A wheat-corn-sunflower rotation method for reducing phosphorus and carbon sequestration based on green manure activation of soil nutrients

Abstract

The present application relates to the field of crop cultivation and soil improvement technology, and discloses a wheat-corn-sunflower rotation phosphorus reduction and carbon fixation method based on green manure activated soil nutrients, which comprises initial soil diagnosis, spring wheat sowing and harvesting, corn sowing and harvesting, and sunflower sowing. The present application breaks through the limitation of traditional wheat-corn binary rotation, constructs a diversified rotation system of "gramineae (wheat)-gramineae (corn)-compositae deep-rooted crops (sunflower)", and embeds green manure in the rotation of each year. The rotation of crops of different families effectively breaks the survival cycle of soil-borne diseases and pests, and reduces the plant protection risk. Meanwhile, the deep root system of sunflower can absorb and utilize lower layer soil nutrients and improve soil physical structure.

Description

Technical Field

[0001] This invention relates to the fields of crop cultivation and soil improvement technology, and more specifically, to a method for reducing phosphorus and sequestering carbon through wheat-corn-sunflower rotation based on green manure to activate soil nutrients. Background Technology

[0002] Currently, while ensuring food security, my country's agricultural production faces multiple pressures, including soil degradation, resource constraints, and environmental protection. The intensive farming model, characterized by high input and high output, has long relied on the large-scale application of chemical fertilizers, leading to a series of pressing technical challenges: Soil fertility imbalance and low phosphorus use efficiency: Long-term excessive application of chemical phosphate fertilizers leads to a large accumulation of residual phosphorus in the soil, but the proportion of available phosphorus for crops has not increased accordingly. This not only wastes valuable phosphate rock resources but also exacerbates the risk of non-point source pollution. Simply reducing phosphate fertilizer application often results in insufficient phosphorus absorption by crops in the current season, leading to yield reduction risks. Current technologies lack a synergistic solution that can efficiently activate existing soil phosphorus reserves and achieve phosphorus reduction without yield reduction.

[0003] The application of green manure is rudimentary, and its nutrient activation efficiency is not fully utilized: Although returning green manure to the field is widely recognized as a traditional soil-enhancing technique, its application in modern crop rotation systems still has significant shortcomings. Existing technologies mostly employ a single green manure variety and a simple plowing and mulching method, making it difficult to synchronize its nutrient release patterns with the nutrient requirements of the main crop. More importantly, the application of green manure residues as a key carbon source to drive the activation of soil microorganisms (such as phosphorus-solubilizing bacteria) has not been systematically designed, and the "leverage effect" of green manure in activating insoluble phosphorus in the soil and alleviating microbial phosphorus limitation has not been effectively activated and utilized.

[0004] The crop rotation system design is simplistic and lacks synergy among multiple ecological objectives: Existing dryland crop rotation models are mostly centered on the yield benefits of two crops (such as wheat-corn), resulting in a single model that fails to integrate multiple objectives such as continuous soil fertility improvement, phosphorus resource conservation, and farmland carbon sequestration. In particular, technical solutions for incorporating deep-rooted, soil-nourishing crops such as sunflowers into crop rotation and for time-series synergistic effects with green manure are still lacking.

[0005] It is evident that existing technologies suffer from technical problems such as the limited ecological function of crop rotation patterns and the underutilization of the potential of green manure to activate soil nutrients. Therefore, the present invention proposes a method for reducing phosphorus and sequestering carbon through wheat-corn-sunflower rotation based on green manure to activate soil nutrients, which has important practical significance. Summary of the Invention

[0006] In view of this, the present invention proposes a method for reducing phosphorus and sequestering carbon through wheat-corn-sunflower rotation based on green manure to activate soil nutrients, aiming to solve at least one of the problems in the above-mentioned background technology.

[0007] This invention proposes a method for phosphorus reduction and carbon sequestration through wheat-corn-sunflower rotation based on green manure activation of soil nutrients, comprising the following steps: Initial soil diagnosis: Soil samples were taken from the field before spring wheat sowing to test the available phosphorus content in the soil; Wheat sowing and harvesting: Wheat is sown in early March, and base fertilizer is applied at the same time. During the fertilization period, the amount of phosphate fertilizer applied is determined based on the detected available phosphorus content in the soil. Wheat is harvested in mid-July, and the wheat straw is crushed and returned to the field. Green manure sowing: Green manure is planted in late July after wheat harvest, and the green manure and straw are crushed and plowed back into the field in late October; Corn sowing and harvesting: Corn is sown in mid-to-late April of the following year. Soil samples are taken one day before sowing to test the available phosphorus content in the soil. Base fertilizer is applied simultaneously with sowing. During the fertilization period, the amount of phosphate fertilizer applied is determined based on the detected available phosphorus content in the soil. Corn is harvested in late September of the same year. Green manure sowing: After the corn seedlings emerge, plant green manure, and during the peak flowering period of the green manure, crush the green manure straw and plow it back into the field; Sunflower and green manure sowing: Green manure is sown in early April of the third year, and sunflowers are sown in late May. Base fertilizer is applied before sowing. During the application of base fertilizer, the amount of phosphate fertilizer applied is determined based on the detected available phosphorus content in the soil. One week after the sunflowers emerge, the green manure straw is crushed and turned back into the field. The sunflowers are harvested in mid-September of the same year, thus completing one crop rotation cycle.

[0008] Furthermore, the strategy for determining the amount of phosphate fertilizer to apply based on the detected available phosphorus content in the soil is as follows: When the available phosphorus content in the soil is >25 mg / kg, reduce the application of phosphate fertilizer by 50% from the baseline of 150 kg / ha; When the available phosphorus content in the soil is greater than or equal to 25 mg / kg and greater than 15 mg / kg, the application of phosphate fertilizer should be reduced by 30% from the baseline of 150 kg / ha. When the available phosphorus content in the soil is ≤15mg / kg, reduce the application of phosphate fertilizer by 20% from the baseline of 150kg / hectare.

[0009] Furthermore, the wheat sowing and harvesting includes the following steps: Before sowing, wheat seeds are coated with a phosphate-solubilizing agent at a dosage of 1% of the seed weight. Wheat was sown in early March using mechanical row sowing at a rate of 300 kg / ha, with a row spacing of 15 cm and a sowing depth of 3 cm. Apply base fertilizer simultaneously at the time of sowing, determine the amount of phosphate fertilizer according to the judgment strategy, and then mix phosphate fertilizer, nitrogen fertilizer and potassium fertilizer and apply them into the soil layer 5 cm below the seed row and 10 cm deep. Irrigate as needed during the wheat growing season and apply nitrogen fertilizer as topdressing during the jointing stage. Harvest the wheat in mid-July, crush the straw and cover it on the soil. Within 3 days of harvesting, turn the straw back into the field to a depth of 20cm.

[0010] Furthermore, the sowing and harvesting of the corn includes the following steps: Soil samples were taken the day before sowing to test the available phosphorus content in the soil; The sowing method adopts no-till single-seed precision sowing, with a planting density of 90,000 plants / hectare, a row spacing of 55 cm, a plant spacing of about 20 cm, and a sowing depth of 3-5 cm; Apply base fertilizer simultaneously at the time of sowing, determine the amount of phosphate fertilizer according to the judgment strategy, and then mix phosphate fertilizer, nitrogen fertilizer, potassium fertilizer and phosphate-solubilizing bacteria and apply them simultaneously to the soil 8 cm below the side of the seed. After harvesting corn, the straw is crushed and returned to the field.

[0011] Furthermore, the sowing of the sunflower includes the following steps: Before sowing, prepare the land, determine the amount of phosphate fertilizer to be applied according to the judgment strategy, and mix the phosphate fertilizer, potassium fertilizer and nitrogen fertilizer together and apply them 8 cm below the side of the sowing row. The sowing method is hill sowing, with a sowing rate of 12 kg / ha, a row spacing of 70 cm, a plant spacing of 60 cm, and a sowing depth of 3-4 cm. Top-dressing should be done during the budding stage of sunflowers, applying nitrogen fertilizer to the soil near the roots of the sunflowers, followed by irrigation. After harvesting, prepare the land.

[0012] Furthermore, once the sunflowers have reached the flowering stage, spray the sunflower leaves with a 0.3% solution of potassium dihydrogen phosphate.

[0013] Furthermore, the seeding rate of the green manure is 60 kg / ha; When sowing green manure after wheat harvest: No-till row sowing with a row spacing of 20cm and a sowing depth of 1-2cm is adopted. When planting green manure after corn seedlings emerge: use no-till row sowing between corn rows, and sow in furrows in the middle of the corn rows at a depth of 2-3 cm; When sowing green manure in late April of the third year: no-till strip sowing is adopted, with a sowing depth of 3-5cm.

[0014] Furthermore, the green manure consists of arrowhead pea and hairy vetch, and is sown in a ratio of arrowhead pea to hairy vetch of 6:4.

[0015] Furthermore, after crushing the green manure, apply phosphate-solubilizing bacteria at a rate of 15 kg / ha before turning it over.

[0016] Furthermore, the phosphate-solubilizing agent is Bacillus megaterium with a viable count ≥1.0 × 10⁻⁶. 8 .

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention conducts soil testing before the critical planting stages of three main crops—wheat, corn, and sunflower—achieving dynamic nutrient management. This method completely changes the traditional extensive fertilization model based on experience, enabling real-time responses to the actual impact of the previous season's crop absorption, straw return to the field, and green manure decomposition on the soil phosphorus pool. Based on the latest testing data, it implements tiered phosphorus reduction decisions, ensuring a significant reduction in external phosphorus input to utilize residual phosphorus when soil phosphorus is abundant, and conservatively reducing application when phosphorus is low to guarantee yield. This systematically resolves the contradiction between phosphorus reduction and yield reduction in principle.

[0018] 2. This invention breaks through the limitations of the traditional wheat-corn binary rotation, constructing a diversified rotation system of "Gramineae (wheat) – Gramineae (corn) – Asteraceae deep-rooted crops (sunflower)," and embedding green manure into the annual rotation. The rotation of different crop families effectively disrupts the survival cycle of soil-borne diseases and pests, reducing plant protection risks. Simultaneously, the deep root system of sunflowers can absorb and utilize nutrients from the lower soil layers and improve soil physical structure. Furthermore, this application optimizes and spatially integrates carbon sequestration measures such as "green manure return to the field" and "full return of wheat / corn straw" within a two-year rotation cycle, forming an organic-inorganic composite soil carbon pool enhancement system. Green manure and straw provide easily decomposable organic carbon to stimulate microbial activity and improve the soil microenvironment. Detailed Implementation

[0019] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0020] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0021] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0022] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0023] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0024] This invention provides a method for phosphorus reduction and carbon sequestration in wheat-corn-sunflower rotation based on green manure activation of soil nutrients, comprising the following steps: Initial soil diagnosis: Soil samples were taken from the field before spring wheat sowing to test the available phosphorus content in the soil; Wheat sowing and harvesting: Wheat is sown in early March, and base fertilizer is applied at the same time. During the fertilization period, the amount of phosphate fertilizer applied is determined based on the detected available phosphorus content in the soil. Wheat is harvested in mid-July, and the wheat straw is crushed and returned to the field. Green manure sowing: Green manure is planted in late July after wheat harvest, and the green manure and straw are crushed and plowed back into the field in late October; Corn sowing and harvesting: Corn is sown in mid-to-late April of the following year. Soil samples are taken one day before sowing to test the available phosphorus content in the soil. Base fertilizer is applied simultaneously with sowing. During the fertilization period, the amount of phosphate fertilizer applied is determined based on the detected available phosphorus content in the soil. Corn is harvested in late September of the same year. Green manure sowing: After the corn seedlings emerge, plant green manure, and during the peak flowering period of the green manure, crush the green manure straw and plow it back into the field; Sunflower and green manure sowing: Green manure is sown in early April of the third year, and sunflowers are sown in late May. Base fertilizer is applied before sowing. During the application of base fertilizer, the amount of phosphate fertilizer applied is determined based on the detected available phosphorus content in the soil. During the peak flowering period of green manure, the green manure straw is crushed and plowed back into the field. Sunflowers are harvested in mid-September of the same year, thus completing one crop rotation cycle.

[0025] Specifically, the initial soil diagnosis procedure is as follows: 15 days before wheat sowing, use a soil auger to collect 10 soil samples from the 0-20 cm topsoil layer using the "S" shaped sampling method, test the available phosphorus content in the samples (using the Olsen method), and take the average value.

[0026] Understandably, this invention conducts soil testing before the critical planting stages of the three main crops—wheat, corn, and sunflower—achieving dynamic nutrient management. This method completely changes the traditional extensive fertilization model based on experience, enabling real-time responses to the actual impact of the previous season's crop absorption, straw return to the field, and green manure decomposition on the soil phosphorus pool. Based on the latest testing data, it implements tiered phosphorus reduction decisions, ensuring a significant reduction in external phosphorus input to utilize residual phosphorus when soil phosphorus is abundant, and conservatively reducing application when phosphorus is low to guarantee yield. This systematically resolves the contradiction between phosphorus reduction and yield reduction in principle.

[0027] Understandably, this invention breaks through the limitations of the traditional wheat-corn binary rotation, constructing a diversified rotation system of "Gramineae (wheat) – Gramineae (corn) – Asteraceae deep-rooted crops (sunflower)," and embedding green manure into the annual rotation. The rotation of different crop families effectively disrupts the survival cycle of soil-borne diseases and pests, reducing plant protection risks. Simultaneously, the deep root system of sunflowers can absorb and utilize nutrients from the lower soil layers and improve soil physical structure. Furthermore, this application optimizes and spatially integrates carbon sequestration measures such as "green manure return to the field" and "full return of wheat / corn straw" within a two-year rotation cycle, forming an organic-inorganic composite soil carbon pool enhancement system. Green manure and straw provide easily decomposable organic carbon to stimulate microbial activity and improve the soil microenvironment.

[0028] In this invention, the strategy for determining the amount of phosphate fertilizer to be applied based on the detected available phosphorus content in the soil is as follows: When the available phosphorus content in the soil is >25 mg / kg, reduce the application of phosphate fertilizer by 50% from the baseline of 150 kg / ha; When the available phosphorus content in the soil is greater than or equal to 25 mg / kg and greater than 15 mg / kg, the application of phosphate fertilizer should be reduced by 30% from the baseline of 150 kg / ha. When the available phosphorus content in the soil is ≤15mg / kg, reduce the application of phosphate fertilizer by 20% from the baseline of 150kg / hectare.

[0029] Understandably, the decision-making strategy of implementing graded phosphorus reduction based on actual testing data (reducing application by 20%-50%) ensures that when soil phosphorus is "abundant," external phosphorus input is significantly reduced to utilize "residual phosphorus," while when phosphorus is "low," application is conservatively reduced to safeguard yield. This systematically resolves the contradiction of "reducing phosphorus equals reducing yield" in principle, achieving a reduction in chemical phosphate fertilizers while activating the soil's existing phosphorus reserves to ensure stable or even increased crop yields.

[0030] In this invention, the winter wheat sowing and harvesting includes the following steps: The wheat sowing and harvesting process includes the following steps: Before sowing, wheat seeds are coated with a phosphate-solubilizing agent at a dosage of 1% of the seed weight. Wheat was sown in early March using mechanical row sowing at a rate of 300 kg / ha, with a row spacing of 15 cm and a sowing depth of 3 cm. Apply base fertilizer simultaneously at the time of sowing, determine the amount of phosphate fertilizer according to the judgment strategy, and then mix phosphate fertilizer, nitrogen fertilizer and potassium fertilizer and apply them into the soil layer 5 cm below the seed row and 10 cm deep. Irrigate as needed during the wheat growing season and apply nitrogen fertilizer as topdressing during the jointing stage. Harvest the wheat in mid-July, crush the straw and cover it on the soil. Within 3 days of harvesting, turn the straw back into the field to a depth of 20cm.

[0031] Specifically, the amount of nitrogen fertilizer and potassium fertilizer used in the base fertilizer is 90 kg / ha of nitrogen fertilizer and 50 kg / ha of potassium fertilizer; the amount of nitrogen fertilizer used in the top dressing is 120 kg / ha.

[0032] Understandably, this step, by integrating precision sowing, microbial inoculation, dynamic phosphorus reduction decision-making based on soil testing, and nitrogen fertilization deferred technology, ensured the construction of a high-yield wheat population. This step not only established an optimized rhizosphere microenvironment for the current wheat season (by activating rhizosphere phosphorus through microbial coating), but more importantly, it significantly reduced systemic phosphorus input by implementing initial phosphorus fertilizer reduction based on initial soil diagnostic data; its side-deep fertilization and straw return to the field provided initial organic matter for the soil carbon pool; and the phased regulation of nitrogen fertilizer (basal application + jointing topdressing) ensured the temporal matching of nutrient supply and crop demand under the background of phosphorus reduction.

[0033] In this invention, the sowing and harvesting of corn includes the following steps: Soil samples were taken the day before sowing to test the available phosphorus content in the soil; The sowing method adopts no-till single-seed precision sowing, with a planting density of 90,000 plants / hectare, a row spacing of 55 cm, a plant spacing of about 20 cm, and a sowing depth of 3-5 cm; Apply base fertilizer simultaneously at the time of sowing, determine the amount of phosphate fertilizer according to the judgment strategy, and then mix phosphate fertilizer, nitrogen fertilizer, potassium fertilizer and phosphate-solubilizing bacteria and apply them simultaneously to the soil 8 cm below the side of the seed. After harvesting corn, the straw is crushed and returned to the field.

[0034] Specifically, the amount of nitrogen fertilizer used in the base fertilizer is 120 kg / ha, and the amount of potassium fertilizer used is 75 kg / ha; when applying the base fertilizer, the base fertilizer and the phosphorus-solubilizing bacteria are mixed together at a mass ratio of 50:1 and then applied together; the amount of nitrogen fertilizer used in the top dressing is 210 kg / ha.

[0035] Understandably, this step, through secondary soil testing for phosphorus reduction decisions and co-sowing with microbial fertilizer, aims to reduce fertilizer use in corn while simultaneously enhancing soil biological activation. This step first re-tests and makes phosphorus reduction decisions based on the new state of the soil phosphorus pool after green manure incorporation; its no-till direct seeding effectively maintains soil moisture and structure, saving farming time; and by mixing phosphorus-solubilizing microorganisms with base fertilizer in a specific ratio, it is directly applied to the rhizosphere area below and to the side of the seed using a seed-fertilizer co-sowing machine, achieving targeted delivery of functional microorganisms. This significantly promotes the activation and absorption of phosphorus nutrients (including those released from the decomposition of previous crop straw) by corn roots, continuously reducing systemic phosphorus fertilizer input while ensuring corn yield.

[0036] In this invention, the sowing of the sunflower includes the following steps: Before sowing, prepare the land, determine the amount of phosphate fertilizer to be applied according to the judgment strategy, and mix the phosphate fertilizer, potassium fertilizer and nitrogen fertilizer together and apply them 8 cm below the side of the sowing row. The sowing method is row sowing, with a sowing rate of 12 kg / ha, a row spacing of 70 cm, a plant spacing of 60 cm, and a sowing depth of 3-4 cm. Top-dressing should be done during the budding stage of sunflowers, applying nitrogen fertilizer to the soil near the roots of the sunflowers, followed by irrigation. After harvesting, prepare the land.

[0037] Specifically, the amount of nitrogen fertilizer used in the base fertilizer is 97.5 kg / ha, and the amount of potassium fertilizer is 30 kg / ha; the amount of nitrogen fertilizer used in the top dressing is 52.5 kg / ha. Specifically, the nitrogen fertilizer in the base fertilizer includes: 52.5 kg / ha of fast-acting nitrogen fertilizer and 45 kg / ha of bio-carbon-based slow-release nitrogen fertilizer, wherein the bio-carbon-based slow-release nitrogen fertilizer is prepared using the preparation method of patent CN104529636A.

[0038] Specifically, the application rate of the 0.3% potassium dihydrogen phosphate is 500 L / ha.

[0039] Understandably, the use of bio-carbon-based slow-release nitrogen fertilizer here can balance nitrogen competition in the early stages of green manure decomposition.

[0040] In this invention, the sowing rate of the green manure is 60 kg / ha; When sowing green manure after wheat harvest: use no-till row sowing with a row spacing of 15cm and a sowing depth of 1-2cm; When planting green manure after corn seedlings emerge: use no-till row sowing between corn rows, and sow in furrows in the middle of the corn rows at a depth of 2-3 cm; When sowing green manure in early April of the third year: no-till strip sowing is adopted, with a sowing depth of 3-5cm.

[0041] The green manure consists of arrowhead pea and hairy vetch, and is sown in a ratio of arrowhead pea to hairy vetch of 6:4. After crushing the green manure, apply the phosphorus-solubilizing agent at a rate of 15 kg / ha before turning it over.

[0042] Specifically, at harvest time, the green manure straw is crushed, and then phosphate-solubilizing bacteria are applied at a rate of 15 kg / ha before being turned over.

[0043] It is understood that the three green manure sowing and plowing steps of this invention, by adapting to the differentiated planting patterns of summer fallow, intercropping during the corn growing season, and intercropping during the sunflower growing season in the wheat-corn-sunflower rotation cycle, achieve continuous activation of soil insoluble phosphorus throughout the rotation cycle, support the gradient reduction of phosphate fertilizer application, improve soil organic carbon fixation capacity and arable land fertility, simultaneously reduce soil exposure and water loss, suppress weed growth in the field, ensure stable yield and quality improvement of wheat, corn, and sunflower within the rotation system, and build an efficient and sustainable dryland farmland phosphorus reduction and carbon sequestration production system.

[0044] Example 1 Initial soil conditions: available phosphorus (Olsen-P) content is 12.0 mg / kg, soil organic matter content is 12.0 g / kg, and the area is 1 hectare.

[0045] Raw materials: Prepare Yongliang No. 4 wheat seeds, Simon No. 6 corn seeds, SH363 sunflower seeds, arrowhead pea and hairy vetch green manure seeds (6:4), and compound phosphorus-degrading bacteria (Bacillus megaterium, ≥1.0×10⁻⁶). 8 CFU / g), urea, superphosphate, potassium chloride, and straw biochar-based slow-release nitrogen fertilizer.

[0046] Specific steps: S1. On March 1st of the first year, a mixed soil sample of 0-20 cm was collected using the "S" shaped method. The test results showed that the available phosphorus (Olsen-P) content in the soil was 12.0 mg / kg and the organic matter content was 12.0 g / kg.

[0047] S2. Before sowing, treat the seeds with a phosphorus-solubilizing agent at 1.0% of the seed weight, and then mechanically sow the seeds on March 10th of the first year using a wheat precision seeder with side-deep fertilization function. The sowing rate was 300 kg / ha, the row spacing was 15 cm, and the sowing depth was 3 cm. Based on the judgment strategy, the application of phosphate fertilizer (P2O5) was reduced by 20% from the baseline of 150 kg / ha, and the actual application rate was 120 kg / ha. At the time of sowing, 120 kg of phosphate fertilizer (P2O5), 90 kg of nitrogen fertilizer (N) and 50 kg of potassium fertilizer (K2O) were applied as base fertilizer by a seeder, 5 cm below the seed row and 10 cm deep. After applying 120 kg of nitrogen fertilizer (N) at the wheat jointing stage, irrigation was carried out immediately. On July 19 of the same year, the wheat was harvested by a combine harvester with a crushing device, leaving a stubble height of <15 cm. The straw was crushed to <10 cm and then spread evenly. Within 3 days after harvest, the straw was fully plowed back into the field by a heavy rotary tiller to a depth of 20 cm, and then water was irrigated to promote decomposition.

[0048] S3. On July 25th of the first year, green manure was sown using no-till row seeding. 60 kg / ha of arrowhead pea and hairy vetch seeds were sown using a no-till row seeder with a row spacing of 20 cm and a sowing depth of 1-2 cm. On October 25th of the same year, the green manure and its straw were crushed using a straw crusher. Then, 15 kg of phosphate-solubilizing bacteria was diluted 300 times with water and sprayed onto the surface of the green manure. Immediately afterward, a rotary tiller was used to turn the soil down to an 18 cm layer.

[0049] S5. Soil samples were taken the day before sowing (April 22nd of the following year) and the available phosphorus content was 10.5 mg / kg. On April 23rd of the following year, single-seed precision sowing was carried out using a no-till corn precision seeder at a planting density of 90,000 plants / ha, row spacing of 55 cm, plant spacing of approximately 20 cm, and sowing depth of 3-5 cm. Based on the judgment strategy, the application of phosphate fertilizer (P2O5) was reduced by 20% from the baseline of 150 kg / ha, with an actual application of 120 kg / ha. At sowing, 120 kg of phosphate fertilizer (P2O5), 120 kg of nitrogen fertilizer (N), and 75 kg of potassium fertilizer (K2O) were mixed with 10.2 kg of phosphorus-solubilizing bacteria and applied simultaneously to the side and below the seeds at a depth of 8 cm. Nitrogen fertilizer was applied as a top dressing at the large trumpet stage at a rate of 210 kg / ha. The corn was harvested on September 28th of the following year, and the corn stalks were crushed and evenly covered on the ground.

[0050] S4. After the corn seedlings emerged, green manure was sown on April 28 using the no-till row sowing method between corn rows. 60 kg / ha of a mixture of arrowhead pea and hairy vetch seeds were sown in furrows in the middle of the corn rows. On July 2, when the green manure was in full bloom, it was crushed with a straw crusher. Then, 15 kg of phosphorus-releasing bacteria was diluted 300 times with water and sprayed onto the surface of the green manure. It was immediately turned over with a rotary tiller to a soil layer of 18 cm. Ten days after turning over (March 30), soil samples were taken for testing, and the available phosphorus in the soil was 21.5 mg / kg.

[0051] S5. Green manure was sown on April 1st of the third year using no-till row sowing at a rate of 60 kg / ha and a sowing depth of 3-5 cm. Sunflowers were sown between the green manure rows on May 23rd of the same year at a rate of 12 kg / ha, with a row spacing of 70 cm, a plant spacing of 60 cm, and a sowing depth of 3-4 cm. Based on the judgment strategy, the application of phosphate fertilizer (P2O5) was reduced by 30% from the baseline of 150 kg / ha, with an actual application of 105 kg / ha. At the time of sowing, 105 kg of phosphate fertilizer (P2O5), 52.5 kg of quick-acting nitrogen fertilizer (N), 45 kg of bio-carbon-based slow-release nitrogen fertilizer (calculated by the mass of N), and 30 kg of potassium fertilizer (K2O) were applied in strips 8 cm below and to the side of the sowing row using a seeder. On July 3rd of the same year (budding stage), 52.5 kg of quick-acting nitrogen fertilizer (N) was applied near the roots of the plants, followed by watering. One week after sunflower emergence on June 15th, the green manure was pulverized using a straw shredder. Then, 15 kg of phosphate-solubilizing bacteria was diluted 300 times with water and sprayed onto the surface of the green manure, immediately followed by rotary tilling to a depth of 18 cm. On July 30th (sunflower flowering stage), a 0.3% potassium dihydrogen phosphate solution was sprayed on the leaves at a rate of 450 L. On September 16th of the same year, when the back of the sunflower heads turned yellow and the seeds hardened, a combine harvester was used for harvesting. After harvesting, field stubble was removed, and the stubble was pulverized and returned to the field.

[0052] Example 2 Initial soil conditions: available phosphorus (Olsen-P) content is 20.0 mg / kg, soil organic matter content is 13.5 g / kg, and the area is 1 hectare.

[0053] Raw materials: Prepare Yongliang No. 4 wheat seeds, Simon No. 6 corn seeds, SH361 sunflower seeds, arrowhead pea and hairy vetch green manure seeds (6:4), and compound phosphate-degrading bacteria (Bacillus megaterium, ≥1.0×10⁻⁶). 8 CFU / g), urea, superphosphate, potassium chloride, and straw biochar-based slow-release nitrogen fertilizer.

[0054] Specific steps: S1. On March 1st of the first year, a mixed soil sample of 0-20 cm was collected using the "S" shaped method. The test results showed that the soil available phosphorus (Olsen-P) content was 20.0 mg / kg and the organic matter content was 13.5 g / kg.

[0055] S2. Before sowing, treat the seeds with a phosphorus-solubilizing agent at 1.0% of the seed weight, and then mechanically sow the seeds on March 10th of the first year using a wheat precision seeder with side-deep fertilization function. The sowing rate was 300 kg / ha, the row spacing was 15 cm, and the sowing depth was 3 cm. Based on the judgment strategy, the application of phosphate fertilizer (P2O5) was reduced by 30% from the baseline of 150 kg / ha, and the actual application rate was 105 kg / ha. At the time of sowing, 105 kg of phosphate fertilizer (P2O5), 90 kg of nitrogen fertilizer (N) and 50 kg of potassium fertilizer (K2O) were applied as base fertilizer by a seeder, 5 cm below the seed row and 10 cm deep. 120 kg of nitrogen fertilizer (N) was applied at the wheat jointing stage and irrigation was carried out immediately. On July 19 of the same year, the wheat was harvested by a combine harvester with a crushing device. The stubble height was <15 cm. The straw was crushed to <10 cm and then spread evenly. Within 3 days after harvest, the straw was fully plowed into the field by a heavy rotary tiller to a depth of 20 cm, and then water was irrigated to promote decomposition.

[0056] S3. On July 25th of the first year, green manure was sown using no-till row seeding. 60 kg / ha of arrowhead pea and hairy vetch seeds were sown using a no-till row seeder with a row spacing of 20 cm and a sowing depth of 1-2 cm. On October 25th of the same year, the green manure straw was crushed using a straw crusher. Then, 15 kg of phosphate-solubilizing bacteria was diluted 300 times with water and sprayed onto the surface of the green manure. Immediately afterward, a rotary tiller was used to turn the soil down to an 18 cm layer.

[0057] S4. Soil samples were taken for testing the day before sowing (April 22nd of the following year), and the available phosphorus content was 18 mg / kg. On April 23rd of the following year, single-seed precision sowing was carried out using a no-till corn precision seeder, with a planting density of 90,000 plants / ha, row spacing of 55 cm, plant spacing of approximately 20 cm, and sowing depth of 3-5 cm. Based on the judgment strategy, the application of phosphate fertilizer (P2O5) was reduced by 30% from the baseline of 150 kg / ha, with an actual application of 105 kg / ha. At sowing, 105 kg of phosphate fertilizer (P2O5), 120 kg of nitrogen fertilizer (N), and 75 kg of potassium fertilizer (K2O) were mixed with 9.6 kg of phosphorus-solubilizing bacteria and applied simultaneously to the side and below the seeds at a depth of 8 cm. Nitrogen fertilizer was applied as a top dressing at the large trumpet stage, with an application rate of 210 kg / ha. The corn was harvested on September 28th of the following year, and the corn stalks were crushed and evenly covered on the ground.

[0058] S5. After the corn seedlings emerged, green manure was sown on April 28 using a no-till row sowing method between the corn rows. 60 kg / ha of a mixture of arrowhead pea and hairy vetch seeds were sown in furrows in the middle of the corn rows. On July 2, when the green manure was in full bloom, it was crushed with a straw crusher. Then, 15 kg of phosphorus-releasing bacteria was diluted 300 times with water and sprayed onto the surface of the green manure. Immediately afterward, it was turned over with a rotary tiller to a soil layer of 18 cm. Soil samples were taken 10 days after turning over, and the available phosphorus in the soil was 32 mg / kg.

[0059] S6. Green manure was sown on April 1st of the third year using no-till row sowing at a rate of 60 kg / ha and a depth of 3-5 cm. Sunflowers were sown on May 28th using a seeder at a rate of 12 kg / ha, with a row spacing of 70 cm, a plant spacing of 60 cm, and a sowing depth of 4 cm. Based on the judgment strategy, the application of phosphate fertilizer (P2O5) was reduced by 50% from the baseline of 150 kg / ha, with an actual application of 75 kg / ha. At the time of sowing, 75 kg of phosphate fertilizer (P2O5), 52.5 kg of quick-acting nitrogen fertilizer (N), 45 kg of bio-carbon-based slow-release nitrogen fertilizer (calculated by the mass of N), and 30 kg of potassium fertilizer (K2O) were applied in rows 8 cm below and to the side of the sowing row using a seeder. During the budding stage of the same year, 52.5 kg of quick-acting nitrogen fertilizer (N) was applied near the roots of the plants in holes, followed by watering. On June 15th, one week after the sunflowers emerged, the green manure was pulverized using a straw shredder. Then, 15 kg of phosphate-solubilizing bacteria was diluted 300 times with water and sprayed onto the surface of the green manure, immediately followed by tilling with a rotary tiller to a soil layer of 18 cm. During the flowering period, a 0.3% potassium dihydrogen phosphate solution was sprayed on the leaves at a rate of 450 L. On September 17th of the same year, when the back of the sunflower heads turned yellow and the seeds hardened, they were harvested using a combine harvester. After harvesting, the stubble in the field was removed, and the straw was pulverized and returned to the field.

[0060] Example 3 Initial soil conditions: available phosphorus (Olsen-P) content is 30.0 mg / kg, soil organic matter content is 15 g / kg, and the area is 1 hectare.

[0061] Raw materials: Prepare Yongliang No. 4 wheat seeds, Simon 3358 corn seeds, SH361 sunflower seeds, arrowhead pea and hairy vetch green manure seeds (6:4), and compound phosphate-degrading bacteria (Bacillus megaterium, ≥1.0×10⁻⁶). 8 CFU / g), urea, superphosphate, potassium chloride, and straw biochar-based slow-release nitrogen fertilizer.

[0062] Specific steps: S1. On March 1st of the first year, a mixed soil sample of 0-20 cm was collected using the "S" shaped method. The test results showed that the soil available phosphorus (Olsen-P) content was 20.0 mg / kg and the organic matter content was 13.5 g / kg.

[0063] S2. Before sowing, treat the seeds with a phosphorus-solubilizing agent at 1.0% of the seed weight, and then perform mechanical row sowing on March 14 of the first year using a wheat precision seeder with side-deep fertilization function. The sowing rate was 300 kg / ha, the row spacing was 15 cm, and the sowing depth was 3 cm. Based on the judgment strategy, the application of phosphate fertilizer (P2O5) was reduced by 50% from the baseline of 150 kg / ha, and the actual application rate was 75 kg / ha. At the time of sowing, 75 kg of phosphate fertilizer (P2O5), 90 kg of nitrogen fertilizer (N) and 50 kg of potassium fertilizer (K2O) were applied as base fertilizer by a seeder, 5 cm below the seed row and 10 cm deep. 120 kg of nitrogen fertilizer (N) was applied at the wheat jointing stage and irrigation was carried out immediately. On July 19 of the same year, the wheat was harvested with a combine harvester with a crushing device. The stubble height was <15 cm. The straw was crushed to <10 cm and then spread evenly. Within 3 days after harvest, the straw was fully turned back into the field with a heavy rotary tiller to a depth of 20 cm. Then, water was irrigated to promote decomposition.

[0064] S3. On July 25th of the first year, green manure was sown using no-till row seeding. 60 kg / ha of arrowhead pea and hairy vetch seeds were sown using a no-till row seeder with a row spacing of 20 cm and a sowing depth of 1-2 cm. On October 25th of the same year, the green manure straw was crushed using a straw crusher. Then, 15 kg of phosphate-solubilizing bacteria was diluted 300 times with water and sprayed onto the surface of the green manure. Immediately afterward, a rotary tiller was used to turn the soil down to an 18 cm layer.

[0065] S4. Soil samples were taken for testing the day before sowing (April 22nd of the following year), and the available phosphorus content was 24.8 mg / kg. On April 23rd of the following year, single-seed precision sowing was carried out using a no-till corn planter at a planting density of 90,000 plants / ha, with a row spacing of 55 cm, a plant spacing of approximately 20 cm, and a sowing depth of 3-5 cm. Based on the judgment strategy, the application of phosphate fertilizer (P2O5) was reduced by 30% from the baseline of 150 kg / ha, with an actual application of 105 kg / ha. At sowing, 105 kg of phosphate fertilizer (P2O5), 120 kg of nitrogen fertilizer (N), and 75 kg of potassium fertilizer (K2O) were mixed with 9.6 kg of phosphorus-solubilizing bacteria and applied simultaneously to the side and below the seeds at a depth of 8 cm. Nitrogen fertilizer was applied as a top dressing at the large trumpet stage at a rate of 210 kg / ha. The corn was harvested on September 28th of the following year, and the corn stalks were crushed and evenly covered on the ground.

[0066] S4. After the corn seedlings emerged, green manure was sown on April 28 using a no-till row sowing method between the corn rows. 60 kg / ha of a mixture of arrowhead pea and hairy vetch seeds were sown in furrows in the middle of the corn rows. On July 2, when the green manure was in full bloom, it was crushed with a straw crusher. Then, 15 kg of phosphorus-releasing bacteria was diluted 300 times with water and sprayed onto the surface of the green manure. Immediately afterward, it was turned over with a rotary tiller to a soil layer of 18 cm. Soil samples were taken 10 days after turning over and tested. The available phosphorus in the soil was 38.5 mg / kg.

[0067] S5. Green manure was sown on April 1st of the third year using no-till row sowing at a rate of 60 kg / ha and a sowing depth of 3-5 cm. On May 28th of the same year, sunflowers were sown using a seeder at a rate of 12 kg / ha, with a row spacing of 70 cm, a plant spacing of 60 cm, and a sowing depth of 3-4 cm. Based on the judgment strategy, the application of phosphate fertilizer (P2O5) was reduced by 50% from the baseline of 150 kg / ha, with an actual application of 75 kg / ha. At the time of sowing, 75 kg of phosphate fertilizer (P2O5), 52.5 kg of quick-acting nitrogen fertilizer (N), 45 kg of bio-carbon-based slow-release nitrogen fertilizer (calculated by the mass of N), and 30 kg of potassium fertilizer (K2O) were applied in rows 8 cm below and to the side of the sowing row using a seeder. During the budding stage of the same year, 52.5 kg of quick-acting nitrogen fertilizer (N) was applied near the roots of the plants in holes, followed by watering. On June 15th, the green manure was pulverized using a straw shredder, and then 15 kg of phosphate-solubilizing bacteria agent was diluted 300 times with water and sprayed onto the surface of the green manure. Immediately afterward, it was tilled to a soil layer of 18 cm using a rotary tiller. During the flowering period, a 0.3% potassium dihydrogen phosphate solution was sprayed on the leaves at a rate of 450 L. On September 15th of the same year, when the back of the sunflower heads turned yellow and the seeds hardened, they were harvested using a combine harvester. After harvesting, the stubble in the field was removed, and the straw was pulverized and returned to the field using a straw shredder.

[0068] Comparative Example 1 In the same area, a 1-hectare plot with soil conditions similar to those in Example 1 was selected as a control. The conventional wheat-corn rotation pattern was implemented without planting green manure, and chemical fertilizers were applied at the conventional rate (phosphate fertilizer P2O5 application rate: 150 kg / ha for wheat and 150 kg / ha for corn).

[0069] Effect test Comparison of total phosphorus fertilizer (P2O5) input during wheat and corn planting As shown in Table 1: Table 1: Comparison of Total Phosphate Fertilizer (P2O5) Input (Wheat + Corn Seasons)

[0070] As can be seen, the three embodiments of the present invention, through dynamic decision-making based on soil testing, all achieved significantly lower total phosphate fertilizer inputs (240.0, 210.0, and 150.0 kg / ha) than the fixed input (300.0 kg / ha) in the comparative embodiment. Embodiments 1, 2, and 3 achieved reductions of 60.0, 90.0, and 150.0 kg / ha, respectively, representing reductions of up to 20%, 30%, and 50%.

[0071] Comparison of changes in soil organic matter content The soil organic matter content before and after crop rotation in Examples 1-3 was measured respectively, and the results are shown in Table 2: Table 2: Comparison of changes in soil organic matter content

[0072] After implementing a complete crop rotation cycle of the present invention, the soil organic matter in all three embodiments achieved stable growth, with a growth rate of up to 6.7%.

[0073] Comparison of total annual grain yield of crops (results are shown in Table 3): Table 3: Comparison of Total Annual Grain Yield of Crops

[0074] As can be seen, under the premise of significant phosphorus reduction (20%-50%), this invention, through diversified crop rotation and nutrient optimization management, not only ensured the yield of staple crops but also additionally increased the output of oil crops (sunflower), resulting in an annual total yield (19,500-21,300 kg / ha) that comprehensively surpassed the comparative example (18,000 kg / ha). Calculations show that Examples 1, 2, and 3 achieved yield increases of 1,500, 2,000, and 3,300 kg / ha, respectively, representing increases of 8.3%, 11.1%, and 18.3%.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for phosphorus reduction and carbon sequestration through wheat-corn-sunflower rotation based on green manure activation of soil nutrients, characterized in that, Includes the following steps: Initial soil diagnosis: Soil samples were taken from the field before spring wheat sowing to test the available phosphorus content in the soil; Wheat sowing and harvesting: Wheat is sown in early March, and base fertilizer is applied at the same time. During the fertilization period, the amount of phosphate fertilizer applied is determined based on the detected available phosphorus content in the soil. Wheat is harvested in mid-July, and the wheat straw is crushed and returned to the field. Green manure sowing: Green manure is planted in late July after wheat harvest, and the green manure and straw are crushed and plowed back into the field in late October; Corn sowing and harvesting: Corn is sown in mid-to-late April of the following year. Soil samples are taken one day before sowing to test the available phosphorus content in the soil. Base fertilizer is applied simultaneously with sowing. During the fertilization period, the amount of phosphate fertilizer applied is determined based on the detected available phosphorus content in the soil. Corn is harvested in late September of the same year. Green manure sowing: After the corn seedlings emerge, plant green manure, and during the peak flowering period of the green manure, crush the green manure straw and plow it back into the field; Sunflower and green manure sowing: Green manure is sown in early April of the third year, and sunflowers are sown in late May. Base fertilizer is applied before sowing. During the application of base fertilizer, the amount of phosphate fertilizer applied is determined based on the detected available phosphorus content in the soil. Within one week after the sunflowers emerge, the green manure straw is crushed and turned back into the field. Sunflowers are harvested in mid-September of the same year, thus completing one crop rotation cycle.

2. The method for phosphorus reduction and carbon sequestration in wheat-corn-sunflower rotation based on green manure activation of soil nutrients according to claim 1, characterized in that, The strategy for determining the amount of phosphate fertilizer to apply based on the detected available phosphorus content in the soil is as follows: When the available phosphorus content in the soil is >25 mg / kg, reduce the application of phosphate fertilizer by 50% from the baseline of 150 kg / ha; When the available phosphorus content in the soil is greater than or equal to 25 mg / kg and greater than 15 mg / kg, the application of phosphate fertilizer should be reduced by 30% from the baseline of 150 kg / ha. When the available phosphorus content in the soil is ≤15mg / kg, reduce the application of phosphate fertilizer by 20% from the baseline of 150kg / hectare.

3. The method for phosphorus reduction and carbon sequestration in wheat-corn-sunflower rotation based on green manure activation of soil nutrients according to claim 2, characterized in that, The wheat sowing and harvesting process includes the following steps: Before sowing, wheat seeds are coated with a phosphate-solubilizing agent at a dosage of 1% of the seed weight. Wheat was sown in early March using mechanical row sowing at a rate of 300 kg / ha, with a row spacing of 15 cm and a sowing depth of 3 cm. Apply base fertilizer simultaneously at the time of sowing, determine the amount of phosphate fertilizer according to the judgment strategy, and then mix phosphate fertilizer, nitrogen fertilizer and potassium fertilizer and apply them into the soil layer 5 cm below the seed row and 10 cm deep. Irrigate as needed during the wheat growing season and apply nitrogen fertilizer as topdressing during the jointing stage. Harvest the wheat in mid-July, crush the straw and cover it on the soil. Within 3 days of harvesting, turn the straw back into the field to a depth of 20cm.

4. The method for phosphorus reduction and carbon sequestration in wheat-corn-sunflower rotation based on green manure activation of soil nutrients according to claim 3, characterized in that, The sowing and harvesting of the corn includes the following steps: Soil samples were taken the day before sowing to test the available phosphorus content in the soil; The sowing method adopts no-till single-seed precision sowing, with a planting density of 90,000 plants / hectare, a row spacing of 55 cm, a plant spacing of about 20 cm, and a sowing depth of 3-5 cm; Apply base fertilizer simultaneously at the time of sowing, determine the amount of phosphate fertilizer according to the judgment strategy, and then mix phosphate fertilizer, nitrogen fertilizer, potassium fertilizer and phosphate-solubilizing bacteria and apply them simultaneously to the soil 8 cm below the side of the seed. After harvesting corn, the straw is crushed and returned to the field.

5. The method for phosphorus reduction and carbon sequestration in wheat-corn-sunflower rotation based on green manure activation of soil nutrients according to claim 4, characterized in that, The sowing of the sunflower includes the following steps: Before sowing, prepare the land, determine the amount of phosphate fertilizer to be applied according to the judgment strategy, and mix the phosphate fertilizer, potassium fertilizer and nitrogen fertilizer together and apply them 8 cm below the side of the sowing row. The sowing method is hill sowing, with a sowing rate of 12 kg / ha, a row spacing of 70 cm, a plant spacing of 60 cm, and a sowing depth of 3-4 cm. Top-dressing should be done during the budding stage of sunflowers, applying nitrogen fertilizer to the soil near the roots of the sunflowers, followed by irrigation. After harvesting, prepare the land.

6. The method for phosphorus reduction and carbon sequestration in wheat-corn-sunflower rotation based on green manure activation of soil nutrients according to claim 5, characterized in that, Once the sunflowers have reached the flowering stage, spray the sunflower leaves with a 0.3% solution of potassium dihydrogen phosphate.

7. The method for phosphorus reduction and carbon sequestration in wheat-corn-sunflower rotation based on green manure activation of soil nutrients according to claim 6, characterized in that, The sowing rate for the green manure is 60 kg / ha; When sowing green manure after wheat harvest: No-till row sowing with a row spacing of 20cm and a sowing depth of 1-2cm is adopted. When planting green manure after corn seedlings emerge: use no-till row sowing between corn rows, and sow in furrows in the middle of the corn rows at a depth of 2-3 cm; When sowing green manure in early April of the third year: no-till strip sowing is adopted, with a sowing depth of 3-5cm.

8. The method for phosphorus reduction and carbon sequestration in wheat-corn-sunflower rotation based on green manure activation of soil nutrients according to claim 7, characterized in that, The green manure consists of arrowhead pea and hairy vetch, which are sown together in a ratio of 6:

4.

9. The method for phosphorus reduction and carbon sequestration in wheat-corn-sunflower rotation based on green manure activation of soil nutrients as described in claim 8, characterized in that, After crushing the green manure, apply the phosphorus-solubilizing agent at a rate of 15 kg / ha before turning it over.

10. The method for phosphorus reduction and carbon sequestration in wheat-corn-sunflower rotation based on green manure activation of soil nutrients according to claim 9, characterized in that, The phosphate-solubilizing agent is Bacillus megaterium with a viable count ≥1.0 × 10⁻⁶. 8 .

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