Soil loosening agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of soil improvement, in particular to a soil loosening agent and a preparation method and application thereof. The soil loosening agent comprises the following raw materials in parts by mass: 5-10 parts of corn starch, 1-3 parts of sodium trimetaphosphate, 1-2 parts of amylase, 5-15 parts of acrylamide, 0.1-1 part of ammonium persulfate, 1-5 parts of a cross-linking agent, 1-2 parts of an emulsifier, 5-15 parts of methyl methacrylate, 1-5 parts of dopamine, 1-3 parts of a complex microbial inoculant, 10-20 parts of bentonite and 1-5 parts of humic acid. The soil loosening effect is good, formation of aggregate structures can be promoted, the water retention and ventilation effects are excellent, good growth of plant roots is guaranteed, and the soil is more suitable for crop growth; meanwhile, the crop growth and development characters can be improved, the crop yield is increased, and both production and income are increased.

Description

Technical Field

[0001] The present invention relates to the technical field of soil improvement, and in particular to a soil loosening agent and a preparation method and application thereof. Background Art

[0002] Soil is an unfixed structural layer on the earth's land surface composed of minerals, organic matter, water, air and organisms, with fertility and for plant growth. my country has a relatively small per capita arable land area, and the fertilizer application is unscientific. The unscientific use of chemical fertilizers over the years will increase the density of the soil, reduce the proportion of soil pores, and reduce the soil's water retention capacity.

[0003] With the development of mechanized operations in my country, soil compaction in agricultural lands across the country is becoming increasingly severe, seriously affecting the planting and growth of crops. Compacted soil will restrict root growth, causing crops to consume more nutrients than non-compacted crops, reducing the ability of crops to obtain nutrients.

[0004] In the long-term crop production, problems such as soil compaction, high soil bulk density, and high compaction are very prominent, which seriously restricts the health and sustainable development of crops. Soil compaction is an important factor affecting crop growth, which has a great impact on soil bulk density, soil porosity, and soil moisture. At present, compacted soil has poor water regulation ability. At the same time, the soil is in an anaerobic environment for a long time, and the microbial activity is low, which affects the soil carbon and nitrogen cycle and the soil nutrient supply capacity, and reduces soil fertility.

[0005] In order to improve the soil and enhance soil properties, straw biochar, rice husk biochar, etc. are often added to the soil. Although this has certain effects, the improvement effect is still insufficient and the duration is short.

[0006] As a high molecular polymer, polyacrylamide has good effects on improving soil physical properties, alleviating soil compaction and maintaining soil moisture. Therefore, it is particularly important to use polyacrylamide and find a soil loosening agent that can effectively improve soil properties, reduce soil bulk density and compaction, improve soil water retention and increase crop yields. Summary of the invention

[0007] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a soil loosening agent and a preparation method and application thereof.

[0008] A soil loosening agent, the raw materials of which include, by weight: 5-10 parts of corn starch, 1-3 parts of sodium trimetaphosphate, 1-2 parts of amylase, 5-15 parts of acrylamide, 0.1-1 parts of ammonium persulfate, 1-5 parts of a cross-linking agent, 1-2 parts of an emulsifier, 5-15 parts of methyl methacrylate, 1-5 parts of dopamine, 1-3 parts of a composite bacterial agent, 10-20 parts of bentonite, and 1-5 parts of humic acid.

[0009] Preferably, the crosslinking agent is at least one of divinylbenzene and ethylene glycol dimethacrylate.

[0010] Preferably, the emulsifier is sodium lauryl sulfate.

[0011] Preferably, the composite bacterial agent includes: Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus mucilaginosus.

[0012] Preferably, the concentration of live Bacillus subtilis is 4-6×10 10 cfu / g, the concentration of live Bacillus amyloliquefaciens is 1-3×10 10 cfu / g, the concentration of live Bacillus colloids is 5-9×10 9 cfu / g.

[0013] The preparation method of the soil loosening agent comprises the following steps: S1. Add corn starch to sodium hydroxide solution, stir at 50-70° C. for 10-30 min, add sodium trimetaphosphate and continue stirring for 5-15 min, adjust the system to be neutral, filter, wash, and vacuum dry to obtain activated starch; S2, adding amylase to disodium hydrogen phosphate-citric acid buffer and stirring evenly to obtain enzyme solution; S3, adding acrylamide and activated starch to water and stirring evenly, adding ammonium persulfate, crosslinking agent and emulsifier thereto and stirring evenly, adding methyl methacrylate thereto dropwise under stirring, stirring at 60-80° C. for 2-5 hours after the addition is complete, cooling to room temperature, centrifuging, washing, and vacuum drying to obtain microsphere blanks; S4, adding the microsphere blank to the enzyme solution, performing enzymolysis at 30-40°C for 5-10 hours, inactivating at high temperature, adjusting the pH value of the system to 8-9, adding dopamine, performing ultrasonic treatment at 50-60°C for 5-10 hours, centrifuging, washing, and vacuum drying to obtain microspheres; S5. Add the composite bacterial agent to the microspheres and carry out ultrasonic treatment for 5-15 minutes. Add bentonite and humic acid, mix evenly, sieve and granulate.

[0014] Preferably, in S1, the concentration of the sodium hydroxide solution is 1-2 mol / L.

[0015] Preferably, in S4, the ultrasonic frequency is 5-12 kHz.

[0016] Preferably, in S5, the ultrasonic frequency is 2-8 kHz.

[0017] The method for using the soil loosening agent is to apply the soil loosening agent together with base fertilizer, and the dosage of the soil loosening agent is 4-6kg / mu.

[0018] The invention not only has a good effect of loosening the soil, but also can promote the formation of a granular structure, has excellent water retention and ventilation effects, ensures the good growth of plant roots, and makes the soil more suitable for crop growth; at the same time, it can improve the growth and development characteristics of crops and increase crop yields, thereby increasing production and income.

[0019] The present invention utilizes cross-linked microspheres formed by compounding hydrophilic acrylamide and hydrophobic methyl methacrylate, which can effectively regulate the water absorption and swelling effect of the microspheres, effectively avoid excessive water absorption and swelling of the microspheres, and then graft starch structures therein, and form a porous structure after enzymatic hydrolysis, which not only makes the binding strength of polydopamine thereon high, but also has excellent adsorption and viscosity performance for composite bacteria, and has extremely high stability, effectively ensuring that microorganisms penetrate into the soil, repair the aggregate structure, and break the soil compaction. At the same time, the microorganisms continue to grow and reproduce in the soil, which has a long-term improvement effect on deep compacted soil, fundamentally improves soil compaction, and forms a virtuous cycle of the soil system. It has been found through experiments that the present invention can not only increase the soil water content, but also has an obvious loosening effect on 40-60cm soil.

[0020] The present invention loads polydopamine on the outer layer of the microsphere blank, which has excellent hydrophilicity and excellent adhesion to the soil. It cooperates with bentonite and humic acid to loosen the soil and retain water, effectively promote the soil aggregate structure, and change the soil porosity and bulk density. It not only has a good soil loosening effect, but also has a safe, green and biodegradable raw material, effectively increases the activity of microorganisms to enhance the utilization of organic matter, and has a stable aggregate structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a comparison chart of soil bulk density of 0-20cm, 20-40cm and 40-60cm in Example 5, Comparative Example 1, Comparative Example 2 and Blank group; Figure 2 It is a comparison chart of soil moisture content at 0-20cm and 20-40cm in Example 5, Comparative Example 1, Comparative Example 2, and Blank group; Figure 3 It is a comparison chart of soil compaction at 0-20cm, 20-40cm and 40-60cm of Example 5, Comparative Example 1, Comparative Example 2 and Blank group; Figure 4 It is a comparison chart of the soluble sugar content and starch content of the branches of Example 5, Comparative Example 1, Comparative Example 2, and the blank group. DETAILED DESCRIPTION

[0022] The present invention will be further explained below in conjunction with specific embodiments.

[0023] Amylase was purchased from Hebei Tuohai Biotechnology Co., Ltd. with an enzyme activity of 20,000 U / g; Bacillus subtilis was derived from the China General Microbiological Culture Collection Center with a number of CGMCC1.821; Bacillus amyloliquefaciens was derived from the China General Microbiological Culture Collection Center with a number of CGMCC1.857; and Bacillus mucilaginosus was derived from the China Center for Type Culture Collection with a number of CCTCC KB 20082790.

[0024] Example 1

[0025] A soil loosening agent, whose raw materials include: 5kg corn starch, 1kg sodium trimetaphosphate, 1kg amylase, 5kg acrylamide, 0.1kg ammonium persulfate, 1kg divinylbenzene, 1kg sodium dodecyl sulfate, 5kg methyl methacrylate, 1kg dopamine, 1kg composite bacterial agent, 10kg bentonite and 1kg humic acid.

[0026] The compound bacterial agent includes: the concentration of live bacteria is 4×10 10 cfu / g of Bacillus subtilis, the concentration of live bacteria is 1×10 10 cfu / g of Bacillus amyloliquefaciens, with a live bacteria concentration of 5×10 9 cfu / g of Bacillus mucilaginosus.

[0027] The preparation method of the soil loosening agent comprises the following steps: S1. Add corn starch to 50 kg of 1 mol / L sodium hydroxide solution, stir at 50° C. for 10 min, add sodium trimetaphosphate and continue stirring for 5 min, adjust the system to be neutral, filter, wash, and vacuum dry to obtain activated starch; S2, adding amylase to 100 kg of disodium hydrogen phosphate-citric acid buffer solution with a pH of 6-7 and stirring evenly to obtain an enzyme solution; S3, adding acrylamide and activated starch to 50 kg of deionized water and stirring evenly, adding ammonium persulfate, divinylbenzene and sodium dodecyl sulfate thereto and stirring evenly, adding methyl methacrylate dropwise thereto under stirring, stirring at 60 ° C for 2 h after the addition is complete, cooling to room temperature, centrifuging, washing, and vacuum drying to obtain microsphere blanks; S4, adding the microsphere blank to the enzyme solution, performing enzymolysis at 30°C for 5 hours, high temperature inactivation, adjusting the pH value of the system to 8-9, adding dopamine, performing ultrasonic treatment at 50°C for 5 hours with an ultrasonic frequency of 5kHz, centrifuging, washing, and vacuum drying to obtain microspheres; S5. Add the composite bacterial agent to the microspheres and perform ultrasonic treatment for 5 minutes at an ultrasonic frequency of 2 kHz. Add bentonite and humic acid, mix evenly, pass through a 90-mesh sieve, and granulate.

[0028] Example 2

[0029] A soil loosening agent, whose raw materials include: 10kg corn starch, 3kg sodium trimetaphosphate, 2kg amylase, 15kg acrylamide, 1kg ammonium persulfate, 5kg divinylbenzene, 2kg sodium dodecyl sulfate, 15kg methyl methacrylate, 5kg dopamine, 3kg composite bacterial agent, 20kg bentonite and 5kg humic acid.

[0030] The compound bacterial agent includes: the concentration of live bacteria is 6×10 10 cfu / g of Bacillus subtilis, with a live bacteria concentration of 3×10 10 cfu / g of Bacillus amyloliquefaciens, with a live bacteria concentration of 9×10 9 cfu / g of Bacillus mucilaginosus.

[0031] The preparation method of the soil loosening agent comprises the following steps: S1. Add corn starch to 80 kg of 2 mol / L sodium hydroxide solution, stir at 70° C. for 30 min, add sodium trimetaphosphate and continue stirring for 15 min, adjust the system to be neutral, filter, wash, and vacuum dry to obtain activated starch; S2, adding amylase to 200 kg of disodium hydrogen phosphate-citric acid buffer solution with a pH of 6-7 and stirring evenly to obtain an enzyme solution; S3, adding acrylamide and activated starch to 100 kg of deionized water and stirring evenly, adding ammonium persulfate, divinylbenzene and sodium dodecyl sulfate thereto and stirring evenly, adding methyl methacrylate dropwise thereto under stirring, stirring at 80° C. for 5 h after the addition is complete, cooling to room temperature, centrifuging, washing, and vacuum drying to obtain a microsphere blank; S4, adding the microsphere blank to the enzyme solution, performing enzymolysis at 40°C for 10 hours, high temperature inactivation, adjusting the pH value of the system to 8-9, adding dopamine, performing ultrasonic treatment at 60°C for 10 hours with an ultrasonic frequency of 12 kHz, centrifuging, washing, and vacuum drying to obtain microspheres; S5. Add the composite bacterial agent to the microspheres and perform ultrasonic treatment for 15 minutes at an ultrasonic frequency of 8 kHz. Add bentonite and humic acid, mix evenly, pass through a 110-mesh sieve, and granulate.

[0032] Example 3

[0033] A soil loosening agent, whose raw materials include: 7kg corn starch, 2.5kg sodium trimetaphosphate, 1.2kg amylase, 12kg acrylamide, 0.3kg ammonium persulfate, 4kg ethylene glycol dimethacrylate, 1.2kg sodium lauryl sulfate, 12kg methyl methacrylate, 2kg dopamine, 2.5kg composite bacterial agent, 12kg bentonite, and 4kg humic acid.

[0034] The compound bacterial agent includes: the concentration of live bacteria is 5.5×10 10 cfu / g of Bacillus subtilis, with a live bacteria concentration of 1.5×10 10 cfu / g of Bacillus amyloliquefaciens, with a live bacteria concentration of 8×10 9 cfu / g of Bacillus mucilaginosus.

[0035] The preparation method of the soil loosening agent comprises the following steps: S1. Add corn starch to 60 kg of 1.5 mol / L sodium hydroxide solution, stir at 65° C. for 15 min, add sodium trimetaphosphate and continue stirring for 12 min, adjust the system to be neutral, filter, wash, and vacuum dry to obtain activated starch; S2, adding amylase to 130 kg of disodium hydrogen phosphate-citric acid buffer solution with a pH of 6-7 and stirring evenly to obtain an enzyme solution; S3, adding acrylamide and activated starch to 90 kg of deionized water and stirring evenly, adding ammonium persulfate, ethylene glycol dimethacrylate and sodium dodecyl sulfate thereto and stirring evenly, adding methyl methacrylate dropwise thereto under stirring, stirring at 65 ° C for 4 h after the addition is complete, cooling to room temperature, centrifuging, washing, and vacuum drying to obtain microsphere blanks; S4, adding the microsphere blank to the enzyme solution, performing enzymolysis at 33°C for 9 hours, high temperature inactivation, adjusting the pH value of the system to 8-9, adding dopamine, performing ultrasonic treatment at 52°C for 9 hours, the ultrasonic frequency being 6kHz, centrifuging, washing, and vacuum drying to obtain microspheres; S5. Add the composite bacterial agent to the microspheres and perform ultrasonic treatment for 12 minutes at an ultrasonic frequency of 3 kHz. Add bentonite and humic acid, mix evenly, pass through a 100-mesh sieve, and granulate.

[0036] Example 4

[0037] A soil loosening agent, whose raw materials include: 9kg corn starch, 1.5kg sodium trimetaphosphate, 1.8kg amylase, 8kg acrylamide, 0.7kg ammonium persulfate, 2kg ethylene glycol dimethacrylate, 1.8kg sodium lauryl sulfate, 8kg methyl methacrylate, 4kg dopamine, 1.5kg composite bacterial agent, 18kg bentonite, and 2kg humic acid.

[0038] The compound bacterial agent includes: the concentration of live bacteria is 4.5×10 10 cfu / g of Bacillus subtilis, with a live bacteria concentration of 2.5×10 10 cfu / g of Bacillus amyloliquefaciens, with a live bacteria concentration of 6×10 9 cfu / g of Bacillus mucilaginosus.

[0039] The preparation method of the soil loosening agent comprises the following steps: S1. Add corn starch to 70 kg of 1.5 mol / L sodium hydroxide solution, stir at 55° C. for 25 min, add sodium trimetaphosphate and continue stirring for 8 min, adjust the system to be neutral, filter, wash, and vacuum dry to obtain activated starch; S2, adding amylase to 170 kg of disodium hydrogen phosphate-citric acid buffer with a pH of 6-7 and stirring evenly to obtain an enzyme solution; S3, adding acrylamide and activated starch to 70 kg of deionized water and stirring evenly, adding ammonium persulfate, ethylene glycol dimethacrylate and sodium dodecyl sulfate thereto and stirring evenly, adding methyl methacrylate dropwise thereto under stirring, stirring at 75 ° C for 3 h after the addition is complete, cooling to room temperature, centrifuging, washing, and vacuum drying to obtain microsphere blanks; S4, adding the microsphere blank to the enzyme solution, performing enzymolysis at 37°C for 7 hours, high temperature inactivation, adjusting the pH value of the system to 8-9, adding dopamine, performing ultrasonic treatment at 58°C for 7 hours, the ultrasonic frequency is 9kHz, centrifuging, washing, and vacuum drying to obtain microspheres; S5. Add the composite bacterial agent to the microspheres and carry out ultrasonic treatment for 8 minutes at an ultrasonic frequency of 6 kHz. Add bentonite and humic acid and mix evenly. Pass through a 100-mesh sieve and granulate.

[0040] Example 5

[0041] A soil loosening agent, whose raw materials include: 8kg corn starch, 2kg sodium trimetaphosphate, 1.5kg amylase, 10kg acrylamide, 0.5kg ammonium persulfate, 3kg ethylene glycol dimethacrylate, 1.5kg sodium lauryl sulfate, 10kg methyl methacrylate, 3kg dopamine, 2kg composite bacterial agent, 15kg bentonite, and 3kg humic acid.

[0042] The compound bacterial agent includes: the concentration of live bacteria is 5×10 10 cfu / g of Bacillus subtilis, with a live bacteria concentration of 2×10 10 cfu / g of Bacillus amyloliquefaciens, with a live bacteria concentration of 7×10 9 cfu / g of Bacillus mucilaginosus.

[0043] The preparation method of the soil loosening agent comprises the following steps: S1. Add corn starch to 65 kg of 1.5 mol / L sodium hydroxide solution, stir at 60° C. for 20 min, add sodium trimetaphosphate and continue stirring for 10 min, adjust the system to be neutral, filter, wash, and vacuum dry to obtain activated starch; S2, adding amylase to 150 kg of disodium hydrogen phosphate-citric acid buffer solution with a pH of 6-7 and stirring evenly to obtain an enzyme solution; S3, adding acrylamide and activated starch to 80 kg of deionized water and stirring evenly, adding ammonium persulfate, ethylene glycol dimethacrylate and sodium dodecyl sulfate thereto and stirring evenly, adding methyl methacrylate dropwise thereto under stirring, stirring at 70 ° C for 3.5 h after the addition is complete, cooling to room temperature, centrifuging, washing, and vacuum drying to obtain a microsphere blank; S4, adding the microsphere blank to the enzyme solution, performing enzymolysis at 35°C for 8 hours, high temperature inactivation, adjusting the pH value of the system to 8-9, adding dopamine, performing ultrasonic treatment at 55°C for 8 hours, the ultrasonic frequency being 7.5kHz, centrifuging, washing, and vacuum drying to obtain microspheres; S5. Add the composite bacterial agent to the microspheres and perform ultrasonic treatment for 10 minutes at an ultrasonic frequency of 4.5 kHz. Add bentonite and humic acid, mix evenly, pass through a 100-mesh sieve, and granulate.

[0044] Comparative Example 1

[0045] A soil loosening agent, whose raw materials include: 8kg corn starch, 2kg sodium trimetaphosphate, 10kg acrylamide, 0.5kg ammonium persulfate, 3kg ethylene glycol dimethacrylate, 1.5kg sodium lauryl sulfate, 10kg methyl methacrylate, 3kg dopamine, 2kg composite bacterial agent, 15kg bentonite, and 3kg humic acid.

[0046] The compound bacterial agent includes: the concentration of live bacteria is 5×10 10 cfu / g of Bacillus subtilis, with a live bacteria concentration of 2×10 10 cfu / g of Bacillus amyloliquefaciens, with a live bacteria concentration of 7×10 9 cfu / g of Bacillus mucilaginosus.

[0047] The preparation method of the soil loosening agent comprises the following steps: S1. Add corn starch to 65 kg of 1.5 mol / L sodium hydroxide solution, stir at 60° C. for 20 min, add sodium trimetaphosphate and continue stirring for 10 min, adjust the system to be neutral, filter, wash, and vacuum dry to obtain activated starch; S2, adding acrylamide and activated starch to 80 kg of deionized water and stirring evenly, adding ammonium persulfate, ethylene glycol dimethacrylate and sodium dodecyl sulfate thereto and stirring evenly, adding methyl methacrylate dropwise thereto under stirring, stirring at 70 ° C for 3.5 h after the addition is complete, cooling to room temperature, centrifuging, washing, and vacuum drying to obtain a microsphere blank; S3, adding the microsphere blank to 151.5 kg of disodium hydrogen phosphate-citric acid buffer with a pH of 8-9, adding dopamine thereto, ultrasonically treating at a temperature of 55° C. for 8 h with an ultrasonic frequency of 7.5 kHz, centrifuging, washing, and vacuum drying to obtain microspheres; S4. Add the composite bacterial agent to the microspheres and carry out ultrasonic treatment for 10 minutes at an ultrasonic frequency of 4.5 kHz. Add bentonite and humic acid and mix evenly. Pass through a 100-mesh sieve and granulate.

[0048] Comparative Example 2

[0049] A soil loosening agent, whose raw materials include: 8kg corn starch, 2kg sodium trimetaphosphate, 1.5kg amylase, 10kg acrylamide, 0.5kg ammonium persulfate, 3kg ethylene glycol dimethacrylate, 1.5kg sodium lauryl sulfate, 10kg methyl methacrylate, 2kg composite bacterial agent, 15kg bentonite and 3kg humic acid.

[0050] The compound bacterial agent includes: the concentration of live bacteria is 5×10 10 cfu / g of Bacillus subtilis, with a live bacteria concentration of 2×10 10 cfu / g of Bacillus amyloliquefaciens, with a live bacteria concentration of 7×10 9 cfu / g of Bacillus mucilaginosus.

[0051] The preparation method of the soil loosening agent comprises the following steps: S1. Add corn starch to 65 kg of 1.5 mol / L sodium hydroxide solution, stir at 60° C. for 20 min, add sodium trimetaphosphate and continue stirring for 10 min, adjust the system to be neutral, filter, wash, and vacuum dry to obtain activated starch; S2, adding amylase to 150 kg of disodium hydrogen phosphate-citric acid buffer solution with a pH of 6-7 and stirring evenly to obtain an enzyme solution; S3, adding acrylamide and activated starch to 80 kg of deionized water and stirring evenly, adding ammonium persulfate, ethylene glycol dimethacrylate and sodium dodecyl sulfate thereto and stirring evenly, adding methyl methacrylate dropwise thereto under stirring, stirring at 70 ° C for 3.5 h after the addition is complete, cooling to room temperature, centrifuging, washing, and vacuum drying to obtain a microsphere blank; S4, adding the microsphere blank to the enzyme solution, performing enzymolysis at 35°C for 8 hours, high temperature inactivation, centrifugation, washing, and vacuum drying to obtain the microspheres; S5. Add the composite bacterial agent to the microspheres and perform ultrasonic treatment for 10 minutes at an ultrasonic frequency of 4.5 kHz. Add bentonite and humic acid, mix evenly, pass through a 100-mesh sieve, and granulate.

[0052] A comparative field test was conducted in a vineyard in Huailai County, Zhangjiakou City, Hebei Province, and plots were randomly divided into Example 5, Comparative Example 1, Comparative Example 2 and a blank group. White milk grapes were used as the experimental object, with 3 replicates per plot and 5 plants per replicate.

[0053] In Example 5, Comparative Example 1 and Comparative Example 2, the soil loosening agent obtained in Example 5, Comparative Example 1 and Comparative Example 2 was applied to the soil together with decomposed chicken manure, and the application amount of the soil loosening agent in each group was 5 kg / mu, and the application amount of decomposed chicken manure was 1500 kg / mu; and the blank group was irrigated with clear water as a control. The rest of the operations in each group were consistent with conventional water and fertilizer field management.

[0054] In October (after grape harvest), soil samples were taken from each group, and the soil bulk density at 0-20cm, 20-40cm and 40-60cm was measured by the ring knife method; the soil water content at 0-20cm and 20-40cm was measured by the alcohol combustion method; and the soil compaction tester was used to measure the soil compaction at a depth of 20cm, 40cm and 60cm.

[0055] like Figure 1 to Figure 2 As shown, the soil bulk density and soil compactness of the soil in Example 5 group were always the smallest, while the water content was the highest, which was better than that of the comparative example 1-2 group and the blank group (P < 0.05).

[0056] After grapes were collected in each group, branches at the 5th node were selected, internodes were removed, dried and ground, and the contents of soluble sugar and starch in the branches were determined by anthrone colorimetry.

[0057] like Figure 4 As shown, the soluble sugar content and starch content of the branches of Example 5 group were the highest, which were better than those of the comparative example 1-2 groups and the blank group (P < 0.05).

[0058] The applicant believes that the reason for the above results is that the cross-linked microspheres formed by the compounding of hydrophilic acrylamide and hydrophobic methyl methacrylate in the present invention can effectively regulate the water absorption and swelling effect of the microspheres, effectively avoid excessive water absorption and swelling of the microspheres, and then graft starch structure therein, and form a porous structure after enzymatic hydrolysis, which not only makes the binding strength of polydopamine thereon high, but also has excellent adsorption and viscosity properties for composite bacteria, and extremely high stability, effectively ensuring that microorganisms penetrate into the soil, repair the aggregate structure, and break up soil compaction. At the same time, the microorganisms continue to grow and reproduce in the soil, which has a long-term improvement effect on deep compacted soil, fundamentally improves soil compaction, and forms a virtuous cycle of the soil system. The present invention loads polydopamine on the outer layer of the microsphere blank to improve hydrophilicity, and has excellent adhesion performance with the soil. In combination with bentonite and humic acid, it has significant effects on loosening the soil and retaining water, effectively promotes the soil aggregate structure, and changes the soil porosity and bulk density. It not only has a good soil loosening effect, but also has safe raw materials, is green and biodegradable, effectively increases microbial activity to enhance the utilization of organic matter, and has a stable aggregate structure.

[0059] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A soil loosening agent, characterized in that: The raw materials include, by mass, 5-10 parts of corn starch, 1-3 parts of sodium trimetaphosphate, 1-2 parts of amylase, 5-15 parts of acrylamide, 0.1-1 parts of ammonium persulfate, 1-5 parts of cross-linking agent, 1-2 parts of emulsifier, 5-15 parts of methyl methacrylate, 1-5 parts of dopamine, 1-3 parts of composite bacterial agent, 10-20 parts of bentonite and 1-5 parts of humic acid.

2. The soil loosening agent according to claim 1, characterized in that: The crosslinking agent is at least one of divinylbenzene and ethylene glycol dimethacrylate.

3. The soil loosening agent according to claim 1, characterized in that: The emulsifier is sodium lauryl sulfate.

4. The soil loosening agent according to claim 1, characterized in that: The composite bacterial agent includes: Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus mucilaginosus.

5. The soil loosening agent according to claim 4, characterized in that: The concentration of live Bacillus subtilis is 4-6×10 10 cfu / g, the concentration of live Bacillus amyloliquefaciens is 1-3×10 10 cfu / g, the concentration of live Bacillus colloids is 5-9×10 9 cfu / g.

6. A method for preparing the soil loosening agent according to any one of claims 1 to 5, characterized in that: The steps include: S1. Add corn starch to sodium hydroxide solution, stir at 50-70° C. for 10-30 min, add sodium trimetaphosphate and continue stirring for 5-15 min, adjust the system to be neutral, filter, wash, and vacuum dry to obtain activated starch; S2, adding amylase to disodium hydrogen phosphate-citric acid buffer and stirring evenly to obtain enzyme solution; S3, adding acrylamide and activated starch to water and stirring evenly, adding ammonium persulfate, crosslinking agent and emulsifier thereto and stirring evenly, adding methyl methacrylate thereto dropwise under stirring, stirring at 60-80° C. for 2-5 hours after the addition is complete, cooling to room temperature, centrifuging, washing, and vacuum drying to obtain microsphere blanks; S4, adding the microsphere blank to the enzyme solution, performing enzymolysis at 30-40°C for 5-10 hours, inactivating at high temperature, adjusting the pH value of the system to 8-9, adding dopamine, performing ultrasonic treatment at 50-60°C for 5-10 hours, centrifuging, washing, and vacuum drying to obtain microspheres; S5. Add the composite bacterial agent to the microspheres and carry out ultrasonic treatment for 5-15 minutes. Add bentonite and humic acid, mix evenly, sieve and granulate.

7. The method for preparing the soil loosening agent according to claim 6, characterized in that: In S1, the concentration of the sodium hydroxide solution is 1-2 mol / L.

8. The method for preparing the soil loosening agent according to claim 6, characterized in that: In S4, the ultrasound frequency is 5-12kHz.

9. The method for preparing the soil loosening agent according to claim 6, characterized in that: In S5, the ultrasound frequency is 2-8kHz.

10. A method for using the soil loosening agent according to any one of claims 1 to 5, characterized in that: The soil loosening agent according to any one of claims 1 to 5 is applied together with base fertilizer in an amount of 4 to 6 kg / mu.

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