Biochar-based slow-release fertilizer as well as preparation method and application thereof

Abstract

The invention discloses a charcoal-based slow release fertilizer as well as a preparation method and application thereof, and belongs to the technical field of bio-organic fertilizers. The biochar-based slow-release fertilizer is prepared from the following raw materials in parts by weight: 50 to 60 parts of functionalized biochar, 8 to 10 parts of compound microbial agent, 3 to 5 parts of green plum extract, 30 to 40 parts of slow-release nutritional ingredients and 5 to 7 parts of binder, the compound microbial agent is prepared from sporosarcina sibirica, cysticercus aucuba and bacillus parlicheniformis. Under the combined action of functional biochar, citric acid treatment, humic acid and microbial activity, soil alkalinity is gradually neutralized, the pH value is reduced, the soil physical and chemical properties of the saline-alkali soil are remarkably improved, the stress resistance of plants is improved, the growth of the plants is remarkably improved, and then the yield is increased; the biochar slow release technology ensures that nutrients are slowly and stably released in the whole growth period of crops, rapid nutrient leaching loss caused by irrigation or rainfall in saline-alkali soil is avoided, and fertilizer fixation caused by uncomfortable pH is also reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bio-organic fertilizer, and particularly relates to a biochar-based slow-release fertilizer as well as a preparation method and application thereof. BACKGROUND

[0002] With global climate change and population growth, sustainable use of land resources has become one of the research hotspots. Saline-alkali soil is a type of land unsuitable for agricultural production due to high content of salt and alkaline substances in the soil, and has characteristics such as poor soil physical properties, low fertility, and fragile ecological environment. Saline-alkali soil not only leads to crop yield reduction, but also seriously threatens the health of the ecological environment. In addition, due to global climate change and improper irrigation and tillage measures, the area of land affected by salinization continues to increase. Saline-alkali soil can adversely affect crop growth, causing at least huge economic losses to global agricultural production every year. On the one hand, it increases the osmotic pressure of the soil solution, hinders the normal absorption of water by the root system, leading to physiological dehydration of the crop, and at the same time causes excessive accumulation of active oxygen, leading to oxidative damage; on the other hand, it reduces the chlorophyll content in the leaves, leading to a decrease in photosynthetic capacity and inhibiting the normal growth of the plant.

[0003] Saline-alkali soil improvement is an important issue for agricultural development, and researchers have explored various measures such as chemical improvement, physical improvement, and biological improvement. Saline-alkali soil is usually improved by physical methods such as soil covering and land management, biological methods such as phytoremediation and microbial remediation, and chemical methods such as application of organic fertilizer, humic acid, biomass charcoal, and conditioning agents, however, these improvement measures have certain limitations. Biochar, as a carbon-based porous material obtained by pyrolysis of organic matter such as agricultural waste and forestry residues under anaerobic or low-oxygen conditions, has characteristics such as high specific surface area, rich surface functional groups, and high porosity. However, the pH and salt content of biochar are generally high, and its application effect in saline-alkali soil improvement is still controversial. Therefore, the present application explores a biochar-based slow-release fertilizer in combination with biochar and microorganisms, which effectively improves saline-alkali soil and promotes the growth of plants. SUMMARY

[0004] The present application aims to provide a biochar-based slow-release fertilizer which effectively improves saline-alkali soil and promotes the growth of plants.

[0005] To achieve the above technical purposes, the technical solution adopted by the present application is as follows: A biochar-based slow-release fertilizer, comprising the following raw materials by weight: functionalized biochar 50-60 parts, composite microbial agent 8-10 parts, green plum extract 3-5 parts, slow-release nutrient component 30-40 parts, and bonding agent 5-7 parts. The composite microbial agent comprises Siberian Bacillus circulans, Abnormality Leptospore Mycelium of Caucasus, and Paraclostridium.

[0006] Further, the Siberian S. sphaeroides is purchased from China General Microbiological Culture Collection Center, the preservation number is CGMCC 1.12516, and the original preservation date is March 20, 2013; the abnormal L. arthrosporeum of Caucasus is purchased from China General Microbiological Culture Collection Center, the preservation number is CGMCC 3.6655, and the original preservation date is September 1, 2003; the B. paralicheniformis is purchased from China General Microbiological Culture Collection Center, the preservation number is CGMCC 1.15832, and the original preservation date is September 20, 2016.

[0007] Further, the preparation method of the complex microbial agent is as follows: (1) the Siberian S. sphaeroides and the B. paralicheniformis are respectively expanded and cultured by using LB culture medium, and the culture is ended when the OD 600 =3.0, and the Siberian S. sphaeroides fermentation liquor and the B. paralicheniformis fermentation liquor are obtained respectively; (2) the abnormal L. arthrosporeum of Caucasus is expanded and cultured by using PDA culture medium, and the culture is ended when the spore number reaches 1×10 8 CFU / mL by using a hemocytometer, and the abnormal L. arthrosporeum of Caucasus fermentation liquor is obtained; (3) the Siberian S. sphaeroides fermentation liquor, the B. paralicheniformis fermentation liquor and the abnormal L. arthrosporeum of Caucasus fermentation liquor are mixed according to the volume ratio of 1:1:1, and are freeze-dried into a freeze-dried powder to obtain the microbial agent, then the microbial agent is soaked in 10% sucrose solution for 2h, and 1% skimmed milk powder of the mass of the microbial agent is added and uniformly mixed to obtain the complex microbial agent.

[0008] Further, the mass ratio of the microbial agent to the 10% sucrose solution in the step (3) is 1:5.

[0009] Further, the preparation method of the functionalized biochar is as follows: the rice husk and bentonite are mixed according to the volume ratio of 4:1, pyrolyzed under oxygen-limited conditions at 500℃ for 1.5h, soaked in a 0.8mol / L citric acid solution for 3h after cooling, sprayed with 2% humic acid solution, and placed for 12h, and then dried to obtain the functionalized biochar.

[0010] Further, the slow-release nutrient component includes A component and B component; the preparation method of the A component is as follows: 100g of urea particles are placed in an oven and dried at 50℃ for 30 minutes, 1-2g of polyglutamic acid and 2-3g of humic acid are added into 50ml of deionized water, stirred at 50℃ for 30 minutes to form a uniform coating liquid; the dried urea is poured into a small fluidized bed coating machine, the temperature is set to 45-50℃, and the stirring rate is 30-50rpm, the coating liquid is uniformly sprayed on the surface of the urea particles, after the spraying is completed, the temperature and stirring are maintained, and the drying is continued for 1-2h to obtain the A component; The preparation method of the B component is: uniformly mixing potassium dihydrogen phosphate and ammonium sulfate at a mass ratio of 3:1 to obtain a potassium phosphate fertilizer, then mixing the potassium phosphate fertilizer with biochar, finally adding water to increase adhesion, drying and curing, passing through a 2mm sieve, and obtaining the B component.

[0011] Further, the mass ratio of the A component to the B component is 3:2; and the mass-volume ratio of the potassium phosphate fertilizer, biochar and water in the B component is 100g:5g:5mL.

[0012] Further, the binder is a 5% carboxymethyl cellulose sodium aqueous solution.

[0013] A preparation method of a biochar-based slow-release fertilizer, which is prepared by the following steps: uniformly stirring functionalized biochar and a composite microbial agent, adding slow-release nutrient components and green plum extract, spraying a binder every 5 minutes, spraying the binder for 3 times, feeding the mixture into a disc granulator, the granulation particle size is 3-5mm, and after granulation is completed, drying at 40 DEG C to obtain the final product biochar-based slow-release fertilizer.

[0014] The application also provides the application of the biochar-based slow-release fertilizer, and the biochar-based slow-release fertilizer is applied to improve saline-alkali soil and promote plant growth.

[0015] The application uses functionalized biochar, and the huge specific surface area and surface charge of the biochar can adsorb and fix Na⁺, Cl⁻ and other salt ions in soil solution, temporarily reduce the salt concentration in soil solution, and directly reduce the stress of salt on crop roots. The rice hull charcoal used in the formula is usually alkaline, but subsequent soaking with citric acid and spraying with humic acid can neutralize the alkalinity, so that it is more suitable for improving alkaline soil to effectively adjust pH. In addition, the porous structure of the biochar provides a breeding place for the subsequent addition of the composite microbial agent, and protects them from the harsh soil environment.

[0016] Siberian spore eight-polyhedron can survive in an environment with high pH and high salt concentration, and can produce organic acids in the metabolic process, which can neutralize the alkalinity of the soil, reduce the pH value of the soil, and make it close to neutral; the bacteria can also secrete extracellular polysaccharides and other sticky substances to bond small particles together to form soil aggregate structure, which can increase the porosity of the soil, improve the air permeability and water retention, and make the hardened and hard saline-alkali soil become loose, which is beneficial to the stretching of plant roots; in addition, it also has the effect of dissolving phosphorus, effectively dissolving the fixed phosphorus in the soil, and improving the fertilizer utilization rate.

[0017] The parabacillus aberrans can excrete osmoregulation substances such as proline to the outside of cells, which can help plants resist osmotic stress of saline-alkali land, maintain water in plant cells, and improve the stress resistance of plants; and can produce plant hormones IAA, which can directly stimulate plant cell division and elongation, promote root development, make plants more robust, and thus improve yield.

[0018] The mycelium of the abnormal entophlyctochaeta caucasica forms a huge network structure in the soil, binds small soil particles together to form a stable aggregate structure, effectively improves the soil hardening, and cooperates with the biochar to effectively improve the soil ventilation and water permeability; in addition, the huge mycelium network greatly increases the water absorption surface area of plants, helps plants to obtain water in the saline-alkali land with serious osmotic stress. Salt stress can produce a large amount of active oxygen to cause oxidative damage to plants, and the fungus can enhance the activity of antioxidant enzymes in plants and improve the stress resistance of plants.

[0019] The slow-release component includes A component and B component; wherein the A component sprays polyglutamic acid on the surface of urea to form a gel layer, effectively slows down the release of nutrients, and humic acid can also adjust the soil pH value and promote root absorption, and the combination of the two can simultaneously improve the slow-release property and effectiveness of urea; the B component fixes phosphorus and potassium fertilizer on the biochar, utilizes the adsorption property of biochar, also plays a role in slow-release and fixation reduction, and ensures that the phosphorus fertilizer can be more effectively utilized in the saline-alkali land which is prone to phosphorus fixation.

[0020] The green plum extract contains organic acids (such as citric acid) which can reduce the soil pH value, the organic acids can combine with sodium ions in the soil to form soluble complexes, promote salt leaching, and reduce the total salt content and harmful ion concentration of the soil. At the same time, it can activate the fixed nutrients in the soil, promote the release of phosphorus, potassium and other elements, and enhance the nutrient absorption of plants.

[0021] Beneficial effects The present application uses functional biochar, green plum extract and microbial activity to jointly neutralize the alkalinity of the soil, reduce the pH value, significantly improve the soil physical and chemical properties of the saline-alkali land and the stress resistance of plants, significantly improve the growth of plants and thus improve the yield; the slow-release technology of biochar in the present application ensures that the nutrients are slowly and stably released during the entire growth period of crops, avoids the rapid leaching of nutrients caused by irrigation or rainfall in the saline-alkali land, and also reduces the fertilizer fixation caused by unsuitable pH. DETAILED DESCRIPTION

[0023] The technical solutions of the present application are further described below in conjunction with specific embodiments, but are not limited thereto.

[0024] Embodiment 1, a biochar-based slow-release fertilizer, comprising the following raw materials by weight: functionalized biochar 50 parts, composite microbial agent 8 parts, green plum extract 3 parts, slow-release nutrient component 30 parts, binder 5 parts; The composite microbial agent comprises: S. sibirica, A. anomum, and B. paralicheniformis.

[0025] The S. sibirica has a preservation number of CGMCC 1.12516; the A. anomum has a preservation number of CGMCC 3.6655; and the B. paralicheniformis has a preservation number of CGMCC 1.15832.

[0026] The preparation method of the composite microbial agent is as follows: (1) S. sibirica and B. paralicheniformis are respectively expandedly cultured with LB medium, and the culture is ended when OD 600 =3.0, and S. sibirica fermentation liquor and B. paralicheniformis fermentation liquor are respectively obtained; (2) A. anomum is expandedly cultured with PDA medium, and the culture is ended when the spore number reaches 1×10 8 CFU / mL by using a hemocytometer, and A. anomum fermentation liquor is obtained; (3) S. sibirica fermentation liquor, B. paralicheniformis fermentation liquor, and A. anomum fermentation liquor are mixed in a volume ratio of 1:1:1, and the mixture is freeze-dried into a freeze-dried powder to obtain the microbial agent, then the microbial agent is soaked in 10% sucrose solution for 2 h, and 1% skimmed milk powder of the mass of the microbial agent is added and uniformly mixed to obtain the composite microbial agent.

[0027] In step (3), the mass ratio of the microbial agent to the 10% sucrose solution is 1:5.

[0028] The preparation method of the functionalized biochar is as follows: rice husk and bentonite are mixed in a volume ratio of 4:1, pyrolyzed at 500°C under oxygen-limited conditions for 1.5 h, soaked in a 0.8 mol / L citric acid solution for 3 h after cooling, sprayed with 2% humic acid solution, and then placed for 12 h, and dried to obtain the functionalized biochar.

[0029] The slow-release nutrient component comprises A component and B component; the preparation method of the A component is as follows: 100 g of urea particles are placed in an oven and dried at 50°C for 30 minutes, 1 g of polyglutamic acid and 2 g of humic acid are added to 50 ml of deionized water, stirred at 50°C for 30 minutes to form a uniform coating liquid; the dried urea is poured into a small-scale fluidized bed coating machine, the temperature is set to 45°C, and the stirring rate is set to 30 rpm, the coating liquid is uniformly sprayed on the surface of the urea particles, after the spraying is completed, the temperature and stirring are maintained, and the drying is continued for 1 h to obtain the A component; The preparation method of the B component is: mixing potassium dihydrogen phosphate and ammonium sulfate uniformly in a mass ratio of 3:1 to obtain a potassium phosphate fertilizer, then mixing the potassium phosphate fertilizer with biochar, finally adding water to increase adhesion, drying and curing, passing through a 2mm sieve to obtain the B component.

[0030] The mass ratio of the A component to the B component is 3:2; the mass-volume ratio of the potassium phosphate fertilizer, biochar and water in the B component is 100g:5g:5mL.

[0031] The binder is a 5% carboxymethyl cellulose sodium aqueous solution.

[0032] A preparation method of a biochar-based slow-release fertilizer, prepared by the following steps: uniformly stirring functionalized biochar and a composite microbial agent, adding slow-release nutrient components and green plum extract, spraying a binder every 5 minutes, the binder being sprayed for 3 times, feeding the mixture into a disc granulator, the granulation particle size being 3-5mm, drying at 40℃ after granulation is completed to obtain the final product biochar-based slow-release fertilizer.

[0033] Example 2, a biochar-based slow-release fertilizer, comprising the following raw materials by weight: functionalized biochar 55 parts, composite microbial agent 9 parts, green plum extract 4 parts, slow-release nutrient components 35 parts, binder 6 parts; The composite microbial agent comprises: S. sibirica, A. anomum and B. paralicheniformis.

[0034] The S. sibirica has a preservation number of CGMCC 1.12516; the A. anomum has a preservation number of CGMCC 3.6655; and the B. paralicheniformis has a preservation number of CGMCC 1.15832.

[0035] The preparation method of the composite microbial agent is: (1) separately expanding the culture of S. sibirica and B. paralicheniformis with LB medium, culturing until OD 600 =3.0, ending the culture, and obtaining S. sibirica fermentation liquor and B. paralicheniformis fermentation liquor respectively; (2) expanding the culture of A. anomum with PDA medium, counting with a hemocytometer, ending the culture when the spore number reaches 1×10 8 CFU / mL, and obtaining A. anomum fermentation liquor; (3) mixing the S. sibirica fermentation liquor, the B. paralicheniformis fermentation liquor and the A. anomum fermentation liquor according to a volume ratio of 1:1:1, freeze-drying to obtain a freeze-dried powder to obtain the microbial agent, then soaking the microbial agent in 10% sucrose solution for 2h, and adding 1% skimmed milk powder to the microbial agent to mix uniformly to obtain the composite microbial agent.

[0036] The mass ratio of the microbial agent to the 10% sucrose solution in the step (3) is 1:5.

[0037] The preparation method of the functionalized biochar is as follows: rice husks and bentonite are mixed at a volume ratio of 4:1, pyrolysis is carried out under oxygen-limited conditions at 500 DEG C for 1.5 h, after cooling, soaking is carried out in a 0.8 mol / L citric acid solution for 3 h, after drying, spraying is carried out with a 2% humic acid solution, and after standing for 12 h, drying is carried out to obtain the functionalized biochar.

[0038] The slow-release nutrient component comprises an A component and a B component; the preparation method of the A component is as follows: 100 g of urea particles are placed in an oven and dried at 50 DEG C for 30 min, 2 g of polyglutamic acid and 2 g of humic acid are added to 50 ml of deionized water, stirring is carried out at 50 DEG C for 30 min to form a uniform coating liquid; the dried urea is poured into a small-scale fluidized bed coating machine, the temperature is set to 50 DEG C, the stirring rate is 40 rpm, the coating liquid is uniformly sprayed on the surface of the urea particles, after the spraying is completed, the temperature and stirring are maintained, and drying is continued for 2 h to obtain the A component; The preparation method of the B component is as follows: potassium dihydrogen phosphate and ammonium sulfate are uniformly mixed at a mass ratio of 3:1 to obtain a phosphate-potassium fertilizer, the phosphate-potassium fertilizer is then mixed with biochar, and finally water is added to increase adhesion, drying and solidification are carried out, and the mixture is passed through a 2 mm sieve to obtain the B component.

[0039] The mass ratio of the A component to the B component is 3:2; the mass-volume ratio of the phosphate-potassium fertilizer, biochar and water in the B component is 100 g:5 g:5 ml.

[0040] The binder is a 5% carboxymethyl cellulose sodium aqueous solution.

[0041] A preparation method of a biochar-based slow-release fertilizer, prepared by the following steps: uniformly stirring functionalized biochar and a composite microbial agent, adding slow-release nutrient components and green plum extract, spraying a binder every 5 min, spraying the binder for 3 times, feeding the mixture into a disc granulator, the granulation particle size is 3-5 mm, after the granulation is completed, drying is carried out at 40 DEG C to obtain the final product biochar-based slow-release fertilizer.

[0042] Example 3, a biochar-based slow-release fertilizer, comprising the following raw materials by weight: functionalized biochar 60 parts, composite microbial agent 10 parts, green plum extract 5 parts, slow-release nutrient component 40 parts, and binder 7 parts; The composite microbial agent comprises: Paenibacillus sibiricus, Abnormal Cephalotrichium caucasium, and Brevibacillus parabiofilmis.

[0043] The S. sibirica has a preservation number of CGMCC 1.12516; the A. anomodochium has a preservation number of CGMCC 3.6655; and the B. paralicheniformis has a preservation number of CGMCC 1.15832.

[0044] The preparation method of the complex microbial agent is as follows: (1) The S. sibirica and the B. paralicheniformis are respectively expandedly cultured with LB medium, and the culture is ended when the OD 600 =3.0, and the S. sibirica fermentation liquor and the B. paralicheniformis fermentation liquor are respectively obtained; (2) The A. anomodochium is expandedly cultured with PDA medium, and the culture is ended when the spore number reaches 1×10 8 CFU / mL, and the A. anomodochium fermentation liquor is obtained; (3) The S. sibirica fermentation liquor, the B. paralicheniformis fermentation liquor and the A. anomodochium fermentation liquor are mixed according to a volume ratio of 1:1:1, and are freeze-dried into a freeze-dried powder to obtain the microbial agent, then the freeze-dried powder is soaked in 10% sucrose solution for 2h, and 1% skimmed milk powder is added to the microbial agent to obtain the complex microbial agent.

[0045] The mass ratio of the microbial agent to the 10% sucrose solution in the step (3) is 1:5.

[0046] The preparation method of the functionalized biochar is as follows: rice husks and bentonite are mixed according to a volume ratio of 4:1, pyrolysis is carried out under oxygen-limited conditions at 500℃ for 1.5h, the pyrolysis product is soaked in a 0.8mol / L citric acid solution for 3h after cooling, 2% humic acid solution is sprayed on the pyrolysis product after drying, and the pyrolysis product is left to stand for 12h, and the functionalized biochar is obtained after drying.

[0047] The slow-release nutrient component comprises an A component and a B component; the preparation method of the A component is as follows: 100g of urea particles are placed in an oven and dried at 50℃ for 30min, 1-2g of polyglutamic acid and 2-3g of humic acid are added to 50ml of deionized water, and the mixture is stirred at 50℃ for 30min to form a uniform coating liquid; the dried urea is poured into a small-scale fluidized bed coating machine, the temperature is set to 50℃, and the stirring rate is set to 50rpm, the coating liquid is uniformly sprayed on the surface of the urea particles, and after the spraying is completed, the temperature and stirring are maintained, and the drying is continued for 2h to obtain the A component. The preparation method of the B component is as follows: potassium dihydrogen phosphate and ammonium sulfate are uniformly mixed according to a mass ratio of 3:1 to obtain a phosphorus-potassium fertilizer, the phosphorus-potassium fertilizer is mixed with biochar, and finally water is added to increase adhesion, and the mixture is dried and solidified, and then sieved through a 2mm sieve to obtain the B component.

[0048] The mass ratio of component A to component B is 3:2; the mass-volume ratio of phosphorus and potassium fertilizer, biochar and water in component B is 100g:5g:5mL.

[0049] The binder is a 5% sodium carboxymethyl cellulose aqueous solution.

[0050] A method for preparing a biochar-based slow-release fertilizer comprises the following steps: mixing functionalized biochar with a compound microbial agent, adding slow-release nutrients and plum extract, spraying a binder every 5 minutes, and spraying the binder in 3 applications, feeding the mixture into a disc granulator, granulating the particles to a size of 3-5 mm, and drying at 40°C after granulation to obtain the final product, biochar-based slow-release fertilizer.

[0051] Comparative Example 1: Compared with Example 1, this comparative example changed the strains in the compound microbial agent to Siberian Bacillus and Caucasian Aberranty in a volume ratio of 1:1. All other raw materials and steps were the same as in Example 1.

[0052] Comparative Example 2: Compared with Example 1, this comparative example changed the strains in the compound microbial agent to Bacillus spp. Siberianis and Bacillus paralichrysogenum in a volume ratio of 1:1. All other raw materials and steps were the same as in Example 1.

[0053] Comparative Example 3: Compared with Example 1, this comparative example changed the strains in the compound microbial agent to Bacillus anomalae and Bacillus paralichrysum in a volume ratio of 1:1. All other raw materials and steps were the same as in Example 1.

[0054] Comparative Example 4: Compared with Example 1, this comparative example is identical to Example 1 except that the strain in the compound microbial agent is changed to only Bacillus siberianis.

[0055] Comparative Example 5: Compared with Example 1, this comparative example is identical to Example 1 except that the strain in the compound microbial agent is changed to only *Pseudomonas aeruginosa*.

[0056] Comparative Example 6: Compared with Example 1, this comparative example is identical to Example 1 except that the strain in the compound microbial agent is changed to Bacillus paralicheniformis.

[0057] Comparative Example 7: Compared with Example 1, this comparative example is identical to Example 1 except that no plum extract was added.

[0058] Performance testing Planting Trial The tested variety was Zhangshugang chili pepper, and the experimental site was coastal saline-alkali land. The soil physicochemical properties of the saline-alkali land were as follows: pH value 8.61, organic matter content 12.41 g / kg, and soil bulk density 1.6 g / cm³. 3, alkali-hydrolyzable nitrogen 62.38 mg / kg, available potassium 35.67 mg / kg, available phosphorus 25.49 mg / kg.

[0059] The experiment sets 11 treatments: using the biochar-based slow-release fertilizer of examples 1-3 and comparative examples 1-7 and the control conventional fertilization (compound fertilizer N-P2O5-K2O = 15-15-15, 40 kg / mu is applied), the slow-release fertilizer of each treatment group is applied at 200 kg / mu, each treatment is set with 3 repetitions, and the plot area is 100 m 2 , and is arranged randomly. The slow-release fertilizer of each treatment group is applied once before the colonization of the plants. The rest of the production management is the same as the conventional during the whole growth period.

[0060] In the fruiting period, 10 pepper plants of each treatment group are selected to measure the plant height, plant width and single plant fruiting number, and 10 pepper plants with similar growth vigor are selected to measure the fruit length and single fruit weight, and the plot yield is measured at the time of harvesting. The above data are shown in Table 1.

[0061] Table 1: Growth indexes and yield of peppers in each treatment group As shown in Table 1, the biochar-based slow-release fertilizer of examples 1-3 can effectively promote plant growth and improve pepper yield. It is shown that the biochar-based slow-release fertilizer of examples can effectively improve the soil physical and chemical properties of saline-alkali land and improve the stress resistance of plants, thereby significantly improving the growth of plants and further improving the yield. The comparative examples 1-7 change the microbial species and components in the biochar-based slow-release fertilizer, and the promotion effect on plants is reduced to different degrees, which shows that the microbial strains and Chinese plum extract are essential for the improvement of saline-alkali land and the stress resistance of plants.

[0062] After the peppers are picked, 0-20 cm soil samples are collected in each plot by using the five-point method, the pH value is tested by using the potential method, the soil conductivity is measured by using the conductance instrument method, the soil bulk density is measured by using the cutting ring method, the organic matter content is measured by using the potassium dichromate oxidation and heating method, the alkali-hydrolyzable nitrogen content is measured by using the alkali-hydrolyzation diffusion method, the available phosphorus content is measured by using the NaHCO3 extraction-molybdenum antimony resistance colorimetric method, and the soil available potassium content is measured by using the NH4OAC extraction-flame photometry method. The above detection data are shown in Table 2.

[0063] Table 2: Soil physical and chemical properties of each treatment group As shown in Table 2, the biochar-based slow-release fertilizer of examples 1-3 can improve the soil physical and chemical properties of saline-alkali land, which specifically shows that the pH value of saline-alkali land is effectively reduced, the soil conductivity is reduced, the bulk density is reduced, and the contents of organic matter, alkali-hydrolyzable nitrogen, available phosphorus and available potassium are increased.

[0064] It should be noted that the above-mentioned embodiments only illustrate some but not all of the preferred ways for implementing the present application. Obviously, based on the above-mentioned embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work should belong to the protection scope of the present application.

Claims

1. A biochar-based slow release fertilizer, characterized in that, Raw materials including the following weight parts: functionalized biochar 50-60 parts, composite microbial agent 8-10 parts, green plum extract 3-5 parts, slow-release nutrient component 30-40 parts, binder 5-7 parts; The composite microbial agent comprises: S. sibirica, A. anomodama, and B. paralicheniformis.

2. The biochar-based slow release fertilizer according to claim 1, characterized in that, The S. sibirica has a preservation number of CGMCC 1.12516, the A. anomodama has a preservation number of CGMCC 3.6655, and the B. paralicheniformis has a preservation number of CGMCC 1.15832.

3. The biochar-based slow release fertilizer of claim 1, wherein, The preparation method of the composite microbial agent is as follows: (1) Siberian spore eight ball and vice licheniformis were respectively expanded with LB medium, and the culture was ended when OD 600 =3.0, and Siberian spore eight ball fermentation broth and vice licheniformis fermentation broth were obtained respectively. (2) The L. gigantheron was expanded cultured with PDA medium, and the number of spores was counted with a hemocytometer. The culture was ended when the number of spores reached 1×10 8 CFU / mL, and the L. gigantheron fermentation broth was obtained. (3) The S. sibirica fermentation liquor, the B. paralicheniformis fermentation liquor, and the A. anomodama fermentation liquor are mixed in a volume ratio of 1:1:1, and are freeze-dried into a freeze-dried powder to obtain the microbial agent, then the microbial agent is soaked in 10% sucrose solution for 2 hours, and 1% skimmed milk powder of the mass of the microbial agent is added and uniformly mixed to obtain the composite microbial agent.

4. The biochar-based slow release fertilizer according to claim 3, characterized in that, In the step (3), the mass ratio of the microbial agent to the 10% sucrose solution is 1:

5.

5. The biochar-based slow release fertilizer of claim 1, wherein, The preparation method of the functionalized biochar is as follows: rice husks and bentonite are mixed in a volume ratio of 4:1, pyrolysis is performed under limited oxygen conditions at 500 DEG C for 1.5 hours, after cooling, the pyrolysis product is soaked in a 0.8 mol / L citric acid solution for 3 hours, after drying, the product is sprayed with a 2% humic acid solution, and is left to stand for 12 hours, and after drying, the functionalized biochar is obtained.

6. The biochar-based slow release fertilizer of claim 1, wherein, The slow-release nutrient component comprises A component and B component; the preparation method of the A component is as follows: 100 g of urea particles are placed in an oven and dried at 50 DEG C for 30 minutes, 1-2 g of polyglutamic acid and 2-3 g of humic acid are added to 50 ml of deionized water, and stirring is performed at 50 DEG C for 30 minutes to form a uniform coating liquid; the dried urea is poured into a small fluidized bed coating machine, the temperature is set to 45-50 DEG C, the stirring rate is 30-50 rpm, and the coating liquid is uniformly sprayed on the surface of the urea particles, after the spraying is completed, the temperature and stirring are maintained, and drying is continued for 1-2 hours to obtain the A component; The preparation method of the B component is as follows: potassium dihydrogen phosphate and ammonium sulfate are uniformly mixed in a mass ratio of 3:1 to obtain a phosphorus-potassium fertilizer, the phosphorus-potassium fertilizer is then mixed with biochar, and finally water is added to increase adhesion, drying and solidification are performed, and the product is passed through a 2 mm sieve to obtain the B component.

7. The biochar-based slow release fertilizer according to claim 6, characterized in that, The mass ratio of the A component to the B component is 3:2; and the mass-volume ratio of the phosphorus-potassium fertilizer, the biochar, and the water in the B component is 100 g:5 g:5 ml.

8. The biochar-based slow release fertilizer of claim 1, wherein, The binder is a 5% carboxymethyl cellulose sodium aqueous solution.

9. A method of producing the biochar-based slow release fertilizer according to any one of claims 1 to 8, characterized in that, The biochar-based slow-release fertilizer is prepared by the following steps: the functionalized biochar and the composite microbial agent are uniformly stirred, the slow-release nutrient component and the green plum extract are added, the binder is sprayed every 5 minutes, the spraying of the binder is completed in three times, the mixture is fed into a disc granulator, the granulation particle size is 3-5 mm, after the granulation is completed, drying is performed at 40 DEG C, and the final product, the biochar-based slow-release fertilizer, is obtained.

10. Use of the biochar-based slow release fertilizer according to any one of claims 1 to 8, characterized in that, The biochar-based slow-release fertilizer is applied to improve saline-alkali soil and promote plant growth.

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