Preparation and use method for carbon- and silicon-based polymer soil conditioner capable of enhancing crop stress resistance

Abstract

The present invention relates to the technical field of soil remediation. Disclosed are a preparation and use method for a carbon- and silicon-based polymer soil conditioner capable of enhancing crop stress resistance. The method comprises using cheap and easily available straw waste, adding various reactants such as methyl silicone oil, urea, potassium persulfate, and potassium thiosulfate, and performing a prepolymerization reaction to obtain a carbon-containing silicon-based natural polymer material having water-retaining and salt-absorbing functions. By means of a series of polymerization reactions with calcium lignosulfonate, polyacrylamide, etc., a soil conditioner having enhanced crop stress resistance is prepared. The conditioner is formed by polymerizing silicone, an organic polymer water-retaining material, and other components, has water-retaining and fertilizer-retaining functions, and can also prevent physiological drought in crops caused by soil salinization, thereby improving the soil structure, enhancing the crop stress resistance, promoting the crop growth, and achieving a continuous increase in crop yield.

Description

Preparation and application method of a carbon-silicon based polymeric soil conditioner that can enhance crop stress resistance Technical Field

[0001] This invention belongs to the field of soil remediation technology, specifically relating to the preparation and application method of a carbon-silicon-based polymeric soil conditioner that can enhance crop stress resistance. Background Technology

[0002] Low- and medium-yield farmland not only has low soil organic matter content but also suffers from other environmental factors that limit crop production, making it a significant obstacle to the sustained increase in my country's grain output. The total cultivated land area in Xinjiang's irrigated areas is approximately 90 million mu (6.67 million hectares), of which about 35 million mu (2.33 million hectares) are saline-alkali land, accounting for 37.7% of the total cultivated land area. Soil salinization refers to the phenomenon where salts in the subsoil rise to the surface with moisture and accumulate in the topsoil layer. In saline soil environments, crops are forced to absorb sodium (Na₂O₃). + Cl - This leads to salt ion toxicity in crops, causing physiological drought and preventing or even killing them. Furthermore, due to the consistently high temperatures and low rainfall in Xinjiang, nearly two-thirds of the land suffers from drought, severely impacting the sustainable development of Xinjiang's agriculture. Although the widespread adoption of drip irrigation under mulch film in Xinjiang has reduced the impact of drought on crop growth to some extent, this technology cannot fundamentally solve the problem. Therefore, developing a soil conditioner that can increase soil organic matter content, retain soil nutrients, and maximize soil moisture retention is a fundamental solution to the regional geographical and climatic deficiencies. Patent CN107841314A discloses a soil conditioner whose core components include organic components such as amino acids and citric acid, which can regulate soil pH and alleviate soil salinity, achieving a low-cost, high-yield goal. Patent CN103756685A discloses a soil conditioner whose main components include humic acid, attapulgite powder, and potassium feldspar powder. This conditioner regulates soil pH and activates nutrients in the soil, thereby enhancing the crop's resistance to salinity and alkalinity and achieving a good effect on improving saline-alkali soils. Although the above-mentioned soil conditioners contain organic, inorganic, and biological components, the components are simply mixed together without forming a complex, which reduces the synergy between the components and makes it difficult to achieve the long-term effectiveness of the material.

[0003] In recent years, researchers have used straw biomass raw materials to prepare a series of highly absorbent materials. Patent CN202111513908.9 discloses a straw-based water-absorbing and retaining agent and its preparation method. After pretreating straw with a urea-based alkaline solution, propylene oxide is added as an etherifying agent for etherification, and formaldehyde and other catalysts are added for further reaction, resulting in a water-absorbing material. Although this method uses inexpensive straw as the base material, the preparation process involves the addition of organic reaction solvents with certain toxicity, which can easily lead to secondary pollution. Patent CN201710718420.7 discloses a straw biomass-based water-retaining agent and its preparation method. After treating straw with yeast fermentation, acrylic acid, ammonium persulfate, and N,N-methylenebisacrylamide are added and reacted to prepare a straw-based material with water absorption capacity. This method requires a nitrogen atmosphere for reaction, making large-scale production difficult.

[0004] To address the prominent problems of persistent soil salinization and declining topsoil quality, this invention utilizes inexpensive and readily available straw waste, adding various reactants such as methyl silicone oil, urea, potassium persulfate, and potassium thiosulfate. Through a prepolymerization reaction, a carbon-silicon-based natural polymer material with water-retaining and salt-absorbing functions is obtained. This material is then further polymerized with calcium lignosulfonate, polyacrylamide, and other components to prepare a soil conditioner that enhances crop stress resistance. This conditioner is polymerized from organosilicon, organic polymer water-retaining materials, and other trace elements. It possesses water and fertilizer retention functions, and can also prevent physiological drought in crops caused by soil salinization, thereby improving soil structure, enhancing crop stress resistance, promoting crop growth, and achieving a sustained increase in crop yield. Summary of the Invention

[0005] This invention establishes a method for preparing and applying a carbon-silicon-based polymeric soil conditioner that can enhance crop stress resistance. The method utilizes straw waste and pretreatment with urea, persulfate, etc., to prepare a carbon-silicon-based natural polymeric material. Through a series of prepolymerization reactions, a soil conditioner with water-retaining and salt-absorbing functions is prepared. This soil conditioner has a simple synthesis process, low cost, and can be used on a large scale to improve saline-alkali land, enhance soil water and fertilizer retention capacity, strengthen crop stress resistance, and thus increase crop yield.

[0006] The technical solution of this invention:

[0007] A method for preparing a carbon-silicon-based polymeric soil conditioner that can enhance crop stress resistance, comprising the following steps:

[0008] (1) Take 20-30 parts by weight of crushed straw, 1-5 parts by weight of methyl silicone oil as branched monomer, 1-2 parts by weight of urea as activator, and 10-20 parts by weight of N,N-dimethylformamide as reaction solution. Mix thoroughly and let stand at room temperature for 5-8 hours to allow methyl silicone oil to fully penetrate into the cellulose hydroxyl surface of the straw powder. Through the hydrogen bond protection effect formed by urea amino and branched monomer, a natural network branched macromolecular complex containing silicone oil is obtained. Then, add 1-2 parts by weight of potassium hydroxide to adjust the pH of the reaction solution, 5-10 parts by weight of potassium thiosulfate as reducing agent, and 1-2 parts by weight of ammonium persulfate as initiator and oxidant. Stir thoroughly and carry out grafting and polymerization reaction at 30-50℃ for 10-15 hours. After standing, separate the solid and liquid to obtain carbon silicon-based natural polymer material a with water retention and salt absorption function.

[0009] (2) Take 20 parts by weight of calcium lignin sulfonate, 1-5 parts by weight of urea as a crosslinking agent, 5-10 parts by weight of ferrous sulfate cation exchanger, and 50-100 parts by weight of distilled water into a reaction vessel. After stirring, react fully at 50-80℃ for 20-30 hours to allow calcium lignin sulfonate and ferrous sulfate cations to fully exchange and form lignin iron salt. At the same time, the urea amino group forms hydrogen bonds with the benzene-containing hydroxyl groups on the lignin, thereby prepolymerizing to obtain a macromolecular chain of lignin iron and calcium lignin sulfonate complex; then add 1- 10 parts by weight of polyacrylamide monomer, 1-5 parts by weight of ammonium persulfate as an initiator, 10-50 parts by weight of bentonite as a pore-forming agent, and 5-10 parts by weight of polyvinyl alcohol as a crosslinking agent are continuously stirred to completely dissolve the monomer. The polymerization reaction is carried out at 30-80℃ for 10-24 hours, so that the hydroxyl groups on the lignin iron and lignin sulfonate calcium complex form hydrogen bonds with the amino groups on the polyacrylamide monomer. At the same time, under the action of the initiator and the crosslinking agent, macromolecular chains are formed, resulting in a viscous mixed solution b with water-retaining function.

[0010] (3) At room temperature, mix 20 parts by mass of carbon silicon-based natural polymer material a and 20 parts by mass of viscous mixed solution b thoroughly. Add 1-2 parts by mass of manganese sulfate and 1-5 parts by mass of zinc sulfate in sequence. Stir thoroughly and add distilled water to make the liquid exactly 1000 parts by mass. Shake and react at room temperature for 15-48 hours. Let stand for 10-15 hours, separate the solid and liquid, and dry naturally to obtain a carbon silicon-based polymer soil conditioner with salt absorption and water retention functions that can enhance crop stress resistance.

[0011] The application of the carbon-silicon based polymeric soil conditioner obtained above depends on the farmland and soil conditions and the crop type. The prepared soil conditioner can be used under fertigation or drip irrigation conditions, and the specific application methods are as follows.

[0012] For saline-alkali soil: the application rate is 10-100 L / mu, applied by irrigation or drip irrigation once, or determined according to crop type and irrigation frequency. The application rate is 10-40 L / mu for slightly saline-alkali soil; 20-80 L / mu for moderately saline-alkali soil; and 40-100 L / mu for severely saline-alkali soil.

[0013] For low- to medium-yield fields: the application rate is 10-100 L / mu, applied by irrigation or drip irrigation once, or determined according to crop type and irrigation frequency. When the yield is more than 70% lower than the local crop yield, the application rate is 10-100 L / mu; when the yield is more than 50% lower than the local crop yield, the application rate is 40-100 L / mu.

[0014] For desertified land: the application rate is 30-100L / mu, applied by irrigation, drip irrigation, or determined according to crop type and irrigation frequency. When the soil layer 0-60cm and below is desertified, the application rate is 60-100L / mu; when the soil layer 0-40cm is desertified, the application rate is 40-100L / mu; and when the soil layer 0-20cm is desertified, the application rate is 30-100L / mu.

[0015] The straw waste mentioned includes crop straw such as cotton, corn, wheat, and rice.

[0016] The methods of applying the soil conditioner include applying it to the soil with water before sowing, applying it gradually with water and fertilizer during the crop growth period, and applying it once with water during the crop growing season.

[0017] The soil conditioner is applied at a rate of 10-100L per mu (approximately 0.067 hectares) in the field, diluted 500-1000 times.

[0018] The beneficial effects of this invention are as follows: This invention utilizes inexpensive and readily available straw waste, adding various reactants such as methyl silicone oil, urea, ammonium persulfate, and potassium thiosulfate. Under mild conditions, the dense structure of the straw is broken down, and through a prepolymerization reaction, a carbon-silicon-based natural polymer material with water-retaining and salt-absorbing functions is obtained. This material has a loose and porous structure, which helps to improve the material's adsorption capacity. Furthermore, through a series of polymerization reactions between the carbon-silicon-based natural polymer material and calcium lignin sulfonate, polyacrylamide, etc., while simultaneously adding beneficial metal elements Zn and Mn required for crop growth, the stress resistance of crops is improved, thus preparing a soil conditioner that enhances crop stress resistance. The synthesis process of this soil conditioner is simple and inexpensive. The main synthetic components can all serve as nutrients required for crop growth, and it can be used on a large scale to improve saline-alkali land, enhance the soil's water and fertilizer retention capacity, strengthen crop stress resistance, and thereby increase crop yield. Attached Figure Description

[0019] Figure 1 shows the salt absorption and water retention effects of the soil conditioner.

[0020] Figure 2 shows the effect of soil conditioning on the improvement of saline-alkali sandy soil. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0022] Example 1: Preparation and Performance Evaluation of Soil Conditioner

[0023] Weigh out 50.0g of crushed straw waste, 2.5g of methyl silicone oil, and 3.0g of urea, and add them to 50mL of N,N-dimethylformamide solution. Mix thoroughly and let stand at room temperature for 5h to allow the methyl silicone oil to fully penetrate into the cellulose hydroxyl surface of the straw powder. Then add 2.5g of potassium hydroxide to adjust the pH of the reaction solution, add 15.0g of potassium thiosulfate and 4.0g of ammonium persulfate, stir thoroughly, and react at 40℃ for 10h. After the reaction is complete, let stand for solid-liquid separation to obtain carbon silicon-based natural polymer material a1. Repeat this step 3 times to obtain 3 identical carbon silicon-based natural polymer material a1.

[0024] Three portions of calcium lignosulfonate (20.0g), urea (2.0g), and ferrous sulfate (5.0g) were weighed out sequentially and added to separate reaction vessels containing 50mL of distilled water. After thorough stirring, the mixtures were reacted at 50℃ for 20 hours. Then, 1.0g, 2.0g, and 5.0g of polyacrylamide monomer, 1.0g of ammonium persulfate, 20.0g of bentonite, and 10.0g of polyvinyl alcohol were added sequentially, and the mixtures were stirred continuously until completely dissolved. The polymerization reaction was carried out at 40℃ for 15 hours to obtain viscous mixed solutions b1, b2, and b3 with water-retaining properties.

[0025] Three portions of carbon-silicon-based natural polymer material a1 were thoroughly mixed with viscous mixed solutions b1, b2, and b3 at room temperature. Then, 1.0 g of manganese sulfate and 2.0 g of zinc sulfate were added sequentially, and the mixture was stirred thoroughly. Distilled water was added to bring the liquid volume to exactly 1000 parts by mass. The mixture was shaken and reacted at room temperature for 15 hours, then allowed to stand for 10 hours. Solid-liquid separation was performed, and the mixture was dried naturally for 2 days to obtain carbon-silicon-based polymer soil conditioners A1, A2, and A3, which possess salt absorption and water retention functions and enhance crop stress resistance. Salt and water absorption tests were conducted to analyze the water and salt absorption capacity of the soil conditioners. As shown in Figure 1, as the amount of polyacrylamide monomer increased from 1.0 g to 5.0 g, the water absorption and salt absorption capacity of the prepared soil conditioners increased by 38.1% and 47.4%, respectively. This indicates that increasing the amount of polyacrylamide monomer helps improve the water and salt absorption capacity of the soil conditioners.

[0026] Example 2: Preparation of carbon-silicon-based natural polymer materials with good water absorption capacity

[0027] Weigh out 50.0g of crushed straw waste, 5.0g of methyl silicone oil, and 4.0g of urea, and add them to 50mL of N,N-dimethylformamide solution. Mix thoroughly and let stand at room temperature for 5h to allow the methyl silicone oil to fully penetrate into the cellulose hydroxyl surface of the straw powder. Then add 2.5g of potassium hydroxide to adjust the pH of the reaction solution, add 20.0g of potassium thiosulfate and 4.0g of ammonium persulfate, and stir thoroughly. React at 30℃, 40℃, and 50℃ for 15h respectively. After the reaction is completed, let stand to separate the solid and liquid, and obtain carbon-silicon-based natural polymer materials prepared under different temperature conditions.

[0028] To compare the water absorption capacity of the materials, carbon-containing biomass materials were prepared under the above conditions without the addition of methyl silicone oil and urea. 50.0 g of crushed straw waste was weighed and added to 50 mL of N,N-dimethylformamide solution, mixed thoroughly, and then 2.5 g of potassium hydroxide was added to adjust the pH of the reaction solution. 20.0 g of potassium thiosulfate and 4.0 g of ammonium persulfate were then added and stirred thoroughly. The reactions were carried out at 30℃, 40℃, and 50℃ for 15 h respectively. After the reaction, the solid and liquid phases were separated by standing, yielding the carbon-containing biomass materials prepared without the addition of methyl silicone oil and urea. Water absorption tests were conducted to compare the water absorption performance of the materials prepared under different conditions. The results showed that, under three reaction temperatures of 30℃, 40℃, and 50℃, compared with carbon-containing biomass materials prepared without the addition of methyl silicone oil and urea, the water absorption of carbon-containing silicon-based biomass materials prepared with the addition of methyl silicone oil and urea increased by 6.1%-13.7%. Furthermore, the water absorption of the prepared carbon-containing silicon-based biomass materials increased with increasing reaction temperature, which further indicates that the reaction temperature has a positive contribution to the water absorption capacity of the material.

[0029] Example 3: Preparation of lignin-based polymer materials with good salt absorption capacity

[0030] Three portions of calcium lignosulfonate (20.0g), urea (3.0g), and ferrous sulfate (6.0g) were weighed out sequentially and added to separate reaction vessels containing 50mL of distilled water. After thorough stirring, the mixtures were reacted at 50℃, 60℃, 70℃, and 80℃ for 30 hours each. Then, 5.0g of polyacrylamide monomer, 2.0g of ammonium persulfate, 20.0g of bentonite, and 10.0g of polyvinyl alcohol were added sequentially, stirring continuously until completely dissolved. The mixtures were then subjected to polymerization at 40℃ for 15 hours, yielding viscous mixed solutions with water-retaining properties prepared under different temperature conditions.

[0031] To compare the effects of urea and ferrous sulfate, a control experiment was set up. 20.0 g of calcium lignosulfonate was weighed and added to a reaction vessel containing 50 mL of distilled water. After thorough stirring, the mixture was reacted at 50℃, 60℃, 70℃, and 80℃ for 30 h each. Then, 5.0 g of polyacrylamide monomer, 2.0 g of ammonium persulfate, 20.0 g of bentonite, and 10.0 g of polyvinyl alcohol were added sequentially, stirring continuously until completely dissolved. The polymerization reaction was carried out at 40℃ for 15 h, yielding a viscous mixed solution prepared without the addition of urea and ferrous sulfate. Salt absorption tests were conducted to compare the salt absorption performance of the materials prepared under different conditions. The results showed that, under three reaction temperatures of 50℃, 60℃, 70℃, and 80℃, the salt absorption capacity of the viscous mixed solution prepared with the addition of urea and ferrous sulfate increased by 4.8%-15.2% compared with the viscous mixed solution prepared without the addition of urea and ferrous sulfate. At the same time, the salt absorption capacity of the prepared carbon-silicon-based biomass materials increased with the increase of reaction temperature, which further indicates that more composite products will be produced with the increase of reaction temperature.

[0032] Example 4: Evaluation of the effect of soil conditioner on improving saline-alkali soil

[0033] This experiment was conducted on sandy land. Soil conditioners A1, A2, and A3 prepared in Example 1 were used and applied according to different soil types. The materials were diluted with water and applied by drip irrigation.

[0034] The application rate was 60 L / mu when the soil layer from 0-60 cm and below was sandy, 40 L / mu when the soil layer from 0-40 cm was sandy, and 30 L / mu when the soil layer from 0-20 cm was sandy. Soil surface samples were collected periodically to test the salinity, and control treatments were also provided. The results are shown in Figure 2. With the increase of polyacrylamide monomer dosage in the soil conditioner, the salinity in different sandy soil layers gradually decreased, with the largest reductions being 65.3% (0-60 cm), 21.6% (0-40 cm), and 38.5% (0-20 cm), respectively. This indicates that the soil conditioner has a better salt control effect on deeper soil layers.

Claims

1. A method for preparing a carbon-silicon-based polymeric soil conditioner that can enhance crop stress resistance, characterized in that, The steps are as follows: (1) Take 20-30 parts by weight of crushed straw, 1-5 parts by weight of methyl silicone oil as branched monomer, 1-2 parts by weight of urea as activator, and 10-20 parts by weight of N,N-dimethylformamide as reaction solution. Mix thoroughly and let stand at room temperature for 5-8 hours to allow methyl silicone oil to fully penetrate into the cellulose hydroxyl surface of the straw powder. Through the hydrogen bond protection effect formed by urea amino and branched monomer, a natural network branched macromolecular complex containing silicone oil is obtained. Then, add 1-2 parts by weight of potassium hydroxide to adjust the pH of the reaction solution, 5-10 parts by weight of potassium thiosulfate as reducing agent, and 1-2 parts by weight of ammonium persulfate as initiator and oxidant. Stir thoroughly and carry out grafting and polymerization reaction at 30-50℃ for 10-15 hours. After standing, separate the solid and liquid to obtain carbon silicon-based natural polymer material a with water retention and salt absorption function. (2) Take 20 parts by weight of calcium lignin sulfonate, 1-5 parts by weight of urea as a crosslinking agent, 5-10 parts by weight of ferrous sulfate cation exchanger, and 50-100 parts by weight of distilled water into a reaction vessel. After stirring, react fully at 50-80℃ for 20-30 hours to allow calcium lignin sulfonate and ferrous sulfate cations to fully exchange and form lignin iron salt. At the same time, the urea amino group forms hydrogen bonds with the benzene-containing hydroxyl groups on the lignin, thereby prepolymerizing to obtain a macromolecular chain of lignin iron and calcium lignin sulfonate complex; then add 1- 10 parts by weight of polyacrylamide monomer, 1-5 parts by weight of ammonium persulfate as an initiator, 10-50 parts by weight of bentonite as a pore-forming agent, and 5-10 parts by weight of polyvinyl alcohol as a crosslinking agent are continuously stirred to completely dissolve the monomer. The polymerization reaction is carried out at 30-80℃ for 10-24 hours, so that the hydroxyl groups on the lignin iron and lignin sulfonate calcium complex form hydrogen bonds with the amino groups on the polyacrylamide monomer. At the same time, under the action of the initiator and the crosslinking agent, macromolecular chains are formed, resulting in a viscous mixed solution b with water-retaining function. (3) At room temperature, mix 20 parts by mass of carbon silicon-based natural polymer material a and 20 parts by mass of viscous mixed solution b thoroughly. Add 1-2 parts by mass of manganese sulfate and 1-5 parts by mass of zinc sulfate in sequence. Stir thoroughly and add distilled water to make the liquid exactly 1000 parts by mass. Shake and react at room temperature for 15-48 hours. Let stand for 10-15 hours, separate the solid and liquid, and dry naturally to obtain a carbon silicon-based polymer soil conditioner with salt absorption and water retention functions that can enhance crop stress resistance.

2. The method for preparing the carbon-silicon based polymeric soil conditioner according to claim 1, characterized in that, The straw waste mentioned includes straw from cotton, corn, wheat, and rice.

3. The application of the carbon-silicon-based polymeric soil conditioner obtained by the preparation method of the carbon-silicon-based polymeric soil conditioner according to claim 1 or 2, characterized in that, The application method for this carbon-silicon based polymer soil conditioner needs to be based on the farmland and soil conditions and the type of crop; the specific application method is as follows: For saline-alkali land: the application rate of carbon-silicon-based polymeric soil conditioner is 10-40 L / mu for mildly saline-alkali land; 20-80 L / mu for moderately saline-alkali land; and 40-100 L / mu for severely saline-alkali land. The application rate can be determined by fertigation, drip irrigation with water, or based on crop type and irrigation frequency. For low- to medium-yield fields: when yields are more than 70% lower than local crop yields, the application rate of carbon-silicon-based polymer soil conditioner is 10-100 L / mu; when yields are more than 50% lower than local crop yields, the application rate of carbon-silicon-based polymer soil conditioner is 40-100 L / mu; the application rate can be determined by fertigation, drip irrigation, or based on crop type and irrigation frequency. For desertified land: when the soil layer from 0-60cm and below is desertified, the application rate of carbon-silicon based polymer soil conditioner is 60-100L / mu; when the soil layer from 0-40cm is desertified, the application rate of carbon-silicon based polymer soil conditioner is 40-100L / mu; when the soil layer from 0-20cm is desertified, the application rate of carbon-silicon based polymer soil conditioner is 30-100L / mu; it can be applied by fertigation or drip irrigation once, or determined according to crop type and irrigation frequency.

4. The application according to claim 3, characterized in that, The methods of using the carbon-silicon based polymer soil conditioner include applying it to the soil with water before sowing, applying it gradually with water and fertilizer during the crop growth period, and applying it once with water during the crop growing season.

5. The application according to claim 3, characterized in that, The soil conditioner is applied at a rate of 10-100L per mu (approximately 0.067 hectares) in the field, diluted 500-1000 times.

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