ultrapure water, distilled water, tap water and deionized water, preferably tap water.

Step 2: mixing the protein material and the calcium-containing emulsion, and stirring uniformly to obtain a mixed solution.

In step 2, the protein material may include protein waste, and the protein waste may be selected from one or a mixture of at least two of plant protein waste, microbial cells, sludge, animal hair, animal hoof and horn, and blood.

In the step 1 and the step 2, the mass ratio of the calcium source raw material, the solvent and the protein raw material is (10-70): (80-1400): 100.

And step 3: and (3) reacting the mixed solution under a heating condition, filtering after the reaction is finished, and concentrating the filtrate to a concentrated solution with the concentration of 20-30%.

In step 3, the reaction temperature is 100-200 ℃, preferably 110-180 ℃, and more preferably 120-160 ℃.

In the step 3, the reaction time is 1-8 h, preferably 1.5-6 h, and more preferably 2-5 h.

In step 3, the method of concentration is evaporation using a multiple effect evaporator.

In step 3, the pH value of the final product is in the range of 10-14, preferably 11-13.

Examples

Adding 1000kg of pulverized rapeseed cake into a mixing barrel, and using 2m³Dissolving 220kg of quicklime in tap water to prepare lime emulsion, inputting the lime emulsion into a mixing barrel added with rapeseed cakes, uniformly stirring, inputting the uniformly stirred mixture into a reaction kettle by using a pump, introducing 0.2Mpa of water vapor into the reaction kettle, heating to 137 ℃, preserving heat for 3 hours, sampling by using a measuring cylinder, and if the solution is in a turbid state, indicating that the lime slightly soluble in water is not converted into a final product. If precipitation is rapid and the supernatant is a clear liquid, it indicates that the clear liquid has been converted to the final product, i.e., the peptide calcium salt. At this time, use is made of 40m²And (3) filtering by using a plate-and-frame machine, concentrating the filtrate by using a multi-effect evaporator until the filtrate reaches 20Be0, determining the concentration of the peptide calcium salt to Be 28% (w/v) by using a spectrophotometer method, and determining the pH value to Be 12.2 by using a pH test paper, wherein the concentrated solution is the repairing agent, namely the peptide calcium salt, provided by the embodiment.

The calcium peptidate prepared in the embodiment is a peptidic substance, and a molecular polymer between protein and amino acid is formed by linking 2 to hundreds of amino acids through peptide bonds. Through detection, the nutritional rice has high nutritional value, is rich in amino acid, has the advantages of good solubility, low viscosity, high concentration, strong fluidity, good thermal stability and the like, and is a usable resource with high value.

Experimental materials: the crop variety is Zheng wheat 103.

Normal soil: the soil to be tested was taken from englery red soil, which is an acid soil, and the physicochemical properties of the acid soil are shown in table 1. Removing the stones and the residue of the mobile crops in the soil by using tweezers, naturally drying, crushing the soil by using a mortar, sieving by using a 2mm sieve, and uniformly mixing for later use.

Table 1: physicochemical properties of acid soil

Total nitrogen (g/kg)	Total phosphorus (g/kg)	Total potassium (g/kg)	pH	Organic matter (g/kg)	Volume weight
						0.65	0.81	0.40	4.5	15.4	1.2

And (3) polluted soil: as the cadmium concentration in most cadmium-polluted soil in China is about 2mg/kg, the polluted soil with the total cadmium concentration of 2mg/kg and 5mg/kg is prepared. Uniformly spraying the standard cadmium stock solution on the standby normal soil to ensure that the total cadmium concentration reaches 2mg/kg and 5mg/kg respectively, fully and uniformly stirring, and filling into a plastic basket. Adding tap water according to 80% of the field water holding capacity, covering and sealing, opening the cover every 3 days for ventilation, aging after 30 days, taking out 3 soil samples for air drying, and sieving by using a 2mm nylon sieve for later use.

0mg/kg, 2mg/kg and 5mg/kg of soil are briefly described below as Cd0, Cd2 and Cd 5.

Compound fertilizer: nitrogen 14-phosphorus 5-potassium 6 type compound fertilizer produced by complete fertilizer industry limited of yellow stone city.

1. Fertilizing method

Respectively applying peptide calcium salt in normal soil and polluted soil, and adding compound fertilizer as a control group. The normal soil is filled with 4 kg/pot of soil, the polluted soil is filled with 2 kg/pot of soil, the nitrogen content of each pot is 0.33g/kg, 6.25g of compound fertilizer and 10g of peptide calcium salt and 4.5g of potassium dihydrogen phosphate are calculated and applied.

The physicochemical properties of the home-made peptide calcium salt are shown in table 2.

Table 2: physicochemical Properties of self-made peptide calcium salt

Nitrogen (%)	Potassium (mg/kg)	Calcium (g/kg)	pH	Protein (%)	Phosphorus (g/kg)	Coarse ash (%)
							9.57	212	63.87	12.2	59.8	0.35	18.1

2. Sample processing method

Respectively planting wheat seeds in wet normal soil and contaminated soil, applying compound fertilizer or peptide calcium salt + potassium dihydrogen phosphate for treatment, and sampling four times when the wheat seeds are cultured for 58 days, 108 days, 129 days and 144 days to obtain a seedling stage I, a seedling stage II, an elongation stage I and an elongation stage II. The wheat plants were digged gently to keep the root hairs intact.

3. Determination of the experiment

When in sampling, the whole pot of plants and the soil are taken out together, and the soil is beaten by a wooden hammer to soften the soil block, so that the single wheat plant can be taken out completely. The firmest part between the overground part and the underground part of the wheat is pinched and continuously and slowly twisted, so that the single wheat plant is completely taken out. The soil is filled back into the flowerpot for standby, and the wheat is washed clean by slow water flow.

Three wheat plants with similar growth vigor and good development are selected from the wheat plants taken out from each pot as representative samples, and the length of the overground part and the underground part is measured.

And (3) drying the taken wheat samples, drying the samples to constant weight by using a vacuum drying oven at a set temperature of 105 ℃, and measuring the dry weight of each plant.

4. Analysis of Experimental data

In the numbering described below:

ca represents that the applied fertilizer is peptide calcium salt, F represents that the applied fertilizer is compound fertilizer;

m represents the sampling of Cd2 and Cd5 in the seedling stage, B represents the sampling of Cd2 and Cd5 in the jointing stage, and C represents the sampling of Cd2 and Cd5 in the heading stage;

h is a sample of Cd 0; y is the spare sample.

(1) Growth of wheat in seedling stage

Table 3.1 shows the growth of wheat at seedling stage I. The seedling stage I is 56 days after sowing. Measuring the length of the overground part and the underground part of the wheat on the same day after sampling, and then putting the wheat into an oven to dry for about 36 hours, and weighing the dry weight of the single plant.

TABLE 3.1 growth of wheat at seedling stage I

As shown in Table 3.1, it can be seen that, in the stage I of seedling stage, the wheat with the longest overground part length is the wheat with the peptide calcium salt applied in Cd0 soil, the wheat with the longest underground part length is the wheat with the peptide calcium salt applied in Cd5 soil, and the wheat with the heaviest single plant dry weight is the wheat with the peptide calcium salt applied in Cd2 soil.

In the stage I of the seedling stage, the advantages of the peptide calcium salt are obviously greater than those of the compound fertilizer, particularly, the wheat with the peptide calcium salt applied to Cd2 soil is obviously superior to the compound salt group in terms of single trunk, the length of the overground part of the wheat and the underground part of the wheat are also obviously superior to that of the compound fertilizer group, and the root system length of the wheat with the peptide calcium salt applied to Cd5 soil is also obviously longer than that of the compound fertilizer group. Therefore, in the seedling stage I, the difference between the peptide calcium salt and the compound fertilizer in the acid soil without cadmium pollution is not large, and the peptide calcium salt has obvious advantages in the acid soil with cadmium pollution.

Table 3.2 shows the growth of wheat at seedling stage ii. And the seedling stage II is to take samples 107 days after sowing. Measuring the length of the overground part and the underground part of the wheat on the same day after sampling, and then putting the wheat into an oven to dry for about 36 hours, and weighing the dry weight of the single plant.

TABLE 3.2 growth of wheat at seedling stage II

As shown in Table 3.2, it can be seen that, in the seedling stage II, the overground part of the wheat is the wheat with the longest length which is obtained by applying peptide calcium salt in Cd0 soil, but the difference between the overground part of the wheat and the compound fertilizer group is not large; the longest length of the underground part of the wheat is the wheat applied with peptide calcium salt in Cd5 soil, and the length of the underground part of the wheat is obviously longer than that of the wheat under other conditions; the heaviest dry weight of each plant is the wheat with the peptide calcium salt applied in Cd5 soil, and the wheat is obviously heavier than the wheat under other conditions. In addition, the wheat applied with the compound fertilizer in the Cd2 soil can be seen, the dry weight of a single plant is hardly increased, and the root system length is the shortest. The cadmium in low concentration can inhibit the absorption of the wheat on nutrient substances, the peptide calcium salt protects the wheat from receiving the cadmium inhibition effect and promotes the growth of root systems, but the compound fertilizer does not have the effect; cadmium stress is generated by the high-concentration cadmium, and the growth of root systems is promoted by the self-protection function of the wheat, so that the absorption of nutrient substances by the wheat is promoted, and the growth speed is accelerated.

In the second stage of seedling stage, the advantages of the peptide calcium salt are also obviously greater than those of the compound fertilizer, especially the wheat with the peptide calcium salt applied in Cd5 soil is obviously superior to the compound salt group in terms of single plant stem, and the length of the overground part of the wheat and the underground part of the wheat are also obviously superior to those of the compound fertilizer group. Therefore, in the seedling stage II, the peptide calcium salt has obvious advantages in cadmium-polluted acid soil.

(2) Growth of wheat in the jointing stage

After the wheat enters the elongation stage, the phenomenon of wheat plant death begins to occur, and the number of the wheat which survives after the seedling stage II is 35 in each group.

Table 3.3 shows the growth of wheat in the jointing stage I. The jointing stage I is sampling 128 days after sowing. Measuring the length of the overground part and the underground part of the wheat on the same day after sampling, and then putting the wheat into an oven to dry for about 36 hours, and weighing the dry weight of the single plant.

TABLE 3.3 growth of wheat in jointing stage I

Sample numbering	Length of aerial parts (cm)	Length of underground part (cm)	Dry weight of individual plant (g)	dead/Total plants
					Cd₀-Ca-H	42.3	9.93	0.75	0/35
Cd₀-F-H	39.90	7.63	0.32	0/35
					Cd₂-Ca-B	36.40	22.07	1.02	0/35
Cd₂-F-B	35.30	16.50	0.60	3/35
					Cd₅-Ca-B	43.13	18.93	1.51	1/35
Cd₅-F-B	42.17	18.90	1.35	2/35

As shown in Table 3.2, it can be seen that, at the stage of the elongation stage I, the wheat plants begin to die, wherein 3 wheat plants in the compound fertilizer group in Cd2 soil, 1 wheat plant in the peptide calcium salt group in Cd5 soil, 2 wheat plants in the compound fertilizer group in Cd5 soil, and the rest groups do not find the wheat plants die.

In addition, it can be seen that the overground part of the wheat is the longest in length, namely the wheat applied with the peptide calcium salt in Cd0 soil, but the difference from the rest groups is not big, and the difference from the seedling stage II is not big; the longest length of the underground part of the wheat is the wheat applied with peptide calcium salt in Cd2 soil, and the length of the underground part of the wheat is obviously longer than that of the wheat under other conditions; the heaviest dry weight of each plant is wheat applied with peptide calcium salt in Cd5 soil, and the wheat is obviously heavier than wheat under other conditions.

In the stage I of the jointing stage, the advantages of the peptide calcium salt are obviously greater than those of the compound fertilizer, and the peptide calcium salt is superior in both the survival rate of wheat and the growth condition of wheat.

Table 3.4 shows the growth of wheat in the jointing stage II. The jointing stage II is sampling 143 days after sowing. Measuring the length of the overground part and the underground part of the wheat on the same day after sampling, and then putting the wheat into an oven to dry for about 36 hours, and weighing the dry weight of the single plant.

TABLE 3.4 growth of wheat in jointing stage II

Sample numbering	Length of aerial parts (cm)	Length of underground part (cm)	Dry weight of individual plant (g)	dead/Total plants
					Cd₀-Ca-H	43.77	19.73	1.14	1/35
Cd₀-F-H	42.37	18.70	1.07	1/35
					Cd₂-Ca-B	44.75	31.73	3.76	4/35
Cd₂-F-B	50.57	22.70	1.46	5/35
					Cd₅-Ca-B	58.60	15.73	2.52	7/35
Cd₅-F-B	55.80	14.80	2.12	10/35

As shown in Table 3.2, it can be seen that wheat plant death occurred in all groups during the stage II of the jointing stage. The number of dead plants in the second stage of the jointing stage written in Table 3.4 is the sum of the number of dead plants in the second stage of the jointing stage and the number of dead plants in the first stage of the jointing stage.

It can be seen that in the cadmium-free polluted soil, the number of dead plants of the wheat in the peptide calcium salt group is equivalent to that of the wheat in the compound fertilizer group, and the dead plants of the wheat in the peptide calcium salt group have no obvious advantages or disadvantages; however, in the soil polluted by cadmium, the number of dead plants of the wheat in the peptide calcium salt group is less than that of the wheat in the compound fertilizer group, and the method is more obvious in the environment polluted by high-concentration cadmium. In addition, in the soil without cadmium pollution, the overground part length and the underground part length of the wheat in the peptide calcium salt group and the wheat in the compound fertilizer group are not obviously different from the single-plant dry weight average, and the peptide calcium salt group is slightly superior, which shows that the peptide calcium salt group and the compound fertilizer group have no obvious advantages and disadvantages under the condition without cadmium pollution.

Furthermore, it can be seen that the longest length of the aerial parts of wheat is the wheat to which the peptide calcium salt is applied in Cd5 soil; the longest length of the underground part of the wheat is the wheat applied with peptide calcium salt in Cd2 soil, and the length of the underground part of the wheat is obviously longer than that of the wheat under other conditions; the heaviest dry weight of each plant is the wheat with the peptide calcium salt applied in Cd2 soil, and the wheat is obviously heavier than the wheat under other conditions.

Moreover, it can be seen that the root length of wheat in Cd0 soil is significantly longer than before in the jointing stage II, while the root length of wheat in Cd5 soil is significantly shorter than before. This shows that under the action of cadmium stress, wheat releases vital potential in advance, excessive cadmium element is absorbed, and the root system of the wheat is atrophied and dies gradually in the later period.

Through the research on the growth condition and the survival rate of wheat in acid soil by the peptide calcium salt, the following conclusion is reached:

① the peptide calcium salt can repair the root system of wheat, and has obvious effect under the condition of cadmium pollution, especially under the condition of low-concentration cadmium pollution.

② the calcium salt of peptide has protective effect on wheat under cadmium pollution concentration, and can protect the absorption of nutrients of wheat under cadmium pollution condition.

③ the peptide calcium salt has effect in repairing wheat root system, prolonging the service life of wheat, and increasing the survival rate of wheat.

Compared with the common compound fertilizer, the peptide calcium salt can repair the root system of wheat, promote the growth of wheat, promote the absorption of nutrient substances by wheat and protect the wheat from being damaged by cadmium, thereby improving the survival rate of the wheat.

It should be noted that the above embodiments are only examples, and those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be construed as the protection scope of the present invention.

Claims

1. The application of the repairing agent in repairing the root system of crops growing in cadmium-polluted acid soil is characterized in that the preparing method of the repairing agent comprises the following steps:

mixing a calcium source raw material and a solvent to obtain calcium-containing emulsion;

mixing a protein raw material with the calcium-containing emulsion, and uniformly stirring to obtain a mixed solution;

reacting the mixed solution under a heating condition, filtering to obtain a filtrate after the reaction is finished, and concentrating the filtrate to a concentrated solution with the concentration of 20-30%;

wherein the concentration is evaporation using a multiple effect evaporator; the pH value of the concentrated solution is 10-14, and preferably 11-13.

2. Use according to claim 1, wherein the crop plants are selected from wheat.

3. The use according to claim 1, wherein,

the concentration of cadmium in the cadmium-polluted acid soil is 1-3 mg/kg.