A kind of growth-promoting microbial fertilizer specially used for saline-alkali land and preparation method thereof

Abstract

The invention discloses a special growth-promoting microbial fertilizer for saline-alkali land and a preparation method thereof, belonging to the technical field of growth-promoting microbial fertilizers, organic manure, ammonium humate, microbial agent particles, crop straw, slow-release phosphate fertilizer particles, hydroxyapatite, chitosan and citric acid are mixed in proportion to obtain a special growth-promoting microbial fertilizer for saline-alkali land; the granular microbial agent carrier of the invention uses biochar particles and iron-carbon composite microspheres as a matrix, and raw materials such as fly ash form a foamed porous adhesive substance under the action of alkali excitation, and the matrix such as biochar particles is bonded to help form a stable porous structure, provide a suitable environment for the growth of phosphate-solubilizing bacteria, and improve its phosphate-solubilizing growth-promoting effect. The microbial agent particles have good water absorption, can absorb sodium ions in the soil after watering, and the calcium and magnesium components contained in the fly ash-based adhesive substance can exchange with sodium ions to play a fixing role, thereby reducing the salt stress effect on crops.

Description

Technical Field

[0001] The invention belongs to the technical field of growth-promoting microbial fertilizers, and in particular relates to a special growth-promoting microbial fertilizer for saline-alkali land and a preparation method thereof. Background Art

[0002] Phosphorus is one of the essential nutrients for plant growth and development. It is generally present in high levels in the soil. However, more than 95% of phosphorus is ineffective phosphorus and cannot be directly absorbed and utilized by plants. Most cultivated soils are still in a phosphorus-deficient state, and phosphorus fertilizers still need to be applied during crop cultivation. If inorganic fertilizers are applied for a long time, the utilization rate of soil nutrients will decrease, and the yield of crops will also drop significantly. Ineffective phosphorus is due to the reaction of phosphorus with Ca 2+ , Fe 3+ , Fe 2+ 、Al 3+ They combine to form insoluble phosphates, and phosphate-solubilizing bacteria can convert the phosphorus that is difficult for these crops to absorb and utilize into an absorbable and utilizeable form. Therefore, the application of organic fertilizers containing phosphate-solubilizing bacteria can not only increase the soil organic matter content and improve soil structure, but also increase the utilization rate of phosphorus by crops such as soybeans and corn, thereby increasing crop yields.

[0003] Northern Anhui has a temperate monsoon climate, with warm and humid springs but cold and dry winters. Evaporation is strong, and the cold and dry climate promotes the development of saline-alkali land. Saline-alkali land is a special type of soil. The most notable feature of saline-alkali land is its high salt content and low soil fertility, which is not conducive to crop growth. Chemical or biological improvement is generally used. Biological improvement includes planting salt-tolerant plants and microbial agents.

[0004] Conventional microbial organic fertilizers have a general effect on improving saline-alkali land, and crop growth is still inhibited. Functional microorganisms such as phosphate-solubilizing bacteria find it difficult to fully exert their growth-promoting effects. Therefore, there is a need for a phosphate-solubilizing and growth-promoting microbial fertilizer that can reduce the stress of saline-alkali land on crops. Summary of the invention

[0005] The purpose of the present invention is to provide a special growth-promoting microbial fertilizer for saline-alkali land and a preparation method thereof. The growth-promoting microbial fertilizer containing raw materials such as bacterial agent particles can adsorb and fix salt in the soil, reduce the stress on crops, and synergistically enhance the phosphorus-solubilizing and growth-promoting effect of the microbial fertilizer.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A special growth-promoting microbial fertilizer for saline-alkali land, comprising the following raw materials by weight:

[0008] 40-50 parts of organic manure, 10-15 parts of ammonium humate, 8-12 parts of bacterial agent granules, 6-8 parts of crop straw, 4-5 parts of slow-release phosphate fertilizer granules, 4-5 parts of hydroxyapatite, 2-4 parts of chitosan and 0.5-1 part of citric acid.

[0009] Furthermore, the bacterial agent granules are prepared by the following steps:

[0010] Step 1: Inoculate Pseudomonas wilfordii WSX12P in LB liquid medium at a dosage of 1%, culture at 35°C and 180 r / min for 24 h to obtain seed solution, transfer the seed solution to 20 times the volume of LB liquid medium for expansion culture for 24 h, and then dilute with LB liquid medium until the number of viable bacteria is ≥ 2 × 10 9 cfu / mL, and obtain the phosphate-solubilizing bacteria solution.

[0011] Pseudomonas veronii WSX12P was deposited on February 7, 2023 at the General Microbiology Center of China Culture Collection Committee, Beijing, China, with the deposit number CGMCC NO.26519 and the classification name Pseudomonas veronii.

[0012] Step 2: Add biochar particles, fly ash, silicate cement, sepiolite fiber, water and potassium hydroxide as an alkali activator into the stirring tank, stir at a stirring speed of 150-250r / min for 10-15min, then add iron-carbon composite microspheres and sorbitan monostearate as a surfactant, stir for 2-3min, then add 26% hydrogen peroxide and continue stirring for 2-3min, pour the mixture into a mold and let it stand for 12-24h, transfer it to a constant temperature drying oven, high temperature curing at 70-80℃ for 24h, and crush it to obtain a granular bacterial agent carrier with a particle size of 0.4-0.8cm.

[0013] Step 3: Add the granular bacterial agent carrier and the phosphate-solubilizing bacteria solution into the fermentation tank at a mass ratio of 1:5-6, and carry out fixed culture at 30°C and 100-150r / min for 12-16h, filter, ventilate and dry to obtain bacterial agent granules.

[0014] Furthermore, in step 2, the mass ratio of the biochar particles, fly ash, silicate cement, sepiolite fiber, water, potassium hydroxide, iron-carbon composite microspheres, sorbitan monostearate and hydrogen peroxide is 10: 4-5: 0.8-1.2: 0.8-1.2: 2-4: 1: 1-1.5: 0.02-0.03: 0.2-0.3.

[0015] Furthermore, the iron-carbon composite microspheres are prepared by the following steps:

[0016] (1) Add polyether polyol, potassium oleate and deionized water into a reactor, stir for 15-20 min at 20-25°C and 300-500 r / min, then add glucose into the reactor, continue stirring for 20-30 min, use polyether polyol and potassium oleate as templates and glucose as carbon source, then keep the reaction at 175-185°C for 12 h, filter the reaction solution, wash the filter cake with deionized water for 2-3 times, transfer it to a tubular furnace, heat it to 750-800°C at a rate of 3-5°C / min, keep it for 100-120 min and cool it naturally to obtain hollow carbon spheres.

[0017] (2) Add the hollow carbon spheres and 10 times the volume of 10% hydrochloric acid into a stirring tank, stir at 200-300 r / min for 2-4 hours, centrifuge and filter, wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry to obtain pretreated hollow carbon spheres.

[0018] (3) The pretreated hollow carbon spheres and a 0.15 mol / L ferric chloride solution were added to a reactor, stirred at 200-300 r / min for 3-4 h, and then the pH value was adjusted to 10 with a 1 mol / L sodium hydroxide solution. The reaction was stirred at 75-85 °C for 8-10 h, and centrifuged and filtered. The filter cake was washed with deionized water until the last washing liquid was neutral, and vacuum dried to obtain iron-carbon composite microspheres.

[0019] Furthermore, the mass ratio of polyether polyol, potassium oleate, deionized water and glucose is 1:1.2:500-550:80-85.

[0020] Furthermore, the dosage ratio of the pretreated hollow carbon spheres and the ferric chloride solution is 1 g: 2-2.5 mL.

[0021] Furthermore, the slow-release phosphate fertilizer granules are prepared by the following steps:

[0022] Add oxidized starch and deionized water into a reactor, stir and gelatinize at 75-80°C and 200-300r / min for 20-30min, cool naturally, then add sodium tripolyphosphate and glycolic acid as a catalyst into the reactor, continue stirring for 5-10min, then stir and react at 65-70°C for 2.5-3h, then add gelling treatment liquid into the reactor, stir for 20-30min, evacuate and maintain pressure at 25-30°C for 1h, transfer the product into a mold, freeze-dry, and crush to obtain slow-release phosphate fertilizer granules.

[0023] Furthermore, the mass ratio of oxidized starch, deionized water, sodium tripolyphosphate, glycolic acid and gelling treatment liquid is 5:10:3-3.5:0.04-0.05:4-5.

[0024] Furthermore, the gel treatment liquid is obtained by mixing polyvinyl alcohol, gelatin and deionized water in a mass ratio of 1:1:20.

[0025] A method for preparing a growth-promoting microbial fertilizer specifically for saline-alkali land comprises the following steps:

[0026] Organic manure, ammonium humate, bacterial agent granules, crop straw, slow-release phosphate fertilizer granules, hydroxyapatite, chitosan and citric acid are mixed in a mass ratio of 40-50:10-15:8-12:6-8:4-5:4-5:2-4:0.5-1 to obtain a growth-promoting microbial fertilizer specifically for saline-alkali land.

[0027] Beneficial effects of the present invention:

[0028] 1. In the special growth-promoting microbial fertilizer for saline-alkali land of the present invention, organic manure can increase the soil aggregate structure and improve the soil's ability to retain water and fertilizer. Organic matter can produce acidic substances after being decomposed by microorganisms, thereby reducing the soil pH value, helping to reduce the accumulation of soil salt and alleviate the degree of salinization; ammonium humate has the ability to regulate the pH of the soil, enhance the soil's ability to retain water and fertilizer, and create good conditions for the growth of crop roots; crop straw can form an organic physical isolation layer in the soil, cut off the capillary connection inside the soil body, and prevent the salt in the bottom of the soil from moving upward; chitosan can significantly affect the soil environment and soil nutrient status, and alleviate the growth stress caused by saline-alkali land; citric acid can neutralize the alkaline components in the soil, improve the stress resistance of plants, reduce the toxic effects of salt on plants, and promote the development of plant roots, increase the absorption area of ​​the roots, and improve the absorption efficiency of plants for nutrients; hydroxyapatite and slow-release phosphate fertilizer particles can provide phosphorus to meet the growth requirements of crops requiring phosphorus.

[0029] 2. The granular bacterial agent carrier of the present invention uses biochar particles and iron-carbon composite microspheres as the matrix, and raw materials such as fly ash form a foamed porous adhesive substance under the action of alkali excitation, which bonds the biochar particles and other matrices, helps to form a stable porous structure, thereby facilitating the adsorption of more phosphate-solubilizing bacteria liquid, providing a suitable environment for the growth of phosphate-solubilizing bacteria, and improving its phosphate-solubilizing growth-promoting effect. The bacterial agent particles have good water absorption and can absorb sodium ions in the soil after watering, and the calcium and magnesium components contained in the fly ash-based adhesive substance can exchange with sodium ions to play a fixing role, thereby reducing the salt stress on crops.

[0030] Hollow carbon balls have a large specific surface area and more pores. The surface can load more magnetic nano-ferroferric oxide particles to form iron-carbon composite microspheres that can produce magnetic biological effects with phosphate-solubilizing bacteria, catalyze the decomposition of harmful substances in microbial metabolites, and improve the activity of phosphate-solubilizing bacteria and other microorganisms, thereby releasing more hyphae, effectively increasing the binding capacity of soil particles, promoting the formation of soil aggregates, and improving the growth-promoting effect of the microbial fertilizer.

[0031] 3. Iron-carbon composite microspheres can adsorb microplastics through electrostatic adsorption, avoid the inhibitory effect of excessive microplastics on crop growth, and reduce the enrichment of microplastics by crops. Therefore, the special growth-promoting microbial fertilizer for saline-alkali land of the present invention has application prospects in improving food security. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1: The present invention provides a growth-promoting microbial fertilizer specifically for saline-alkali land, which is prepared by the following method:

[0034] S1: Pseudomonas spp. WSX12P was inoculated into LB liquid medium at a dosage of 1%, and cultured at 35°C and 180 r / min for 24 h to obtain seed solution. The seed solution was transferred to 20 times the volume of LB liquid medium for expansion culture for 24 h, and then diluted with LB liquid medium until the number of viable bacteria was ≥ 2 × 10 9 cfu / mL, and obtain the phosphate-solubilizing bacteria solution.

[0035] Pseudomonas wolskii WSX12P was deposited in the General Microbiology Center of China Committee for Microbiological Culture Collection on February 7, 2023, with the deposit number CGMCC NO.26519.

[0036] S2: Add 10kg of polyether polyol, 12kg of potassium oleate and 5000kg of deionized water into the reactor, stir for 15min at 20℃ and 300r / min, then add 800kg of glucose into the reactor, continue stirring for 20min, use polyether polyol and potassium oleate as templates and glucose as carbon source, then keep the reaction at 175℃ for 12h, filter the reaction liquid, wash the filter cake twice with deionized water, transfer it to a tubular furnace, heat to 750℃ at a rate of 3℃ / min, keep it warm for 100min and cool it naturally to obtain hollow carbon spheres.

[0037] S3: Add hollow carbon spheres and 10 times the volume of 10% hydrochloric acid into a stirring kettle, stir at 200 r / min for 2 hours, centrifuge and wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry to obtain pretreated hollow carbon spheres; add 10 kg of pretreated hollow carbon spheres and 20 L of 0.15 mol / L ferric chloride solution into a reactor, stir at 200 r / min for 3 hours, then adjust the pH value to 10 with 1 mol / L sodium hydroxide solution, stir and react at 75°C for 8 hours, centrifuge and wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry to obtain iron-carbon composite microspheres.

[0038] S4: Add 10kg of biochar particles, 4kg of fly ash, 0.8kg of Portland cement, 0.8kg of sepiolite fiber, 2kg of water and 1kg of potassium hydroxide as an alkali activator into a stirring tank, stir for 10 minutes at a stirring speed of 150r / min, then add 1kg of iron-carbon composite microspheres and 0.02kg of sorbitan monostearate as a surfactant, stir for 2 minutes, then add 0.2kg of 26% hydrogen peroxide and continue stirring for 2 minutes, pour the mixture into a mold and let it stand for 12 hours, transfer it to a constant temperature drying oven, high temperature cure at 70°C for 24 hours, and crush it to obtain a granular bacterial agent carrier with a particle size of 0.4-0.8cm.

[0039] S5: Add 10 kg of granular bacterial agent carrier and 50 kg of phosphate-solubilizing bacteria liquid into the fermentation tank, immobilize and culture for 12 h at 30°C and 100 r / min, filter, ventilate and dry to obtain bacterial agent granules.

[0040] S6: Polyvinyl alcohol, gelatin and deionized water are mixed in a mass ratio of 1:1:20 to obtain a gelling treatment liquid; 5 kg of oxidized starch and 10 kg of deionized water are added into a reactor, and the mixture is stirred for gelatinization at 75°C and 200 r / min for 20 minutes, and the mixture is cooled naturally. Then, 3 kg of sodium tripolyphosphate and 0.04 kg of glycolic acid as a catalyst are added into the reactor, and the stirring is continued for 5 minutes. Then, the mixture is stirred for reaction at 65°C for 2.5 hours, and then 4 kg of the gelling treatment liquid is added into the reactor. After stirring for 20 minutes, the mixture is vacuumed and pressure-maintained at 25°C for 1 hour. The product is transferred into a mold for freeze-drying and crushing to obtain slow-release phosphate fertilizer granules.

[0041] S7: Evenly mix 40 kg of organic manure, 10 kg of ammonium humate, 8 kg of bacterial agent granules, 6 kg of crop straw, 4 kg of slow-release phosphate fertilizer granules, 4 kg of hydroxyapatite, 2 kg of chitosan and 0.5 kg of citric acid to obtain a growth-promoting microbial fertilizer specifically for saline-alkali land.

[0042] Example 2: The present invention provides a growth-promoting microbial fertilizer specifically for saline-alkali land, which is prepared by the following method:

[0043] S1: Pseudomonas spp. WSX12P was inoculated into LB liquid medium at a dosage of 1%, and cultured at 35°C and 180 r / min for 24 h to obtain seed solution. The seed solution was transferred to 20 times the volume of LB liquid medium for expansion culture for 24 h, and then diluted with LB liquid medium until the number of viable bacteria was ≥ 2 × 10 9 cfu / mL, and obtain the phosphate-solubilizing bacteria solution.

[0044] S2: Add 10kg of polyether polyol, 12kg of potassium oleate and 5200kg of deionized water into the reactor, stir for 18min at 22℃ and 400r / min, then add 820kg of glucose into the reactor, continue stirring for 25min, use polyether polyol and potassium oleate as templates and glucose as carbon source, then keep warm at 180℃ for 12h, filter the reaction liquid, wash the filter cake twice with deionized water, transfer it to a tubular furnace, heat to 760℃ at a rate of 4℃ / min, keep warm for 110min and cool naturally to obtain hollow carbon spheres.

[0045] S3: Add hollow carbon spheres and 10 times the volume of 10% hydrochloric acid into a stirring kettle, stir at 250r / min for 3h, centrifuge and wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry to obtain pretreated hollow carbon spheres; add 10kg of pretreated hollow carbon spheres and 22L of 0.15mol / L ferric chloride solution into a reactor, stir at 250r / min for 3.5h, then adjust the pH value to 10 with 1mol / L sodium hydroxide solution, stir and react at 80℃ for 9h, centrifuge and wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry to obtain iron-carbon composite microspheres.

[0046] S4: Add 10kg of biochar particles, 4.5kg of fly ash, 0.9kg of silicate cement, 0.9kg of sepiolite fiber, 3kg of water and 1kg of potassium hydroxide as an alkali activator into the stirring tank, stir for 12 minutes at a stirring speed of 200r / min, then add 1.2kg of iron-carbon composite microspheres and 0.025kg of sorbitan monostearate as a surfactant, stir for 2 minutes, then add 0.2kg of 26% hydrogen peroxide and continue stirring for 2 minutes, pour the mixture into a mold and let it stand for 16 hours, transfer it to a constant temperature drying oven, high temperature cure at 75°C for 24 hours, and crush it to obtain a granular bacterial agent carrier with a particle size of 0.4-0.8cm.

[0047] S5: 10 kg of granular bacterial agent carrier and 55 kg of phosphate-solubilizing bacteria liquid were added into the fermentation tank, fixedly cultured at 30°C and 120 r / min for 14 h, filtered, ventilated and dried to obtain bacterial agent granules.

[0048] S6: Polyvinyl alcohol, gelatin and deionized water are mixed in a mass ratio of 1:1:20 to obtain a gelling treatment liquid; 5 kg of oxidized starch and 10 kg of deionized water are added into a reactor, stirred and gelatinized at 78°C and 250 r / min for 25 minutes, cooled naturally, and then 3.2 kg of sodium tripolyphosphate and 0.045 kg of glycolic acid as a catalyst are added into the reactor, and stirring is continued for 8 minutes, and then stirring and reacting at 68°C for 2.8 hours, and then 4.5 kg of gelling treatment liquid is added into the reactor, and after stirring for 25 minutes, vacuum is drawn and pressure is maintained at 28°C for 1 hour, and the product is transferred to a mold for freeze drying and crushing to obtain slow-release phosphate fertilizer granules.

[0049] S7: 44 kg of organic manure, 12 kg of ammonium humate, 10 kg of bacterial agent granules, 7 kg of crop straw, 4.5 kg of slow-release phosphate fertilizer granules, 4.5 kg of hydroxyapatite, 3 kg of chitosan and 0.8 kg of citric acid are mixed evenly to obtain a growth-promoting microbial fertilizer specifically for saline-alkali land.

[0050] Example 3: The present invention provides a growth-promoting microbial fertilizer specifically for saline-alkali land, which is prepared by the following method:

[0051] S1: Pseudomonas spp. WSX12P was inoculated into LB liquid medium at a dosage of 1%, and cultured at 35°C and 180 r / min for 24 h to obtain seed solution. The seed solution was transferred to 20 times the volume of LB liquid medium for expansion culture for 24 h, and then diluted with LB liquid medium until the number of viable bacteria was ≥ 2 × 10 9 cfu / mL, and obtain the phosphate-solubilizing bacteria solution.

[0052] S2: Add 10kg of polyether polyol, 12kg of potassium oleate and 5300kg of deionized water into the reactor, stir for 18min at 22℃ and 400r / min, then add 830kg of glucose into the reactor, continue stirring for 25min, use polyether polyol and potassium oleate as templates and glucose as carbon source, then keep warm at 180℃ for 12h, filter the reaction liquid, wash the filter cake with deionized water for 3 times, transfer it to a tubular furnace, heat to 780℃ at a rate of 4℃ / min, keep warm for 110min and cool naturally to obtain hollow carbon spheres.

[0053] S3: Add hollow carbon spheres and 10 times the volume of 10% hydrochloric acid into a stirring kettle, stir at 250r / min for 3h, centrifuge and wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry to obtain pretreated hollow carbon spheres; add 10kg of pretreated hollow carbon spheres and 22L of 0.15mol / L ferric chloride solution into a reactor, stir at 250r / min for 3.5h, then adjust the pH value to 10 with 1mol / L sodium hydroxide solution, stir and react at 80℃ for 9h, centrifuge and wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry to obtain iron-carbon composite microspheres.

[0054] S4: Add 10kg of biochar particles, 4.5kg of fly ash, 1kg of Portland cement, 1kg of sepiolite fiber, 3kg of water and 1kg of potassium hydroxide as an alkali activator into a stirring tank, stir for 12 minutes at a stirring speed of 200r / min, then add 1.4kg of iron-carbon composite microspheres and 0.025kg of sorbitan monostearate as a surfactant, stir for 3 minutes, then add 0.3kg of 26% hydrogen peroxide and continue stirring for 3 minutes, pour the mixture into a mold and let it stand for 20 hours, transfer it to a constant temperature drying oven, high temperature cure at 75°C for 24 hours, and crush it to obtain a granular bacterial agent carrier with a particle size of 0.4-0.8cm.

[0055] S5: 10 kg of granular bacterial agent carrier and 5 kg of phosphate-solubilizing bacteria liquid were added into the fermentation tank, fixedly cultured for 15 h at 30°C and 130 r / min, filtered, ventilated and dried to obtain bacterial agent granules.

[0056] S6: Polyvinyl alcohol, gelatin and deionized water are mixed in a mass ratio of 1:1:20 to obtain a gelling treatment liquid; 5 kg of oxidized starch and 10 kg of deionized water are added into a reactor, and the mixture is stirred for gelatinization at 78°C and 250 r / min for 25 minutes, and the mixture is cooled naturally. Then, 3.3 kg of sodium tripolyphosphate and 0.048 kg of glycolic acid as a catalyst are added into the reactor, and the stirring is continued for 8 minutes. Then, the mixture is stirred for reaction at 68°C for 2.8 hours, and then 4.6 kg of the gelling treatment liquid is added into the reactor. After stirring for 25 minutes, the mixture is vacuumed and pressure-maintained at 28°C for 1 hour. The product is transferred into a mold for freeze-drying and crushing to obtain slow-release phosphate fertilizer granules.

[0057] S7: 48 kg of organic manure, 13 kg of ammonium humate, 11 kg of bacterial agent granules, 7 kg of crop straw, 4.5 kg of slow-release phosphate fertilizer granules, 4.5 kg of hydroxyapatite, 3.2 kg of chitosan and 0.8 kg of citric acid are mixed evenly to obtain a growth-promoting microbial fertilizer specifically for saline-alkali land.

[0058] Example 4: The present invention provides a growth-promoting microbial fertilizer specifically for saline-alkali land, which is prepared by the following method:

[0059] S1: Pseudomonas spp. WSX12P was inoculated into LB liquid medium at a dosage of 1%, and cultured at 35°C and 180 r / min for 24 h to obtain seed solution. The seed solution was transferred to 20 times the volume of LB liquid medium for expansion culture for 24 h, and then diluted with LB liquid medium until the number of viable bacteria was ≥ 2 × 10 9 cfu / mL, and obtain the phosphate-solubilizing bacteria solution.

[0060] S2: Add 10kg of polyether polyol, 12kg of potassium oleate and 5500kg of deionized water into the reactor, stir for 20min at 25℃ and 500r / min, then add 850kg of glucose into the reactor, continue stirring for 30min, use polyether polyol and potassium oleate as templates and glucose as carbon source, then keep the reaction at 185℃ for 12h, filter the reaction liquid, wash the filter cake with deionized water for 3 times, transfer it to a tubular furnace, heat to 800℃ at a rate of 5℃ / min, keep it warm for 120min and cool it naturally to obtain hollow carbon spheres.

[0061] S3: Add hollow carbon spheres and 10 times the volume of 10% hydrochloric acid into a stirring kettle, stir at 300 r / min for 4 hours, centrifuge and wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry to obtain pretreated hollow carbon spheres; add 10 kg of pretreated hollow carbon spheres and 25 L of 0.15 mol / L ferric chloride solution into a reactor, stir at 300 r / min for 4 hours, then adjust the pH value to 10 with 1 mol / L sodium hydroxide solution, stir and react at 85°C for 10 hours, centrifuge and wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry to obtain iron-carbon composite microspheres.

[0062] S4: Add 10kg biochar particles, 5kg fly ash, 1.2kg Portland cement, 1.2kg sepiolite fiber, 4kg water and 1kg potassium hydroxide as an alkali activator into the stirring tank, stir for 15min at a stirring speed of 250r / min, then add 1.5kg iron-carbon composite microspheres and 0.03kg sorbitan monostearate as a surfactant, stir for 3min, then add 0.3kg hydrogen peroxide with a mass fraction of 26% and continue stirring for 3min, pour the mixture into a mold and let it stand for 24h, transfer it to a constant temperature drying oven, high temperature cure at 80℃ for 24h, and crush it to obtain a granular bacterial agent carrier with a particle size of 0.4-0.8cm.

[0063] S5: Add 10 kg of granular bacterial agent carrier and 60 kg of phosphate-solubilizing bacteria liquid into the fermentation tank, immobilize and culture for 16 hours at 30°C and 150 r / min, filter, ventilate and dry to obtain bacterial agent granules.

[0064] S6: Polyvinyl alcohol, gelatin and deionized water are mixed in a mass ratio of 1:1:20 to obtain a gelling treatment liquid; 5 kg of oxidized starch and 10 kg of deionized water are added into a reactor, and the mixture is stirred for gelatinization at 80°C and 300 r / min for 30 minutes, and naturally cooled. Then, 3.5 kg of sodium tripolyphosphate and 0.05 kg of glycolic acid as a catalyst are added into the reactor, and the stirring is continued for 10 minutes. Then, the mixture is stirred for reaction at 70°C for 3 hours, and then 5 kg of gelling treatment liquid is added into the reactor. After stirring for 30 minutes, the mixture is vacuumed and pressure-maintained at 30°C for 1 hour. The product is transferred into a mold for freeze-drying and crushing to obtain slow-release phosphate fertilizer granules.

[0065] S7: Evenly mix 50 kg of organic manure, 15 kg of ammonium humate, 12 kg of bacterial agent granules, 8 kg of crop straw, 5 kg of slow-release phosphate fertilizer granules, 5 kg of hydroxyapatite, 4 kg of chitosan and 1 kg of citric acid to obtain a growth-promoting microbial fertilizer specifically for saline-alkali land.

[0066] The LB liquid culture medium used in the embodiment includes 10 g / L tryptone, 5 g / L yeast extract and 10 g / L sodium chloride; the organic manure is purchased from Nantong Zhongren Biofertilizer Co., Ltd.; the crop straw is corn straw; the hydroxyapatite is micron-sized powder; and the remaining raw materials are all commercially available products.

[0067] Comparative Example 1: Based on Example 4, the iron-carbon composite microspheres prepared in step S3 are not added in step S4, and the other steps remain unchanged to prepare a saline-alkali land growth-promoting microbial fertilizer.

[0068] Comparative Example 2: Based on Example 4, in step S4, the iron-carbon composite microspheres are replaced with hollow carbon spheres of the same mass in step S2, and the other steps remain unchanged to prepare a saline-alkali land growth-promoting microbial fertilizer.

[0069] Comparative Example 3: Based on Example 4, in step S5, the granular bacterial agent carrier is replaced with biochar particles of the same mass, and the other steps remain unchanged to prepare a saline-alkali land growth-promoting microbial fertilizer.

[0070] Preparation of samples: Select a transparent polyvinyl chloride tube with an inner diameter of 60 mm and a length of 120 mm, set a 300-mesh nylon mesh at the bottom of the tube and fill it with 15 cm thick fine river sand, and mix the different saline-alkali land-specific growth-promoting microbial fertilizers in Example 1-Example 4 and Comparative Example 1-Comparative Example 3 with the test soil (taken from Yongqiao District, Suzhou City, Anhui Province) in a mass ratio of 1:15 to obtain test soil samples, and then take the same mass of test soil samples and fill them into the tube, the distance between the upper surface of the test soil sample and the top of the tube is <10 cm, and then fill the tube with 5 cm thick fine river sand, and seal the top with a 300-mesh nylon mesh to obtain different samples.

[0071] Polystyrene fluorescent microsphere group: polystyrene fluorescent microspheres were dispersed in deionized water to prepare a polystyrene dispersion with a mass concentration of 20 mg / mL. The fluorescence intensity was determined to be 400 a.u. under the conditions of excitation wavelength of 455 nm, emission wavelength of 510 nm and slit width of 10 nm by fluorescence spectrophotometry. Three groups of samples were placed in a 1L flask at the bottom of the sample. 500 mL of polystyrene dispersion was poured from the top of the sample until no liquid dripped from the bottom of the sample. The fluorescence intensity of the liquid in the cup was detected under the same conditions by fluorescence spectrophotometry to judge the adsorption effect on polystyrene fluorescent microspheres. The smaller the fluorescence intensity, the better the adsorption effect on microplastics.

[0072] Sodium chloride group: add 1L of sodium chloride solution with a mass concentration of 0.5mol / L into a container with a cover, place different samples horizontally in the sodium chloride solution for 1h, and then hang them until no liquid drips from the bottom of the sample, and detect the concentration of sodium ions in the liquid in the container. The lower the concentration, the better the adsorption effect of salt.

[0073] The two groups of test results were averaged three times, and the adsorption results of each sample on different pollution sources are shown in the following table:

[0074] Table 1 Adsorption results of each sample on different pollution sources

[0075]

[0076] It can be seen from Table 1 that after the sample adsorption in Examples 1 to 4, the fluorescence intensity of the liquid in the beaker in the polystyrene fluorescent microsphere group is low. Combining Comparative Examples 1 and 2, it is shown that the iron-carbon composite microspheres loaded with magnetic nano-ferroferric oxide have a good adsorption effect on the polystyrene fluorescent microspheres, and the fluorescence intensity in Comparative Example 3 is further improved, indicating that the three-dimensional porous structure of the inoculant particles also has an adsorption effect on the fluorescent microspheres.

[0077] The sodium ion concentration of the liquid in the container in Comparative Example 3 is higher, while the sodium ion concentration of the liquid in the container after adsorption of the other samples is lower. This is because the adhesive material composed of the matrix such as fly ash contains more calcium and magnesium substances, which have a better replacement and fixation effect on sodium ions.

[0078] Comparative Example 4: Based on Example 3, the slow-release phosphate fertilizer granules are replaced with sodium tripolyphosphate of the same mass in step S7, and the other steps remain unchanged to prepare a saline-alkali land growth-promoting microbial fertilizer.

[0079] A pot test was conducted on Example 4 and Comparative Examples 1 to 4. The test soil and different saline-alkali soil growth-promoting microbial fertilizers were mixed evenly at a mass ratio of 5:1, and one group was not mixed with saline-alkali soil growth-promoting microbial fertilizers as a blank control. There were 6 test groups in total, each group was repeated 6 times, a total of 36 pots, and each pot was filled with 3 kg of test soil. Polystyrene fluorescent microspheres and sodium chloride were used for treatment, and a corn pot test was conducted under the stress of 5 g / kg sodium chloride and 5 g / kg polystyrene fluorescent microspheres.

[0080] Four corn seeds (Zhongyu 335) were sown in each pot. After germination, water was sprayed with a watering can every day to ensure that the soil moisture content was 70%. Four weeks after germination, the average plant height, maximum root length, and dry weight of the aboveground and underground parts of each pot of corn were measured. The agronomic indicators of the potted test corn plants are shown in the following table:

[0081] Table 2 Agronomic index results of corn plants in potted test

[0082]

[0083] It can be seen from Table 2 that after using the saline-alkali soil growth-promoting microbial fertilizer in Example 4, the agronomic indicators of the corn seedlings are better than those of Comparative Examples 1 to 4 and the blank control. The agronomic indicators in Comparative Example 4 are slightly worse because sodium tripolyphosphate is more soluble under higher soil moisture, and thus is lost too quickly. The slow-release phosphate fertilizer granules can improve the utilization rate of phosphorus.

[0084] The agronomic indicators in Comparative Examples 1 and 2 are poor, which may be because the iron-carbon composite microspheres added in the examples can adsorb polystyrene microplastics and prevent microplastics from inhibiting the growth of corn. Combined with Comparative Example 3, it may be because the biological activity of phosphate-solubilizing bacteria in the microbial agent particles under this structure is better, which can convert more phosphorus into a form that can be absorbed by corn seedlings, thereby improving the growth-promoting effect.

[0085] It should be noted that, in this article, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0086] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A growth-promoting microbial fertilizer specially used for saline-alkali land, characterized in that: The following raw materials are included by mass: 40-50 parts of organic manure, 10-15 parts of ammonium humate, 8-12 parts of bacterial agent granules, 6-8 parts of crop straw, 4-5 parts of slow-release phosphate fertilizer granules, 4-5 parts of hydroxyapatite, 2-4 parts of chitosan and 0.5-1 part of citric acid; The bacterial agent granules are prepared by the following steps: Step 1: add biochar particles, fly ash, silicate cement, sepiolite fiber, water and potassium hydroxide as an alkali activator into a stirring kettle, stir at a stirring speed of 150-250r / min for 10-15min, then add iron-carbon composite microspheres and sorbitan monostearate as a surfactant, stir for 2-3min, then add 26% hydrogen peroxide and continue stirring for 2-3min, pour the mixture into a mold and let it stand for 12-24h, transfer it to a constant temperature drying oven, high temperature curing at 70-80℃ for 24h, and crush it to obtain a granular bacterial agent carrier with a particle size of 0.4-0.8cm; Step 2: Add the granular bacterial agent carrier and the phosphate-solubilizing bacteria solution into the fermentation tank at a mass ratio of 1:5-6, and immobilize and culture for 12-16 hours at 30°C and 100-150r / min, filter, ventilate and dry to obtain bacterial agent granules; The mass ratio of the biochar particles, fly ash, silicate cement, sepiolite fiber, water, potassium hydroxide, iron-carbon composite microspheres, sorbitan monostearate and hydrogen peroxide in step 1 is 10: 4-5: 0.8-1.2: 0.8-1.2: 2-4: 1: 1-1.5: 0.02-0.03: 0.2-0.3; The slow-release phosphate fertilizer granules are prepared by the following steps: Add oxidized starch and deionized water into a reactor, stir and gelatinize at 75-80°C and 200-300r / min for 20-30min, cool naturally, then add sodium tripolyphosphate and glycolic acid as a catalyst into the reactor, continue stirring for 5-10min, then stir and react at 65-70°C for 2.5-3h, then add gelling treatment liquid into the reactor, stir for 20-30min, evacuate and maintain pressure at 25-30°C for 1h, transfer the product into a mold, freeze-dry, and crush to obtain slow-release phosphate fertilizer granules.

2. The growth-promoting microbial fertilizer for saline-alkali land according to claim 1, characterized in that: The phosphate-solubilizing bacteria solution is prepared by the following steps: Pseudomonas wilfordii WSX12P was inoculated into LB liquid medium at a dosage of 1%, and cultured at 35°C and 180 r / min for 24 h to obtain seed solution. The seed solution was transferred to 20 times the volume of LB liquid medium for expansion culture for 24 h, and then diluted with LB liquid medium until the number of viable bacteria was ≥ 2 × 10 9 cfu / mL, and obtain the phosphate-solubilizing bacteria solution.

3. The growth-promoting microbial fertilizer for saline-alkali land according to claim 1, characterized in that: The iron-carbon composite microspheres are prepared by the following steps: The pretreated hollow carbon spheres and a 0.15 mol / L ferric chloride solution were added to a reaction kettle, stirred at 200-300 r / min for 3-4 h, then the pH value was adjusted to 10 with a 1 mol / L sodium hydroxide solution, stirred at 75-85° C. for 8-10 h, centrifuged, and the filter cake was washed with deionized water until the last washing liquid was neutral, and vacuum dried to obtain iron-carbon composite microspheres; The dosage ratio of the pretreated hollow carbon spheres to the ferric chloride solution is 1 g: 2-2.5 mL.

4. The growth-promoting microbial fertilizer for saline-alkali land according to claim 3, characterized in that: The pretreated hollow carbon spheres are prepared by the following steps: The hollow carbon spheres and 10 times the volume of 10% hydrochloric acid by mass were added into a stirring tank, stirred at 200-300 r / min for 2-4 hours, centrifuged and filtered, the filter cake was washed with deionized water until the last washing liquid was neutral, and vacuum dried to obtain pretreated hollow carbon spheres.

5. The growth-promoting microbial fertilizer for saline-alkali land according to claim 4, characterized in that: The hollow carbon spheres are prepared by the following steps: Add polyether polyol, potassium oleate and deionized water into a reactor, stir for 15-20 min at 20-25°C and 300-500 r / min, then add glucose into the reactor, continue stirring for 20-30 min, use polyether polyol and potassium oleate as templates and glucose as carbon source, then keep the temperature at 175-185°C for 12 h, filter the reaction solution, wash the filter cake with deionized water for 2-3 times, transfer to a tubular furnace, heat to 750-800°C at a rate of 3-5°C / min, keep the temperature for 100-120 min and cool naturally to obtain hollow carbon spheres; The mass ratio of the polyether polyol, potassium oleate, deionized water and glucose is 1:1.2:500-550:80-85.

6. The growth-promoting microbial fertilizer for saline-alkali land according to claim 1, characterized in that: The mass ratio of the oxidized starch, deionized water, sodium tripolyphosphate, glycolic acid and gelling treatment liquid is 5:10:3-3.5:0.04-0.05:4-5.

7. The growth-promoting microbial fertilizer for saline-alkali land according to claim 1, characterized in that: The gel treatment liquid is obtained by mixing polyvinyl alcohol, gelatin and deionized water in a mass ratio of 1:1:

20.

8. The method for preparing a growth-promoting microbial fertilizer specifically for saline-alkali land according to claim 1, comprising the following steps: Organic manure, ammonium humate, bacterial agent granules, crop straw, slow-release phosphate fertilizer granules, hydroxyapatite, chitosan and citric acid are mixed in a mass ratio of 40-50:10-15:8-12:6-8:4-5:4-5:2-4:0.5-1 to obtain a growth-promoting microbial fertilizer specifically for saline-alkali land.

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