Soil amendment for reducing swelling-shrinkage property of Shajiang black soil and application of soil amendment

Abstract

The invention discloses a soil conditioner capable of reducing the swelling-shrinkage property of Shajiang black soil and application of the soil conditioner, and belongs to the technical field of soil improvement type fertilizer.The soil conditioner is prepared from fermented manure, bio-based gel powder, charcoal, potassium humate and epoxy cross-linking agent microspheres, and the bio-based gel powder has good water absorption and water retention; the porosity of the shajiang black soil can be increased after the shajiang black soil absorbs water and swells, the amino-modified straw fibers contained in the shajiang black soil contain a large number of amino groups, released epoxidized protocatechuic acid can be cross-linked with the amino groups, the riveting fixing effect is achieved, the mechanical strength and the structural stability of the bio-based gel after water absorption are improved, and the moisture absorption effect of the shajiang black soil is improved. The bio-based gel still has a good supporting effect after water loss of the soil, water loss shrinkage of the shajiang black soil of a deep ploughing layer can be resisted, the swelling ratio of the bio-based gel can be reduced after water is absorbed again, and therefore the swelling-shrinkage property of the shajiang black soil is reduced, and the ploughing quality is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of soil improving fertilizers, and in particular relates to a soil improver for reducing the swelling and shrinkage of sand ginger black soil and an application thereof. Background Art

[0002] Shajiang black soil is a semi-hydromorphic soil developed on river and lake sediments through de-swamping. The Huaibei Plain in the south of the Huanghuaihai Plain is the largest distribution area of ​​Shajiang black soil in China, with a total area of ​​about 4 million hectares. In addition, it is also distributed in Henan, Jiangsu, Shandong and other provinces. The soil of Shajiang black soil is deep, and the profile has a tillage layer, a sub-tillage layer, a residual black soil layer, a redox transition layer and a Shajiang soil layer from top to bottom.

[0003] Shajiang black soil is a medium-low yield field soil type, but the area where it is located is generally flat, with good water and heat conditions, high mechanization level, and great potential for increasing production. Therefore, it is necessary to improve the soil of Shajiang black soil. The Chinese invention patent with announcement number CN112042308B announces a soil improvement method and its application, which applies finished compost to the soil and performs deep plowing and deep turning, uses ridge cultivation and water-fertilizer integration technology to manage soil moisture, thereby increasing the content of crude fiber organic matter in the soil and improving the physical and chemical structure and tillage properties of the soil.

[0004] However, the clay content of Shajiang black soil is high and rich in expansive montmorillonite minerals. It expands and sticks when wet, and cracks and becomes rigid when dry. It exhibits the "four highs" characteristics of high soil bulk density, high soil strength, high shrinkage and expansion, and high Shajiang content, resulting in poor water permeability and air permeability. The above method requires the mixing of a large amount of organic fertilizer, and simply mixing in organic matter such as organic fertilizer and crop straw has limited effect on improving the swelling and shrinkage of Shajiang black soil. Therefore, how to effectively improve the swelling and shrinkage of Shajiang black soil and improve the quality of cultivated land is of great significance to ensuring my country's food security and promoting sustainable agricultural development. Summary of the invention

[0005] The purpose of the present invention is to provide a soil conditioner for reducing the swelling and shrinkage of sandy black soil and its application. The soil conditioner containing raw materials such as fermented manure, bio-based gel powder and epoxy crosslinking agent microspheres is applied during the tillage of the sandy black soil to increase the soil organic matter content. The bio-based gel powder can absorb water and swell to improve water retention. At the same time, the amino-modified straw fiber containing a large amount of amino groups can improve the mechanical strength and structural stability of the bio-based gel after water absorption through a cross-linking reaction with epoxidized protocatechuic acid. It can still play a good supporting role after the soil loses water, thereby resisting the swelling and shrinkage of the sandy black soil and improving the quality of cultivated land.

[0006] The purpose of the present invention can be achieved by the following technical solutions: A soil conditioner for reducing the swelling and shrinkage of sandy black soil, comprising the following raw materials by weight: 100-150 servings of fermented manure 35-45 parts of bio-based gel powder 30-35 parts of biochar Potassium humate 20-30 parts Epoxy crosslinker microspheres 8-14 parts The soil conditioner for reducing the swelling and shrinkage of sand ginger black soil can be obtained by uniformly mixing the above raw materials.

[0007] Furthermore, the moisture content of the fermented manure is less than 5%.

[0008] Further, the bio-based gel powder is prepared by the following steps: Step 1: crush the crop straw, add water to grind it, filter it, remove large-sized impurities, and obtain a fiber slurry with a fiber length of 1.5±0.2 mm and a solid content of 10 w / v%; add the fiber slurry and a sodium hydroxide solution with a concentration of 0.1 mol / L into a reactor, stir at 80-85°C and 200-300 r / min for 40-60 min, add epichlorohydrin to the reactor after natural cooling, continue stirring for 6-7 hours, centrifuge and filter, wash the filter cake with anhydrous ethanol and deionized water for 2-3 times respectively, and vacuum dry it to obtain epoxidized straw fiber; Step 2: Add epoxidized straw fiber and deionized water into a reactor and stir to mix, then add fatty amine monomer into the reactor, stir and react for 6-8 hours at 70-80°C and 200-300r / min, centrifuge and filter, wash the filter cake with deionized water 2-3 times, and vacuum dry to obtain amino-modified straw fiber.

[0009] Step 3: Add acrylic acid, sodium hydroxide and deionized water into the reactor, stir and mix, then add 2-acrylamido-2-methylpropanesulfonic acid, amino-modified straw fiber, ammonium persulfate as an initiator and N,N'-methylenebisacrylamide as a cross-linking agent into the reactor, stir and react at 55-60°C and 200-300r / min for 10-12min, soak the reaction product in anhydrous ethanol for 3-5min, wash with deionized water 2-3 times, vacuum dry, crush, and pass through an 80-mesh sieve to obtain a bio-based gel powder.

[0010] Furthermore, in step 1, the volume ratio of the fiber slurry, the sodium hydroxide solution and epichlorohydrin is 5-6:3:1.

[0011] Furthermore, in step 2, the mass ratio of epoxidized straw fiber, deionized water and fatty amine monomer is 2:4-6:1.

[0012] Furthermore, in step 2, the fatty amine monomer is any one of diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

[0013] Furthermore, in step three, the mass ratio of acrylic acid, sodium hydroxide, deionized water, 2-acrylamido-2-methylpropanesulfonic acid, amino-modified straw fiber, initiator and cross-linking agent is 9:3.1:20:3:2.5-3:0.12-0.14:0.015-0.016.

[0014] Further, epoxy crosslinker microspheres are prepared by the following steps: Step 1: Add protocatechuic acid, anhydrous potassium carbonate and dimethyl sulfoxide to a reactor, stir at 300-500r / min for 3-5min, then add allyl chloride dropwise to the reactor under stirring at 0°C, stir and react at 30°C for 35-40h after the addition is complete, then stir and mix the reaction product with 1-2 times the volume of deionized water, extract with ethyl acetate for 3-5 times, combine the organic phases and wash with saturated chlorine and sodium solutions for 2-3 times, then dry and remove the water with anhydrous magnesium sulfate, and remove the organic solvent by rotary evaporation to obtain allylated protocatechuic acid; Step 2: adding allylated protocatechuic acid, dichloromethane and peroxybenzoic acid as an epoxidation reagent into a reactor, stirring at 0°C and 300-500r / min for 40-60min, then stirring and reacting at 40-45°C for 35-40h, cooling the reaction product at -10°C for crystallization for 4-5h, filtering to remove the generated benzoic acid solid crystals, and then washing the filtrate with a 10% sodium sulfite solution, a 5% sodium carbonate solution and a saturated sodium chloride solution for 2-3 times, then drying with anhydrous magnesium sulfate to remove water, and rotary evaporation to remove the organic solvent to obtain epoxidized protocatechuic acid; Step 3: dissolving epoxidized protocatechuic acid in dichloromethane to prepare a core solution with a mass fraction of 0.8-1%, and dissolving polylactic acid-glycolic acid copolymer in hexafluoroisopropanol to prepare a shell solution with a mass fraction of 5-6%; transferring the core solution and the shell solution to the liquid supply system of the coaxial electrostatic spray device, supplying liquid to the coaxial nozzle at a shell solution flow rate of 2-2.2 mL / h and a core solution flow rate of 0.22-0.25 mL / h at a voltage of 15-20 kV and a receiving distance of 15-20 cm, and using the coaxial electrostatic spraying method, epoxy crosslinking agent microspheres with epoxidized protocatechuic acid as the core and polylactic acid-glycolic acid copolymer as the shell are prepared.

[0015] Furthermore, in step 1, the mass ratio of protocatechuic acid, anhydrous potassium carbonate, dimethyl sulfoxide and allyl chloride is 1.55:4.1-4.2:50-60:4.8.

[0016] Furthermore, in step 2, the dosage ratio of allylated protocatechuic acid, dichloromethane and peroxybenzoic acid is 2.71:60-70:6.9-8.3.

[0017] Furthermore, in step 3, the average diameter of the epoxy crosslinking agent microspheres is 10±0.5 μm.

[0018] Beneficial effects of the present invention: 1. The soil conditioner for reducing the swelling and shrinkage of sand ginger black soil of the present invention can reduce the soil shrinkage rate, help stabilize the soil structure, prevent the sand ginger black soil from becoming compacted, and thus be beneficial to the growth and development of crop roots. In the soil conditioner of the present invention, fermented manure helps increase soil organic matter, improve the soil microbial environment, promote the decomposition and release of soil organic matter, and provide nutrients for crop growth; biochar has a porous structure, which helps to fix nutrients and adsorb harmful substances such as heavy metals and organic pollutants in the soil; potassium humate helps to improve the soil's ability to retain fertilizer, improve the soil aggregate structure, make the soil more loose, and improve the air permeability and water permeability of the sand ginger black soil.

[0019] 2. In the soil conditioner of the present invention, the shell of the epoxy crosslinking agent microspheres is polylactic acid-glycolic acid copolymer, and the core is epoxidized protocatechuic acid. The coating form of the core-shell structure is conducive to the stable storage and sustained release of epoxidized protocatechuic acid.

[0020] The bio-based gel powder has excellent water absorption and water retention properties. After absorbing water and swelling, it helps to increase the porosity of the sand ginger black soil. The amino-modified straw fibers contained therein contain a large number of amino groups. The released epoxidized protocatechuic acid can cross-link with the amino groups, playing a riveting and fixing role, which helps to improve the mechanical strength and structural stability of the bio-based gel after water absorption. After the soil loses water, it can still play a good supporting role and resist the water loss and shrinkage of the sand ginger black soil in the plow layer. After absorbing water again, the swelling ratio of the bio-based gel will also decrease, which helps to reduce the swelling and shrinkage of the sand ginger black soil.

[0021] In soils at different depths using this soil conditioner, the difference in soil shrinkage is smaller, which is beneficial to maintaining consistent soil expansion and shrinkage in cultivated areas at different depths, thereby improving the quality of cultivated land. DETAILED DESCRIPTION

[0022] 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.

[0023] Example 1: This example provides a soil conditioner for reducing the swelling and shrinkage of sandy black soil, which is prepared by the following steps: S1: Crush the crop straw, add water to grind it, filter it, remove large-sized impurities, and obtain a fiber slurry with a fiber length of 1.5±0.2 mm and a solid content of 10 w / v%; add 500 L of fiber slurry and 300 L of 0.1 mol / L sodium hydroxide solution into a reactor, stir at 80°C and 200 r / min for 40 min, add 100 L of epichlorohydrin into the reactor after natural cooling, continue stirring for 6 h, centrifuge and filter, wash the filter cake twice with anhydrous ethanol and deionized water respectively, and vacuum dry it to obtain epoxidized straw fiber.

[0024] S2: 80 kg of epoxidized straw fiber and 160 kg of deionized water were added into a reactor and stirred to mix. Then, 40 kg of diethylenetriamine was added into the reactor. The mixture was stirred to react at 70°C and 200 r / min for 6 h. The mixture was centrifugally filtered. The filter cake was washed twice with deionized water and vacuum dried to obtain amino-modified straw fiber.

[0025] S3: Add 90 kg of acrylic acid, 31 kg of sodium hydroxide and 200 kg of deionized water into the reactor, stir and mix, then add 30 kg of 2-acrylamido-2-methylpropanesulfonic acid, 25 kg of amino-modified straw fiber, 1.2 kg of ammonium persulfate as an initiator and 0.15 kg of N,N'-methylenebisacrylamide as a cross-linking agent into the reactor, stir and react at 55 ° C and 200 r / min for 10 minutes, soak the reaction product in anhydrous ethanol for 3 minutes, wash it twice with deionized water, vacuum dry, crush it, and pass it through an 80-mesh sieve to obtain a bio-based gel powder.

[0026] S4: Add 15.5 kg of protocatechuic acid, 41 kg of anhydrous potassium carbonate and 500 kg of dimethyl sulfoxide into the reactor, stir at 300 r / min for 3 min, then add 48 kg of propylene chloride dropwise into the reactor under stirring conditions at 0°C, stir and react at 30°C for 35 h after the addition is complete, then stir and mix the reaction product with 1 volume of deionized water, extract with ethyl acetate for 3 times, combine the organic phases, wash with saturated chlorine and sodium solutions for 2 times, then dry the organic phase with anhydrous magnesium sulfate to remove water, and remove the organic solvent by rotary evaporation to obtain allylated protocatechuic acid.

[0027] S5: 10.84 kg of allylated protocatechuic acid, 240 kg of dichloromethane and 27.6 kg of peroxybenzoic acid as an epoxidation reagent were added into a reactor, stirred at 0°C and 300 r / min for 40 min, then stirred and reacted at 40°C for 35 h, the reaction product was cooled and crystallized at -10°C for 4 h, filtered to remove the generated benzoic acid solid crystals, and then the filtrate was washed twice with a 10% sodium sulfite solution, a 5% sodium carbonate solution and a saturated sodium chloride solution, respectively, and then dried with anhydrous magnesium sulfate to remove water, and the organic solvent was removed by rotary evaporation to obtain epoxidized protocatechuic acid.

[0028] S6: Dissolve epoxidized protocatechuic acid in dichloromethane to prepare a core solution with a mass fraction of 0.8%, and dissolve polylactic acid-glycolic acid copolymer in hexafluoroisopropanol to prepare a shell solution with a mass fraction of 5%; transfer the core solution and the shell solution to the liquid supply system of the coaxial electrostatic spray device, and supply liquid to the coaxial nozzle at a shell solution flow rate of 2 mL / h and a core solution flow rate of 0.22 mL / h at a voltage of 15 kV and a receiving distance of 15 cm. Use the coaxial electrostatic spray method to prepare epoxy crosslinking agent microspheres with epoxidized protocatechuic acid as the core and polylactic acid-glycolic acid copolymer as the shell and an average diameter of 10±0.5 μm.

[0029] S7: 100 kg of fermented manure with a moisture content of less than 5%, 35 kg of bio-based gel powder, 30 kg of biochar, 20 kg of potassium humate and 8 kg of epoxy cross-linking agent microspheres are mixed evenly to obtain a soil conditioner for reducing the swelling and shrinkage of sand ginger black soil.

[0030] Example 2: This example provides a soil conditioner for reducing the swelling and shrinkage of sandy black soil, which is prepared by the following steps: S1: Crush the crop straw, add water to grind it, filter it, remove large-sized impurities, and obtain a fiber slurry with a fiber length of 1.5±0.2 mm and a solid content of 10 w / v%; add 550 L of fiber slurry and 300 L of 0.1 mol / L sodium hydroxide solution into a reactor, stir at 82°C and 250 r / min for 50 min, add 100 L of epichlorohydrin into the reactor after natural cooling, continue stirring for 6.5 h, centrifuge and filter, wash the filter cake with anhydrous ethanol and deionized water for 2.5 times respectively, and vacuum dry it to obtain epoxidized straw fiber.

[0031] S2: 80 kg of epoxidized straw fiber and 200 kg of deionized water were added into a reactor and stirred to mix, then 40 kg of triethylenetetramine was added into the reactor, stirred to react for 7 h at 75 ° C and 250 r / min, centrifuged and filtered, the filter cake was washed twice with deionized water, and vacuum dried to obtain amino-modified straw fiber.

[0032] S3: Add 90 kg of acrylic acid, 31 kg of sodium hydroxide and 200 kg of deionized water into the reactor, stir and mix, then add 30 kg of 2-acrylamido-2-methylpropanesulfonic acid, 27.5 kg of amino-modified straw fiber, 1.3 kg of ammonium persulfate as an initiator and 0.155 kg of N,N'-methylenebisacrylamide as a cross-linking agent into the reactor, stir and react at 58 ° C and 250 r / min for 11 minutes, soak the reaction product in anhydrous ethanol for 4 minutes, wash it twice with deionized water, vacuum dry, crush it, and pass it through an 80-mesh sieve to obtain a bio-based gel powder.

[0033] S4: Add 15.5 kg of protocatechuic acid, 41.5 kg of anhydrous potassium carbonate and 550 kg of dimethyl sulfoxide into the reactor, stir at 400 r / min for 4 min, then add 48 kg of propylene chloride dropwise into the reactor under stirring conditions at 0°C, stir and react at 30°C for 38 h after the addition is complete, then stir and mix the reaction product with 1.5 times the volume of deionized water, extract with ethyl acetate for 4 times, combine the organic phases, wash with saturated chlorine and sodium solutions twice, then dry the organic phase with anhydrous magnesium sulfate to remove water, and remove the organic solvent by rotary evaporation to obtain allylated protocatechuic acid.

[0034] S5: 10.84 kg of allylated protocatechuic acid, 260 kg of dichloromethane and 30 kg of peroxybenzoic acid as an epoxidation reagent were added into a reactor, stirred at 0°C and 400 r / min for 50 min, then stirred and reacted at 42°C for 38 h, the reaction product was cooled and crystallized at -10°C for 4.5 h, filtered to remove the generated benzoic acid solid crystals, and then the filtrate was washed twice with a 10% sodium sulfite solution, a 5% sodium carbonate solution and a saturated sodium chloride solution, respectively, and then dried with anhydrous magnesium sulfate to remove water, and the organic solvent was removed by rotary evaporation to obtain epoxidized protocatechuic acid.

[0035] S6: Dissolve epoxidized protocatechuic acid in dichloromethane to prepare a core solution with a mass fraction of 0.9%, and dissolve polylactic acid-glycolic acid copolymer in hexafluoroisopropanol to prepare a shell solution with a mass fraction of 5.5%; transfer the core solution and the shell solution to the liquid supply system of the coaxial electrostatic spray device, and supply liquid to the coaxial nozzle at a shell solution flow rate of 2.1 mL / h and a core solution flow rate of 0.23 mL / h at a voltage of 18 kV and a receiving distance of 18 cm. Use the coaxial electrostatic spray method to prepare epoxy crosslinking agent microspheres with epoxidized protocatechuic acid as the core and polylactic acid-glycolic acid copolymer as the shell and an average diameter of 10±0.5 μm.

[0036] S7: 125 kg of fermented manure with a moisture content of less than 5%, 40 kg of bio-based gel powder, 32.5 kg of biochar, 25 kg of potassium humate and 11 kg of epoxy cross-linking agent microspheres were mixed evenly to obtain a soil conditioner that reduces the swelling and shrinkage of sand ginger black soil.

[0037] Example 3: This example provides a soil conditioner for reducing the swelling and shrinkage of sandy black soil, which is prepared by the following steps: S1: Crush the crop straw, add water to grind it, filter it, remove large-sized impurities, and obtain a fiber slurry with a fiber length of 1.5±0.2 mm and a solid content of 10 w / v%; add 600 L of fiber slurry and 300 L of 0.1 mol / L sodium hydroxide solution into a reactor, stir at 85°C and 300 r / min for 60 min, add 100 L of epichlorohydrin into the reactor after natural cooling, continue stirring for 7 h, centrifuge and filter, wash the filter cake with anhydrous ethanol and deionized water for 3 times respectively, and vacuum dry it to obtain epoxidized straw fiber.

[0038] S2: 80 kg of epoxidized straw fiber and 240 kg of deionized water were added into a reactor and stirred to mix. Then, 40 kg of tetraethylenepentamine was added into the reactor. The mixture was stirred to react at 80°C and 300 r / min for 8 h. The mixture was centrifugally filtered. The filter cake was washed with deionized water for 3 times and vacuum dried to obtain amino-modified straw fiber.

[0039] S3: Add 90 kg of acrylic acid, 31 kg of sodium hydroxide and 200 kg of deionized water into the reactor, stir and mix, then add 30 kg of 2-acrylamido-2-methylpropanesulfonic acid, 30 kg of amino-modified straw fiber, 1.4 kg of ammonium persulfate as an initiator and 0.16 kg of N,N'-methylenebisacrylamide as a cross-linking agent into the reactor, stir and react at 60°C and 300 r / min for 12 min, soak the reaction product in anhydrous ethanol for 5 min, wash it with deionized water 3 times, vacuum dry it, crush it, and pass it through an 80-mesh sieve to obtain a bio-based gel powder.

[0040] S4: Add 15.5kg of protocatechuic acid, 42kg of anhydrous potassium carbonate and 600kg of dimethyl sulfoxide into the reactor, stir at 500r / min for 5min, then add 48kg of propylene chloride dropwise into the reactor under stirring at 0℃, stir and react at 30℃ for 40h after the addition is complete, then stir and mix the reaction product with 2 times the volume of deionized water, extract with ethyl acetate for 5 times, combine the organic phases, wash with saturated chlorine and sodium solutions for 3 times, dry and remove water with anhydrous magnesium sulfate, and remove the organic solvent by rotary evaporation to obtain allylated protocatechuic acid.

[0041] S5: 10.84 kg of allylated protocatechuic acid, 280 kg of dichloromethane and 33.2 kg of peroxybenzoic acid as an epoxidation reagent were added into a reactor, stirred at 0°C and 500 r / min for 60 min, then stirred and reacted at 45°C for 40 h, the reaction product was cooled and crystallized at -10°C for 5 h, filtered to remove the generated benzoic acid solid crystals, and then the filtrate was washed 3 times with a 10% sodium sulfite solution, a 5% sodium carbonate solution and a saturated sodium chloride solution, respectively, and then dried with anhydrous magnesium sulfate to remove water, and the organic solvent was removed by rotary evaporation to obtain epoxidized protocatechuic acid.

[0042] S6: Dissolve epoxidized protocatechuic acid in dichloromethane to prepare a core solution with a mass fraction of 1%, and dissolve polylactic acid-glycolic acid copolymer in hexafluoroisopropanol to prepare a shell solution with a mass fraction of 6%; transfer the core solution and the shell solution to the liquid supply system of the coaxial electrostatic spray device, and supply liquid to the coaxial nozzle at a voltage of 20 kV and a receiving distance of 20 cm at a shell solution flow rate of 2.2 mL / h and a core solution flow rate of 0.25 mL / h. Use the coaxial electrostatic spray method to prepare epoxy crosslinking agent microspheres with epoxidized protocatechuic acid as the core and polylactic acid-glycolic acid copolymer as the shell and an average diameter of 10±0.5 μm.

[0043] S7: 150 kg of fermented manure with a moisture content of less than 5%, 45 kg of bio-based gel powder, 35 kg of biochar, 30 kg of potassium humate and 14 kg of epoxy cross-linking agent microspheres were mixed evenly to obtain a soil conditioner that reduces the swelling and shrinkage of sand ginger black soil.

[0044] Comparative Example 1: Based on Example 3, in the process of preparing the bio-based gel powder in step S3, the amino-modified straw fiber is replaced with ordinary straw fiber of the same size, and the other steps remain unchanged to prepare a soil conditioner.

[0045] Comparative Example 2: Based on Example 3, the amount of epoxy crosslinking agent microspheres in step S7 was adjusted to 4 kg, and the other steps remained unchanged to prepare a soil conditioner.

[0046] Comparative Example 3: Based on Example 3, epoxy crosslinking agent microspheres are not added in step S7, and the other steps remain unchanged to prepare a soil conditioner.

[0047] The crop straw used in the embodiments and comparative examples is corn straw, and the other raw materials are conventional commercial products.

[0048] Experiments were conducted on Example 1 to Example 3 and Comparative Example 1 to Comparative Example 3. The experiments were set up at the Yangliu Experimental Station in Suixi County, Huaibei City. A test field was selected, and the soil type was sandy ginger black soil.

[0049] The experiment started in mid-June 2024, and 7 test treatments were set up, all of which were tilled to a depth of 50 cm. Different soil conditioners in the embodiments and comparative examples were evenly mixed into 6 of the test treatments, with an application rate of 5000 kg / mu. The remaining 1 test treatment was a blank control (no soil conditioner was applied). 30 days after the first rainfall (June 21), soil properties were tested at depths of 40-45 cm and 25-30 cm, respectively. The sampling was repeated 3 times, and the sampling method was the ring knife method.

[0050] The sample processing method is as follows: after the samples taken by the ring knife method are saturated with water, the protruding parts are cut off to make the volume of all samples consistent, and then they are dried to constant weight, the height and diameter of the samples are measured respectively, and the volumes of different samples are calculated, so as to evaluate the soil shrinkage rate and soil linear expansion coefficient after different test treatments.

[0051] Soil shrinkage rate = (sample volume before drying - sample volume after drying) / sample volume after drying × 100%.

[0052] Transverse soil linear extension coefficient = (diameter of sample before drying - diameter of sample after drying) / diameter of sample after drying.

[0053] Longitudinal soil linear expansion coefficient = (height of sample before drying - height of sample after drying) / height of sample after drying.

[0054] The results are shown in Table 1: Table 1 As can be seen from Table 1, after applying the soil conditioners in Examples 1 to 3, the soil shrinkage rate, lateral and longitudinal soil linear extension coefficients of the samples were all reduced, indicating that the soil conditioners in this example have a significant inhibitory effect on the soil shrinkage of the sandy black soil. The blank control shows that the fermented manure and other substances in the soil conditioner have a certain inhibitory effect on the soil shrinkage rate at 5-10 cm.

[0055] After applying the soil conditioner in Comparative Examples 1 to 3, the soil shrinkage rate at 20-25 cm was significantly increased compared to that at 5-10 cm. This may be because the epoxy cross-linking agent microspheres were not added or the amount of epoxy cross-linking agent microspheres added was too small, the amino-modified straw fibers were not cross-linked with each other or the cross-linking points were too few, and it was difficult to resist the gravity of the upper soil. In Examples 1 to 3, the amino-modified straw fibers were fully cross-linked, and the strength of the bio-based gel was higher after absorbing water, and it had better resistance to soil shrinkage even in deeper tillage layers.

[0056] 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.

[0057] 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 soil conditioner that reduces the swelling and shrinkage of sandy ginger black soil, characterized in that: The following raw materials are included by mass: 100-150 parts of fermented manure with a moisture content of less than 5% 35-45 parts of bio-based gel powder 30-35 parts of biochar Potassium humate 20-30 parts Epoxy crosslinker microspheres 8-14 parts The bio-based gel powder is prepared by the following steps: Add acrylic acid, sodium hydroxide and deionized water into a reaction kettle, stir and mix, then add 2-acrylamido-2-methylpropanesulfonic acid, amino-modified straw fiber, ammonium persulfate and N,N'-methylenebisacrylamide into the reaction kettle, stir and react at 55-60°C and 200-300r / min for 10-12min, soak the reaction product in anhydrous ethanol for 3-5min, wash with deionized water for 2-3 times, vacuum dry, crush, and pass through an 80-mesh sieve to obtain a bio-based gel powder; The epoxy crosslinker microspheres are prepared by the following steps: Dissolving epoxidized protocatechuic acid in dichloromethane to prepare a 0.8-1wt% core solution, and dissolving polylactic acid-co-glycolic acid in hexafluoroisopropanol to prepare a 5-6wt% shell solution; The core solution and the shell solution are transferred to the liquid supply system of the coaxial electrostatic spray device, and the coaxial nozzle is supplied with liquid at a shell solution flow rate of 2-2.2 mL / h and a core solution flow rate of 0.22-0.25 mL / h. At a voltage of 15-20 kV and a receiving distance of 15-20 cm, epoxy crosslinker microspheres with an average diameter of 10±0.5 μm are prepared.

2. A soil conditioner for reducing the swelling and shrinkage of sandy black soil according to claim 1, characterized in that: The mass ratio of the acrylic acid, sodium hydroxide, deionized water, 2-acrylamide-2-methylpropane sulfonic acid, amino-modified straw fiber, initiator and crosslinking agent is 9:3.1:20:3:2.5-3:0.12-0.14:0.015-0.

016.

3. A soil conditioner for reducing the swelling and shrinkage of sandy black soil according to claim 1, characterized in that: The amino-modified straw fiber is prepared by the following steps: Add epoxidized straw fiber and deionized water into a reactor and stir to mix, then add fatty amine monomer into the reactor, stir and react at 70-80° C. and 200-300 r / min for 6-8 hours, centrifuge and filter, wash the filter cake with deionized water for 2-3 times, and vacuum dry to obtain amino-modified straw fiber; The mass ratio of the epoxidized straw fiber, deionized water and fatty amine monomer is 2:4-6:

1.

4. A soil conditioner for reducing the swelling and shrinkage of sandy black soil according to claim 3, characterized in that: The fatty amine monomer is any one of diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

5. A soil conditioner for reducing the swelling and shrinkage of sandy black soil according to claim 3, characterized in that: The epoxidized straw fiber is prepared by the following steps: The crop straw is crushed, and then water is added to grind the pulp, and filtered to obtain a fiber slurry with a fiber length of 1.5±0.2 mm and a solid content of 10 w / v%. The fiber slurry and a sodium hydroxide solution with a concentration of 0.1 mol / L are added to a reactor, and stirred at 80-85° C. and 200-300 r / min for 40-60 min. After natural cooling, epichlorohydrin is added to the reactor, and stirring is continued for 6-7 h. Centrifugal filtration is performed, and the filter cake is washed with anhydrous ethanol and deionized water for 2-3 times respectively, and vacuum dried to obtain epoxidized straw fiber; The volume ratio of the fiber slurry, the sodium hydroxide solution and epichlorohydrin is 5-6:3:

1.

6. The soil conditioner for reducing the swelling and shrinkage of sandy black soil according to claim 1, characterized in that: The epoxidized protocatechuic acid is prepared by the following steps: Add allylated protocatechuic acid, dichloromethane and perbenzoic acid into a reactor, stir at 0°C and 300-500r / min for 40-60min, stir at 40-45°C for 35-40h, cool and crystallize the reaction product at -10°C for 4-5h, filter, wash the filtrate with 10wt% sodium sulfite solution, 5wt% sodium carbonate solution and saturated sodium chloride solution for 2-3 times, dry with anhydrous magnesium sulfate to remove water, and remove the organic solvent by rotary evaporation to obtain epoxidized protocatechuic acid.

7. A soil conditioner for reducing the swelling and shrinkage of sandy black soil according to claim 6, characterized in that: The usage ratio of the allylated protocatechuic acid, dichloromethane and peroxybenzoic acid is 2.71:60-70:6.9-8.

3.

8. The soil conditioner for reducing the swelling and shrinkage of sandy black soil according to claim 6, characterized in that: The allylated protocatechuic acid is prepared by the following steps: Add protocatechuic acid, anhydrous potassium carbonate and dimethyl sulfoxide to the reactor, stir at 300-500r / min for 3-5min, then add allyl chloride dropwise to the reactor under stirring conditions at 0°C, stir and react at 30°C for 35-40h after the addition is complete, stir and mix the reaction product with 1-2 times the volume of deionized water, extract with ethyl acetate for 3-5 times, combine the organic phases, wash with saturated chlorine and sodium solutions for 2-3 times, dry the organic phase with anhydrous magnesium sulfate to remove water, and remove the organic solvent by rotary evaporation to obtain allylated protocatechuic acid.

9. The soil conditioner for reducing the swelling and shrinkage of sandy black soil according to claim 8, characterized in that: The mass ratio of the protocatechuic acid, anhydrous potassium carbonate, dimethyl sulfoxide and allyl chloride is 1.55:4.1-4.2:50-60:4.

8.

10. Use of the soil conditioner for reducing the swelling and shrinkage of sandy black soil according to any one of claims 1 to 9 in reducing the shrinkage rate of sandy black soil.

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