A method for improving carbon pool stability and soil quality in acidic soil

Abstract

This invention discloses a method for improving the carbon pool stability and soil quality of acidic soils, comprising: S1. Tilling farmland with a pH of 4.5-5.5 2-3 times in mid-March of the same year; S2. Spreading basalt powder onto the surface of the tilled farmland, and tilling again 2-3 times; S3. Planting cereal crops in the farmland in late March of the same year; S4. After harvesting the cereal crops, spreading the straw evenly on the farmland and letting it fallow for 2-3 months. In this invention, basalt powder can absorb carbon dioxide from the atmosphere through natural weathering and convert carbon dioxide into stable inorganic carbonates, increasing the inorganic carbon content of the soil. The addition of basalt powder and weathering can promote the formation of mineral-bound organic carbon, increasing the stability of soil organic carbon. Spreading the straw of planted cereal crops evenly on the farmland can increase the organic carbon content in the soil, promote the formation of soil aggregates, enhance the physical protection ability of aggregates for organic carbon, and strengthen the stability of the soil carbon pool.

Description

Technical Field

[0001] This invention belongs to the field of soil modification technology, specifically relating to a method for improving the carbon pool stability and soil quality of acidic soils. Background Technology

[0002] Soil carbon pools are a major component of terrestrial ecosystem carbon pools, and even small changes in their carbon storage can have a significant impact on atmospheric carbon dioxide concentrations and climate change. Soil carbon pool stability refers to the ability of soil carbon to resist external environmental disturbances and return to its original level under current conditions. Higher soil carbon pool stability is more conducive to carbon capture and accumulation in the soil. Factors affecting soil pool stability include the stability of soil aggregates, the types of soil minerals, soil physicochemical properties, the quality of plant residues input into the soil, and the metabolic rate of microorganisms, among others. The physical protection of aggregates and the chemical protection of soil minerals are crucial factors influencing soil carbon pool stability.

[0003] In recent years, soil acidification in arable land in the subtropical regions of southern my country has become an increasingly prominent problem due to intensive human activities. Soil acidification leads to a decrease in soil nutrient content, affects soil aeration and permeability, alters soil physical structure and microbial community composition, and consequently reduces soil carbon pool and soil quality, threatening agricultural production and the quality of agricultural products in the subtropical regions of southern China. Therefore, it is necessary to carry out soil modification treatments to improve the carbon pool stability and soil quality of acidic soils. Summary of the Invention

[0004] The purpose of this invention is to provide a method for improving the carbon pool stability and soil quality of acidic soils.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A method for improving carbon pool stability and soil quality in acidic soils includes the following steps: S1. In mid-March of that year, the farmland with a pH of 4.5-5.5 was plowed 2-3 times; S2. Sprinkle basalt powder onto the surface of the tilled land and till it again 2-3 times; S3. In late March of that year, cereal crops were planted in the cultivated land that had been treated in step S2; S4. After the cereal crops are harvested, the straw is spread flat on the cultivated land and left fallow for 2-3 months; In this invention, alkaline substances such as calcium oxide and magnesium oxide in basalt powder can neutralize hydrogen ions in the soil, reducing soil acidity. Cations such as calcium and magnesium ions in basalt powder can undergo cation exchange with hydrogen ions in the soil, further reducing soil acidity. Furthermore, basalt powder can absorb atmospheric carbon dioxide through natural weathering and convert it into stable inorganic carbonates, which increase the inorganic carbon content of the soil. Secondly, the addition and weathering of basalt powder significantly increase the content and types of mineral particles in the soil, promoting the formation of mineral-bound organic carbon, enhancing the chemical protection of soil organic carbon by soil minerals, and increasing the stability of soil organic carbon. Thirdly, spreading crop straw (such as grain straw) in the cultivated land can increase the organic carbon content of the soil through returning it to the field, promoting the formation of soil aggregates, enhancing the physical protection of organic carbon by aggregates, and strengthening the stability of the soil carbon pool.

[0006] Optionally, in step S1, the depth of tilling is 15-20cm.

[0007] Optionally, in step S2, the particle size of the basalt powder is less than 0.25 mm.

[0008] In this invention, by selecting basalt powder with a specific particle size, the contact between the soil and the basalt powder can be increased, the weathering rate of the basalt powder can be improved, and the inorganic carbon content, mineral-bound organic carbon content, total nitrogen content and organic carbon stability in the soil can be further improved.

[0009] Optionally, in step S2, the amount of basalt powder used is 45-55 t / ha.

[0010] Preferably, in step S2, the basalt powder is modified basalt powder, and the preparation method of the modified basalt powder is as follows: The obtained basalt powder was introduced into a high-temperature, high-pressure spiral tube for processing. After processing, it was naturally cooled to obtain modified basalt powder.

[0011] In this invention, modified basalt powder is used, which can further increase the carbon content in the soil and improve the stability of the soil carbon pool more efficiently and effectively.

[0012] Optionally, during the treatment process, the gas pressure is 10~12 MPa, the temperature is 560~580℃, the gas flow rate is 30~35 m / s, and the treatment time is 60~70 min.

[0013] Optionally, the aperture of the high-temperature and high-pressure spiral tube is 8~10mm, and the overall outer diameter of the high-temperature and high-pressure spiral tube is 15~20cm.

[0014] Optionally, in step S2, the depth of tilling is 15-20cm.

[0015] Optionally, in step S3, the cereal crop is selected from corn.

[0016] Optionally, in step S3, the row spacing during corn planting is 90-110cm.

[0017] Optionally, in step S3, the plant spacing during corn planting is 45-55cm.

[0018] Optionally, in step S3, the planting density during the corn planting process is 38,000-42,000 plants / ha.

[0019] Optionally, in step S5, the vegetable is selected from baby bok choy.

[0020] Optionally, in step S5, the row spacing during the planting of baby bok choy is 55-65cm.

[0021] Optionally, in step S5, the plant spacing during the planting of baby bok choy is 45-55cm.

[0022] Optionally, in step S5, the density of baby bok choy during planting is 32,000-35,000 plants / ha.

[0023] Beneficial effects: The solution of this invention not only improves the weathering rate of basalt powder, but also improves the stability of inorganic carbon, mineral-bound organic carbon, total nitrogen and organic carbon in the soil, and significantly increases the increase in soil organic carbon stability, while reducing the difficulty of increasing soil organic carbon stability. Detailed Implementation

[0024] The examples provided are for illustrative purposes only and are not intended to limit the scope of the invention. Therefore, non-essential modifications and adjustments made to the embodiments by those skilled in the art based on the above description are still within the protection scope of this invention.

[0025] Example S0. Use a crusher to initially crush the basalt rock, and after crushing, all of it should be passed through a 5-mesh sieve; then use a crusher to further crush the small basalt particles that have passed through the 5-mesh sieve, and after crushing, all of them should be passed through a 60-mesh sieve. Collect the basalt powder after sieving for later use. S1. Select a plot of farmland with a soil pH of 5.1 in Beibei Cang, Chongqing. After harvesting the crops in the farmland in early March 2024, till the soil three times to a depth of 20cm. S2. Divide the cultivated land after step S1 into six groups and perform the following treatments on each group: Sprinkle basalt powder onto the surface of the tilled cultivated land and till it again. S3. By the end of March 2024, corn will be planted in the cultivated land using conventional farming methods, with a row spacing of 100cm, a plant spacing of 50cm, and 2 plants per planting point, with a planting density of approximately 40,000 plants / ha. S4. Harvest corn in July 2024. After harvesting corn, spread the straw flat in the cultivated land and return it to the field. The cultivated land will be left fallow for 2 months. S5. In late September 2024, baby bok choy was planted in cultivated land using conventional farming methods, with a row spacing of 60cm and a plant spacing of 50cm, resulting in a planting density of approximately 33,000 plants / ha. The baby bok choy was harvested in early March of the following year.

[0026] In step S2, the differences between the groups are as follows: In the first group, the soil was tilled twice in mid-March 2024, with a tilling depth of 20cm; the soil was tilled again in mid-March 2024, twice in total, with a tilling depth of 20cm. The second group will plow the soil twice in mid-March 2024, with a plowing depth of 20cm. In mid-March 2024, basalt powder with a mesh size of 60 will be evenly spread on the surface of the cultivated land at an application rate of 2.5kg per square meter (equivalent to 25t / ha). The soil will then be plowed twice again, with a plowing depth of 20cm. The third group differs from the second group in that the application rate of basalt powder is 5 kg / m³. 2 (Equivalent to 50t / ha); The fourth group differs from the second group in that the application rate of basalt powder is 10 kg / m³. 2 (equivalent to 100t / ha); The fifth group differs from the second group in that the application rate of basalt powder is 20 kg / m³. 2 (Equivalent to 200t / ha); Group 6 differs from Group 3 in that it uses modified basalt powder instead of basalt powder. The preparation method of the modified basalt powder is as follows: Basalt powder passing through a 60-mesh sieve was introduced into a high-temperature and high-pressure spiral tube with a pore size of 10 mm and an outer diameter of 18 cm and treated in a nitrogen atmosphere for 65 min. After treatment, it was naturally cooled to obtain modified basalt powder. During the treatment, the nitrogen pressure in the high-temperature and high-pressure spiral tube was 12 MPa, the temperature was 570℃, and the nitrogen flow rate was 32 m / s. Group 7 differs from Group 3 in that it uses basalt powder that has passed through a 30-mesh sieve instead of basalt powder that has passed through a 60-mesh sieve.

[0027] The bulk density, moisture content, pH value, inorganic carbon content, total nitrogen content, mineral-bound organic carbon content, particulate organic carbon content, total organic carbon content, aggregate-bound organic carbon content, soil quality index, and organic carbon stability index of each group of soil were tested. The results are shown in Table 1. Soil bulk density was determined using the ring sampler method; Soil moisture content was determined using the oven-drying method; pH value was tested using the potentiometric method (soil-to-water ratio of 1:2.5, by mass). Inorganic carbon content was determined using a total nitrogen-form carbon analyzer in accordance with the "Investigation of solids - Temperature dependent differentiation of total carbon" (DIN 19539). Total nitrogen content was determined using a total nitrogen-formed carbon analyzer according to the Dumas combustion method; The content of mineral-bound organic carbon and particulate organic carbon was determined by a total nitrogen-form carbon analyzer according to the "Investigation of solids - Temperature dependent differentiation of total carbon" (DIN19539) after sieving. The total organic carbon content was determined using a total nitrogen-form carbon analyzer in accordance with the "Investigation of solids-Temperature dependent differentiation of total carbon" (DIN 19539). The organic carbon content of the aggregates was determined by a total nitrogen-form carbon analyzer according to the "Investigation of solids-Temperature-dependent differentiation of total carbon" (DIN19539) after wet screening. The organic carbon stability index is calculated using the following formula: Organic carbon stability index = mineral-bound organic carbon content / particulate organic carbon content; The soil quality index is calculated using the following formula: Soil quality index

[0028] In the formula, ZB refers to soil indicators (specifically, the indicators from the second row to the last row in Table 1). In this scheme, the number of soil indicators i is 9; ZB iIt is the i-th indicator in Table 1, ZB max and ZB min These are the maximum and minimum values ​​of the soil index in the seven groups, respectively.

[0029] Table 1 Test Results

[0030] Table 1 shows that compared with group 1, groups 2, 3, 4, 5, and 6 all exhibited significant increases in soil pH, inorganic carbon content, mineral-bound organic carbon content, aggregate-bound organic carbon content, soil quality index, and organic carbon stability index. These results indicate that, in this invention, alkaline substances such as calcium oxide and magnesium oxide in basalt powder can neutralize hydrogen ions in the soil, reducing soil acidity; cations such as calcium and magnesium ions in basalt powder can undergo cation exchange with hydrogen ions in the soil, further reducing soil acidity. Furthermore, basalt powder can absorb atmospheric carbon dioxide through natural weathering and convert it into stable inorganic carbonates, which increase the inorganic carbon content of the soil. Secondly, the addition and weathering of basalt powder significantly increase the content and types of mineral particles in the soil, promote the formation of mineral-bound organic carbon, enhance the chemical protection of soil organic carbon by soil minerals, and increase the stability of soil organic carbon. Furthermore, spreading the straw of crops such as grains on cultivated land can increase the organic carbon content in the soil by returning it to the field, promote the formation of soil aggregates, enhance the physical protection of organic carbon by the aggregates, and strengthen the stability of the soil carbon pool.

[0031] As shown in Table 1, compared with other groups, group six exhibited significantly increased inorganic carbon content, mineral-bound organic carbon content, aggregate-bound organic carbon content, soil quality index, and organic carbon stability index. This result indicates that, in this invention, modifying basalt powder of a specific particle size can significantly increase soil carbon content and improve soil carbon pool stability. The specific modification process described in the examples is also crucial, ensuring that the basalt powder remains granular while exhibiting microcracks, ultimately significantly improving the carbon pool stability and soil quality of acidic soils in a relatively shorter time.

[0032] Table 1 shows that, compared with group seven, group three exhibits significantly increased inorganic carbon content, mineral-bound organic carbon content, aggregate-bound organic carbon content, soil quality index, and organic carbon stability index. This result indicates that, in this invention, by selecting basalt powder of a specific particle size, the contact mode between soil and basalt powder can be increased, the weathering rate of basalt powder can be accelerated, and further, the inorganic carbon content, mineral-bound organic carbon content, total nitrogen content, and organic carbon stability in the soil can be improved.

Claims

1. A method for improving the carbon pool stability and soil quality of acidic soils, characterized in that, Includes the following steps: S1. In mid-March of that year, the farmland with a pH of 4.5-5.5 was plowed 2-3 times; S2. Sprinkle basalt powder onto the surface of the tilled land and till it again 2-3 times; S3. In late March of that year, cereal crops were planted in the cultivated land that had been treated in step S2; S4. After the cereal crops are harvested, the straw is spread flat on the cultivated land and left fallow for 2-3 months.

2. The method for improving carbon pool stability and soil quality in acidic soils as described in claim 1, characterized in that, In step S1, the depth of tilling is 15-20cm.

3. The method for improving carbon pool stability and soil quality in acidic soils as described in claim 1, characterized in that, In step S2, the particle size of the basalt powder is less than 0.25 mm.

4. The method for improving carbon pool stability and soil quality in acidic soils as described in claim 1, characterized in that, In step S2, the amount of basalt powder used is 45-55 t / ha.

5. The method for improving carbon pool stability and soil quality in acidic soils as described in claim 1, characterized in that, In step S2, the depth of tilling is 15-20cm.

6. The method for improving carbon pool stability and soil quality in acidic soils as described in claim 1, characterized in that, In step S3, the cereal crop is selected from corn.

7. The method for improving carbon pool stability and soil quality in acidic soils as described in claim 6, characterized in that, In step S3, during the corn planting process, the row spacing is 90-110cm.

8. The method for improving carbon pool stability and soil quality in acidic soils as described in claim 6, characterized in that, In step S3, the spacing between corn plants is 45-55cm.

9. The method for improving carbon pool stability and soil quality in acidic soils as described in claim 1, characterized in that, In step S5, the vegetable is selected from baby bok choy.

10. The method for improving carbon pool stability and soil quality in acidic soils as described in claim 1, characterized in that, The basalt powder is modified basalt powder, and the preparation method of the modified basalt powder is as follows: basalt powder is introduced into a high-temperature and high-pressure spiral tube for treatment, and then naturally cooled after treatment to obtain modified basalt powder.

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