Nutrient preserving agent for improving loess soil and preparation method thereof
By preparing a nutrient retention agent formulated with straw-based foam particles and modified bentonite, the problem of poor nutrient retention performance in sandy soils along the Yellow River was solved, the soil stability and nutrient retention capacity were improved, and soil fertility and crop yield were increased.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF SOIL & FERTILIZER ANHUI ACAD OF AGRI SCI
- Filing Date
- 2024-05-09
- Publication Date
- 2026-07-03
AI Technical Summary
The sandy soils along the Yellow River are characterized by strong sandiness, loose texture, high dispersion, fragile structure, poor water and fertilizer retention capacity, low buffering capacity, low organic matter content, and poor nutrient content, which seriously restricts the improvement of grain production capacity in the region.
By preparing straw-based foam particles and combining them with modified bentonite and other formulations, a nutrient retention agent for improving sandy soil along the Yellow River is prepared. The process includes step one: treating steam-exploded straw fibers under specific conditions and reacting them with substances such as acrylamide to foam them into straw-based foam particles. Combining these with humic acid, biochar, modified bentonite, and sodium alginate, straw-based foam particles with more open pores and a rough surface are formed, which improves soil stability and water and fertilizer retention performance.
It improves the stability and water and fertilizer retention capacity of sandy soil, increases soil cohesion, reduces nutrient loss, enhances soil fertility, and promotes crop growth and yield.
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Figure BDA0004829680760000101
Abstract
Description
Technical Field
[0001] This invention belongs to the field of soil improvement technology, specifically relating to a nutrient retention agent for improving sandy soil along the Yellow River and its preparation method. Background Technology
[0002] The area of sandy soil in the Yellow River floodplains of my country exceeds 58 million mu (approximately 3.9 million hectares), distributed across 63 counties and districts in five provinces: Shandong, Henan, Hebei, Anhui, and Jiangsu. The areas along the Yellow River with sandy soil distribution are flat, rich in light, temperature, water, and heat resources, and are important grain-producing regions in my country. However, due to the parent material being mainly coarse silt and fine sand, coupled with the long-term influence of wind and sand activity, the soil in the Yellow River floodplains is highly sandy, characterized by loose texture, high dispersion, fragile structure, poor aggregation, poor water and fertilizer retention capacity, low buffering capacity, low organic matter content, and poor nutrient content. Furthermore, irrigation and fertilization efficiency is low, severely restricting the improvement of grain production capacity in this region. Therefore, improving and enriching the sandy soil along the Yellow River to increase yield is an urgent problem to be solved in this region, and is of great significance to implementing the national action plan to increase grain production capacity by 100 billion jin (approximately 50 million tons).
[0003] Chinese Patent Publication No. CN105967942B discloses a straw liquefaction liquid for soil improvement and a method for its preparation and improvement. The method uses water as a medium to liquefy straw, resulting in a product that has the dual functions of improving soil pH and supplementing nutrients. After application, it can balance soil pH and supply the soil with nitrogen, phosphorus, potassium, and organic matter nutrients that the soil lacks, promoting crop growth, increasing yield, and achieving high straw utilization and rapid return to the field. However, sandy soils have relatively weak cementing properties and loose soil particles, limiting the retention capacity of the straw liquefaction liquid in sandy soils. Summary of the Invention
[0004] The purpose of this invention is to provide a nutrient retention agent for improving sandy soils along the Yellow River. It is prepared by using crop straw to make straw-based foam particles, and combined with modified bentonite and other formulations to improve the cementation effect of sandy soils and solve the problem of poor soil retention performance of sandy soils. The second purpose is to provide a method for preparing the nutrient retention agent for improving sandy soils along the Yellow River.
[0005] The objective of this invention can be achieved through the following technical solutions:
[0006] A method for preparing a nutrient retention agent for improving sandy soil along the Yellow River includes the following steps:
[0007] Step 1: Transfer the steam-exploded straw fiber to the reaction vessel, then add sodium hydroxide, chloroacetic acid, zinc phosphate and water to the reaction vessel, stir for 2-3 hours at 80-90℃ and 200-300r / min, then adjust the pH of the reaction system to neutral with a 2-3% hydrochloric acid solution, filter, dry to obtain esterified straw fiber.
[0008] Step 2: Add acrylamide and water to the reactor and stir for 10-20 minutes at 25-30℃. Then add sodium bicarbonate, initiator and esterified straw fiber to the reactor and stir for 20-30 minutes at 45-55℃ and 120-150 r / min. Pour into a mold to foam and shape. Cut and crush the foam board to obtain straw-based foam particles.
[0009] Step 3: Mix straw-based foam particles, humic acid, biochar, modified bentonite and sodium alginate evenly in a mass ratio of 12-15:4-5:1-3:4-6:0.5-0.8 to obtain a nutrient retention agent for sandy soil improvement.
[0010] Furthermore, the ratio of steam-exploded straw fiber, sodium hydroxide, chloroacetic acid, zinc phosphate and water is 4-5g: 0.9-1g: 2-2.3g: 0.02-0.03g: 150mL.
[0011] Furthermore, the ratio of acrylamide, water, sodium bicarbonate, initiator, and esterified straw fiber is 8-10g:10mL:0.5-0.7g:0.5-0.6g:8-10g.
[0012] Furthermore, the steam-exploded straw fiber is prepared through the following steps:
[0013] The straw is shredded into short straws of 2-4 cm in length using a straw shredder, transferred to a steam explosion device, reacted under a pressure of 2-2.2 MPa for 5-10 minutes, and then removed and dried to obtain steam-exploded straw fiber.
[0014] Furthermore, straw includes crop straw such as corn straw, rice straw, wheat straw, and sorghum straw.
[0015] Furthermore, the modified bentonite is prepared through the following steps:
[0016] Sodium-based bentonite and water were added to a stirred tank and stirred and dispersed at 100-150 r / min for 10-20 min to obtain a bentonite dispersion with a mass fraction of 50-60%. Acrylic acid monomer was added to the reactor, and the neutralization degree was adjusted to 65-70% with a sodium hydroxide aqueous solution with a mass fraction of 10-30%. The bentonite dispersion was then added to the reactor. Hydroxypropyl acrylate and N,N-methylenebisacrylamide as a crosslinking agent were added to the reactor under nitrogen protection. The mixture was stirred at 200-500 r / min for 5-10 min, followed by ultrasonic dispersion for 5-10 min. An initiator was added to the reactor, and the mixture was stirred at 55-60℃ for 30-40 min. The reaction product was precipitated with anhydrous ethanol, and the precipitate was dried to constant weight by forced air drying, pulverized, and passed through a 150-200 mesh sieve to obtain modified bentonite.
[0017] Furthermore, the ratio of acrylic monomer, bentonite dispersion, N,N-methylenebisacrylamide, hydroxypropyl acrylate and initiator is 80-100g: 150-200g: 0.15-0.2g: 15-18g: 0.18-0.22g.
[0018] Furthermore, the acrylic monomer is acrylic acid or methacrylic acid.
[0019] Furthermore, the initiator is potassium persulfate or ammonium persulfate.
[0020] The beneficial effects of this invention are:
[0021] The nutrient retention agent of this invention contains straw-based foam particles, humic acid, biochar, modified bentonite, and sodium alginate, and is suitable for sandy soil improvement. The preparation of straw-based foam particles realizes the recycling of crop straw.
[0022] Straw-based foam particles have more open pores and a rougher surface, which helps to embed soil particles and increase the stability of sandy soils. Modified bentonite is combined with water-absorbing resin, which improves its hydrophilicity and helps to form hydrogels in ascending soil, filling the pores between soil aggregates and improving the stability of sandy soils. With the adhesion provided by modified bentonite and sodium alginate, straw-based foam particles make sandy soils more aggregated and increase their water retention and fertilizer retention capacity.
[0023] Steam explosion of straw can kill pathogenic microorganisms and destroy its original dense structure, resulting in loosely structured steam-exploded straw fibers. Under alkaline conditions and catalysis by zinc phosphate, the steam-exploded straw fibers are modified by chloroacetic acid esterification, which introduces more active groups for the straw fibers to participate in subsequent reactions. This helps to prepare straw-based foam particles with stable pores. These straw-based foam particles are biodegradable and environmentally friendly.
[0024] The humic acid and biochar in the nutrient retention agent for sandy soil improvement of this invention have good adsorption properties, which can adsorb and retain nutrients in the soil, further reduce nutrient loss, and improve soil fertility. Detailed Implementation
[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0026] Example 1
[0027] This embodiment provides a method for preparing a nutrient retention agent for improving sandy soil along the Yellow River, comprising the following steps:
[0028] Step 1: Shred the sorghum stalks into short stalks with a length of 2-4cm using a straw shredder, transfer them to a steam explosion equipment, react them under a pressure of 2MPa for 5 minutes, and then remove and dry them to obtain steam-exploded straw fibers.
[0029] 40 kg of steam-exploded straw fiber was transferred to a reaction vessel, and then 9 kg of sodium hydroxide, 20 kg of chloroacetic acid, 0.2 kg of zinc phosphate and 1500 L of water were added to the reaction vessel. The mixture was stirred at 80 °C and 200 r / min for 2 h. The pH of the reaction system was then adjusted to neutral with a 2% hydrochloric acid solution. The mixture was filtered and dried to obtain esterified straw fiber.
[0030] Step 2: Add 40 kg of acrylamide and 50 kg of water to the reactor and stir for 10 min at 25°C. Then add 2.5 kg of sodium bicarbonate as a foaming agent, 2.5 kg of potassium persulfate as an initiator, and 40 kg of esterified straw fiber to the reactor and stir for 20 min at 45°C and 120 r / min. Pour the mixture into a mold to foam and shape it. Cut and crush the shaped foam board to obtain straw-based foam particles.
[0031] Step 3: Add 100 kg of sodium-based bentonite and 100 kg of water to a stirred tank and stir and disperse at 100 r / min for 10 min to obtain a bentonite dispersion with a mass fraction of 50%.
[0032] Add 8 kg of acrylic acid to the reactor and adjust the neutralization degree to 65% with a 10% sodium hydroxide aqueous solution. Then add 15 kg of bentonite dispersion to the reactor. Under nitrogen protection, add 1.5 kg of hydroxypropyl acrylate and 15 g of N,N-methylenebisacrylamide as a crosslinking agent to the reactor. Stir at 200 r / min for 5 min, then ultrasonically disperse for 5 min. Add 18 g of potassium persulfate as an initiator to the reactor and stir at 55 °C for 30 min. Precipitate the reaction product with anhydrous ethanol, dry the precipitate to constant weight by forced air, pulverize, and pass through a 150 mesh sieve to obtain modified bentonite.
[0033] Mix 12 kg of straw-based foam granules, 4 kg of humic acid, 1 kg of biochar, 4 kg of modified bentonite, and 0.5 kg of sodium alginate evenly to obtain a nutrient retention agent for sandy soil improvement.
[0034] Example 2
[0035] This embodiment provides a method for preparing a nutrient retention agent for improving sandy soil along the Yellow River, comprising the following steps:
[0036] Step 1: Crush wheat straw into short straws of 2-4cm in length using a straw shredder, transfer them to a steam explosion device, react them under a pressure of 2.1MPa for 6 minutes, then remove and dry them to obtain steam-exploded straw fibers;
[0037] 42 kg of steam-exploded straw fiber was transferred to a reaction vessel, and then 9.3 kg of sodium hydroxide, 21 kg of chloroacetic acid, 0.24 kg of zinc phosphate and 1500 L of water were added to the reaction vessel. The mixture was stirred at 85 °C and 250 r / min for 2.5 h. The pH of the reaction system was then adjusted to neutral with a 2% hydrochloric acid solution. The mixture was filtered and dried to obtain esterified straw fiber.
[0038] Step 2: Add 42kg of acrylamide and 50kg of water to the reactor and stir for 15 minutes at 25℃. Then add 2.8kg of sodium bicarbonate as a foaming agent, 2.8kg of ammonium persulfate as an initiator, and 43kg of esterified straw fiber to the reactor and stir for 25 minutes at 50℃ and 130r / min. Pour the mixture into a mold to foam and shape it. Cut and crush the shaped foam board to obtain straw-based foam particles.
[0039] Step 3: Add 105 kg of sodium-based bentonite and 90 kg of water to a stirred tank and stir and disperse at 120 r / min for 15 min to obtain a bentonite dispersion with a mass fraction of 54%.
[0040] Add 9 kg of methacrylic acid to the reactor, adjust the neutralization degree to 68% with a 15% sodium hydroxide aqueous solution, then add 18 kg of bentonite dispersion to the reactor, and then add 1.6 kg of hydroxypropyl acrylate and 18 g of N,N-methylenebisacrylamide as a crosslinking agent to the reactor under nitrogen protection. Stir at 300 r / min for 8 min, then ultrasonically disperse for 8 min. Add 20 g of ammonium persulfate as an initiator to the reactor, stir at 58 °C for 35 min, precipitate the reaction product with anhydrous ethanol, dry the precipitate to constant weight by forced air, pulverize, and pass through a 180 mesh sieve to obtain modified bentonite.
[0041] Mix 13 kg of straw-based foam granules, 4.5 kg of humic acid, 2 kg of biochar, 5 kg of modified bentonite, and 0.6 kg of sodium alginate evenly to obtain a nutrient retention agent for sandy soil improvement.
[0042] Example 3
[0043] This embodiment provides a method for preparing a nutrient retention agent for improving sandy soil along the Yellow River, comprising the following steps:
[0044] Step 1: Crush rice straw and sorghum straw into short straws with a length of 2-4cm using a straw shredder, transfer them to a steam explosion equipment, react under a pressure of 2.1MPa for 8 minutes, then remove and dry to obtain steam-exploded straw fiber;
[0045] 45 kg of steam-exploded straw fiber was transferred to a reaction vessel, and then 9.5 kg of sodium hydroxide, 22 kg of chloroacetic acid, 0.25 kg of zinc phosphate and 1500 L of water were added to the reaction vessel. The mixture was stirred at 85 °C and 250 r / min for 2.5 h. The pH of the reaction system was then adjusted to neutral with a 3% hydrochloric acid solution. The mixture was filtered and dried to obtain esterified straw fiber.
[0046] Step 2: Add 45 kg of acrylamide and 50 kg of water to the reactor and stir for 15 min at 28°C. Then add 3.2 kg of sodium bicarbonate as a foaming agent, 2.8 kg of ammonium persulfate as an initiator, and 48 kg of esterified straw fiber to the reactor and stir for 25 min at 50°C and 140 r / min. Pour the mixture into a mold to foam and shape it. Cut and crush the shaped foam board to obtain straw-based foam particles.
[0047] Step 3: Add 110 kg of sodium-based bentonite and 90 kg of water to a stirred tank and stir and disperse at 135 r / min for 15 min to obtain a bentonite dispersion with a mass fraction of 55%.
[0048] Add 9 kg of methacrylic acid to the reactor, adjust the neutralization degree to 68% with a 20% sodium hydroxide aqueous solution, then add 18 kg of bentonite dispersion to the reactor, and then add 1.7 kg of hydroxypropyl acrylate and 18 g of N,N-methylenebisacrylamide as a crosslinking agent to the reactor under nitrogen protection. Stir at 350 r / min for 8 min, then ultrasonically disperse for 8 min. Add 20 g of ammonium persulfate as an initiator to the reactor, stir at 58 °C for 35 min, precipitate the reaction product with anhydrous ethanol, dry the precipitate to constant weight by forced air, pulverize, and pass through a 180 mesh sieve to obtain modified bentonite.
[0049] Mix 13.5 kg of straw-based foam granules, 4.5 kg of humic acid, 2 kg of biochar, 5 kg of modified bentonite, and 0.7 kg of sodium alginate evenly to obtain a nutrient retention agent for sandy soil improvement.
[0050] Example 4
[0051] This embodiment provides a method for preparing a nutrient retention agent for improving sandy soil along the Yellow River, comprising the following steps:
[0052] Step 1: Crush the corn stalks into short stalks with a length of 2-4cm using a straw shredder, transfer them to a steam explosion equipment, react them under a pressure of 2.2MPa for 10 minutes, then remove and dry them to obtain steam-exploded straw fibers;
[0053] 50 kg of steam-exploded straw fiber was transferred to a reaction vessel, and then 10 kg of sodium hydroxide, 23 kg of chloroacetic acid, 0.3 kg of zinc phosphate and 1500 L of water were added to the reaction vessel. The mixture was stirred for 3 h at 90 °C and 300 r / min. The pH of the reaction system was then adjusted to neutral with a 3% hydrochloric acid solution. The mixture was filtered and dried to obtain esterified straw fiber.
[0054] Step 2: Add 50 kg of acrylamide and 50 kg of water to the reactor and stir for 20 min at 30°C. Then add 3.5 kg of sodium bicarbonate as a foaming agent, 3 kg of potassium persulfate as an initiator, and 50 kg of esterified straw fiber to the reactor and stir for 30 min at 55°C and 150 r / min. Pour the mixture into a mold to foam and shape it. Cut and crush the shaped foam board to obtain straw-based foam particles.
[0055] Step 3: Add 120 kg of sodium-based bentonite and 80 kg of water to a stirred tank and stir and disperse at 150 r / min for 20 min to obtain a bentonite dispersion with a mass fraction of 60%.
[0056] 10 kg of acrylic acid was added to the reactor, and the neutralization degree was adjusted to 70% with a 30% sodium hydroxide aqueous solution. Then, 20 kg of bentonite dispersion was added to the reactor. Then, under nitrogen protection, 1.8 kg of hydroxypropyl acrylate and 20 g of N,N-methylenebisacrylamide as a crosslinking agent were added to the reactor. The mixture was stirred at 500 r / min for 10 min, and then ultrasonically dispersed for 10 min. 22 g of potassium persulfate as an initiator was added to the reactor, and the mixture was stirred at 60 °C for 40 min. The reaction product was precipitated with anhydrous ethanol, the precipitate was dried by forced air to constant weight, pulverized, and passed through a 200-mesh sieve to obtain modified bentonite.
[0057] Mix 15 kg of straw-based foam granules, 5 kg of humic acid, 3 kg of biochar, 6 kg of modified bentonite, and 0.8 kg of sodium alginate evenly to obtain a nutrient retention agent for sandy soil improvement.
[0058] Comparative Example 1: Based on Example 4, the modified bentonite was replaced with conventional sodium-based bentonite, while the other steps remained unchanged, to prepare a nutrient retention agent.
[0059] Comparative Example 2: Based on Example 4, the straw-based foam particles were replaced with the steam-exploded straw fiber in step one, while the other steps remained unchanged, to prepare a nutrient retention agent.
[0060] Comparative Example 3: Based on Example 4, without adding straw-based foam particles and modified bentonite, and keeping the other steps unchanged, a nutrient retention agent was prepared.
[0061] The steam explosion equipment is a QB1000 from Henan Zhengdao Qibao Environmental Protection Technology Co., Ltd.; the straw shredder is an ETS1600 with a blade width of 40mm.
[0062] Performance tests were conducted on Examples 1-4 and Comparative Examples 1-3:
[0063] The test sand was selected from Shucheng County, Lu'an City, with a pH of 7.9 and a bulk density of 1.44 g / cm³. 3 Pass through a 100-mesh sieve.
[0064] In the examples and comparative examples, the nutrient retention agent and the test sand were mixed evenly at a mass ratio of 1:9 to obtain different samples. Then, 50g of each sample was placed into a nylon mesh bag of the same specification. The nylon mesh bag was transferred to a beaker with a volume of 500mL, and the same volume of distilled water was added to immerse the nylon mesh bag. The bag was allowed to fully absorb water for 24h. The nylon mesh bag was then removed and drained. The mass difference before and after water absorption was measured, which is the mass of water absorbed by the sample, to evaluate the water retention of the nutrient retention agent.
[0065] A PVC pipe with an inner diameter of 40 mm and a height of 80 mm was selected as the test mold. A nylon mesh with a 300-mesh aperture was placed at the bottom of the PVC pipe. Different samples were filled into the test mold with the same mass, and the distance between the top of the sample and the top of the PVC pipe was less than 10 mm. The top of the PVC pipe was sealed with a 300-mesh nylon mesh. Then, the sample was rinsed with distilled water to balance it and eliminate nutrients that could have been leached away (no ammonium ions were detected in the rinsing liquid). The sample was allowed to stand for 7 days to dry.
[0066] A beaker was placed at the bottom of a PVC pipe, and 500 mL of ammonium bicarbonate solution with an ammonium ion concentration of 200 mg / L was added from the top of the PVC pipe. The first rinsing solution was collected. Two days later, the pipe was rinsed again with 500 mL of distilled water, and the second rinsing solution was collected. The concentration of ammonium ions in the liquids collected in the beakers in the two rinsing solutions was measured to evaluate the fertilizer retention properties of the nutrient retention agent.
[0067] Different samples were taken from PVC pipes after drying for 7 days. After removing the test mold, different cylindrical test pieces were taken out. The maximum axial stress when different test pieces cracked was tested using a strain-controlled unconfined pressure gauge (Yuzhan Instruments) to evaluate the aggregation effect of nutrient retention agent on sandy soil.
[0068] The results are shown in Table 1:
[0069] Table 1
[0070]
[0071]
[0072] As shown in Table 1, the sample in the example absorbed the most water and had the greatest stress during cracking, indicating stronger water retention and agglomeration properties. Furthermore, the concentration of ammonium ions in the first rinsing solution was lower, suggesting that the sample in the example had a stronger adsorption capacity for nutrients. The comparative examples show that modified bentonite has an improving effect on the water retention of sandy soil, and both modified bentonite and straw-based foam particles can improve the agglomeration effect of sandy soil.
[0073] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0074] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a nutrient retention agent for improving sandy soil along the Yellow River, characterized in that, Includes the following steps: Step 1: Add steam-exploded straw fiber, sodium hydroxide, chloroacetic acid, zinc phosphate and water to the reaction vessel, stir at 80-90℃ and 200-300r / min for 2-3h, then adjust the pH of the reaction system to neutral with 2-3wt% hydrochloric acid solution, filter, dry to obtain esterified straw fiber. Step 2: Add acrylamide and water to the reactor and stir at 25-30℃ for 10-20 minutes. Then add sodium bicarbonate, initiator and esterified straw fiber to the reactor and stir at 45-55℃ and 120-150 r / min for 20-30 minutes. Foam and shape the product, then shear and crush it to obtain straw-based foam particles. Step 3: Mix straw-based foam particles, humic acid, biochar, modified bentonite and sodium alginate evenly in a mass ratio of 12-15:4-5:1-3:4-6:0.5-0.8 to obtain a nutrient retention agent for sandy soil improvement. The modified bentonite described in step three is prepared through the following steps: Add acrylic monomer to the reactor, adjust the neutralization degree to 65-70% with 10-30wt% sodium hydroxide aqueous solution, then add 50-60wt% bentonite dispersion to the reactor, and then add hydroxypropyl acrylate and N,N-methylenebisacrylamide under nitrogen protection. Stir at 200-500 r / min for 5-10 min, ultrasonically disperse for 5-10 min, add initiator to the reactor, stir at 55-60℃ for 30-40 min, precipitate the reaction product with anhydrous ethanol, dry to constant weight, pulverize, and pass through a 150-200 mesh sieve to obtain modified bentonite; The ratio of acrylic monomer, bentonite dispersion, N,N-methylenebisacrylamide, hydroxypropyl acrylate and initiator is 80-100g:150-200g:0.15-0.2g:15-18g:0.18-0.22g; The acrylic monomer is acrylic acid or methacrylic acid; The initiator is potassium persulfate or ammonium persulfate.
2. The method for preparing a nutrient retention agent for improving sandy soil along the Yellow River according to claim 1, characterized in that, The ratio of steam-exploded straw fiber, sodium hydroxide, chloroacetic acid, zinc phosphate and water in step one is 4-5g: 0.9-1g: 2-2.3g: 0.02-0.03g: 150mL.
3. The method for preparing a nutrient retention agent for improving sandy soil along the Yellow River according to claim 1, characterized in that, The ratio of acrylamide, water, sodium bicarbonate, initiator and esterified straw fiber used in step two is 8-10g:10mL:0.5-0.7g:0.5-0.6g:8-10g.
4. The method for preparing a nutrient retention agent for improving sandy soil along the Yellow River according to claim 1, characterized in that, The steam-exploded straw fiber described in step one is prepared through the following steps: The straw is shredded into short straws of 2-4 cm in length using a straw shredder, transferred to a steam explosion device, reacted under a pressure of 2-2.2 MPa for 5-10 minutes, removed and dried to obtain steam-exploded straw fiber.
5. The method for preparing a nutrient retention agent for improving sandy soil along the Yellow River according to claim 4, characterized in that, The straw is at least one of corn straw, rice straw, wheat straw, and sorghum straw.
6. A nutrient retention agent for improving sandy soil along the Yellow River, characterized in that, It is prepared by the preparation method described in any one of claims 1-5.