A method for repairing farmland cadmium pollution

Abstract

The present invention discloses a method for repairing cadmium pollution in farmland, and belongs to the technical field of soil remediation. Specifically, the following steps are included: (1) after tilling the soil, adding the mixed potassium humate and malonic acid, tilling and mixing, and adding malic acid to the soil after two to three weeks, tilling and mixing; (2) planting sorghum and Sedum sutchuenensis on the soil treated in step (1) in an intercropping manner. In the present application, the cadmium elements enriched in sorghum and Sedum sutchuenensis are mainly concentrated in their stems and leaves, and Sedum sutchuenensis relies on its root system to transport the cadmium elements. The present invention can increase the yield of Sedum sutchuenensis by applying agricultural potassium humate to the soil, and increase the enrichment of heavy metal elements in the aboveground part. At the same time, by applying agricultural potassium humate and malic acid, the soil pH can be effectively reduced and the content of effective heavy metals in the soil can be increased, which is beneficial to the transportation of heavy metal elements by Sedum sutchuenensis, and further increases the enrichment effect of Sedum sutchuenensis.

Description

Technical Field

[0001] The invention belongs to the technical field of soil pollution remediation, and specifically relates to a method for remediating farmland cadmium pollution. Background Art

[0002] At present, the overall soil environmental situation is not optimistic. Soil pollution is serious in some areas, and the environmental quality of cultivated soil is worrying. Among them, cadmium is one of the main characteristic pollutants of soil pollution. In agriculture, farmland contaminated by cadmium for a long time will lead to antagonistic competition between cadmium and soil nutrients, further disrupting the physiological properties of crops, thereby limiting the normal growth of crops. At the same time, cadmium enters the human body through the food chain, concentrated in bones, liver and kidneys, causing human diseases and even cancer. According to statistics, about 90% of the cadmium ingested by the human body comes from food, and 70% of the cadmium comes from plant food. Therefore, it is urgent to find practical measures to treat the soil in polluted areas to ensure crop production and food safety.

[0003] Regarding heavy metal pollution in soil, phytoremediation is a cadmium pollution control measure that is relatively environmentally friendly, relatively simple to operate, and relatively low-cost, and has good application prospects. The principle of phytoremediation is to utilize the enrichment of heavy metals by heavy metal hyperaccumulators, enrich the heavy metals in the soil into the plants, and finally achieve the purpose of heavy metal pollution remediation through centralized treatment. However, in many studies on phytoremediation, phytoremediation is often limited in its actual application in the treatment of heavy metal-contaminated farmland due to its slow remediation efficiency, easy occupation of agricultural production time, and immature technology. Therefore, it is particularly critical to improve its remediation efficiency. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for repairing cadmium pollution in farmland. The present application utilizes potassium humate and low-molecular organic acids in combination to strengthen the intercropping of Sedum robur and sorghum to repair cadmium pollution in farmland, thereby providing a method for repairing soil cadmium pollution that takes into account both production and repair and ensures the quality of cultivated land.

[0005] To achieve the above purpose, the technical solution adopted by the present invention to solve the technical problem is:

[0006] A method for remediating farmland cadmium pollution, characterized in that it comprises the following steps:

[0007] (1) After the soil is plowed, add the mixed potassium humate and malonic acid and plow and mix well. After two to three weeks, add malic acid to the soil and plow and mix well.

[0008] (2) Planting sorghum and Sedum roxburghii in an intercropping manner on the soil treated in step (1).

[0009] Furthermore, the dosage of potassium humate is 1.5-5 L / mu, and the dosage of malonic acid is 0.05-0.5 mol / m 2 .

[0010] Furthermore, the dosage of potassium humate is 2-3 L / mu, and the dosage of malonic acid is 0.05-0.15 mol / m 2 .

[0011] Furthermore, the dosage of potassium humate is 2.67L / mu, and the dosage of malonic acid is 0.1mol / m 2 .

[0012] Furthermore, potassium humate is agricultural potassium humate.

[0013] Furthermore, the dosage of malic acid is 0.05 to 0.5 mol / m 2 .

[0014] Furthermore, the dosage of malic acid is 0.1 mol / m 2 .

[0015] Furthermore, the specific methods of intercropping are as follows:

[0016] Sorghum and Sedum truncatum were interplanted in strips with 1 sorghum plant and 2 Sedum truncatum plants. The horizontal and vertical spacing between two adjacent Sedum truncatum plants was 15-18cm, the horizontal spacing between sorghum and Sedum truncatum plants was 15-18cm, and the vertical spacing between two adjacent sorghum plants was 30-36cm.

[0017] Beneficial effects of the present invention:

[0018] 1. The cadmium elements enriched in sorghum and Sedum truncatum are mainly concentrated in their stems and leaves, and Sedum truncatum relies on its root system to transport the cadmium elements. The present invention can increase the yield of Sedum truncatum by applying agricultural potassium humate to the soil and increase the enrichment of heavy metal elements in the aboveground part. At the same time, the application of agricultural potassium humate and malic acid can effectively reduce the soil pH and increase the content of effective heavy metals in the soil, which is beneficial to the transportation of heavy metal elements by Sedum truncatum and further increases the enrichment effect of Sedum truncatum.

[0019] 2. Based on the original row planting method, the present invention adds Sedum serrata between two rows of sorghum, which can reduce the absorption of heavy metals in the soil by sorghum during the planting process. At the same time, Sedum serrata has the effect of super-enrichment of heavy metals, thereby ensuring the yield of sorghum crops while controlling heavy metal pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the intercropping of sorghum and Sedum sedum in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0022] Example 1

[0023] A method for remediating farmland cadmium pollution comprises the following steps:

[0024] (1) Add 2.67 L / mu of agricultural potassium humate to a concentration of 0.1 mol / m 2 After ploughing, the malic acid was mixed with 0.1 mol / m 2 Apply to soil and mix well.

[0025] (2) Sorghum and Sedum robur were interplanted in strips with one sorghum plant and two Sedum robur plants. The horizontal and vertical spacing between two adjacent Sedum robur plants was 17 cm, the horizontal spacing between sorghum and Sedum robur plants was 17 cm, and the vertical spacing between two adjacent sorghum plants was 34 cm.

[0026] Among them, the tested activators are agricultural humic acid premium root (humic acid 10%, solution), malic acid, and malonic acid.

[0027] Example 2

[0028] A method for remediating farmland cadmium pollution comprises the following steps:

[0029] (1) Add 2.2 L / mu of agricultural potassium humate to a concentration of 0.08 mol / m 2 After ploughing, the malic acid was mixed with malonic acid and applied to the soil, and then ploughed and mixed again. After two weeks, the added concentration of malic acid was 0.05 mol / m 2 Apply to soil and mix well.

[0030] (2) Sorghum and Sedum robur were interplanted in strips with one sorghum plant and two Sedum robur plants. The horizontal and vertical spacing between two adjacent Sedum robur plants was 17 cm, the horizontal spacing between sorghum and Sedum robur plants was 17 cm, and the vertical spacing between two adjacent sorghum plants was 34 cm.

[0031] Among them, the tested activators are agricultural humic acid premium root (humic acid 10%, solution), malic acid, and malonic acid.

[0032] Example 3

[0033] A method for remediating farmland cadmium pollution comprises the following steps:

[0034] (1) Add 2.5 L / mu of agricultural potassium humate to a concentration of 0.15 mol / m 2 After ploughing, the malic acid was mixed with malonic acid and applied to the soil, and then ploughed and mixed again. After two weeks, the concentration of malic acid added was 0.15 mol / m 2 Apply to soil and mix well.

[0035] (2) Sorghum and Sedum robur were interplanted in strips with one sorghum plant and two Sedum robur plants. The horizontal and vertical spacing between two adjacent Sedum robur plants was 17 cm, the horizontal spacing between sorghum and Sedum robur plants was 17 cm, and the vertical spacing between two adjacent sorghum plants was 34 cm.

[0036] Among them, the tested activators are agricultural humic acid premium root (humic acid 10%, solution), malic acid, and malonic acid.

[0037] Comparative Example 1

[0038] The step (2) in Example 1 is changed to strip intercropping of sorghum and Sedum sutchuenensis in a 1:1 ratio, wherein the spacing between two adjacent sorghum plants of Sedum sutchuenensis in the horizontal direction is 17 cm, and the spacing between two adjacent sorghum plants of Sedum sutchuenensis in the vertical direction is 34 cm; the remaining steps are the same as in Example 1.

[0039] Comparative Example 2

[0040] The agricultural potassium humate, malic acid and malonic acid in the embodiment are eliminated, and the remaining steps are the same as those in embodiment 1.

[0041] Comparative Example 3

[0042] The malic acid in the example was eliminated, and the malonic acid was added twice. The remaining steps were the same as those in Example 1.

[0043] Comparative Example 4

[0044] The agricultural potassium humate in the embodiment is eliminated, and the remaining steps are the same as those in embodiment 1.

[0045] Comparative Example 5

[0046] The malonic acid in the example was eliminated, and the malic acid was added twice. The remaining steps were the same as those in Example 1.

[0047] Comparative Example 6

[0048] The step (1) in Example 1 is changed to that the agricultural potassium humate is mixed with malic acid and applied first, and then malonic acid is applied. The remaining steps are the same as in Example 1.

[0049] Comparative Example 7

[0050] The malonic acid in Example 1 was replaced with oxalic acid of the same concentration, and the remaining steps were the same as in Example 1.

[0051] The yield and cadmium concentration under the planting mode of Example 1 and the comparative example were tested, and the test results are shown in Table 1.

[0052] Table 1 Output and cadmium concentration

[0053]

[0054]

[0055] Table 2 Cadmium content in soil

[0056]

[0057] Figure 1 The 1:2 sorghum and Sedum strip planting pattern in Example 1 is shown. Compared with the 1:1 sorghum and Sedum strip planting pattern in Comparative Example 1, the planting density of sorghum has not changed, and the planting density of Sedum has doubled in Example 1 due to the expansion of the longitudinal spacing of Sedum. This planting method does not change the planting density of sorghum, and to a certain extent guarantees the yield of sorghum crops. The Sedum with increased density can effectively enrich heavy metals in the soil in the gaps between sorghum, thereby reducing the absorption of cadmium in the soil by sorghum. It can be seen from Table 1 that under the planting mode of Example 1, the biomass and cadmium concentration of Sedum are higher than those of other treatments; compared with Comparative Example 1, the density and biomass of Sedum in Example 1 are large, and the ability to enrich the cadmium content in the soil is stronger; compared with Example 1, the biomass of Comparative Example 3 is not much different, but the ability to enrich the cadmium content in the soil is significantly weaker than that of Example 1. In the planting mode of Example 1, the grain yield of sorghum is slightly lower than that in the conventional planting mode, which shows that the yield in this mode can be guaranteed to be normal; the cadmium content in the grain is not high, which meets the requirements of the "National Food Safety Standard for Contaminants in Food" (GB2762-2022); compared with the 1:1 intercropping mode in Comparative Example 1, due to the planting density, the yield is reduced, but the cadmium content in the sorghum grain is reduced by 9.57%. As can be seen from Table 2, Example 1 has the best effect on reducing the cadmium content in the soil, and the cadmium content in the soil is reduced by 23.19%, which is better than the comparative example.

[0058] Table 3 Available cadmium content in soil under different treatments (mg / kg)

[0059] deal with 7 days 14 days 21 days 28 days Example 1 0.335 0.334 0.369 0.421 Comparative Example 1 0.334 0.335 0.373 0.418 Comparative Example 2 0.207 0.194 0.219 0.201 Comparative Example 3 0.374 0.373 0.416 0.406 Comparative Example 4 0.326 0.31 0.358 0.391 Comparative Example 5 0.312 0.343 0.361 0.394 Comparative Example 6 0.313 0.352 0.374 0.402 Comparative Example 7 0.301 0.325 0.346 0.389

[0060] Table 4 Soil pH values ​​under different treatments

[0061] deal with 7 days 14 days 21 days 28 days Example 1 5.78 5.01 5.52 5.28 Comparative Example 1 5.74 5.06 5.61 5.48 Comparative Example 2 6.48 6.63 6.71 6.53 Comparative Example 3 6.12 5.62 5.52 5.63 Comparative Example 4 5.82 5.03 5.25 5.54 Comparative Example 5 5.77 5.63 5.51 5.62 Comparative Example 6 5.74 5.61 5.50 5.61 Comparative Example 7 5.89 5.72 5.43 5.57

[0062] As shown in Table 4, compared with Comparative Example 2, the soil pH values ​​of the remaining treatments significantly decreased with the increase in the application amount. As can be seen from Table 3, compared with Comparative Example 2, different strengthening measures can significantly increase the content of effective cadmium, and the content of effective cadmium increases with the increase in the application amount of agricultural potassium humate, malic acid, malonic acid and combined application. When the environmental pH value is in a certain acidic range, it can promote the migration and transformation of soil heavy metals and promote the absorption of heavy metals by mineral sedum. pH value is an important factor affecting the effective state of metals, and the treatment of Example 1 in this experiment is more suitable.

[0063] Table 5 Effects of different modes on the enrichment coefficient, transport coefficient and cadmium extraction efficiency of Sedum sedum

[0064]

[0065] As can be seen from Table 5, the enrichment coefficient of Sedum sedum is root < stem < leaf. The aboveground transport coefficient of Example 1 is greater than that of other treatments, and its cadmium extraction efficiency is 21.02%, which is much higher than that of Comparative Examples 1, 2, 3, 4, 5, 6 and 7, that is, the soil repair ability of Example 1 under the intercropping mode is stronger than that of Comparative Examples 2, 3, 4, 5, 6 and 7. Therefore, under the mode of Example 1, the repair effect of Sedum sedum is more obvious, and the effect of repairing while producing can be achieved, and the yield of crops can be guaranteed.

[0066] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for remediating farmland cadmium pollution, characterized in that: The following steps are involved: (1) After the soil is plowed, add the mixed potassium humate and malonic acid and plow and mix. Two weeks later, add malic acid to the soil and plow and mix. The dosage of potassium humate is 2-3 L / mu, and the dosage of malonic acid is 0.05-0.15 mol / m 2 ; The dosage of malic acid is 0.05~0.5mol / m 2 ; (2) Planting sorghum and Sedum roxburghii in strips with one sorghum plant and two Sedum roxburghii plants on the soil treated in step (1).

2. The method for remediating farmland cadmium pollution according to claim 1, characterized in that: The dosage of potassium humate is 2.67L / mu, and the dosage of malonic acid is 0.1mol / m 2 .

3. The method for remediating farmland cadmium pollution according to claim 1, characterized in that: The dosage of malic acid is 0.1 mol / m 2 .

4. The method for remediating farmland cadmium pollution according to claim 1, characterized in that: The specific methods of intercropping are as follows: The horizontal and vertical spacing between two adjacent plants of Sedum serrata is 15-18cm, the horizontal spacing between sorghum and Sedum serrata is 15-18cm, and the vertical spacing between two adjacent plants of sorghum is 30-36cm.

Images