Method for synergistically improving farmland black soil plough layer carbon storage capacity and stability

Abstract

The invention relates to a method for synergistically improving farmland black soil plough layer carbon storage capacity and stability, and belongs to the field of agricultural soil protection. In order to solve the problems of low carbon immobilization efficiency and poor stability in the prior art, the core of the invention is to construct a synergistic system of carbon source directional enrichment-carbonization micro-zone creation-nitrogen slow release matching. The method is characterized by comprising the following steps: crushing autumn corn straws, and intensively covering a seeding belt with the crushed corn straws; in the next spring, ridge cleaning, deep scarification, rotary tillage, fertilization and sowing are completed at a time in a straw-free belt through a strip tillage and fine sowing machine, and a controlled-release and quick-acting nitrogen fertilizer combination is adopted as base fertilizer; returning the straws to the field in autumn of the next year; and before sowing in the third year, returning straws to alternate sowing belts. The organic carbon content of a plough layer is increased, the mineralization rate is reduced, and the soil structure and the water and fertilizer utilization efficiency are synchronously improved.

Description

TECHNICAL FIELD

[0001] The present invention relates to the technical field of black soil cultivation protection and agricultural low-carbon production, in particular to a method for synergistically improving the carbon storage capacity and stability of the plough layer of farmland black soil. BACKGROUND

[0002] Soil carbon storage is the largest carbon repository in the terrestrial ecosystem, and its small changes can significantly affect atmospheric carbon dioxide concentration and global climate change process. As a typical soil type with high organic matter content, the stability and expansion of the plough layer carbon storage of farmland black soil play a key role in maintaining soil fertility and global carbon balance.

[0003] Straw return to the field as an important means to improve soil organic matter has been widely used in black soil areas. However, there are two technical bottlenecks in the traditional full amount of straw return to the field: first, the uniform distribution of straw in the plough layer leads to carbon source dilution, making it difficult to form an effective carbon enrichment effect; second, due to the high carbon-nitrogen ratio (C / N) in the early stage of straw decomposition, nitrogen sources will be competed with crops, causing seasonal nitrogen fixation, which not only affects the growth of seedlings, but also accelerates the mineralization of existing organic carbon due to the "priming effect" of microorganisms, resulting in the contradictory situation of "low carbon fixation efficiency and high carbon loss risk" in the short term. Therefore, it is difficult to achieve efficient and stable expansion of black soil carbon storage by relying solely on straw return to the field.

[0004] Strip tillage as a protective tillage method helps to reduce the mineralization rate of soil organic carbon by reducing soil disturbance. However, if there is no effective cooperation with straw management, its ability to fix exogenous carbon is limited; at the same time, if nitrogen fertilizer management is not proper, the concentrated straw in the strip will exacerbate the problem of nitrogen fixation. In terms of nitrogen fertilizer management, although reasonable nitrogen, phosphorus and potassium ratio can promote soil carbon conversion, the release curve of conventional quick-acting nitrogen fertilizer is seriously mismatched with the nitrogen demand curve of straw decomposition-carbon fixation. The lack of nitrogen in the early stage inhibits decomposition and causes nitrogen competition, while the excess of nitrogen in the later stage accelerates mineralization. Existing technologies mainly improve in single dimension such as straw return to the field, strip tillage or fertilizer application, and cannot solve the problem of synergistic regulation of "carbon source enrichment-micro-environment-nutrient matching" from the system level. At present, there is a lack of a nitrogen slow-release regulation strategy that can accurately match the straw decomposition process to synergistically optimize the carbon conversion and stabilization path.

[0005] INVENTION CONTENT (I) The problem to be solved by the present invention is that existing black soil protection technologies mainly focus on single measures such as straw returning, strip tillage or fertilizer optimization, and cannot systematically solve the core contradiction of increasing the capacity of the plough layer carbon pool. Specifically, first, the traditional straw returning method has low carbon retention efficiency due to the dispersion of carbon source, slow decomposition rate and imbalance of carbon and nitrogen ratio, and is prone to cause stage nitrogen fixation, affecting crop growth. Second, the conventional fertilization system does not match the straw decomposition process, making it difficult to coordinate the transformation and stability of carbon, and even accelerating the mineralization of existing organic carbon. Third, there is a lack of a technology system that combines "carbon source input-microenvironment creation-nutrient regulation" to achieve the coordinated improvement of the "capacity" and "stability" of the plough layer carbon pool. Therefore, the present invention aims to overcome the above-mentioned defects and provide an integrated method for efficiently and stably increasing the capacity of the plough layer carbon pool of farmland black soil.

[0006] (II) Technical solution A method for simultaneously improving the capacity and stability of the plough layer carbon pool of farmland black soil, characterized in that: directional enrichment of carbon source is achieved through annual alternation of strip tillage and straw mulching, a microstructure conducive to carbon fixation is created in the non-seeding strip without straw through deep scarification-rotary tillage combined operation, and a nitrogen fertilizer combination containing controlled-release urea and quick-acting fertilizer is applied to match the nitrogen demand of the straw decomposition process, thereby achieving the increase of the organic carbon content in the plough layer and the decrease of the organic carbon mineralization rate.

[0007] Preferably, the annual alternation of strip tillage and straw mulching specifically includes the following cycle: S1: In the first year, after the harvest of the previous crop, the straw is crushed and mulched in the non-seeding strip of the current year; S2: In the second year, strip tillage, fertilization and seeding are carried out in the seeding strip without straw mulching; S3: In the second year, the crop is harvested and the straw is crushed and mulched on the ground surface; S4: In the third year, the straw in the seeding strip of the first year is moved to the sides using a strip tillage device to form a new clean seeding strip and seeding is carried out; S5: Repeat steps S1-S4 to form a two-year cycle of alternating straw mulching strip and seeding strip.

[0008] Preferably, the ratio of the width of the seeding strip to the width of the straw mulching strip is 1.2:1 to 1.44:1.

[0009] Preferably, in the deep scarification-rotary tillage combined operation, the deep scarification depth is 20-25 cm and the rotary tillage depth is 10-15 cm.

[0010] Preferably, in the nitrogen fertilizer combination, the controlled-release urea accounts for 40-60% of the total nitrogen amount applied at the bottom, and the release time of the controlled-release urea is 40-50 days.

[0011] A method for stabilizing and increasing the capacity of the carbon pool in the plough layer of a black soil in a farmland, characterized in that it comprises the following steps: (1) in late September to early October, the previous corn is harvested with stubble left, the stubble height is 5-10 cm, and the corn stalks are crushed to a length of ≤10 cm and evenly spread on the surface of the planting zone of the current year to form a straw covering zone with a width of 90-100 cm; (2) in late April to early May of the next year, when the 10 cm ground temperature stabilizes at 7-10℃, a strip-cultivator-seeder is used to work on the planting zone without straw covering with a width of 120-130 cm, completing the tasks of pushing stubble, 20-25 cm deep loosening, 10-15 cm strip rotary tillage, base fertilizer application and precision seeding at one time, wherein the amount of straw residue on the planting zone after pushing stubble is <10%; (3) herbicides are applied during the corn seedling stage, nitrogen fertilizer is applied during the corn bell-mouth stage, and foliar fertilizer and insecticides are sprayed during the grain filling stage; (4) in late September to early October of the next year, corn is harvested with stubble left, and the corn stalks are crushed and returned to the field; (5) before planting in the third year, the strip-cultivator-seeder is used to move the straw in the planting zone of the first year to the covering zones on both sides, arrange a new planting zone and plant corn; (6) steps (1) to (5) are repeated to form a corn straw-returning-to-field strip tillage and planting mode with a two-year cycle.

[0012] Preferably, the application amount of the base fertilizer in step (2) is: N: 110-120 kg / hm², P2O5: 50-60 kg / hm², K2O: 50-60 kg / hm²; wherein 50% of the base-applied nitrogen fertilizer is controlled-release urea with a N content of 44% and a release time of 40-50 days.

[0013] Preferably, the working width of the strip-cultivator-seeder in step (2) is consistent with the planting row spacing, and includes a stubble-pushing wheel, a fertilizer box, a seeder, a rotary tillage knife, a covering disc and a pressing wheel.

[0014] Preferably, the amount of fertilizer applied in the corn bell-mouth stage in step (3) is N: 180-190 kg / hm².

[0015] The beneficial effects of the present application are: compared with the prior art, the present application has significant synergistic effect by integrating straw returning to field, strip tillage and fertilizer optimization, and the specific beneficial effects include: (1) synchronous improvement of carbon pool capacity and stability: through directional enrichment of carbon source and accurate matching of nitrogen, not only the soil organic carbon content is significantly improved, but also the mineralization activity of organic carbon is effectively reduced, realizing the dual goals of "capacity increase" and "capacity stability". (2) improvement of soil physical structure and ecological function: the combination of strip tillage and straw mulching significantly improves the soil structure, increases the total porosity, improves the soil water storage capacity and water use efficiency, and greatly reduces the soil erosion. (3) improvement of nutrient utilization efficiency and crop yield: the optimized application of controlled-release urea and phosphorus and potassium fertilizer improves the nitrogen utilization rate, and the soil carbon-nitrogen ratio (C / N) is stabilized in the appropriate range. This optimized soil environment promotes the growth and development of corn, improves the uniformity of emergence, and finally realizes the yield increase, saves the cost of tillage and fertilization, and realizes the synergistic improvement of economic benefit and ecological benefit. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings needed in the specific embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0017] Figure 1 The method flowchart provided by the embodiment of the present application is shown in the figure; Figure 2 is the comparison chart of farmland black soil organic carbon content under different tillage measures in the embodiment of the present application; Figure 3 is the dynamic chart of farmland black soil organic carbon mineralization under different tillage measures in the embodiment of the present application; Figure 4 is the comparison chart of farmland black soil organic carbon cumulative mineralization under different tillage measures in the embodiment of the present application; Figure 5 is the comparison chart of farmland black soil organic carbon relative mineralization under different tillage measures in the embodiment of the present application. DETAILED DESCRIPTION

[0018] The technical solutions of the present application will be described in detail below with reference to the embodiments, obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0019] like Figure 1 As shown, one embodiment of this invention patent provides a method for synergistically improving the carbon pool capacity and stability of the black soil topsoil in farmland.

[0020] Example 1: From late September to early October, the previous corn crop is harvested with stubble left at a height of 5-10 cm. The corn stalks are then completely crushed to a length of ≤10 cm and evenly spread on the surface of the planting strip for that year, forming a straw cover strip with a width of 90-100 cm. From late April to early May of the following year, when the soil temperature at 10 cm depth is stable at 7-10℃, a strip tillage and dense planting precision seeder is used on a planting strip with a width of 120-130 cm without straw cover. This process completes stubble clearing, 20-25 cm deep loosening, 10-15 cm strip rotary tillage, basal fertilizer application, and precision seeding in one operation. The operating width of the strip tillage and dense planting precision seeder is consistent with the row spacing and includes a stubble wheel, fertilizer box, seeder, rotary tiller blade, covering disc, and press wheel. The residual straw content in the sowing strip after stubble clearing is <10%. The base fertilizer application rates are: N: 110-120 kg / hm², P2O5: 50-60 kg / hm², K2O: 50-60 kg / hm². 50% of the base nitrogen fertilizer is controlled-release urea with a 44% N content and a release time of 40-50 days. Herbicides are applied during the corn seedling stage, and 180-190 kg / hm² of nitrogen fertilizer is applied as topdressing during the corn's large trumpet stage. Foliar fertilizer and insecticides are sprayed during the grain-filling stage. From late September to early October of the following year, the corn stubble is left after harvest, and the corn straw is crushed and returned to the field. Before sowing in the third year, a strip tillage and high-density planting machine is used to move the straw from the first year's sowing strip to the cover strips on both sides, creating new sowing strips for corn planting. These steps are repeated to form a two-year cycle of corn straw return strip tillage planting.

[0021] Example 2: This embodiment was conducted at a black soil experimental base in Keshan County, Heilongjiang Province. The initial soil organic carbon content in the 0-20 cm soil layer was 20.13 g / kg. Two treatments were set up in the experiment: conventional tillage (PT) and strip tillage (ST) of the present invention.

[0022] The specific implementation of strip tillage (ST) of this invention is as follows: (1) After the corn harvest in late September, leave a stubble height of 8 cm, crush the straw to a length of 5-8 cm, and evenly cover it in the planting strip of the year, with a covering strip width of 95 cm. (2) In early May of the following year, when the soil temperature at 10 cm depth is stable at 8℃, use a strip tillage and dense planting precision seeder to operate in a planting strip with a width of 125 cm. Push the stubble and clear the ridges until the straw residue is less than 8%, then carry out deep loosening at 22 cm and rotary tillage at 12 cm. At the same time, apply base fertilizer: pure nitrogen 115 kg / hm² (of which 50% is controlled-release urea with a release period of 45 days), P2O5 55 kg / hm², K2O 55 kg / hm², with a fertilization depth of 13 cm and a distance of 7 cm from the seed. Sow the corn variety "Zhonghe 209" at a planting depth of 7 cm and a density of 5800 plants / hm². (3) Apply 0.75 mL / hm² of 26% thiamethoxam·isoxazole suspension for weed control during the seedling stage; apply 185 kg / hm² of pure nitrogen during the large trumpet stage; and spray 0.8 kg / hm² of potassium dihydrogen phosphate and 1.5 L / hm² of organometallic protease during the grain-filling stage. (4) Leave stubble at the autumn harvest and return the straw to the field after crushing. (5) In the spring of the third year, return the straw from the first year's sowing strip to both sides to form a new sowing strip for continued planting. The traditional tillage (PT) treatment uses tillage to a depth of 30 cm, and the straw is mixed evenly and returned to the field. The type and amount of fertilizer are the same as those in the ST treatment.

[0023] The measurement results are as follows Figures 2 to 5 As shown. Figure 2 The results showed that in the 0-10 cm soil layer, the soil organic carbon content in the ST treatment was significantly higher than that in the PT treatment (P<0.05). Figure 3 , Figure 4 and Figure 5 The results showed that the organic carbon mineralization, cumulative mineralization, and relative mineralization in the ST treatment were significantly lower than those in the PT treatment at all cultivation stages (P<0.05). This demonstrates that the method of the present invention effectively inhibits the mineralization and decomposition of organic carbon while increasing the soil organic carbon content, and significantly enhances the capacity and stability of the carbon pool in the black soil topsoil.

[0024] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for synergistically enhancing the carbon pool capacity and stability of the topsoil layer in farmland black soil, characterized in that, By alternating strip tillage and straw mulching year after year, carbon sources are enriched in a targeted manner. In straw-free seeding strips, a micro-zone structure conducive to carbon fixation is created through deep loosening and rotary tillage. A nitrogen fertilizer combination containing controlled-release urea and fast-acting fertilizer is applied to match the nitrogen demand of the straw decomposition process, thereby increasing the organic carbon content of the topsoil and reducing the organic carbon mineralization rate.

2. The method for synergistically improving the carbon pool capacity and stability of the topsoil layer in farmland according to claim 1, characterized in that, The interannual alternation of strip tillage and straw mulching specifically includes the following cycles: S1: In the first autumn, after the previous crop is harvested, all the straw is crushed and concentrated to cover the non-sown areas of that year. S2: In the second spring, strip tillage, fertilization and sowing are carried out in the seeding strip without straw cover; S3: In the autumn of the second year, harvest the seasonal crops and shred the straw to cover the ground; S4: In the third spring, use strip tillage equipment to move the straw from the first year's sowing strip to both sides, forming a new clean sowing strip for sowing; S5: Repeat steps S1-4 to form a two-year cycle of alternating straw mulch and sowing belts.

3. A method for synergistically improving the carbon pool capacity and stability of the topsoil layer in farmland according to claim 1 or 2, characterized in that, The ratio of the width of the sowing strip to the width of the straw covering strip is 1.2:1 to 1.44:

1.

4. The method for synergistically improving the carbon pool capacity and stability of the black soil topsoil layer in farmland according to claim 1, characterized in that, In the deep tillage-rotary tillage combined operation, the deep tillage depth is 20-25 cm, and the rotary tillage depth is 10-15 cm.

5. The method for synergistically improving the carbon pool capacity and stability of the topsoil layer in farmland according to claim 1, characterized in that, In the nitrogen fertilizer combination, controlled-release urea accounts for 40% to 60% of the total nitrogen applied as a base fertilizer, and the release time of the controlled-release urea is 40 to 50 days.

6. A method for stabilizing and increasing the carbon pool in the topsoil of farmland black soil, characterized in that, The following steps are included: (1) From late September to early October, the previous corn crop is harvested with stubble left at a height of 5-10 cm. The corn stalks are then crushed to a length of ≤10 cm and evenly spread on the surface of the planting strip for the current year to form a straw covering strip with a width of 90-100 cm; (2) From late April to early May of the following year, when the soil temperature at 10 cm depth is stable at 7-10℃, a strip tillage and dense planting precision seeder is used on a planting strip with a width of 120-130 cm without straw covering to complete stubble clearing, 20-25 cm deep loosening, and 10-15 cm deep loosening in one operation. (3) Apply herbicides during the corn seedling stage, apply nitrogen fertilizer during the corn tasseling stage, and spray foliar fertilizer and insecticide during the grain filling stage; (4) Leave stubble when the corn is harvested from late September to early October of the following year, and crush the corn straw and return it to the field; (5) Before the third year of planting, use a strip tillage and dense planting precision seeder to return the straw in the first year's planting strip to the cover strips on both sides, and arrange a new planting strip and plant corn; (6) Repeat steps (1) to (5) to form a two-year cycle of corn straw return strip tillage planting pattern.

7. The method for stabilizing and increasing the carbon pool in the topsoil of farmland according to claim 6, characterized in that, The application rate of the base fertilizer in step (2) is: N: 110-120 kg / hm², P2O5: 50-60 kg / hm², K2O: 50-60 kg / hm²; among which, 50% of the base nitrogen fertilizer is controlled-release urea with a N content of 44% and a release time of 40-50 days.

8. The method for stabilizing and increasing the carbon pool in the topsoil of farmland according to claim 6, characterized in that, The working width of the strip tillage dense planting precision seeder described in step (2) is consistent with the sowing row spacing, and includes a stubble wheel, fertilizer box, seeder, rotary tiller, soil covering disc and compaction wheel.

9. The method for stabilizing and increasing the carbon pool in the topsoil of farmland according to claim 6, characterized in that, The amount of topdressing fertilizer applied to corn during the large trumpet stage in step (3) is N: 180-190 kg / hm².

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