Straw and green manure synergistic returning method in fallow period of rice-vegetable rotation area

Abstract

The invention relates to the technical field of agricultural soil improvement, and particularly discloses a straw and green manure synergistic returning method in a fallow period in a rice-vegetable rotation area, which takes land to nourish land as a core, and aims to solve the problems of rice-vegetable rotation soil degradation and short fallow period in a hot area. Through precise time sequence connection, cooperative turning and pressing in the optimal period (from the full blooming period to the initial pod period of the green manure) and an original dry tillage and wet retting decomposition process (sunning upturned soil for 2-3 days after turning and then irrigating for field retting for 7-10 days), efficient cooperative utilization and rapid decomposition of the straw and the green manure in the temporary fallow period are achieved. According to the method, an endogenous-driven land cultivation mode is constructed, soil organic matter can be remarkably increased (0.2%-0.4% can be increased continuously in three years), the soil structure is improved, acidification is corrected, application of chemical nitrogen fertilizer of next-stubble vegetables is reduced by 30%-50%, a complete'land cultivation-land cultivation 'ecological and benefit closed loop is formed, the problem that soil is unbalanced in use and cultivation under high-intensity cultivation is effectively solved, and the method is suitable for large-scale popularization and application. The method has remarkable ecological, economic and social benefits.

Description

Technical Field

[0001] This invention relates to the field of agricultural soil improvement technology, and more specifically, to a method for the synergistic return of straw and green manure to the field during the fallow period in rice-vegetable rotation areas. Background Technology

[0002] The rice-vegetable rotation area in Hainan is an important production base for tropical specialty agricultural products in my country, playing a strategic role in ensuring food security and vegetable supply. However, the region's typical hot and humid climate, combined with the inherent high multiple cropping index and intensive farming patterns of rice-vegetable rotation, poses a severe challenge to the sustainable use of arable land. Long-term continuous cropping has led to a series of increasingly prominent degradation problems, including declining soil organic matter content, increased acidification, nutrient imbalance, soil compaction, and microbial community disorder. In particular, the short growth cycle and high nutrient absorption intensity of vegetables result in a "predatory" consumption of soil nutrients, further accelerating soil degradation and increasing the risk of agricultural non-point source pollution. Therefore, exploring and establishing a sustainable soil "use-nourishment integration" technology system suitable for this region has become an urgent need to ensure the sustainable development of high-efficiency tropical agriculture.

[0003] Against this backdrop, the concept of "using land to nourish land" is considered a fundamental approach to achieving soil health management. Its core lies in actively cultivating soil fertility by utilizing the material cycles and biological processes within the agricultural ecosystem, reducing dependence on external resource inputs. Specifically, in the rice-vegetable rotation system, a short fallow period (usually 2-3 months) is utilized by sowing green manure and synergistically incorporating it into the field with the previous crop's straw, achieving "crop-livestock integration." This aims to improve soil physical and chemical properties, enhance basic soil fertility, provide endogenous nutrients, reduce fertilizer application, and obtain both ecological and economic benefits. However, transforming this concept into a highly efficient and stable technical solution that can be widely applied in production still faces the following key challenges:

[0004] 1. The time window for "soil conditioning" is extremely limited: The annual production rhythm of rice-vegetable rotation is tight, and the actual available time for soil rest and fertilization is usually only 2-3 months. Traditional soil conditioning measures (such as long-term fallow and planting green manure with a long conventional growth period) cannot be integrated into the existing production system due to the mismatch of cycles.

[0005] 2. Low resource utilization efficiency of "soil nourishment": While returning rice straw to the field can supplement organic carbon, its inherently high carbon-to-nitrogen ratio can easily lead to uncoordinated decomposition processes under high temperature and humidity conditions. In the short term, this may induce microorganisms to compete with crops for nitrogen, which in turn inhibits the growth of subsequent vegetable seedlings, contradicting the original intention of "soil nourishment." A search revealed that the existing technology disclosed in Chinese patent document CN117837329, "A Method for Co-returning Straw and Green Manure to the Field during the Fallow Period in Rice-Vegetable Rotation Areas," involves the alternating return of rice and rapeseed straw with the addition of exogenous composting agents and bio-fertilizers. Although this method has some effect on improving soil phosphorus and potassium levels, it has significant limitations. First, it targets the rice-oilseed rotation model, which differs significantly from the rice-vegetable rotation model in terms of crop physiological characteristics, soil nutrient output patterns, and pest and disease systems. Therefore, it cannot directly address the rapid soil depletion and degradation caused by vegetable cultivation. Second, this technology does not introduce green manure crops with biological nitrogen-fixing capabilities, lacking the core "soil-nourishing" link of rapidly and actively replenishing and regulating the nitrogen cycle from within the system. This makes it insufficient in mitigating or avoiding the "nitrogen competition" effect of straw return to the field. Third, its decomposition promotion mainly relies on commercially available composting agents and bio-fertilizers, failing to fully utilize and optimize natural agronomic processes under tropical climates (such as water and tillage management) to regulate decomposition. This results in higher costs and the stability of its effects is dependent on exogenous products.

[0006] 3. The practical contradiction between "land use" and "soil maintenance": Under high-intensity, high-efficiency planting systems, producers often focus more on short-term output and easily neglect or compress the necessary soil maintenance process. How to design a technology that enables the "soil maintenance" process itself to be rapid and effective, and whose output (enhanced soil fertility) can be directly converted into reduced fertilizer input and lower production costs for the next crop, thereby achieving a unified and win-win situation between "land use" and "soil maintenance" in terms of time arrangement and economic benefits, is a problem that existing technical solutions have failed to systematically solve.

[0007] In conclusion, although the concept of "using land to nourish land" is important and urgent, existing technologies have not yet provided a dedicated technical method that fully fits the characteristics of the tropical rice-vegetable rotation system, can efficiently utilize the short fallow period, and truly achieve "integration of planting and breeding" and "balance between use and maintenance".

[0008] To address these issues, this application proposes a method for the coordinated return of straw and green manure to the field during the fallow period in rice-vegetable rotation areas. Summary of the Invention

[0009] The purpose of this invention is to solve the technical problems mentioned in the background section and to provide a method for the synergistic return of straw and green manure to the field during the fallow period in rice-vegetable rotation areas.

[0010] The above-mentioned objective of the present invention is achieved as follows:

[0011] A method for co-returning straw and green manure to the field during the fallow period in rice-vegetable rotation areas includes the following steps:

[0012] (1) Drainage of previous rice crop and in-situ treatment of straw: Drain the water in the field 10-15 days before the harvest of the previous rice crop; at harvest time, use a harvester with a shredding and spreading device to harvest the straw at a low stubble, crush the straw to 5-8 cm and spread it evenly on the field surface.

[0013] (2) Precision sowing of fast-growing leguminous green manure: Select leguminous green manure varieties with a growth period of 70-90 days and sow using one of the following two methods:

[0014] Mode A: Sow the rice between the rows 15-20 days before the harvest of the previous rice crop;

[0015] Mode B: Broadcast within 3 days after the previous rice harvest; drain the furrows immediately after sowing;

[0016] (3) Key growth management during the green manure growing season: After the green manure seedlings emerge, apply quick-acting nitrogen fertilizer or compound fertilizer according to the seedling condition;

[0017] (4) The best time for straw and green manure to be turned over together: When the selected green manure variety grows to the full flowering stage to the early pod stage, it is turned over and pressed into the soil tillage layer together with the straw treated in step (1).

[0018] (5) "Dry plowing and wet composting" optimized decomposition process: plowing and compacting the field under dry conditions; after plowing and compacting, sun-dry the clods for 2-3 days, and then irrigate the field for 7-10 days;

[0019] (6) Precise reduction of fertilizer application for the next crop: Based on the amount of green manure and straw returned to the field, reduce the amount of chemical nitrogen fertilizer applied in the base fertilizer for the next crop.

[0020] Furthermore, in step (2), the legume green manure variety is sesbania, tamarisk, or milkvetch.

[0021] Furthermore, in step (2), the sowing amount of sesbania is 2-3 kg / mu, the sowing amount of tamarisk is 3-4 kg / mu, and the sowing amount of milkvetch is 1.5-2.5 kg / mu.

[0022] Furthermore, in step (4), the depth of the overturning is 20-25 cm.

[0023] Furthermore, in step (5), 3-8 kg of urea per mu is applied as starting nitrogen during plowing or before sun-drying to adjust the carbon-nitrogen ratio.

[0024] Furthermore, in step (6), the next crop is vegetables, and the reduction in chemical nitrogen fertilizer is 30%-50%.

[0025] Furthermore, before turning over in step (4) or during sun-drying in step (5), a soil acidity correction step is also included: for acidic soils with a pH value below 5.5, apply 50-150 kg of lime or soil conditioner per mu.

[0026] Furthermore, it also includes disease and pest risk management steps: if the previous crop of rice is severely affected by diseases and pests, the corresponding straw will be removed from the field for harmless treatment or fully decomposed and inactivated before being returned to the field; after returning to the field, green prevention and control measures will be adopted for disease and pest monitoring and control.

[0027] Furthermore, the method is applicable to farmland in tropical or subtropical regions with a fallow period of 2-3 months in rice-vegetable rotation or rice-rice-vegetable rotation patterns.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention provides a method for the synergistic return of straw and green manure to the field during the fallow period in rice-vegetable rotation areas. This method fully constructs and realizes a highly efficient "land-for-land" cycle system, achieving significant and quantifiable progress and multiple benefits, as detailed below:

[0030] 1. The solution of this invention significantly slows down soil degradation and specifically improves soil fertility. Addressing the common problems of low soil organic matter content and acidification in rice-vegetable rotation farmland, this invention effectively increases soil organic matter content by planting leguminous green manure such as sesbania and tamarisk, combined with straw plowing and returning to the field. Continuous implementation for three years can increase soil organic matter content by 0.2% to 0.4%. Simultaneously, this method improves soil aggregate structure, increases porosity, and has a significant improvement effect on acidic soils, fundamentally improving the arable land soil environment and solving key constraints affecting the yield and quality of winter melons and vegetables.

[0031] 2. The method of this invention can effectively restore the ecological imbalance of farmland, reduce production costs and risks, and transform the idle period of farmland during the rainy season into an active period for ecological soil conservation. Planting green manure to cover the ground effectively inhibits the growth of weeds, cuts off the breeding grounds of pathogens and pests, and reduces the source of diseases and pests in winter melons and vegetables from the source. The strong biological nitrogen fixation capacity and nutrient return function of leguminous green manure make planting one acre of sesbania equivalent to applying one ton of organic fertilizer, which can significantly replace or reduce the use of organic fertilizer and base fertilizer for the next crop, and reduce the planting costs for farmers.

[0032] 3. The method of this invention realizes the efficient recycling of agricultural resources and promotes green and low-carbon development. It efficiently transforms rice straw, which is traditionally regarded as waste, and specially planted green manure plants into high-quality soil nutrient resources. Through the mechanized crushing and returning of straw to the field and the synergistic use of green manure, an agricultural circular production model of "waste resource utilization - soil fertilization - fertilizer reduction" is constructed. The method of this invention not only solves the problem of straw disposal, but also improves the quality of cultivated land by reducing the amount of fertilizer applied (especially nitrogen fertilizer, which can be reduced by 30%-50%), thereby directly promoting the green, low-carbon, and circular development of agriculture.

[0033] 4. The method of this invention forms a closed loop of benefits between "land conservation and land use," taking into account ecological, economic, and social benefits. Through "precise timing connection (intercropping / rapid sowing)," "synergistic use of endogenous nutrients (green manure nitrogen fixation + straw carbon source)," and "unique 'dry tillage and wet composting' decomposition process," it successfully transforms the short fallow period into a period of high-efficiency land conservation. Its output is directly reflected in a significant reduction in fertilizer input for the next crop and a reduction in production costs. It achieves the unity of "land use" and "land conservation" in terms of time and benefits, and provides strong technical support for ensuring food security and promoting the sustainable development of agriculture in tropical regions. Attached Figure Description

[0034] Figure 1 This is a flowchart of the method for synergistic return of straw and green manure to the field in an embodiment of the present invention;

[0035] Figure 2 This is a small-area demonstration diagram of Lingao where the method of the present invention is applied in an embodiment of the present invention;

[0036] Figure 3 This is a small-area demonstration diagram of Tunchang where the method of the present invention is applied in an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figure 1-3 The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0038] The implementation of the present invention will be described in detail below with reference to specific embodiments.

[0039] This invention provides a method for the synergistic return of straw and green manure to the field during the fallow period in rice-vegetable rotation areas. Specifically, within a limited fallow period, by optimizing the timing and process, the method achieves efficient synergistic return of straw and leguminous green manure to the field, thereby rapidly improving soil, enhancing soil fertility, and reducing reliance on chemical fertilizers. The specific implementation of this invention is described below.

[0040] Example 1: Application of intercropping in a mildly acidified rice-vegetable rotation area (taking Lingao as an example)

[0041] This embodiment demonstrates the full - process operation and quantitative effects of achieving "seizing the right time to cultivate the land" by adopting the "sowing - in - rotation mode" in a typical field with slightly acidified soil and a healthy previous crop.

[0042] Field and rotation background: Located in Jialai Town, Lingao County, Hainan Province, it is a typical rice - vegetable rotation field. The previous crop was high - quality indica rice, and no serious pests and diseases occurred. The soil type is sandy loam, with basic soil fertility: pH value 5.8, organic matter content 12.3 g / kg (about 1.23%), available nitrogen 85 mg / kg, available phosphorus 15 mg / kg, and available potassium 90 mg / kg. It is planned to plant winter peppers in the next crop.

[0043] The implementation process steps are as follows:

[0044] Step (1): Drainage of the previous crop and straw treatment. In the late filling stage of rice (about 12 days before expected harvest), dig ditches to completely drain the surface water in the field, making the soil in a moist state for the convenience of machinery entering the field. During harvest, select a Kubota PRO988Q combine harvester (equipped with a powerful shredding and spreading device), control the stubble height below 12 cm, ensure that the rice straw is crushed into sections of 5 - 7 cm, and evenly spread over the whole field without piling up.

[0045] Step (2): Precision sowing of green manure. Select "Guizaojing No. 1" sesbania as the green manure variety, whose whole growth period is about 75 days, meeting the window requirement of 70 - 90 days. 18 days before rice harvest (rice dough stage), use a manual hand - cranked seeder to evenly sow sesbania seeds at a rate of 2.8 kg / mu between the rice rows. Immediately after sowing, clean and deepen the drainage ditches around the field and the cross - waist ditches, ensuring that the ditch depth is greater than 25 cm, with all ditches connected and smooth drainage.

[0046] Step (3): Green manure growth promotion management. 10 days after the sesbania emerges (about the three - leaf stage), for areas with sparse emergence and weak growth in part of the field, apply 4 kg of urea per mu as top - dressing to promote even emergence and strong growth, and quickly form ground coverage.

[0047] Step (4): Cooperative plowing and incorporation. 57 days after rice harvest, sesbania enters the full - bloom stage, with a plant height of 1.4 - 1.6 m, and the measured fresh grass yield in the field is 3100 ± 200 kg / mu. At this time, use a 1.8 - m - wide rotary tiller配套 to a Dongfanghong 1404 tractor for tillage operations. During tillage, incorporate the sesbania plants in the full - bloom stage and the rice straw that has been preliminarily air - dried on the ground into the soil together, strictly controlling the tillage depth at 22 ± 2 cm, ensuring that the returned materials are fully buried, and the field surface is flat after tillage, without exposed straw or green manure residues.

[0048] Step (5): "Dry Tillage and Wet Fermentation" Decomposition. Tillage should be carried out during a period of consecutive sunny days when the field surface is dry. After tilling, open all drainage outlets and allow the soil to dry for 2 days. After drying, draw water from the water source to create a shallow water layer of 5-8 cm on the field surface for 8 days of fermentation. During this period, keep the water layer stable and do not drain the water. To accelerate the decomposition of high carbon-to-nitrogen ratio materials, apply 5 kg / mu of urea evenly as "starting nitrogen" before tilling.

[0049] Step (6): Subsequent Planting and Precision Fertilization. After composting, drain the water from the field and let it dry for 1-2 days until the soil is suitable for cultivation. Then, prepare the land, create ridges, and cover with mulch to prepare for transplanting chili seedlings. Based on the nitrogen-fixing and fertilization effect of the fresh green manure (approximately 3100 kg / mu), the base fertilizer plan for the next chili crop is significantly adjusted: compared with the local conventional fertilization (50 kg / mu of 45% compound fertilizer + 500 kg / mu of organic fertilizer), no commercial organic fertilizer is used, the amount of chemical compound fertilizer (15-15-15) is reduced to 30 kg / mu, and an additional 5 kg / mu of urea is added as seedling fertilizer. The pure nitrogen input is reduced by approximately 35% compared to the conventional method.

[0050] Implementation Results and Data Monitoring:

[0051] The chili peppers showed good growth characteristics during the season: they recovered quickly after transplanting, and no yellowing or stunting of seedlings occurred throughout the entire growth period due to straw return to the field. The chili pepper plants were robust, and the incidence of diseases was reduced.

[0052] Changes in soil physicochemical properties (measured after the current season): Soil pH value increased slightly from 5.8 to 5.9; soil organic matter content increased to 13.1 g / kg (an increase of about 0.08 percentage points); soil bulk density decreased from 1.32 g / cm³ to 1.28 g / cm³.

[0053] Economic benefits: Saves about 200 yuan / mu in organic fertilizer costs and reduces chemical fertilizer input by about 30 yuan / mu.

[0054] Example 2: Application of post-harvest sowing mode in moderately acidified rice-vegetable rotation area (taking Tunchang as an example)

[0055] This example demonstrates the effects of using the "post-harvest sowing mode" and supporting acidic soil improvement measures on plots with severe soil acidification that require soil conditioning.

[0056] Field and Crop Rotation Background: Located in Poxin Town, Tunchang County, Hainan Province, this is a rice-vegetable rotation field. The previous rice crop showed sporadic cases of sheath blight. The soil is clay loam with significant acidification issues: pH 5.2, organic matter content 15.1 g / kg, but the soil is compacted. The planned next crop is cowpea.

[0057] The implementation process steps are as follows:

[0058] Step (1): Drainage, straw treatment and diseased straw management. Drainage 15 days before harvest. Mechanical harvesting and crushing of straw. In response to the previous crop sheath blight, implement "pest and disease risk management": manually collect straw from areas with concentrated disease (approximately 15% of the total area), and leave the remaining healthy straw evenly in the field.

[0059] Soil acidity correction: In conjunction with land preparation, spread 80 kg / mu of quicklime evenly on the field surface and mix it with the topsoil through rotary tillage.

[0060] Step (2): Sowing after green manure harvest. Sow the green manure on the second day after rice harvest, while the soil moisture is suitable. Select the "Yueyin" tamarisk variety, which has a growth period of about 85 days. Sow manually at a rate of 3.2 kg / mu, then lightly rake and cover with soil, and also dig drainage ditches.

[0061] Steps (3) and (4): No topdressing was applied during the growth period of tamarisk. 82 days after sowing, tamarisk entered the initial pod stage, with a fresh grass yield of 2600±150 kg / mu. Plowing was carried out using a moldboard plow to a depth of 20-23 cm.

[0062] Step (5): "Dry plowing and wet composting" decomposition. After plowing and pressing, the soil is dried in the sun for 3 days, and then the field is irrigated and composted for 7 days.

[0063] Step (6): Apply fertilizer for the next crop. When planting cowpeas, apply only 25 kg / mu of 15-15-15 compound fertilizer and 20 kg / mu of calcium magnesium phosphate fertilizer as base fertilizer. Compared with conventional fertilization (40 kg / mu of compound fertilizer + 10 kg / mu of urea), the amount of nitrogen fertilizer applied is reduced by more than 40%. At the same time, in order to promote cowpea pod formation, apply 50 g / mu of ammonium molybdate as foliar fertilizer.

[0064] Implementation Results and Data Monitoring:

[0065] Soil improvement effects: Post-season measurements showed that soil pH significantly increased from 5.2 to 5.6, effectively alleviating acidification. Soil looseness was also significantly improved.

[0066] Crop and ecological benefits: During the fallow period, weeds in cowpea fields decreased by approximately 70%, and the incidence of cowpea root rot decreased. Cowpea pods were fuller, and the yield was comparable to that of the full-fertilizer control area.

[0067] Long-term data (after three consecutive years of implementation): The soil organic matter content of this plot increased to 16.8 g / kg, an increase of 0.17 percentage points over three years, with an average annual increase of about 0.057 percentage points, verifying the continuous fertilization effect of the technology.

[0068] Example 3: Adaptive treatment for fields with high incidence of pests and diseases

[0069] This example demonstrates how to adjust the technical solution to ensure safe return of rice to the field when the previous crop is severely affected by pests and diseases.

[0070] Field background: Assume that the previous crop of rice in a certain field was severely affected by rice blast and rice stem borer.

[0071] The method has been adjusted as follows:

[0072] Strict handling of diseased straw (Precaution 1): Discard straw and return it to the field in situ. Collect all rice straw from the field and transport it to a centralized composting site. Use the "film-covered high-temperature composting" technology: Add a special composting agent when stacking the straw, then cover it tightly with black plastic film. Under the high-temperature conditions in Hainan, the internal temperature of the pile can reach 60-70℃, and it will be fully composted in 20-25 days, effectively killing pathogens and insect eggs. The composted organic fertilizer can be used in other plots or as base fertilizer for the next crop.

[0073] Green manure planting and returning to the field: After the straw is cleared from the field, green manure (such as sesbania) is immediately sown in accordance with the method of Example 1 or 2; after the green manure grows to the full flowering period, it is turned over and returned to the field separately; the "dry plowing and wet composting" process is still used when turning over.

[0074] Subsequent crop management: Since only green manure is returned to the field, the reduction ratio of chemical fertilizer for the next crop of vegetables can be assessed based on the amount of fresh green manure. Nitrogen fertilizer can usually be reduced by 20%-30%, and extra attention should be paid to the monitoring and green control of pests and diseases.

[0075] The alternative mode in this embodiment reflects the flexibility and safety of the method of the present invention, solves farmers' concerns about the spread of diseases by returning diseased straw to the field, and makes the method of the present invention applicable to a wider range of conditions.

[0076] Comparative Example: This comparative example is a conventional single straw return mode, designed to highlight the advantages of the synergistic straw return method of the present invention, as detailed below:

[0077] In similar fields in the same area, after rice harvest, only straw is crushed and returned to the field (no green manure is planted), and the field is continuously irrigated for 15 days after plowing. When planting the next crop of chili peppers, the full amount of conventional chemical fertilizer and organic fertilizer (50 kg / mu of 45% compound fertilizer + 500 kg / mu of organic fertilizer) is applied.

[0078] Comparison results:

[0079] Impact on seedlings: 15-20 days after transplanting, chili peppers show obvious yellowing of leaves and slow growth due to nitrogen competition, which can be alleviated by applying additional urea.

[0080] Soil fertility improvement effect: Post-season testing showed no statistically significant increase in soil organic matter content compared to the previous year.

[0081] Costs and risks: Fertilizer costs were not saved, and there is a potential risk of disease due to incomplete straw decomposition.

[0082] In summary, through the comparison of the above embodiments and comparative examples of the present invention, the method of returning straw and green manure to the field in the fallow period of the rice-vegetable rotation area of ​​the present invention has the following advantages: (1) Rapid fertilization: Through the synergy of "green manure nitrogen fixation + straw carbon source" and "dry tillage and wet composting" process, the organic matter of the current season is improved and the soil structure is improved. The cumulative increase in organic matter can reach 0.2%-0.4% for three consecutive years; (2) Reduce fertilizer and increase efficiency: Stably reduce the amount of nitrogen fertilizer used in the next crop of vegetables by 30%-50%, directly reducing production costs; (3) Ecological safety: Effectively suppress weeds during the fallow period, optimize the soil microbial environment, and control the source of pests and diseases through supporting measures such as removing diseased straw from the field; (4) Resource recycling: Efficiently convert agricultural waste (straw) and by-products (green manure) into soil nutrients to form a closed loop.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements 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 the coordinated return of straw and green manure to the field during the fallow period in rice-vegetable rotation areas, characterized in that, Includes the following steps: (1) Drainage of previous rice crop and in-situ treatment of straw: Drain the water in the field 10-15 days before the harvest of the previous rice crop; at harvest time, use a harvester with a shredding and spreading device to harvest the straw at a low stubble, crush the straw to 5-8 cm and spread it evenly on the field surface. (2) Precision sowing of fast-growing leguminous green manure: Select leguminous green manure varieties with a growth period of 70-90 days and sow using one of the following two methods: Mode A: Sow the rice between the rows 15-20 days before the harvest of the previous rice crop; Mode B: Broadcast within 3 days after the previous rice harvest; drain the furrows immediately after sowing; (3) Key growth management during the green manure growing season: After the green manure seedlings emerge, apply quick-acting nitrogen fertilizer or compound fertilizer according to the seedling condition; (4) The best time for straw and green manure to be turned over together: When the selected green manure variety grows to the full flowering stage to the early pod stage, it is turned over and pressed into the soil tillage layer together with the straw treated in step (1). (5) "Dry plowing and wet composting" optimized decomposition process: plowing and compacting the field under dry conditions; after plowing and compacting, sun-dry the clods for 2-3 days, and then irrigate the field for 7-10 days; (6) Precise reduction of fertilizer application for the next crop: Based on the amount of green manure and straw returned to the field, reduce the amount of chemical nitrogen fertilizer applied in the base fertilizer for the next crop.

2. The method for co-returning straw and green manure to the field during the fallow period in a rice-vegetable rotation area according to claim 1, characterized in that, In step (2), the legume green manure variety is sesbania, tamarisk, or milkvetch.

3. The method for co-returning straw and green manure to the field during the fallow period in a rice-vegetable rotation area according to claim 2, characterized in that, In step (2), the sowing amount of sesbania is 2-3 kg / mu, the sowing amount of tamarisk is 3-4 kg / mu, and the sowing amount of milkvetch is 1.5-2.5 kg / mu.

4. The method for co-returning straw and green manure to the field during the fallow period in a rice-vegetable rotation area according to claim 1, characterized in that, In step (4), the depth of the folding is 20-25 cm.

5. The method for co-returning straw and green manure to the field during the fallow period in a rice-vegetable rotation area according to claim 1, characterized in that, In step (5), 3-8 kg of urea per mu is applied as starting nitrogen during plowing or before sun-drying to adjust the carbon-nitrogen ratio.

6. A method for co-returning straw and green manure to the field during the fallow period in a rice-vegetable rotation area according to claim 1, characterized in that, In step (6), the next crop is vegetables, and the reduction of chemical nitrogen fertilizer is 30%-50%.

7. A method for co-returning straw and green manure to the field during the fallow period in a rice-vegetable rotation area according to claim 1, characterized in that, Before turning over in step (4) or during sun drying in step (5), a soil acidity correction step is also included: for acidic soil with a pH value below 5.5, apply 50-150 kg of lime or soil conditioner per mu.

8. A method for co-returning straw and green manure to the field during the fallow period in a rice-vegetable rotation area according to claim 1, characterized in that, It also includes disease and pest risk management steps: if the previous crop of rice was severely affected by diseases and pests, the corresponding straw should be removed from the field for harmless treatment or fully decomposed and inactivated before being returned to the field; after returning to the field, green prevention and control measures should be adopted for disease and pest monitoring and control.

9. A method for co-returning straw and green manure to the field during the fallow period in a rice-vegetable rotation area according to any one of claims 1-8, characterized in that, The method is applicable to farmland in tropical or subtropical regions with a fallow period of 2-3 months in rice-vegetable rotation or rice-rice-vegetable rotation patterns.

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