Biological enhancement method for farmland greenhouse gas emission reduction and saline alkali soil carbon sequestration

Abstract

The invention relates to a biological enhancement method for reducing farmland greenhouse gas emission and increasing saline alkali soil carbon sequestration amount. Aiming at the problems of high cost, easy double salt, unbalanced carbon and nitrogen and the like of the traditional saline-alkali soil improvement technology, the invention provides a method for preparing the microbial fertilizer by taking kitchen waste as a culture medium raw material, culturing plant growth-promoting bacteria at low cost, preparing a microbial inoculant and combining with a composting process. The microbial fertilizer is applied to saline-alkali soil instead of chemical fertilizer, so that the physicochemical property of the soil is improved, the NO emission of the soil is effectively reduced, and the carbon sequestration amount of an agricultural ecosystem is increased by promoting nitrogen absorption and organic carbon accumulation of crops. The method integrates waste resource utilization and soil carbon and nitrogen coordinated regulation and control, has multiple beneficial functions of rapid improvement of saline-alkali soil, crop yield increase, greenhouse gas emission reduction, soil carbon fixation amount increase and the like, and provides technical support for green agriculture development and target realization.

Description

Technical Field

[0001] This invention relates to the field of waste resource recycling technology, specifically to a biofortification method for reducing greenhouse gas emissions from farmland and increasing carbon sequestration in saline-alkali soil, particularly a synergistic regulation technology for biomass waste resource utilization, saline-alkali land improvement, greenhouse gas (N2O) emission reduction, and soil carbon sequestration increase. Background Technology

[0002] Plants struggle to grow in saline-alkali soils, and the carbon sequestration function of saline-alkali ecosystems is poor, resulting in low soil organic matter content and small soil carbon pool capacity. In recent years, microbial fertilizers have become an important agricultural input for saline-alkali land improvement due to their environmental friendliness; however, their high production costs limit their widespread application. Meanwhile, the excessive application of nitrogen fertilizers leads to high N2O emissions from farmland soils, exacerbating the global greenhouse effect.

[0003] On the other hand, the disposal of organic waste such as kitchen waste faces significant challenges, and traditional treatment methods pose a risk of secondary pollution, necessitating new approaches for resource utilization. Therefore, this invention proposes a novel method for the low-cost preparation of microbial fertilizer from kitchen waste, utilizing this fertilizer to improve the physicochemical properties of saline-alkali soils. This microbial fertilizer replaces chemical fertilizers, regulates the soil microbial ecosystem, reduces soil N2O emissions, increases crop yields in saline-alkali lands, and enhances carbon sequestration in saline-alkali soils. Summary of the Invention

[0004] This invention provides a method for reducing greenhouse gas emissions from farmland and increasing carbon sequestration in saline-alkali soils. It utilizes kitchen waste to cultivate plant growth-promoting bacteria at low cost, preparing microbial fertilizer. This microbial fertilizer improves the physicochemical properties and microecology of saline-alkali soils, reducing N2O emissions and increasing carbon sequestration without decreasing crop yields. This invention can provide technical support for the development and achievement of green agriculture goals.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] (1) Preparation of liquid culture medium from kitchen waste: crush kitchen waste, add water to make the soluble solids content (by weight) 2% ~ 7%, boil, pass through a 50-mesh sieve to remove residue, and adjust the pH to 7.0 ~ 8.0 to obtain liquid culture medium.

[0007] (2) Preparation of plant growth-promoting bacteria seed liquid: Bacillus subtilis preserved on slant culture medium was inoculated into an Erlenmeyer flask containing the liquid culture medium obtained in step 1 above. Bacillus subtilis The HA2 strain was cultured at 25–37°C with shaking at 100–200 rpm for 24–48 hours to obtain the seed culture of the plant growth-promoting bacterium HA2.

[0008] (3) Preparation of plant growth-promoting bacteria inoculant: In the liquid culture medium obtained in step 1, inoculate the seed liquid of HA2 strain obtained in step 2 at an inoculation rate of 2% to 10% by weight, and culture at 25 to 37°C with aeration for 24 to 96 hours. When the effective viable count reaches 2×10⁻⁶, the inoculant is ready. 9 The above steps yield a plant growth-promoting bacteria inoculum.

[0009] (4) Preparation of microbial fertilizer: In aerobic composting organic materials, inoculate the plant growth-promoting bacteria inoculant from step 2 above at a weight ratio of 1% to 10%, adjust the material moisture content to 55% to 65%, and carry out high-temperature aerobic fermentation for 3 to 7 days; when the temperature reaches above 70℃ and is maintained for 2 to 3 days, turn the pile, and at the same time inoculate the plant growth-promoting bacteria inoculant from step 2 above at a weight ratio of 1% to 5%, and continue high-temperature aerobic fermentation for 3 to 5 days; when the fermentation temperature drops below 50℃, turn the pile again, and at the same time inoculate the plant growth-promoting bacteria inoculant from step 2 above at a weight ratio of 1% to 5%, and continue mesophilic aerobic fermentation to make the organic materials mature and stabilize, while the plant growth-promoting bacteria multiply in large quantities and form spores; when the moisture content of the organic materials is less than 30% and the material temperature is close to the ambient temperature, the effective viable number of plant growth-promoting bacteria reaches 2×10 8 When the CFU / g is above a certain level, microbial fertilizer or bio-organic fertilizer is obtained.

[0010] (5) Microbial fertilizers enhance carbon sequestration and emission reduction in saline-alkali soils: The microbial fertilizer obtained in step (4) above is evenly spread on the surface of saline-alkali soil at a rate of 6 to 20 tons per hectare, and then tilled to a depth of 25 to 40 cm. Depending on the salinity of the soil, suitable crops or halophytes are planted, and appropriate amounts of fresh water are used for irrigation according to soil moisture. After the crops or halophytes are harvested, the straw, agricultural product processing waste, and other biomass waste are used as raw materials for the production of microbial fertilizer in step (4), and finally returned to the farmland and saline-alkali soil to achieve a circular carbon sequestration process.

[0011] (6) The plant growth-promoting bacteria used in this invention are Bacillus subtilis (B. subtilis). Bacillus subtilis The HA2 strain can grow rapidly using kitchen waste as a substrate. This strain was deposited on May 20, 2019, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with accession number CGMCC No. 17825.

[0012] The beneficial effects achieved by this invention are as follows: This invention provides a microbial culture medium prepared primarily from kitchen waste, which is not only low-cost but also achieves resource utilization of waste; Bacillus subtilis ( Bacillus subtilis The HA2 strain can grow rapidly using food waste culture medium and can enhance the plant's resistance to salt and alkali stress, promoting plant growth. Inoculating compost materials such as straw with the HA2 strain as an inoculant produces microbial fertilizers or bio-organic fertilizers with a large and stable number of effective live bacteria, providing reliable agricultural inputs for the biological improvement of saline-alkali land. Applying the microbial fertilizer prepared in this invention to farmland instead of chemical fertilizers significantly reduces soil salinity and effectively reduces soil N2O emissions. Furthermore, it increases the carbon sequestration of the ecosystem by promoting crop nitrogen absorption and organic carbon accumulation. This method innovatively integrates waste resource utilization with synergistic carbon and nitrogen regulation, possessing the functions of rapid saline-alkali land improvement, increased crop yield, greenhouse gas emission reduction, and increased soil carbon sequestration, providing technical support for the development and achievement of green agriculture goals. Detailed Implementation

[0013] The present invention will be further explained and illustrated below with reference to embodiments. The embodiments given below are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and essence.

[0014] Example 1: Preparation of microbial fertilizer for saline-alkali land improvement from kitchen waste

[0015] Preparation of liquid culture medium from kitchen waste: Crush kitchen waste, add water to a soluble solids content (by weight) of 5%, boil, pass through a 50-mesh sieve to remove residue, and adjust the pH to 7.5 to obtain the liquid culture medium.

[0016] Preparation of plant growth-promoting bacteria seed culture: Bacillus subtilis preserved on slant culture medium (obtained in step 1) was inoculated into an Erlenmeyer flask containing the liquid culture medium obtained in step 1 above. Bacillus subtilis The HA2 strain was cultured at 30℃ and 150 rpm for 36 hours to obtain the seed culture of the plant growth-promoting bacteria HA2 strain.

[0017] Preparation of plant growth-promoting bacteria inoculant: In the liquid culture medium obtained in step 1, inoculate the seed culture of strain HA2 obtained in step 2 at a weight ratio of 5%. Incubate at 30℃ with aeration for 48 hours. When the effective viable count reaches 2×10⁻⁶, the inoculum is ready. 9 The above steps yield a plant growth-promoting bacteria inoculum.

[0018] Preparation of microbial fertilizer: In aerobic composting organic materials, inoculate with the plant growth-promoting bacteria inoculant from step 2 above at a weight ratio of 5%, adjust the material moisture content to 60%, and carry out high-temperature aerobic fermentation for 5 days; when the temperature reaches above 70℃ and is maintained for 2-3 days, turn the pile, and simultaneously inoculate with the plant growth-promoting bacteria inoculant from step 2 above at a weight ratio of 3%, continuing high-temperature aerobic fermentation for 3-5 days; when the fermentation temperature drops below 50℃, turn the pile again, and simultaneously inoculate with the plant growth-promoting bacteria inoculant from step 2 above at a weight ratio of 2%, continuing mesophilic aerobic fermentation to mature and stabilize the organic materials, while the plant growth-promoting bacteria multiply rapidly and form spores; when the organic material moisture content is less than 30% and the material temperature is close to the ambient temperature, the effective viable count of the plant growth-promoting bacteria reaches 2×10⁻⁶. 8 Microbial fertilizer or bio-organic fertilizer is obtained when the CFU / g is above 50% and the organic matter content is greater than 50%, and it meets all the requirements of agricultural standard NY 884-2012.

[0019] Example 2: Microbial fertilizers enhance N2O emission reduction in farmland

[0020] The specific steps for improving saline-alkali land and reducing N2O emissions from saline-alkali farmland using microbial fertilizers are as follows:

[0021] For the uncultivated saline-alkali land in northern my country, after effective rainfall during the planting season, the saline-alkali land should be plowed and leveled. The fertilizer should be evenly spread on the surface of the saline-alkali soil at an application rate of 13.5 tons / hectare, and then plowed again to a depth of 35 cm to evenly incorporate the microbial fertilizer into the saline-alkali soil.

[0022] Under suitable soil moisture conditions, salt-tolerant maize seeds were sown. Irrigation, weed control, and pest and disease management were carried out according to local routine practices. Soil, plant, and gas samples were collected during the process, and the crop was harvested after maturity. A treatment using traditional chemical fertilizers was used as a control group. Soil, plant, and gas samples were collected from both the control group and the example to test soil salinity, organic matter, total nitrogen, and cumulative N2O emission flux. Plant samples were collected to test plant biomass (by dry weight) and nitrogen content, and yield per hectare was calculated. The experimental results are as follows:

[0023] In this embodiment, the soil salinity was 2 g / kg, the organic matter content was 5.21 g / kg, the total nitrogen content was 851 mg / kg, and the cumulative N2O emission flux was 1.36 kg / m³. 2 CO2e was 24.0 t / ha of crop biomass; the control group had soil salinity of 3.03 g / kg, organic matter content of 4.76 g / kg, total nitrogen of 628 mg / kg, and cumulative N2O emission flux of 2.23 kg / m³. 2CO2e content was 23.6 t / ha for crop biomass. The results indicate that this invention can effectively reduce soil salinity and cumulative N2O emission flux, increase soil organic matter and total nitrogen content, and simultaneously increase crop biomass per hectare.

[0024] Example 3: Microbial fertilizers enhance carbon sequestration in saline-alkali land ecosystems

[0025] The specific steps for using microbial fertilizers to improve saline-alkali land and increase the carbon sequestration capacity of the saline-alkali land ecosystem are as follows:

[0026] For the uncultivated saline-alkali land in northern my country, after effective rainfall during the planting season, the saline-alkali land should be plowed and leveled. The fertilizer should be evenly spread on the surface of the saline-alkali soil at a rate of 6.75 tons / hectare, and then plowed again to a depth of 35 cm to evenly incorporate the microbial fertilizer into the saline-alkali soil.

[0027] Under suitable soil moisture conditions, salt-tolerant maize seeds were sown. Irrigation, weed control, and pest and disease management were carried out according to local routine practices. Soil, plant, and gas samples were collected during the process, and the crop was harvested after maturity. Untreated saline-alkali land was used as a control group. Soil and plant samples were collected from both the control group and the example, and the total soil carbon, total organic carbon, and total inorganic carbon were tested to calculate soil carbon sequestration. Plant samples were also collected, and plant biomass (by dry weight), total carbon, total organic carbon, and total inorganic carbon were tested to calculate yield and carbon sequestration per hectare. The experimental results are as follows. In this embodiment, the total soil carbon is 16.1 g / kg, the total soil organic carbon is 2.91 g / kg, the total soil inorganic carbon is 13.2 g / kg, the soil carbon sequestration is 253 t / ha CO2e, the crop biomass per hectare is 10.7 t / ha, the total crop carbon is 238 g / kg, the total crop organic carbon is 236 g / kg, the total crop inorganic carbon is 2.1 g / kg, and the crop carbon sequestration is 9.34 t / ha CO2e. The control group had a total soil carbon of 14.9 g / kg, a total soil organic carbon of 2.37 g / kg, a total soil inorganic carbon of 12.5 g / kg, a soil carbon sequestration of 234 t / ha CO2e, a crop biomass of 6.49 t / ha, a crop total carbon of 228 g / kg, a crop total organic carbon of 226 g / kg, a crop total inorganic carbon of 1.74 g / kg, and a crop carbon sequestration of 5.41 t / ha CO2e.

[0028] The soil bulk density in this experimental area was 1.23 g / cm³. 3 The sampling depth was 35 cm. According to the soil carbon sequestration calculation formula, this embodiment increases the soil carbon sequestration by 19 tCO2e per hectare; indicating that the present invention can effectively increase the soil carbon sequestration of saline-alkali land.

[0029] As demonstrated in the examples, using kitchen waste as the main raw material for plant growth-promoting bacteria culture medium, a low-cost microbial inoculant can be prepared. Combined with agricultural waste composting technology, microbial fertilizer can be produced, enabling the resource utilization of biomass waste, reducing environmental pollution, lowering the production cost of microbial fertilizer, and promoting sustainable agricultural development. Replacing chemical fertilizers with microbial fertilizers for improving saline-alkali land can significantly reduce the salinity of saline-alkali soils, increase soil organic matter content, effectively reduce soil N2O emissions, and improve ecosystem carbon sequestration. The process is simple and easy to promote.

[0030] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A method for reducing greenhouse gas emissions and increasing carbon sequestration in saline-alkali soils in farmland, characterized in that, The microbial fertilizer is used for improving the physical and chemical properties and micro-ecology of saline-alkali soil, reducing N2O emission and increasing the carbon fixation amount of the saline-alkali soil.

2. The method for preparing the microbial fertilizer as claimed in claim 1, characterized in that, The method comprises the following steps: (1) preparing a liquid medium from kitchen waste: the kitchen waste is crushed, water is added to a soluble solid content (weight ratio) of 2% to 7%, boiled, and filtered through a 50-mesh sieve to remove residues, and the pH is adjusted to 7.0 to 8.0 to obtain the liquid medium. (2) Preparation of plant growth-promoting bacteria seed liquid: Bacillus subtilis preserved on slant culture medium was inoculated into an Erlenmeyer flask containing the liquid culture medium obtained in step 1 above. Bacillus subtilis The HA2 strain was cultured at 25–37°C with shaking at 100–200 rpm for 24–48 hours to obtain the seed culture of the plant growth-promoting bacterium HA2. (3) Preparation of the plant growth promoting bacteria inoculant: inoculate the seed liquid of the HA2 strain obtained in step 2 into the liquid medium obtained in step 1 at an inoculation amount of 2% to 10% by weight, and cultivate at 25 to 37°C for 24 to 96 hours with air aeration, so that the effective viable cell count reaches 2 x 10 9 The plant growth promoting bacteria inoculant is obtained above. (4) Preparation of microbial fertilizer: inoculate the plant growth promoting bacteria inoculum of step 2 above in the aerobic compost organic material at a weight ratio of 1% ~ 10%, adjust the moisture content of the material to 55% ~ 65%, and carry out high-temperature aerobic fermentation for 3 ~ 7 days; when the temperature reaches above 70℃ and maintains for 2 ~ 3 days, turn over the pile, at the same time inoculate the plant growth promoting bacteria inoculum of step 2 above at a weight ratio of 1% ~ 5%, and continue to carry out high-temperature aerobic fermentation for 3 ~ 5 days; when the fermentation temperature drops below 50℃, turn over the pile again, at the same time inoculate the plant growth promoting bacteria inoculum of step 2 above at a weight ratio of 1% ~ 5%, and continue to carry out medium-temperature aerobic fermentation, so as to stabilize the organic material, and at the same time the plant growth promoting bacteria multiply in large quantities and form spores; when the moisture content of the organic material is less than 30% and the material temperature approaches the ambient temperature, the effective viable count of the plant growth promoting bacteria reaches 2×10 8 CFU / g or above, i.e. microbial fertilizer or bio-organic fertilizer is obtained. (5) The plant growth-promoting bacteria used in this invention are Bacillus subtilis (B. subtilis). Bacillus subtilis The HA2 strain can grow rapidly using kitchen waste as a substrate. This strain was deposited on May 20, 2019, at the China General Microbiological Culture Collection Center, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with accession number CGMCC No. 17825.

3. The method for reducing the emission of greenhouse gases and increasing the carbon sequestration of saline-alkali soil in farmland according to claim 1, characterized in that, The microbial fertilizer prepared in claim 2 is uniformly applied to the surface layer of the saline-alkali soil at an application amount of 6 to 20 tons per hectare, and then ploughed, with a ploughing depth of 25 to 40 cm. According to the degree of salinity of the soil, suitable crops or halophytes are planted, and the soil is irrigated with an appropriate amount of fresh water according to the soil moisture condition. After the crops or halophytes are harvested, biomass waste such as straw and agricultural processing waste is used as raw material for the production of the microbial fertilizer in step 4, and finally returns to the farmland and saline-alkali soil to realize the cyclic carbon fixation process.