Poly-amino acid type compound microbial organic fertilizer for crop planting and preparation method thereof

Abstract

The present invention discloses a polyamino acid-type composite microbial organic fertilizer for crop planting in the technical field of organic fertilizers and a preparation method thereof, which comprises the following components in parts by weight: 20-30 parts of modified biochar, 150-200 parts of animal manure, 20-30 parts of sodium humate, 1-2 parts of composite bacterial agent, 10-15 parts of mineral powder, and 10-20 parts of modified polyglutamic acid. By adding a composite bacterial agent to the organic fertilizer, the present invention is beneficial to improving the fermentation efficiency and maturity degree of the organic fertilizer and the soil fertility. The present invention also modifies the biochar and polyglutamic acid to improve the competitive adsorption performance of the soil for the biochar and polyglutamic acid, reduce the fixation effect of the soil on glutamic acid, and thus improve the biological availability of glutamic acid small molecules to crops.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic fertilizers, and specifically refers to a polyamino acid-based compound microbial organic fertilizer for crop planting and a preparation method thereof. Background Art

[0002] The use of a large amount of chemical fertilizers can quickly and effectively increase the grain yield per unit area. However, the long-term excessive application of chemical fertilizers results in the residue of excessive chemical fertilizers in the soil, leading to soil compaction and a reduction in the soil microbial population, ultimately causing a decline in soil fertility, and a decrease in the quality and yield of agricultural products. Compared with traditional chemical fertilizers, a new type of fertilizer adds effective auxiliaries to form a new variety of fertilizer that is more efficient and environmentally friendly, which can improve the soil environment and enhance the sustainable development ability of the land. Common new fertilizer varieties include coated controlled-release fertilizers, urea-formaldehyde controlled-release fertilizers, water-soluble compound fertilizers, stable compound fertilizers, alginic acid compound fertilizers, amino acid compound fertilizers, microbial compound fertilizers, organic compound fertilizers, soil conditioners, etc. The controlled-release compound fertilizer mainly controls the release rate of fertilizer nutrients by different coating materials, while taking into account the long-term needs of crop growth in the later stage; the water-soluble compound fertilizer is applied by directly dissolving the product in water and spraying it on the leaves or soil surface of the crop, which is convenient and simple; alginic acid compound fertilizers, amino acid compound fertilizers, organic compound fertilizers, and microbial compound fertilizers are essentially organic-inorganic compound fertilizers, and the production process is generally a wet process, with differences in the formula and mixing process of organic and inorganic components;

[0003] In amino acid compound fertilizers, the organic component mainly consists of amino acids. Amino acids commonly used in fertilizers include glutamic acid and aspartic acid. γ-Polyglutamic acid is formed by the polymerization of D-glutamic acid and L-glutamic acid through an amide bond between the α-amino group and γ-carboxyl group, forming an anionic polymer. Through the hydrophilic carboxyl group and peptide bond on the main chain, it undergoes main chemical reactions, having good water absorption, adsorption, and biodegradability. Polyaspartic acid is a water-soluble protein that can be used as a synergist for new fertilizers, which can enhance the absorption of nitrogen, phosphorus, potassium, and trace elements by crops, thereby improving the quality of fruits, and also has good degradability. However, due to the high cost of polyglutamic acid and polyaspartic acid, they are mostly used as drug carriers in the body. When polyamino acids degrade in farmland soil to form amino acid monomers, the biological availability of amino acid monomers to farmland crops is poor, and the role played in crop growth is small, resulting in a waste of cost. Summary of the Invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a polyamino acid type compound microbial organic fertilizer for crop planting and a preparation method thereof. In order to solve the problem of improving the biological effectiveness of the amino acid fertilizer after degradation, the present invention adds a compound microbial agent to the organic fertilizer, which is beneficial to improving the fermentation efficiency and maturity degree of the organic fertilizer and is beneficial to improving the soil fertility. The present invention also modifies biochar and polyglutamic acid, and adopts a method to improve the competitive adsorption performance of the soil for biochar and polyglutamic acid, reduce the fixation effect of the soil on glutamic acid, and thus improve the biological effectiveness of the crop to small molecule glutamic acid.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows: The present invention provides a polyamino acid type compound microbial organic fertilizer for crop planting and a preparation method thereof. The organic fertilizer comprises the following components in parts by weight:

[0006] Modified biochar 20-30 parts, animal manure 150-200 parts, sodium humate 20-30 parts, compound microbial agent 1-2 parts, mineral powder 10-15 parts, modified polyglutamic acid 10-20 parts;

[0007] Preferably, the compound microbial agent comprises the following components in parts by weight: Bacillus licheniformis 10-15 parts, Bacillus subtilis 5-10 parts, Bacillus thuringiensis 8-12 parts, Bacillus amyloliquefaciens 2-5 parts;

[0008] Preferably, the viable bacteria concentration of Bacillus licheniformis in the compound microbial agent is 3×10 8 CFU / g - 5×10 8 CFU / g, the viable bacteria concentration of Bacillus subtilis is 7×10 8 CFU / g - 8×10 8 CFU / g, the viable bacteria concentration of Bacillus thuringiensis is 3×10 8 CFU / g - 5×10 8 CFU / g, the viable bacteria concentration of Bacillus amyloliquefaciens is 5×10 8 CFU / g - 8×10 8 CFU / g;

[0009] Preferably, the mineral powder comprises the following components in parts by weight: medical stone 8-12 parts, bentonite 10-15 parts, phosphate rock powder 5-10 parts, mica powder 2-5 parts;

[0010] Preferably, the animal manure includes at least one of chicken manure, pig manure, sheep manure, and cow manure;

[0011] The present invention also provides a preparation method of a polyamino acid type compound microbial organic fertilizer for crop planting, which specifically comprises the following steps:

[0012] S1, mixing animal feces and humic acid to obtain a fermentation premix;

[0013] S2, dissolving the composite bacterial agent in deionized water, adding the mixture to the fermentation premix prepared in step S1, mixing evenly, and performing composting fermentation treatment at a composting temperature of 50-55° C., and fermenting at a constant temperature for 24-36 hours to obtain a fermentation product;

[0014] S3, after the fermentation product prepared in S2 is evenly mixed with the mineral powder, the modified biochar and the modified polyglutamic acid are added, the mixture is fully mixed, and the mixture is dried and then crushed. The particle size after crushing is 0.3-0.5 mm, and a polyamino acid type composite microbial organic fertilizer is obtained;

[0015] Preferably, in step S2, the mass concentration of the composite bacterial agent in deionized water is 5-10 g / L;

[0016] Preferably, the method for preparing the modified biochar comprises the following steps:

[0017] S31, placing the crop straw in a ventilated environment at room temperature for natural air drying, crushing and passing through a 2 mm sieve to obtain straw powder;

[0018] S32, placing the straw powder prepared in step S31 in a high-temperature tube furnace for heat treatment, with a program heating parameter of heating to 500-800°C at 10°C / min, and keeping the temperature for 1-3h to obtain straw biochar;

[0019] S33, mixing the straw biochar prepared in step S33 with a nitric acid solution, raising the reaction temperature to 60-70° C., reacting for 1-1.5 hours, washing with deionized water, and drying to obtain modified biochar;

[0020] Preferably, in step S31, the crop straw includes at least one of corn straw, wheat straw, barley straw, sorghum straw, and rape straw;

[0021] Preferably, in step S33, the volume fraction of the nitric acid solution is 60-65%;

[0022] Preferably, in step S33, the mass volume ratio of the straw biochar to the nitric acid solution is 1:30-50 g / mL;

[0023] Preferably, the preparation method of the modified polyglutamic acid specifically comprises the following steps:

[0024] S34. Add an aqueous NaOH solution dropwise to glutamic acid, heat to 200 - 220 °C, and react for 2 - 4 h. After the reaction is completed, place it in a dialysis bag and dialyze with deionized water for 2 d. After freeze-drying, polyglutamic acid is obtained, and the molecular weight of the polyglutamic acid is 5 - 10 kDa;

[0025] S35. Dissolve the polyglutamic acid prepared in step S34 in deionized water, place it under an ice-water bath condition, add EDC and NHS, stir and react, add a long-chain alkyl primary amine compound solution, continue stirring, and react for 24 - 36 h at room temperature. Then place it in a dialysis bag and perform dialysis treatment with deionized water. After freeze-drying, modified polyglutamic acid is obtained; Preferably, in step S34, the mass ratio between the glutamic acid and the aqueous NaOH solution is 10:1 - 2; the mass fraction of NaOH in the aqueous NaOH solution is 40 - 50%;

[0026] Preferably, in step S35, the mass concentration of the polyglutamic acid in deionized water is 20 - 30 g / L;

[0027] Preferably, in step S35, the mass ratio of the added mass of EDC to the mass of polyglutamic acid is 2 - 2.5:1, and the added amount of NHS to the mass of polyglutamic acid is 1 - 1.5:1;

[0028] Preferably, in step S35, the long-chain alkyl primary amine compound includes at least one of n-octylamine, n-decylamine, and n-dodecylamine. The long-chain alkyl primary amine compound is a solution of the long-chain alkyl primary amine compound dissolved in dimethyl sulfoxide, wherein the mass concentration of the long-chain alkyl primary amine compound is 40 - 60 g / L;

[0029] Preferably, in step S35, the mass ratio between the long-chain alkyl compound and the polyglutamic acid is 1 - 2:10.

[0030] The beneficial effects achieved by the present invention are as follows:

[0031] The present invention provides an amino acid row composite microbial organic fertilizer for crop planting and a preparation method thereof. By adding a composite bacterium agent to the organic fertilizer in the present invention, it is beneficial to improve the fermentation efficiency and maturity degree of the organic fertilizer, and beneficial to the improvement of soil fertility. The present invention also modifies biochar and polyglutamic acid, and adopts methods to improve the competitive adsorption performance of the soil for biochar and polyglutamic acid, reduce the fixation effect of the soil on glutamic acid, thereby improving the biological availability of glutamic acid small molecules to crops; in the organic fertilizer of the present invention, a composite bacterium agent is added, and this bacterium agent is composed of multiple types of bacteria, which can decompose different substances in the organic fertilizer and improve the maturity degree and fermentation efficiency of the organic fertilizer; by nitrating and modifying the biochar in the present invention, it is possible to increase the rich active sites on the surface of the biochar, and an adsorption effect can be generated with the soil through electrostatic force and intermolecular hydrogen bond interaction; the modified polyglutamic acid forms an amide bond through the carboxyl group on polyglutamic acid and the amino group on the long-chain alkyl primary amine. Due to the grafting treatment through the amide bond, the long-chain alkyl can protect the carboxyl group on polyglutamic acid from being fixed by the soil. During the long-term existence in the soil environment, the amide bond and the peptide bond on the main chain of polyglutamic acid form glutamic acid monomers under the action of hydrolase, which can be free in the soil pore water. Due to the competitive adsorption of the modified biochar and polyglutamic acid in the soil, the fixation adsorption of the soil on polyglutamic acid or glutamic acid monomers is reduced, so that more glutamic acid can exist in the soil pore water, and thus it is easily absorbed by the crop roots, improving the biological availability of glutamic acid to crops. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the infrared spectrum of the modified polyglutamic acid prepared in Example 1 of the present invention;

[0033] Figure 2 It is the result graph of the glutamic acid content in the soil treated with the organic fertilizers described in Examples 1 - 3 and Comparative Examples 1 - 3;

[0034] Figure 3 It is the result graph of the glutamic acid content in the soil treated with the organic fertilizers described in Examples 1 - 3 and Comparative Examples 1 - 3;

[0035] Figure 4 It is the result graph of the nitrogen fertilizer utilization rate after applying the organic fertilizers described in Examples 1 - 3 and Comparative Examples 1 - 3.

[0036] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to the described content can be applied to the present invention. The preferred methods and materials described herein are only for illustrative purposes and do not limit the content of this application.

[0039] The experimental methods in the following embodiments are all conventional methods unless otherwise specified; the test materials and test strains used in the following embodiments are all obtained from commercial channels unless otherwise specified.

[0040] The sources of the strains used in the present invention are as follows:

[0041] Bacillus licheniformis, deposited in the China Center of Industrial Culture Collection (CICC), with the deposit number CICC 10092;

[0042] Bacillus subtilis, deposited in the China Center of Industrial Culture Collection (CICC), with the deposit number CICC 10085;

[0043] Bacillus thuringiensis, deposited in the China Center of Industrial Culture Collection (CICC), with the deposit number CICC 10060;

[0044] Bacillus amyloliquefaciens, deposited in the China Center of Industrial Culture Collection (CICC), with the deposit number CICC 20469;

[0045] Example 1

[0046] This example provides a polyamino acid type compound microbial organic fertilizer for crop planting. The organic fertilizer includes the following components in parts by weight:

[0047] 20 parts of modified biochar, 150 parts of sheep manure, 20 parts of sodium humate, 1 part of compound microbial agent, 15 parts of mineral powder, and 20 parts of modified polyglutamic acid;

[0048] The composite bacterial agent includes the following components by weight: 15 parts of Bacillus licheniformis, with a live bacteria concentration of 5×10 8 CFU / g, 5 parts of Bacillus subtilis, and the concentration of live bacteria was 7×10 8 CFU / g, 10 copies of Bacillus thuringiensis, and the concentration of live bacteria is 4×10 8 CFU / g, 5 copies of Bacillus amyloliquefaciens, and the concentration of live bacteria was 7×10 8 CFU / g;

[0049] The mineral powder comprises the following components in parts by weight: 10 parts of medical stone, 15 parts of bentonite, 10 parts of phosphate rock powder, and 5 parts of mica powder;

[0050] This embodiment also provides a method for preparing a polyamino acid type composite microbial organic fertilizer for crop planting, which specifically comprises the following steps:

[0051] S1, the sheep manure and humic acid are fully mixed to form a pile for subsequent composting fermentation treatment to obtain a fermentation premix;

[0052] S2, preparing each bacterial agent in the composite bacterial agent by weight, adding deionized water to dissolve it at a mass concentration of 10 g / L, adding it to the fermentation premix prepared in step S1, and performing composting fermentation treatment, maintaining the core temperature of the compost at 50° C., and fermenting at a constant temperature for 36 hours to obtain a fermentation product;

[0053] S3, preparing each component in the mineral powder according to weight parts, mixing it evenly with the fermentation product prepared in step S2, adding modified biochar and modified polyglutamic acid, stirring and mixing, and after drying, crushing the fertilizer to a particle size of 0.5 mm to obtain a polyamino acid type composite microbial organic fertilizer;

[0054] The preparation method of modified biochar specifically comprises the following steps:

[0055] S31, placing the corn stalks in a ventilated environment at room temperature for natural air drying, crushing and passing through a 2 mm sieve to obtain stalk powder;

[0056] S32, placing the straw powder prepared in step S31 into a high-temperature tube furnace, introducing nitrogen, raising the temperature to 600° C. at 10° C. / min in a nitrogen atmosphere, keeping the temperature for 2 hours, and then naturally cooling the reaction system to room temperature to obtain straw biochar;

[0057] S33, prepare a nitric acid aqueous solution with a volume fraction of 60%, fully mix 500 mL of the nitric acid aqueous solution with 10 g of the straw biochar prepared in step S32, raise the temperature to 60°C, stir the reaction at 150 rpm for 1.5 hours, filter, remove the filtrate, repeatedly wash the solid with deionized water to remove residual nitric acid, place in an oven, and dry at 40°C to constant weight to obtain modified biochar;

[0058] The preparation method of the modified polyamino acid specifically comprises the following steps:

[0059] S34, accurately weigh 10g of glutamic acid in a beaker, prepare a NaOH aqueous solution according to a mass fraction of 40%, take 1mL and slowly add it dropwise to the glutamic acid, after the glutamic acid is fully soaked, transfer it to a muffle furnace, raise the temperature to 200°C, after the reaction is completed, cool the reaction system to room temperature, stir the reactants, and then transfer them to a dialysis bag and dialyze them with deionized water for 2 days. After freeze-drying, polyglutamic acid is obtained, and the polyglutamic acid is analyzed by gel permeation chromatography, and its molecular weight is 5734Da;

[0060] S35. Accurately weigh 10 g of polyglutamic acid prepared in step S34, add 500 mL of deionized water and stir until the polyglutamic acid is fully dissolved in the deionized water, transfer to an ice-water bath, add 25 g of EDC and 15 g of NHS, and stir fully for 20 min at a stirring speed of 150 rpm. Accurately weigh 2 g of n-dodecylamine and dissolve it in 50 mL of dimethyl sulfoxide, slowly add it to the reaction system in the ice-water bath, transfer to room temperature, and continue stirring the reaction for 24 h. After the reaction is completed, use a dialysis bag with a molecular weight cutoff of 20 kDa to dialyze with deionized water for 3 days, and freeze-dry to obtain modified polyglutamic acid.

[0061] Figure 1 The infrared spectrum of the modified polyglutamic acid prepared in Example 1, wherein Curve 1 is the polyglutamic acid prepared in step S34, and Curve 2 is the modified polyglutamic acid prepared in step S35. As shown in the figure, in Curves 1 and 2, 1670-1640cm -1 The stretching vibration peak of C=O appears between 1550-1530cm -1 The bending vibration peaks of CN and NH appeared between 1410-1390cm -1 The absorption peak of CO bond appears between 2880-2860cm in curve 2. -1 2930-2910cm -1 The stretching vibration peak of the CH of the long-chain alkyl group appears.

[0062] Example 2

[0063] This embodiment provides a polyamino acid type composite microbial organic fertilizer for crop planting, the organic fertilizer comprising the following components in parts by weight:

[0064] 30 parts of modified biochar, 180 parts of sheep manure, 30 parts of sodium humate, 2 parts of composite bacterial agent, 10 parts of mineral powder, 15 parts of modified polyglutamic acid;

[0065] The composite bacterial agent includes the following components by weight: 12 parts of Bacillus licheniformis, with a live bacteria concentration of 3×10 8 CFU / g, 8 copies of Bacillus subtilis, and the concentration of live bacteria is 8×10 8 CFU / g, 8 copies of Bacillus thuringiensis, and the concentration of live bacteria was 3×10 8 CFU / g, 2 parts of Bacillus amyloliquefaciens, and the concentration of live bacteria was 5×10 8 CFU / g;

[0066] The mineral powder comprises the following components in parts by weight: 8 parts of medical stone, 12 parts of bentonite, 7 parts of phosphate rock powder, and 3 parts of mica powder;

[0067] This embodiment also provides a method for preparing a polyamino acid type composite microbial organic fertilizer for crop planting, which specifically comprises the following steps:

[0068] S1, the sheep manure and humic acid are fully mixed to form a pile for subsequent composting fermentation treatment to obtain a fermentation premix;

[0069] S2, preparing each bacterial agent in the composite bacterial agent by weight, adding deionized water to dissolve it at a mass concentration of 5 g / L, adding it to the fermentation premix prepared in step S1, and performing composting fermentation treatment, maintaining the core temperature of the compost at 55° C., and fermenting at a constant temperature for 24 hours to obtain a fermentation product;

[0070] S3, preparing each component in the mineral powder according to weight parts, mixing it evenly with the fermentation product prepared in step S2, adding modified biochar and modified polyglutamic acid, stirring and mixing, and after drying, crushing the fertilizer to a particle size of 0.3 mm to obtain a polyamino acid type composite microbial organic fertilizer;

[0071] The preparation method of modified biochar specifically comprises the following steps:

[0072] S31, placing the corn stalks in a ventilated environment at room temperature for natural air drying, crushing and passing through a 2 mm sieve to obtain stalk powder;

[0073] S32, placing the straw powder prepared in step S31 into a high-temperature tube furnace, introducing nitrogen, raising the temperature to 500° C. at 10° C. / min in a nitrogen atmosphere, keeping the temperature for 3 hours, and then naturally cooling the reaction system to room temperature to obtain straw biochar;

[0074] S33, prepare a nitric acid aqueous solution with a volume fraction of 65%, fully mix 300 mL of the nitric acid aqueous solution with 10 g of the straw biochar prepared in step S32, raise the temperature to 70°C, stir at 150 rpm for 1 hour, filter, remove the filtrate, repeatedly wash the solid with deionized water to remove residual nitric acid, place in an oven, and dry at 40°C to constant weight to obtain modified biochar;

[0075] The preparation method of the modified polyamino acid specifically comprises the following steps:

[0076] S34, accurately weigh 10g of glutamic acid in a beaker, prepare a NaOH aqueous solution according to a mass fraction of 50%, take 2mL and slowly add it dropwise to the glutamic acid, after the glutamic acid is fully soaked, transfer it to a muffle furnace, raise the temperature to 220°C, after the reaction is completed, cool the reaction system to room temperature, stir the reactants, and then transfer them to a dialysis bag and dialyze them with deionized water for 2 days. After freeze-drying, polyglutamic acid is obtained, and the polyglutamic acid is analyzed by gel permeation chromatography, and its molecular weight is 8291Da;

[0077] S35. Accurately weigh 15 g of polyglutamic acid prepared in step S34, add 500 mL of deionized water and stir until the polyglutamic acid is fully dissolved in the deionized water, transfer to an ice water bath, add 30 g of EDC and 15 g of NHS, and stir fully for 20 min at a stirring speed of 150 rpm. Accurately weigh 3 g of n-octylamine and dissolve it in 50 mL of dimethyl sulfoxide, and slowly add it to the reaction system in the ice water bath. After transferring to room temperature, continue stirring and reacting for 36 hours. After the reaction is completed, use a dialysis bag with a molecular weight cutoff of 20 kDa to dialyze with deionized water for 3 days. After freeze-drying, modified polyglutamic acid is obtained.

[0078] Example 3

[0079] This embodiment provides a polyamino acid type composite microbial organic fertilizer for crop planting, the organic fertilizer comprising the following components in parts by weight:

[0080] 25 parts of modified biochar, 200 parts of sheep manure, 25 parts of sodium humate, 2 parts of composite bacterial agent, 12 parts of mineral powder, 10 parts of modified polyglutamic acid;

[0081] The composite bacterial agent includes the following components by weight: 10 parts of Bacillus licheniformis, with a live bacteria concentration of 4×10 8 CFU / g, 10 copies of Bacillus subtilis, and the concentration of live bacteria is 7×10 8 CFU / g, 12 copies of Bacillus thuringiensis, and the concentration of live bacteria was 5×10 8 CFU / g, 3 parts of Bacillus amyloliquefaciens, and the concentration of live bacteria was 8×10 8 CFU / g;

[0082] The mineral powder comprises the following components in parts by weight: 12 parts of medical stone, 10 parts of bentonite, 5 parts of phosphate rock powder, and 2 parts of mica powder;

[0083] This embodiment also provides a method for preparing a polyamino acid type composite microbial organic fertilizer for crop planting, which specifically comprises the following steps:

[0084] S1, the sheep manure and humic acid are fully mixed to form a pile for subsequent composting fermentation treatment to obtain a fermentation premix;

[0085] S2, preparing each bacterial agent in the composite bacterial agent by weight, adding deionized water to dissolve it at a mass concentration of 8 g / L, adding it to the fermentation premix prepared in step S1, and performing composting fermentation treatment, maintaining the core temperature of the compost at 53° C., and fermenting at a constant temperature for 30 hours to obtain a fermentation product;

[0086] S3, preparing each component in the mineral powder according to weight parts, mixing it evenly with the fermentation product prepared in step S2, adding modified biochar and modified polyglutamic acid, stirring and mixing, and after drying, crushing the fertilizer to a particle size of 0.4 mm to obtain a polyamino acid type composite microbial organic fertilizer;

[0087] The preparation method of modified biochar specifically comprises the following steps:

[0088] S31, placing the corn stalks in a ventilated environment at room temperature for natural air drying, crushing and passing through a 2 mm sieve to obtain stalk powder;

[0089] S32, placing the straw powder prepared in step S31 into a high-temperature tube furnace, introducing nitrogen, raising the temperature to 800° C. at 10° C. / min in a nitrogen atmosphere, keeping the temperature for 1 hour, and then naturally cooling the reaction system to room temperature to obtain straw biochar;

[0090] S33, prepare a nitric acid aqueous solution with a volume fraction of 60%, fully mix 400 mL of the nitric acid aqueous solution with 10 g of the straw biochar prepared in step S32, raise the temperature to 65°C, stir the reaction at a speed of 150 rpm for 1.5 hours, filter, remove the filtrate, repeatedly wash the solid with deionized water to remove residual nitric acid, place in an oven, and dry at 40°C to constant weight to obtain modified biochar;

[0091] The preparation method of the modified polyamino acid specifically comprises the following steps:

[0092] S34. Weigh exactly 10 g of glutamic acid into a beaker, prepare an aqueous NaOH solution according to a mass fraction of 50%, take 2 mL and slowly add it drop by drop to the glutamic acid. After fully wetting the glutamic acid, transfer it to a muffle furnace, raise the temperature to 212 °C. After the reaction is completed and the reaction system is cooled to room temperature, halve the reactants, then transfer them to a dialysis bag and dialyze with deionized water for 2 days. After freeze-drying, polyglutamic acid is obtained. Analyze the polyglutamic acid using a gel permeation chromatograph, and its molecular weight is 6734 Da;

[0093] S35. Weigh exactly 10 g of the polyglutamic acid prepared in step S34, add 500 mL of deionized water and stir until the polyglutamic acid is fully dissolved in the deionized water. Transfer it to an ice-water bath, add 20 g of EDC and 10 g of NHS, and stir thoroughly at a stirring speed of 150 rpm for 20 min. Weigh exactly 2 g of n-decylamine and dissolve it in 40 mL of dimethyl sulfoxide, and slowly add it to the reaction system in the ice-water bath. After transferring to room temperature, continue to stir and react for 36 h. After the reaction is completed, use a dialysis bag with a cut-off molecular weight of 20 kDa and dialyze with deionized water for 3 days. After freeze-drying, modified polyglutamic acid is obtained.

[0094] Comparative Example 1

[0095] This comparative example provides an organic fertilizer and its preparation method. The only difference from Example 1 is that in the organic fertilizer components, ordinary straw biochar is used instead of modified biochar, that is, unmodified straw biochar. In the preparation method of the organic fertilizer, step S33 is not included, and the other components and preparation methods are the same as those in Example 1.

[0096] Comparative Example 2

[0097] This comparative example provides an organic fertilizer and its preparation method. The only difference from Example 1 is that in the organic fertilizer components, ordinary commercially available polyglutamic acid is used instead of modified polyglutamic acid (purchased from Xuankai Biotechnology Co., Ltd., Nanjing, China, with a purity of 92% and an average molecular weight of 100 kDa). In the preparation method of the organic fertilizer, steps S34 and S35 are not included, and the other components and preparation methods are the same as those in Example 1.

[0098] Comparative Example 3

[0099] This comparative example provides an organic fertilizer and its preparation method. The only difference from Example 1 is that in the organic fertilizer components, ordinary straw biochar is used instead of modified biochar, and ordinary commercially available polyglutamic acid is used instead of modified polyglutamic acid. In the preparation method of the organic fertilizer, steps S33 - S35 are not included, and the other components and preparation methods are the same as those in Example 1.

[0100] Experimental Example 1

[0101] This experimental example measured the effects of the organic fertilizers prepared in Examples 1 - 3 and Comparative Examples 1 - 3 on soil fertility. After polyglutamic acid enters the soil environment, the hydrolases produced by soil microorganisms can catalyze and break the peptide bonds in polyglutamic acid, resulting in a large number of glutamic acid monomers being free in the soil environment. Glutamic acid monomers are electronegative, and soil particles can adsorb glutamic acid into the soil through electrostatic forces, intermolecular forces, etc. There are various substances in the soil, such as organic matter, clay minerals, etc. Therefore, the occurrence state of free glutamic acid monomers in the soil may change according to the changes in the soil environment. The adsorption of a large amount of organic matter and clay minerals in the soil on glutamic acid monomers is irreversible, that is, glutamic acid is fixed in soil particles and it is difficult to desorb glutamic acid by natural means. Therefore, the amount of free glutamic acid decreases significantly. Plants can absorb the glutamic acid monomers present in the free pore water between soil particles. This experimental example separated the pore water in the soil treated with Examples 1 - 3 and Comparative Examples 1 - 3 and measured the content of glutamic acid therein.

[0102] The tested soil was collected from Xiaoxian County, Suzhou City, Anhui Province. The soil type is sandy loam, and its soil physical and chemical properties are as follows:

[0103] Soil pH Organic matter Total nitrogen Clay content Silt content Sand content Sandy loam 7.84 8.66 g / kg 0.05 g / kg 15.93 8.91 75.61

[0104] The organic fertilizer and the tested soil were mixed at a mass ratio of 1:100. During the mixing process, 200 mL of deionized water was sprayed. After mixing evenly, at room temperature, according to the light cycle of 16 h / 8 h (light / dark) and light intensity μmol / m 2 / s, it was left standing for 14 d, and an appropriate amount of deionized water was added every day to maintain the soil humidity.

[0105] After standing for 14 d, the soil pore water was collected and the content of glutamic acid monomers therein was measured. The specific method was as follows: Glass wool fibers were filled at the bottom of the syringe, and then 10 g of the treated soil was added. The syringe was transferred to a centrifuge tube and centrifuged at a speed of 8000 rpm for 20 min. The pore water at the bottom of the centrifuge tube was collected and passed through an aqueous phase filter membrane to obtain a sample. The total nitrogen content in the soil was measured by the Kjeldahl method, with the blank soil as a control.

[0106] Figure 2 It is the result graph of the glutamic acid content in the soil treated with the organic fertilizers described in Examples 1 - 3 and Comparative Examples 1 - 3. As shown in the figure, after the soil was treated with the organic fertilizers described in Examples 1 - 3, the nitrogen content in the soil pore water was significantly higher than that in the comparative example treatment. In the case of no addition of exogenous nitrogen, the nitrogen source was provided by free glutamic acid. It can be seen that in the example treatment, the free glutamic acid monomers are difficult to be fixed by soil colloid particles.

[0107] Experimental Example 2

[0108] This experimental example conducted field plot tests on the fertilizers described in Examples 1-3 and Comparative Examples 1-3 to study the effect of organic fertilizers on the growth of green vegetables. The organic fertilizers described in Examples 1-3 and Comparative Examples 1-3 were used as basal fertilizers, and superphosphate and potassium chloride were used to supplement the missing parts of phosphate and potassium fertilizers. The plot area was set to 1 m 2 , and thinning was carried out after the plants grew three leaves. After the green vegetables grew to maturity, samples were taken for measuring various indicators and recording. The nitrogen fertilizer utilization rate was calculated according to the following formula:

[0109] Nitrogen fertilizer utilization rate (%) = (nitrogen content in the treatment group - nitrogen content in the blank group) × dry weight of the plant / nitrogen application rate × 100%.

[0110] Figure 3 is the total nitrogen content of the plants measured after applying the organic fertilizers described in Examples 1-2 and Comparative Examples 1-3, Figure 4 is the result graph of the nitrogen fertilizer utilization rate after applying the organic fertilizers described in Examples 1-3 and Comparative Examples 1-3. As shown in the figure, among the organic fertilizers described in the examples, the total nitrogen content of the plants is significantly higher than that of the plants in the treatment groups of the comparative examples. The nitrogen fertilizer utilization rate ranges from 31.37% to 33.43%. In the treatment groups of the organic fertilizers described in the comparative examples, the nitrogen fertilizer utilization rate of the plants is relatively low. This shows that the organic fertilizers prepared in the examples can improve the fertilizer utilization rate, promote the absorption of crop nutrients, and improve the soil environment.

[0111] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0112] The above describes the present invention and its implementation manners. This description is not restrictive. What is shown in the drawings is only one of the implementation manners of the present invention, and the actual application is not limited thereto. Generally speaking, if those of ordinary skill in the art are inspired by it and design similar ways and embodiments without creative efforts without departing from the purpose of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. Polyamino acid type composite microbial organic fertilizer for crop planting, characterized by: The organic fertilizer comprises the following components in parts by weight: 20-30 parts of modified biochar, 150-200 parts of animal manure, 20-30 parts of sodium humate, 1-2 parts of composite bacterial agent, 10-15 parts of mineral powder, 10-20 parts of modified polyglutamic acid; The composite bacterial agent comprises the following components in parts by weight: 10-15 parts of Bacillus licheniformis, 5-10 parts of Bacillus subtilis, 8-12 parts of Bacillus thuringiensis, and 2-5 parts of Bacillus amyloliquefaciens; The live bacterial concentration of Bacillus licheniformis in the composite bacterial agent is 3×10 8 CFU / g-5×10 8 CFU / g, the concentration of live bacteria of Bacillus subtilis is 7×10 8 CFU / g-8×10 8 CFU / g, the concentration of live bacteria of Bacillus thuringiensis is 3×10 8 CFU / g-5×10 8 CFU / g, the concentration of live bacteria of Bacillus amyloliquefaciens is 5×10 8 CFU / g-8×10 8 CFU / g; The preparation method of the organic fertilizer specifically comprises the following steps: S1, mixing animal feces and sodium humate to obtain a fermentation premix; S2, dissolving the composite bacterial agent in deionized water, adding the mixture to the fermentation premix prepared in step S1, mixing evenly, and performing composting fermentation treatment at a composting temperature of 50-55° C., and fermenting at a constant temperature for 24-36 hours to obtain a fermentation product; S3, after the fermentation product prepared in S2 is evenly mixed with the mineral powder, the modified biochar and the modified polyglutamic acid are added, the mixture is fully mixed, dried and then crushed, and the particle size after crushing is 0.3-0.5 mm, to obtain an organic fertilizer; The preparation method of the modified biochar specifically comprises the following steps: S31, placing the crop straw in a ventilated environment at room temperature for natural air drying, crushing and passing through a 2 mm sieve to obtain straw powder; S32, placing the straw powder prepared in step S31 in a high-temperature tube furnace for heat treatment, with a program heating parameter of heating to 500-800°C at 10°C / min, and keeping the temperature for 1-3h to obtain straw biochar; S33, mixing the straw biochar prepared in step S32 with a nitric acid solution having a volume fraction of 60-65%, raising the reaction temperature to 60-70° C., reacting for 1-1.5 hours, washing with deionized water, and drying to obtain modified biochar; The preparation method of the modified polyglutamic acid specifically comprises the following steps: S34, adding NaOH aqueous solution dropwise to glutamic acid, heating to 200-220° C., reacting for 2-4 hours, placing in a dialysis bag after the reaction is completed, dialyzing with deionized water for 2 days, and freeze-drying to obtain polyglutamic acid, wherein the molecular weight of the polyglutamic acid is 5-10 kDa; S35, dissolving the polyglutamic acid prepared in step S34 in deionized water, placing in an ice water bath, adding EDC and NHS, stirring to react, adding a long-chain alkyl primary amine compound solution, continuing to stir, reacting at room temperature for 24-36 hours, placing in a dialysis bag for dialysis treatment with deionized water, and freeze-drying to obtain modified polyglutamic acid; The long-chain alkyl primary amine compound comprises at least one of n-octylamine, n-decylamine and n-dodecylamine, and the long-chain alkyl primary amine compound solution is a solution of the long-chain alkyl primary amine compound dissolved in dimethyl sulfoxide, wherein the mass concentration of the long-chain alkyl primary amine compound is 40-60 g / L; The mass ratio of the long-chain alkyl primary amine compound to polyglutamic acid is 1-2:

10.

2. The polyamino acid type composite microbial organic fertilizer for crop planting according to claim 1, characterized in that: The mineral powder comprises the following components in parts by weight: 8-12 parts of medical stone, 10-15 parts of bentonite, 5-10 parts of phosphate rock powder, and 2-5 parts of mica powder.

3. The polyamino acid type composite microbial organic fertilizer for crop planting according to claim 2, characterized in that: The animal manure includes at least one of chicken manure, pig manure, sheep manure and cow manure.

4. The polyamino acid type composite microbial organic fertilizer for crop planting according to claim 1, characterized in that: In step S2, the mass concentration of the composite bacterial agent in deionized water is 5-10 g / L.

5. The polyamino acid type composite microbial organic fertilizer for crop planting according to claim 1, characterized in that: In step S31, the crop straw includes at least one of corn straw, wheat straw, barley straw, sorghum straw, and rape straw; and the mass volume ratio of the straw biochar to the nitric acid solution in step S33 is 1:30-50 g / mL.

6. The polyamino acid type composite microbial organic fertilizer for crop planting according to claim 1, characterized in that: In step S35, the mass concentration of the polyglutamic acid in deionized water is 20-30 g / L; the mass ratio of the added mass of the EDC to the polyglutamic acid is 2-2.5:1, and the mass ratio of the added amount of the NHS to the polyglutamic acid is 1-1.5:1.

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