A biological fertilizer and its application in combination with microplastics in enhancing soil carbon sequestration capacity

Abstract

The present invention discloses a biofertilizer and its application in combination with microplastics to enhance soil carbon sequestration. The raw materials of the biofertilizer include a microbial agent and an organic carrier; the strain in the microbial agent is selected from at least one of Bacillus velezensis, Bacillus methylotrophicus, and Bacillus licheniformis; and the organic carrier includes a fermentation product of molasses and animal feces. The present invention combines organic biofertilizer with microplastics to provide a method for enhancing soil carbon sequestration. This method is environmentally friendly, sustainable, and highly efficient. The method can effectively increase soil pH, SOC, and OM, thereby generating better overall benefits.

Description

Technical Field

[0001] The present invention relates to the field of agricultural ecological technology, and in particular to a biological fertilizer and its application in combination with microplastics in enhancing the carbon sequestration capacity of soil. Background Art

[0002] Soil carbon sequestration involves binding existing carbon dioxide in the atmosphere, converting it into a stable carbon-containing compound, and storing it long-term in the soil. Soil carbon sequestration offers modern society an inexpensive environmental protection technology that can effectively reduce greenhouse gas emissions and help humanity address climate change. Improving soil carbon sequestration is crucial for enhancing the ecosystem's carbon retention and sequestration capacity, ensuring global ecological and food security, and achieving the "dual carbon" goals.

[0003] Currently, there are two main methods of carbon sequestration: physical carbon sequestration and biological carbon sequestration. Physical carbon sequestration involves the long-term storage of carbon dioxide in exploited oil and gas wells, coal seams, and the deep sea. Biological carbon sequestration is considered the most promising method for mitigating global warming. Utilizing terrestrial ecosystems to sequester carbon is the most economically viable and environmentally friendly way to slow the rise in atmospheric carbon dioxide concentrations.

[0004] However, soil carbon sequestration currently faces many challenges, such as soil degradation, nutrient loss, and reduced microbial activity. These factors will lead to accelerated decomposition of soil organic matter and reduced soil carbon sequestration capacity and stability.

[0005] Biofertilizer is an organic fertilizer that uses microorganisms or their metabolites to improve soil fertility and plant growth. It can increase the number and activity of beneficial microorganisms in the soil, promote interaction between plant roots and microorganisms, and enhance plant absorption and utilization of nutrients and water, thereby improving plant photosynthesis and yield. It can also inhibit soil-borne diseases and pests, reducing pesticide use.

[0006] Microplastics, defined as plastic particles less than 5 mm in diameter, are a major source of pollution. They can be categorized as primary and secondary microplastics. Primary microplastics refer to micron-sized plastic particles produced during production and are commonly used in industrial manufacturing and personal care product production. Secondary microplastics are typically formed by the fragmentation and reduction of larger pieces of plastic waste through physical, chemical, and biological processes. These include sources such as agricultural mulch, plastic packaging products, and synthetic fibers found in washing machine wastewater.

[0007] Because microplastics are difficult to degrade, they persist in the environment for long periods of time and are spread to various ecosystems through wind, water flow, and the food chain, causing harm to the environment and organisms. Specifically, microplastics affect digestion and absorption in organisms, releasing organic monomers and toxic additives. Adsorption causes complex pollution, interferes with the endocrine function of organisms, induces genetic abnormalities, and harms reproduction and development. In addition, microplastics can alter the physical and chemical properties of the soil, affect soil fauna and microbial communities, and reduce soil quality and fertility. However, under certain conditions, microplastics may also have a positive effect on soil carbon sequestration.

[0008] Currently, there is no research or report on how to combine biofertilizer with microplastics to improve the carbon sequestration capacity of soil.

[0009] In view of this, the present invention is proposed. Summary of the Invention

[0010] The purpose of the present invention is to provide a biological fertilizer and its application in combination with microplastics to improve the carbon sequestration capacity of soil. The combination of the biological fertilizer and microplastics can enhance the carbon sequestration capacity of soil, thereby playing a role in slowing down the greenhouse effect and improving soil fertility.

[0011] The present invention is achieved in that:

[0012] In one aspect, the present invention provides a biological fertilizer, the raw materials of which include a microbial agent and an organic carrier;

[0013] The strains in the microbial agent are selected from Bacillus Velez, Bacillus methylotrophic and Bacillus licheniformis, and the ratio of the number of live bacteria of Bacillus Velez, Bacillus methylotrophic and Bacillus licheniformis in the microbial agent is: 1-3:5-10:5-10; the organic carrier includes molasses fermentation liquid and animal feces fermentation products, and the mass ratio of molasses fermentation liquid and animal feces fermentation products in the organic carrier is 10-40:60-90.

[0014] In some embodiments, the preparation steps of the microbial agent include the following steps:

[0015] S1. aerobically culturing Bacillus velezensis, Bacillus methylotrophicus, and Bacillus licheniformis at 25-35° C. and pH 6.5-7.5 for 24-96 hours;

[0016] S2. After activation and expansion, it is coupled with an embedding material prepared from sodium alginate and calcium chloride, and prepared into a composite microbial agent microcapsule by spray drying, which is a microbial agent.

[0017] In some embodiments, the total number of viable bacteria in the above-mentioned biological fertilizer is ≥2.0×10 8 cfu / g.

[0018] In some embodiments, the deposit number of the above-mentioned Bacillus velez is CGMCCNO.20317.

[0019] In some embodiments, the deposit number of the methylotrophic Bacillus is CCTCCM2013462.

[0020] In some embodiments, the deposit number of the Bacillus licheniformis is CGMCC NO.24738.

[0021] In some embodiments, the raw materials of the above-mentioned biological fertilizer also include regulators, nitrogen fertilizers, phosphorus fertilizers, potassium fertilizers, calcium fertilizers, magnesium fertilizers and trace element fertilizers.

[0022] In some embodiments, the raw materials of biological fertilizer include, by weight: 1 to 10 parts of microbial agent; 30 to 70 parts of organic carrier; 0.5 to 5 parts of regulator; 1 to 10 parts of nitrogen fertilizer; 1 to 15 parts of phosphorus fertilizer; 1 to 10 parts of potassium fertilizer; 1 to 10 parts of calcium fertilizer; 1 to 5 parts of magnesium fertilizer; and 1 to 5 parts of trace element fertilizer.

[0023] In some embodiments, the regulator is a composition of zeolite powder, phosphogypsum and quicklime, wherein the mass ratio of zeolite powder, phosphogypsum and quicklime is 10-45:5-30:5-25.

[0024] In some embodiments, the preparation method of the above-mentioned biological fertilizer comprises the following steps:

[0025] S1. Mixing the honey fermentation liquid and the animal feces fermentation product in a mass ratio to prepare an organic carrier;

[0026] S2, mixing the microbial agent, the organic carrier and the regulator in proportion to obtain a mixture, covering the mixture with a film, punching holes in the film for ventilation, and then fermenting the mixture at a temperature of 50 to 85° C. for 7 to 10 days;

[0027] S3, uncovering the film and stirring the mixture again, and then aging it for 10 to 15 days, and further evaporating the resulting mixture to remove water, thereby obtaining a biofertilizer with an organic matter content of ≥30%;

[0028] S4. Add nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, calcium fertilizer, magnesium fertilizer and trace element fertilizer to the organic biological fertilizer in proportion, and mix well to obtain the biological fertilizer.

[0029] On the other hand, the present invention also provides the application of the above-mentioned biological fertilizer in combination with microplastics in enhancing the carbon sequestration capacity of soil.

[0030] In some embodiments, the microplastics include biodegradable microplastics.

[0031] In some embodiments, the material of the above-mentioned biodegradable microplastics includes at least one of polybutylene adipate terephthalate (PBAT), polycaprolactone (PCL), polybutylene succinate (PBS), polybutylene succinate-adipate (PBSA), carbon dioxide copolymer (PPC), polylactic acid (PLA), polyhydroxyalkanoate (PHA) and starch plastic.

[0032] The present invention has the following beneficial effects:

[0033] (1) The biofertilizer of the present invention uses a mixture of honey fermentation liquid and animal feces fermentation products as an organic carrier, and is fermented with specific microorganisms and organic and inorganic nutrient fertilizers to produce a biofertilizer containing ≥30% organic matter. Compared with traditional organic fertilizers, the biofertilizer of the present invention has complete nutrients and low cost. The obtained organic biofertilizer has stable quality, high fertilizer efficiency, and full functions. Moreover, all the ingredients contained in it are environmentally friendly products, which conforms to the concept of sustainable development.

[0034] (2) The present invention combines organic biofertilizer with microplastics to provide a method for improving soil carbon sequestration capacity, which is environmentally friendly, sustainable, and efficient. This method can effectively improve soil pH, SOC, and OM, thereby producing better comprehensive benefits. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0036] While soil is a significant source of greenhouse gases such as carbon dioxide and methane, it can also serve as a carbon sink through carbon sequestration through soil organic matter. Therefore, reducing greenhouse gas emissions and increasing soil carbon sequestration are of great significance for mitigating climate change. To enhance soil carbon sequestration, the present invention provides a biofertilizer comprising a microbial agent, an organic carrier, a conditioning agent, nitrogen fertilizer, phosphate fertilizer, potash fertilizer, calcium fertilizer, magnesium fertilizer, and trace element fertilizer.

[0037] Specifically, in terms of weight, the raw materials of biological fertilizer include: 1 to 10 parts of microbial agent; 30 to 70 parts of organic carrier; 0.5 to 5 parts of regulator; 1 to 10 parts of nitrogen fertilizer; 1 to 15 parts of phosphorus fertilizer; 1 to 10 parts of potassium fertilizer; 1 to 10 parts of calcium fertilizer; 1 to 5 parts of magnesium fertilizer; and 1 to 5 parts of trace element fertilizer.

[0038] In the present invention, the total number of viable bacteria in the microbial agent is ≥ 2.0×10 8 cfu / g.

[0039] The strains in the microbial agent are selected from Bacillus Velez, Bacillus methylotrophicus and Bacillus licheniformis, and the ratio of the number of viable bacteria of Bacillus Velez, Bacillus methylotrophicus and Bacillus licheniformis in the microbial agent is 1-3:5-10:5-10.

[0040] Preferably, the deposit number of Bacillus velez is CGMCC No. 20317; the deposit number of Bacillus methylotrophicus is CCTCCM2013462; and the deposit number of Bacillus licheniformis is CGMCC No. 24738. The aforementioned Bacillus velez, Bacillus methylotrophicus, and Bacillus licheniformis are all existing strains, disclosed in patents CN202110072888.X, CN201410148228.5, and CN202210864870.8, respectively.

[0041] By adopting the above technical solution, the addition of microbial agents can improve soil fertility and promote crop absorption of nutrients. At the same time, the microorganisms in the composite microbial agents can also release growth hormones, such as indoleacetic acid, in the soil to regulate crop growth.

[0042] Among them, Bacillus Velez can prevent and control plant diseases. It is a soil growth-promoting bacterium that secretes antibacterial metabolites to inhibit the growth of pathogens and induces the plant defense system to resist the invasion of pathogens, thereby achieving biological control. At the same time, Bacillus Velez can secrete a variety of plant hormones and volatile compounds, such as IAA, NH, and ACC deaminases, which can promote plant growth, increase soil nutrients, improve soil structure, and increase fertilizer utilization.

[0043] The antifungal active lipopeptide compounds produced by methylotrophic Bacillus have strong antifungal activity against plant fungal diseases, and have significant control effects on cucumber, tomato gray mold, late blight, cotton yellow wilt and apple tree rot. They can also prevent and control citrus canker, cucumber bacterial angular leaf spot, rice bacterial leaf streak, etc. At the same time, methylotrophic Bacillus produces aminopeptidases and acts as PGPR (plant growth-promoting rhizobacteria) to promote plant growth.

[0044] Bacillus licheniformis can produce endophytic spores, has strong heat resistance and stress resistance, grows fast, has simple nutritional requirements, is easy to survive, colonize and reproduce on the surface of plants, and has strong competition and colonization capabilities, thereby seizing the infection sites of pathogens, consuming the surrounding nutrients, preventing and interfering with the infection of pathogens on plant leaves and other organs, and playing a role in disease prevention and antibacterial. In addition, Bacillus licheniformis can not only inhibit plant pathogens, but also induce the plant's own disease resistance mechanism, thereby enhancing the plant's disease resistance.

[0045] The present invention selected the aforementioned Bacillus Velez, Bacillus methylotrophicus, and Bacillus licheniformis because they have similar functional effects, resulting in a synergistic effect. Furthermore, Bacillus licheniformis is well adapted to alkaline environments. The three strains work together to adapt to more complex environments, enhancing the effectiveness of the microbial agent.

[0046] The organic carrier comprises a fermentation product of honey fermentation liquid and animal feces, specifically, a fermentation product of honey fermentation liquid and livestock feces from a farm or an animal feces from a zoo.

[0047] Preferably, the mass ratio of the honey fermentation liquid to the animal feces fermentation product is 10-40:60-90.

[0048] By adopting the above technical solution, waste is effectively utilized, so not only is the cost low, but also the emission of waste can be reduced, which is beneficial to protecting the environment and the effective utilization of resources.

[0049] At the same time, in order to provide sufficient nutrients for crops, the biological fertilizer of the present invention also includes nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, calcium fertilizer, magnesium fertilizer and trace element fertilizer.

[0050] As for the type of nitrogen fertilizer, it can be ammonium nitrogen fertilizer, nitrate nitrogen fertilizer, urea nitrogen fertilizer or other types of nitrogen fertilizer; the phosphate fertilizer can be monoammonium phosphate, diammonium phosphate, ammonium polyphosphate, nitrophosphate, double-burned phosphate fertilizer, calcium magnesium phosphate fertilizer, triple superphosphate, superphosphate, calcium hydrogen phosphate, phosphate rock or other types of phosphate fertilizer; the potash fertilizer can be potassium nitrate, potassium dihydrogen phosphate, potassium sulfate, potassium chloride or other types of potash fertilizer; the calcium fertilizer can be quicklime, slaked lime, lime powder, gypsum, lime carbonate, calcium nitrate, calcium chloride or other types of calcium fertilizer; the magnesium fertilizer can be magnesium sulfate, magnesium nitrate, magnesium chloride, calcium magnesium phosphate fertilizer, magnesite or other types of magnesium fertilizer; the trace element fertilizer can be molybdenum fertilizer, boron fertilizer, manganese fertilizer, zinc fertilizer, copper fertilizer, iron fertilizer or other types of trace element fertilizer. The specific selection of nitrogen fertilizer, phosphate fertilizer, potash fertilizer, calcium fertilizer, magnesium fertilizer and trace element fertilizer can be selected according to actual needs, and the present invention is not limited to this.

[0051] By preparing the above-mentioned specific microbial strains into microbial agents and compounding them with organic carriers, regulators, nitrogen fertilizers, phosphorus fertilizers, potassium fertilizers, calcium fertilizers, magnesium fertilizers and trace element fertilizers, biological fertilizers are obtained that can increase soil pH, soil organic carbon (SOC) and soil organic matter (OM), thereby promoting plant growth.

[0052] Specifically, the regulator is a composition of zeolite powder, phosphogypsum and quicklime, wherein the mass ratio of zeolite powder, phosphogypsum and quicklime is 10-45:5-30:5-25. The regulator has unique acid-base regulation, adsorption, catalysis, biological activity and anti-toxicity.

[0053] As a general technical concept, the present invention also provides a method for preparing the above-mentioned biological fertilizer, the specific steps of which are as follows:

[0054] (1) Preparation of microbial agents:

[0055] The selected Bacillus velez, Bacillus methylotrophicus and Bacillus licheniformis are aerobically cultured, activated, expanded and fermented, and then coupled with an embedding material prepared from sodium alginate and calcium chloride, and prepared into composite microbial agent microcapsules by spray drying for later use;

[0056] The aerobic culture conditions are as follows: culture at 25-35° C. and pH 6.5-7.5 for 24-96 hours;

[0057] (2) Preparation of organic carrier:

[0058] Mix the honey fermentation liquid with the fermentation product of livestock excrement from a farm or animal excrement from a zoo in a certain proportion and set aside;

[0059] (3) mixing the microbial agent prepared in step (1) and step (2) with the organic carrier in proportion, adding other regulators, covering with a film, punching holes in the film for ventilation, and then fermenting at high temperature. After mixing again, the mixture is matured for 10 to 15 days and further evaporated to remove water, thereby obtaining an organic biofertilizer with an organic matter content of ≥30%. Then, nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, calcium fertilizer, magnesium fertilizer and trace element fertilizer are added to the organic biofertilizer in proportion, and the biofertilizer is obtained after mixing.

[0060] Among them, the temperature of high-temperature fermentation is 50-85°C, and the fermentation time is 7-10 days.

[0061] Experiments have shown that the combination of the bio-fertilizer of the present invention and microplastics will have a significant impact on the physical and chemical properties of the soil: increasing soil pH, SOC and OM, among which the content of SOC and OM is significantly increased compared with the application of bio-fertilizer alone, proving that the combination of bio-fertilizer and microplastics has a synergistic effect.

[0062] The material of the microplastic is selected from at least one of polybutylene adipate terephthalate (PBAT), polycaprolactone (PCL), polybutylene succinate (PBS), polybutylene succinate-adipate (PBSA), carbon dioxide copolymer (PPC), polylactic acid (PLA), polyhydroxyalkanoate (PHA), and starch plastic.

[0063] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0064] The Bacillus velezensis used in the examples of the present invention has a deposit number of CGMCC No. 20317; the Bacillus methylotrophicus has a deposit number of CCTCCM2013462; and the Bacillus licheniformis has a deposit number of CGMCC No. 24738. The biodegradable plastic polybutylene adipate-terephthalate (PBAT) was purchased from Xinjiang Lanshan Tunhe Polyester Co., Ltd.

[0065] The methods used in the following examples are conventional methods unless otherwise specified.

[0066] Example 1

[0067] This embodiment provides a biological fertilizer, the raw materials of which are as follows:

[0068] 60 parts of organic carrier; 10 parts of microbial agent; 5 parts of regulator; 6 parts of nitrogen fertilizer; 5 parts of phosphorus fertilizer; 6 parts of potassium fertilizer; 3 parts of calcium fertilizer; 3 parts of magnesium fertilizer; 2 parts of trace element fertilizer.

[0069] The organic matter carrier includes honey fermentation liquid and fermentation products of poultry and livestock manure from farms or animal manure from zoos, and the mass ratio of honey fermentation liquid to fermentation products of poultry and livestock manure from farms or animal manure from zoos is 1:4.

[0070] The regulator is a composition of zeolite powder, phosphogypsum and quicklime, wherein the mass ratio of zeolite powder, phosphogypsum and quicklime is 45:30:25.

[0071] The number of viable bacteria in the biofertilizer is 200 million per gram, with the ratio of the number of viable bacteria of Bacillus velezensis, Bacillus methylotrophicus, and Bacillus licheniformis being 3:10:10.

[0072] The above-mentioned biological fertilizer is prepared by the following method:

[0073] S1. The selected Bacillus velezensis, Bacillus methylotrophicus, and Bacillus licheniformis were aerobically cultured at 28°C, pH = 6.8 for 60 hours, activated, expanded, and fermented. They were then coupled with an embedding material prepared from sodium alginate and calcium chloride and spray-dried to form composite microcapsules for later use.

[0074] S2. The fermented honey liquid is mixed with farm livestock manure or zoo animal manure fermentation products in proportion and set aside;

[0075] S3. The biological agent prepared in S1 and S2 is mixed with an organic carrier and a regulator in proportion to obtain a mixture, which is covered with a film and holes are punched in the film for ventilation. The mixture is then fermented at high temperature at 65°C for 7 days. The mixture is mixed again and aged for 14 days to obtain an organic biological fertilizer. Nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, calcium fertilizer, magnesium fertilizer and trace element fertilizer are then added to the organic biological fertilizer in proportion and mixed to obtain the biological fertilizer.

[0076] Example 2

[0077] This embodiment provides a biological fertilizer. The specific preparation method is the same as that of Example 1, except that the raw material composition of the biological fertilizer is different. The specific raw material composition is as follows:

[0078] 65 parts of organic carrier; 5 parts of microbial agent; 5 parts of regulator; 6 parts of nitrogen fertilizer; 5 parts of phosphorus fertilizer; 6 parts of potassium fertilizer; 3 parts of calcium fertilizer; 3 parts of magnesium fertilizer; 2 parts of trace element fertilizer.

[0079] Example 3

[0080] This embodiment provides a biological fertilizer. The specific preparation method is the same as that of Example 1, except that the raw material composition of the biological fertilizer is different. The specific raw material composition is as follows:

[0081] 70 parts of organic carrier; 10 parts of microbial agent; 5 parts of regulator; 4 parts of nitrogen fertilizer; 4 parts of phosphorus fertilizer; 4 parts of potassium fertilizer; 3 parts of calcium fertilizer; 3 parts of magnesium fertilizer; 2 parts of trace element fertilizer.

[0082] Example 4

[0083] This embodiment provides a biological fertilizer, and the specific preparation method is the same as that of Example 1, except that the ratio of the number of viable bacteria of Bacillus velezensis, Bacillus methylotrophicus and Bacillus licheniformis in the microbial agent is different. The ratio in this embodiment is: 3:5:5.

[0084] Example 5

[0085] This embodiment provides a biological fertilizer, and the specific preparation method is the same as that of Example 1, except that the ratio of the number of viable bacteria of Bacillus velezensis, Bacillus methylotrophicus and Bacillus licheniformis in the microbial agent is different. The ratio in this embodiment is: 1:10:10.

[0086] Comparative Example 1

[0087] The difference from Example 1 is that no microbial agent is included.

[0088] Comparative Example 2

[0089] The difference from Example 1 is that no organic carrier is contained.

[0090] Comparative Example 3

[0091] The difference from Example 1 is that no organic carrier and microbial agent are contained.

[0092] Comparative Example 4

[0093] The difference from Example 1 is that no regulator is contained.

[0094] Experimental Example 1

[0095] Fertilizer efficiency tests were performed on Examples 1-5 and Comparative Examples 1-4, as follows:

[0096] The biological fertilizers of Examples 1-5 and Comparative Examples 1-4 were added to the soil at 0.5% w / w and mixed. The test crop was Shanghai green. The test adopted a potted culture method with a specification of 230mm×180mm, 6kg of soil per pot, and 6 pots per group. The Shanghai green seeds were disinfected twice with 75% ethanol for 2 minutes each time, and then washed in sterile distilled water for 2 minutes. After germination, 3 seedlings in the four-leaf and one-heart stage with uniform growth and strong root system were selected for transplanting. Fertilization was carried out according to the fertilization plan, and basic indicators such as chlorophyll, plant height, and whole-plant dry weight were measured between the groups after 28 days. The specific effects are shown in Table 1 below. Table 1 also adds a blank control group, in which the blank control group refers to the performance of Shanghai green without fertilizer application.

[0097] Table 1 Comparative data of chlorophyll, plant height, whole plant dry weight and yield increase rate of Shanghai green crops under different treatments

[0098] deal with Chlorophyll (SPAD value) Plant height / cm Whole plant dry weight / g Yield increase rate (%) blank <![CDATA[35.2 d ]]> <![CDATA[22.3 d ]]> <![CDATA[7.80 d ]]> - Example 1 <![CDATA[39.2 a ]]> <![CDATA[27.1 a ]]> <![CDATA[9.90 a ]]> 26.9 Example 2 <![CDATA[38.7 b ]]> <![CDATA[26.6 a ]]> <![CDATA[9.60 a ]]> 23.1 Example 3 <![CDATA[38.5 b ]]> <![CDATA[26.8 a ]]> <![CDATA[9.72 a ]]> 24.6 Example 4 <![CDATA[38.6 b ]]> <![CDATA[26.9 a ]]> <![CDATA[9.60 a ]]> 23.1 Example 5 <![CDATA[38.9 b ]]> <![CDATA[26.9 a ]]> <![CDATA[9.78 a ]]> 25.4 Comparative Example 1 <![CDATA[38.3 b ]]> <![CDATA[26.2 b ]]> <![CDATA[9.18 b ]]> 17.7 Comparative Example 2 <![CDATA[37.7 c ]]> <![CDATA[25.7 c ]]> <![CDATA[8.82 c ]]> 13.1 Comparative Example 3 <![CDATA[37.3 c ]]> <![CDATA[25.4 c ]]> <![CDATA[8.58 c ]]> 10.0 Comparative Example 4 <![CDATA[38.3 b ]]> <![CDATA[26.1 b ]]> <![CDATA[8.94 b ]]> 14.6

[0099] Note: Different lowercase letters in the same row indicate significant differences among different treatments (P<0.05).

[0100] As can be seen from Table 1, the chlorophyll, plant height and whole plant dry weight of the Shanghai greens applied with the biological fertilizers of Examples 1-5 were significantly increased compared with those without the biological fertilizer. Compared with the application of Comparative Examples 1-4, the chlorophyll, plant height and whole plant dry weight were increased, indicating that the biological fertilizers of Examples 1-5 have good fertilizer effects, among which Example 1 has the best fertilizer effect and is the optimal formula.

[0101] Experimental Example 2

[0102] The biological fertilizer of Example 1 was combined with microplastics to verify the soil carbon sequestration effect, and the steps were as follows:

[0103] 1. The test soil was selected from the farmland soil in Guangming District, where plastic products have never been used. The test adopted a potted culture method with a specification of 230mm×180mm and 6kg of soil per pot (specific conditions shall prevail). The basic physical and chemical indicators of the soil (pH, organic matter, etc.) were confirmed. The treatments were as follows: BF (0.5% w / w) and PBAT-MPs (0.1% w / w), BF (0.5% w / w) and PBAT-MPs (0.5% w / w), BF (0.5% w / w) and PBAT-MPs (2.5% w / w); only BF was applied. (0.5% w / w); CF (0.5% w / w) and PBAT-MPs (0.1% w / w), CF (0.5% w / w) and PBAT-MPs (0.5% w / w), CF (0.5% w / w) and PBAT-MPs (2.5% w / w); only CF (0.5% w / w) was applied; 6 pots were repeated for each group; wherein BF is the biological fertilizer corresponding to Example 1, CF is the fertilizer without adding microbial agents corresponding to Comparative Example 1, and CK is the blank group;

[0104] 2. Test crop: Shanghai green, a common economic crop with a growing period of approximately 20-30 days. Shanghai green seeds were sterilized twice with 75% ethanol for 2 minutes each time, then washed in sterile distilled water for 2 minutes. After germination, three seedlings at the four-leaf, one-heart stage with even growth and strong root systems were selected for transplanting.

[0105] 3. Microplastics are biodegradable plastics polybutylene adipate-terephthalate (PBAT);

[0106] 4. Microplastics processing: Degradable plastic polybutylene adipate terephthalate (PBAT) microplastics are crushed in a grinder, and the crushed microplastics are sieved through a 100-mesh sieve to obtain microplastic powder;

[0107] 5. Cultivation period: The cultivation period is 28 days. During this period, the soil moisture content is maintained at 60% to 80% of the maximum water holding capacity of the soil in the field using the weighing method, and the soil properties and pH are observed during the cultivation process.

[0108] 6. Soil physical and chemical index determination: Taking a 28-day planting cycle as an example, measure changes in soil pH, SOC, organic matter, and other indicators. Use relevant national standard methods to test relevant indicators.

[0109] Table 2 Effects of each treatment group on soil physical and chemical indices of the root system of Shanghai Green

[0110]

[0111]

[0112] Note: Different lowercase letters in the same column indicate significant differences among different treatments (P<0.05).

[0113] As can be seen from Table 2, the application of biofertilizer and the addition of PBAT-MPs have a significant impact on the physical and chemical properties of the soil. The application of biofertilizer increased the soil pH (13.32%), SOC (70.81%), and OM (71.18%), while the addition of PBAT-MPs further increased the soil pH. It is worth noting that with the increase in the proportion of MPs added, the SOC and OM contents were significantly promoted, showing a synergistic effect with the effect of biofertilizer. In addition, compared with the application of biofertilizer alone, the addition of 2.5% w / w PBAT-MPs increased the SOC content by 2.63 times and the OM content by 2.68 times, respectively. This may be related to the following reasons: (1) microplastics can act as a potential matrix or carrier to increase the adsorption of organic matter in the soil; (2) microplastics can change the soil structure and porosity, increasing the protective space of organic matter in the soil. However, the pH, SOC, and OM of the fertilizer added in Comparative Example 1, which does not contain microbial agents, are lower, and the carbon sequestration capacity is weak, indicating that microbial agents and microplastics have a synergistic effect on improving the soil's carbon sequestration capacity.

[0114] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An application of a combination of biological fertilizer and microplastics in enhancing soil carbon sequestration capacity, characterized in that: Its raw materials include microbial agents and organic carriers; The strain in the microbial inoculant is selected from Bacillus velez, Bacillus methylotrophicus and Bacillus licheniformis; The ratio of the number of viable bacteria of Bacillus velezensis, Bacillus methylotrophicus and Bacillus licheniformis in the microbial agent is: 1-3:5-10:5-10; The organic carrier includes honey fermentation liquid and animal feces fermentation product, and the mass ratio of honey fermentation liquid to animal feces fermentation product in the organic carrier is 10-40:60-90; The deposit number of the Bacillus velez is CGMCC NO.20317; the deposit number of the Bacillus methylotrophicus is CCTCCM2013462; the deposit number of the Bacillus licheniformis is CGMCC NO.24738; The material of the microplastic is polybutylene adipate terephthalate (PBAT).

2. The use according to claim 1, characterized in that The preparation steps of the microbial agent include the following steps: S1. Bacillus velezensis, Bacillus methylotrophicus, and Bacillus licheniformis were cultured aerobically at 25-35°C and pH 6.5-7.5 for 24-96 hours. S2. After activation and expansion, the microorganism is coupled with an embedding material prepared from sodium alginate and calcium chloride, and spray-dried to prepare a composite microbial agent microcapsule, which is the microbial agent.

3. The use according to claim 2, characterized in that The total number of viable bacteria in the biological fertilizer is ≥ 2.0×10 8 cfu / g.

4. The use according to claim 3, characterized in that The raw materials of the biological fertilizer also include regulators, nitrogen fertilizers, phosphorus fertilizers, potassium fertilizers, calcium fertilizers, magnesium fertilizers and trace element fertilizers.

5. The use according to claim 4, characterized in that The raw materials of the biological fertilizer include, by weight: 1 to 10 parts of microbial agent; 30 to 70 parts of organic carrier; 0.5 to 5 parts of regulator; 1 to 10 parts of nitrogen fertilizer; 1 to 15 parts of phosphate fertilizer; 1 to 10 parts of potassium fertilizer; 1 to 10 parts of calcium fertilizer; 1 to 5 parts of magnesium fertilizer; and 1 to 5 parts of trace element fertilizer.

6. The use according to claim 5, characterized in that The regulator is a composition of zeolite powder, phosphogypsum and quicklime, wherein the mass ratio of zeolite powder, phosphogypsum and quicklime is 10-45:5-30:5-25.

7. The use according to claim 6, characterized in that The preparation method of the biological fertilizer comprises the following steps: S1. Mixing the honey fermentation liquid and the animal feces fermentation product in a mass ratio to prepare an organic carrier; S2, mixing the microbial agent, the organic carrier, and the regulator in proportion to obtain a mixture, covering the mixture with a film, punching holes in the film for ventilation, and then fermenting the mixture at a temperature of 50-85° C. for 7-10 days; S3, uncovering the film and stirring the mixture again, and then aging it for 10 to 15 days, and further evaporating the resulting mixture to remove water, to obtain a biofertilizer with an organic matter content of ≥30%; S4. Add nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, calcium fertilizer, magnesium fertilizer and trace element fertilizer to the organic biological fertilizer in proportion, and mix well to obtain the biological fertilizer.

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