Multifunctional farmland water-retaining agent as well as preparation method and use method thereof

Abstract

The invention relates to the technical field of farmland water-retaining agents, in particular to a multifunctional farmland water-retaining agent as well as a preparation method and a use method thereof, and the multifunctional farmland water-retaining agent comprises the following components in parts by mass: 30-60 parts of a temperature-sensitive monomer, 20-40 parts of a polymer monomer, 1-10 parts of a cross-linking agent, 5-20 parts of a functional filler, 1-5 parts of a surfactant and 0.1-5 parts of an initiator. According to the multifunctional farmland water-retaining agent as well as the preparation method and the use method thereof, the temperature-sensitive monomer exists in the three-dimensional network structure of the provided farmland water-retaining agent, and the water supply mode can be automatically adjusted according to the soil water content and the water demand condition of crops.

Description

Technical Field

[0001] The invention relates to the technical field of farmland water-retaining agents, and in particular to a multifunctional farmland water-retaining agent and a preparation method and a use method thereof. Background Art

[0002] Farmland water retaining agent is an organic high molecular polymer with a unique three-dimensional network structure. It can quickly absorb and retain rainwater or irrigation water in the soil without leakage, thereby ensuring sufficient water in the root zone and slowly releasing it for plant use. Its unique water absorption, water storage and water retention performance plays a decisive role in improving the ecological environment and windbreak and sand fixation projects. It is widely used in the fields of land desertification control, agricultural and forestry crop planting, and landscaping.

[0003] Most of the existing water-retaining agents have relatively simple properties and functions, and are difficult to promote and apply on a large scale to suit different environments. Therefore, finding a water-retaining agent with excellent water absorption and release properties and a wide range of applications is one of the technical problems that need to be solved in this field. Summary of the invention

[0004] The purpose of the present invention is to provide a multifunctional farmland water-retaining agent and a preparation method and a use method thereof. The three-dimensional network structure of the farmland water-retaining agent provided by the present invention contains a temperature-sensitive monomer, which can automatically adjust the water supply according to the soil moisture content and the water demand of the crop.

[0005] To achieve the above purpose, the present invention provides a multifunctional farmland water-retaining agent, wherein the components include, by mass, 30-60 parts of a temperature-sensitive monomer, 20-40 parts of a polymer monomer, 1-10 parts of a crosslinking agent, 5-20 parts of a functional filler, 1-5 parts of a surfactant and 0.1-5 parts of an initiator.

[0006] Preferably, the temperature-sensitive monomer includes one or more of N-isopropylacrylamide, N,N-diethylacrylamide and N-vinylcaprolactam.

[0007] Preferably, the polymer monomers include one or more of aspartic acid, glutamic acid, hydroxymethyl cyclodextrin, hydroxypropyl cyclodextrin, sodium alginate and chitosan.

[0008] Preferably, the crosslinking agent comprises one or more of glutaraldehyde, divinylbenzene and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide.

[0009] Preferably, the functional filler includes one or more of lignin, cellulose nanocrystals, nano-silicon dioxide, graphene and carbon nanotubes.

[0010] The preparation method of the multifunctional farmland water-retaining agent comprises the following steps: S1. Weigh 30-60 parts of temperature-sensitive monomer, 20-40 parts of polymer monomer, 1-10 parts of crosslinking agent, 5-20 parts of functional filler, 1-5 parts of surfactant and 0.1-5 parts of initiator by mass; S2, adding the temperature-sensitive monomer and the polymer monomer to the solvent in sequence, stirring at 200-500 rpm / min at room temperature until the mixture is uniformly mixed, to obtain a first component; S3, mixing the functional filler with the surfactant and the solvent, stirring them evenly and then ultrasonically dispersing them to obtain a second component; S4, mixing the first component in S2 and the second component in S3, stirring, slowly adding an initiator, and continuing stirring until the reaction is complete to obtain a product; S5. Wash the product obtained in S4 with ethanol, dry it, and then crush and granulate it to obtain a farmland water-retaining agent.

[0011] Preferably, in S4, the stirring is carried out at a temperature of 60-70° C., a time of 12-24 h, and a speed of 300 rpm / min.

[0012] Preferably, in S5, the drying temperature is 60-120° C., and the drying time is 6-12 h.

[0013] The method for using the multifunctional farmland water-retaining agent comprises the following steps: S1, mixing the farmland water retaining agent with soil, stirring until the mixture is uniform to obtain a mixture 1 for standby use, mixing the farmland water retaining agent with fertilizer, stirring until the mixture is uniform to obtain a mixture 2 for standby use; S2, after digging 50-60cm into the farmland, evenly spread the second mixture, and spread the soil layer on the second mixture; S3. Spreading mixture 1 on the soil layer in S2 and planting crops in mixture 1.

[0014] Preferably, in S1, the mixing mass ratio of the farmland water retaining agent to the soil is 1:50-80, and the mixing mass ratio of the farmland water retaining agent to the fertilizer is 1:15-20.

[0015] Therefore, the present invention adopts the above-mentioned multifunctional farmland water-retaining agent and its preparation method and use method, and its beneficial effects include: 1. The water retaining agent provided by the present invention has a thermosensitive monomer in the three-dimensional network structure, which can automatically adjust the water supply according to the soil moisture content and the water demand of the crop. When the soil moisture content is low, such as in a drought period or when the crop growth water demand is large, the water retaining agent will gradually release the stored water to supplement the lack of soil moisture. When the soil moisture content is high, such as after rainfall or irrigation, the water retaining agent will absorb and store excess water to prevent water accumulation in the soil from causing problems such as hypoxia and rot of the crop roots; 2. The farmland water retaining agent provided by the present invention has strong water absorption and water retention capabilities, and can form a relatively stable moisture environment in the soil. When fertilizer is applied to the soil, the water absorbed and stored by the water retaining agent can dissolve the fertilizer therein, and the fertilizer will not be easily lost with the leakage of soil moisture, thereby reducing the leaching loss of fertilizer.

[0016] The technical solution of the present invention is further described in detail below through embodiments. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with embodiments. Unless otherwise defined, the technical terms or scientific terms used in the present invention should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs. The above-mentioned features or features mentioned in the specific examples mentioned in the present invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0018] Example 1 The present invention provides a method for preparing a multifunctional farmland water-retaining agent, comprising the following steps: S1. Weigh 60 parts of temperature-sensitive monomer (the molar ratio of N-isopropylacrylamide and N-vinylcaprolactam is 1:2), 30 parts of polymer monomer (hydroxymethylcyclodextrin and sodium alginate are mixed in a mass ratio of 1:1), 8 parts of cross-linking agent glutaraldehyde, 10 parts of functional filler (cellulose nanocrystals and nano-silica are mixed in a mass ratio of 1:1), 1 part of surfactant sodium dodecyl sulfate and 3 parts of initiator ammonium persulfate by mass.

[0019] S2. Add N-isopropylacrylamide, hydroxymethylcyclodextrin and sodium alginate into deionized water in sequence, and stir at 300 rpm / min at room temperature until the mixture is uniformly mixed to obtain a first component.

[0020] S3, mixing cellulose nanocrystals, nano-silicon dioxide, sodium dodecyl sulfate and deionized water, stirring evenly and then dispersing by ultrasonication to obtain a second component.

[0021] S4. Mix the first component in S2 and the second component in S3 and stir at a stirring temperature of 70° C. and a stirring speed of 300 rpm / min. Slowly add ammonium persulfate and continue stirring for 15 hours until the reaction is completed to obtain a product.

[0022] While N-isopropylacrylamide and N-vinylcaprolactam form polymer chains, the free radicals on the polymer chains can react with hydroxymethylcyclodextrin and sodium alginate to form a three-dimensional cross-linked network structure. During the cross-linking reaction, the free radicals on the polymer chains can react with the active groups on the surface of cellulose nanocrystals and nano-silica to form chemical bonds, thereby connecting the cellulose nanocrystals and nano-silica into a three-dimensional cross-linked network.

[0023] S5. Wash the product obtained in S4 with ethanol, dry it, and then crush it into granules. The drying temperature is 80° C. and the drying time is 10 h to obtain a farmland water-retaining agent.

[0024] Example 2 A method for preparing a multifunctional farmland water-retaining agent comprises the following steps: S1. Weigh by mass 50 parts of a thermosensitive monomer (a molar ratio of N,N-diethylacrylamide and N-vinylcaprolactam is 1:2.7), 30 parts of a polymer monomer (a mixture of aspartic acid and chitosan in a mass ratio of 2:1), 8 parts of a cross-linking agent glutaraldehyde, 5 parts of a functional filler (a mixture of lignin and cellulose nanocrystals in a mass ratio of 1:1), 3 parts of a surfactant, sodium dodecyl sulfate, and 3 parts of an initiator, ammonium persulfate.

[0025] S2. Add N,N-diethylacrylamide, aspartic acid and chitosan into deionized water in sequence, and stir at 300 rpm / min at room temperature until the mixture is uniformly mixed to obtain a first component.

[0026] S3, mixing lignin, cellulose nanocrystals, sodium dodecyl sulfate and deionized water, stirring evenly and then dispersing by ultrasonication to obtain a second component.

[0027] S4. Mix the first component in S2 and the second component in S3 and stir at a stirring temperature of 70° C. and a stirring speed of 300 rpm / min. Slowly add ammonium persulfate and continue stirring for 15 hours until the reaction is completed to obtain a product.

[0028] N,N-diethylacrylamide and N-vinylcaprolactam form polymer chains, which react with the active groups on the chitosan and aspartic acid molecular chains to obtain a cross-linked structure. Lignin and cellulose nanocrystals are then connected to the cross-linked structure. The formed cross-linked network is relatively loose, and the pores in the network are larger, making it easier for water molecules to enter the network and interact with the hydrophilic groups.

[0029] S5. Wash the product obtained in S4 with ethanol, dry it, and then crush it into granules. The drying temperature is 60° C. and the drying time is 12 h to obtain a farmland water-retaining agent.

[0030] Example 3 A method for preparing a multifunctional farmland water-retaining agent comprises the following steps: S1. Weigh 50 parts of a temperature-sensitive monomer (a molar ratio of N-isopropylacrylamide to N-vinylcaprolactam is 1:2), 20 parts of a polymer monomer (a mixture of glutamic acid and hydroxypropylcyclodextrin in a mass ratio of 1:1), 8 parts of a cross-linking agent glutaraldehyde, 5 parts of a functional filler (a mixture of nano-silica and graphene in a mass ratio of 1:1), 3 parts of a surfactant sodium dodecyl sulfate, and 3 parts of an initiator ammonium persulfate, by mass.

[0031] S2. Add N-isopropylacrylamide, hydroxymethylcyclodextrin and sodium alginate into deionized water in sequence, and stir at 300 rpm / min at room temperature until the mixture is uniformly mixed to obtain a first component.

[0032] S3, mixing cellulose nanocrystals, nano-silicon dioxide, sodium dodecyl sulfate and deionized water, stirring evenly and then dispersing by ultrasonication to obtain a second component.

[0033] S4. Mix the first component in S2 and the second component in S3 and stir at a stirring temperature of 70° C. and a stirring speed of 300 rpm / min. Slowly add ammonium persulfate and continue stirring for 15 hours until the reaction is completed to obtain a product.

[0034] While N-isopropylacrylamide and N-vinylcaprolactam form polymer chains, free radicals on the polymer chains undergo cross-linking reactions with glutamic acid and hydroxypropylcyclodextrin to obtain a three-dimensional network structure. The hydrophobic cavity of hydroxypropylcyclodextrin can include groups on the surface of nano-silica or graphene, introducing nano-silica or graphene into the cross-linked network.

[0035] S5. Wash the product obtained in S4 with ethanol, dry it, and then crush it into granules. The drying temperature is 80° C. and the drying time is 10 h to obtain a farmland water-retaining agent.

[0036] Example 4 A method for using a multifunctional farmland water-retaining agent comprises the following steps: S1. Mix the water-retaining agent for farmland in Example 1 with soil, stir until the mixture is uniform, and obtain a mixture 1 for later use. Mix the water-retaining agent for farmland in Example 1 with fertilizer, stir until the mixture is uniform, and obtain a mixture 2 for later use.

[0037] In S1, the mixing mass ratio of the water retaining agent for farmland and soil is 1:80, and the mixing mass ratio of the water retaining agent for farmland and fertilizer is 1:15.

[0038] S2. After digging the farmland 50-60cm, evenly spread the second mixture, and spread the soil layer on the second mixture.

[0039] S3. Spreading mixture 1 on the soil layer in S2 and planting crops in mixture 1.

[0040] Example 5 A method for using a multifunctional farmland water-retaining agent comprises the following steps: S1. Mix the water-retaining agent for farmland in Example 2 with soil, stir until the mixture is uniform, and obtain a mixture 1 for later use. Mix the water-retaining agent for farmland in Example 2 with fertilizer, stir until the mixture is uniform, and obtain a mixture 2 for later use.

[0041] In S1, the mixing mass ratio of the water retaining agent for farmland and soil is 1:50, and the mixing mass ratio of the water retaining agent for farmland and fertilizer is 1:15.

[0042] S2. After digging the farmland 50-60cm, evenly spread the second mixture, and spread the soil layer on the second mixture.

[0043] S3. Spreading mixture 1 on the soil layer in S2 and planting crops in mixture 1.

[0044] Example 6 A method for using a multifunctional farmland water-retaining agent comprises the following steps: S1. Mix the water-retaining agent for farmland in Example 3 with soil, stir until the mixture is uniform, and obtain a mixture 1 for later use. Mix the water-retaining agent for farmland in Example 3 with fertilizer, stir until the mixture is uniform, and obtain a mixture 2 for later use.

[0045] In S1, the mixing mass ratio of the water retaining agent for farmland and soil is 1:80, and the mixing mass ratio of the water retaining agent for farmland and fertilizer is 1:20.

[0046] S2. After digging the farmland 50-60cm, evenly spread the second mixture, and spread the soil layer on the second mixture.

[0047] S3. Spreading mixture 1 on the soil layer in S2 and planting crops in mixture 1.

[0048] Comparative Example 1 S1. Weigh 30 parts of polymer monomer hydroxymethyl cyclodextrin, 8 parts of cross-linking agent glutaraldehyde, 10 parts of functional filler (cellulose nanocrystals and nano-silicon dioxide mixed in a mass ratio of 1:1), 1 part of surfactant sodium dodecyl sulfate and 3 parts of initiator ammonium persulfate by mass.

[0049] S2. Add hydroxymethyl cyclodextrin into deionized water, and stir at 300 rpm / min at room temperature until the mixture is uniformly mixed to obtain a first component.

[0050] S3, mixing cellulose nanocrystals, nano-silicon dioxide, sodium dodecyl sulfate and deionized water, stirring evenly and then dispersing by ultrasonication to obtain a second component.

[0051] S4. Mix the first component in S2 and the second component in S3 and stir at a stirring temperature of 70° C. and a stirring speed of 300 rpm / min. Slowly add ammonium persulfate and continue stirring for 15 hours until the reaction is completed to obtain a product.

[0052] S5. Wash the product obtained in S4 with ethanol, dry it, and then crush it into granules. The drying temperature is 80° C. and the drying time is 10 h to obtain a farmland water-retaining agent.

[0053] Comparative Example 2 A method for using a multifunctional farmland water-retaining agent comprises the following steps: S1. Mix the water-retaining agent for farmland in comparative example 1 with soil, stir until the mixture is uniform, and obtain a mixture 1 for later use. Mix the water-retaining agent for farmland in comparative example 1 with fertilizer, stir until the mixture is uniform, and obtain a mixture 2 for later use.

[0054] In S1, the mixing mass ratio of the water retaining agent for farmland and soil is 1:80, and the mixing mass ratio of the water retaining agent for farmland and fertilizer is 1:15.

[0055] S2. After digging the farmland 50-60cm, evenly spread the second mixture, and spread the soil layer on the second mixture.

[0056] S3. Spreading mixture 1 on the soil layer in S2 and planting crops in mixture 1.

[0057] Test Example 1 a. Temperature-water retention test The water retention rate of the water-retaining agent for farmland obtained in Examples 1-3 and Comparative Example 1 was measured at different temperatures. 5 g of the water-retaining agent for farmland (W d ) was immersed in ultrapure water and weighed after full expansion (W eq ), the farmland water retaining agent was dried in a vacuum oven at 20°C, 30°C, 39°C and 60°C respectively. Every 1h, the swollen farmland water retaining agent was weighed (W t ), calculate the water retention rate (W r %), as shown below.

[0058] The water retention rates of the farmland water retaining agents in Examples 1-3 and Comparative Example 1 are shown in Table 1.

[0059] Table 1. Water retention rate data of farmland water retaining agent in Examples 1-3 and Comparative Example 1

[0060] It can be seen from the data in Table 1 that, compared with Comparative Example 1, the farmland water retaining agent of Examples 1-3 exhibits significant temperature-sensitive properties at around 39°C, releasing the water stored therein. This avoids problems such as poor air permeability and root hypoxia caused by excessive moisture in the soil during high temperature periods, while also meeting the higher demand for moisture of crops in high temperature environments. The temperature-sensitive farmland water retaining agent provided by the present invention can create a relatively stable and suitable soil moisture environment for crop growth, help improve crop drought resistance and water use efficiency, promote crop growth and development, and thus improve crop yield and quality.

[0061] b. Germination rate test Wheat seeds were evenly spread into the mixture 1 in Examples 4-6 and Comparative Example 2 and blank soil in a 50*50*10 cm grid and cultured for 15 days under the same conditions. The germination rates of the wheat seeds at 5 days, 10 days and 15 days were statistically analyzed. The results are shown in Table 2.

[0062] Table 2. Seed germination rate statistics

[0063] It can be seen from Table 2 that the seed germination rates in Examples 4-6 are greater than those in Comparative Example 2 and blank soil. In the early stage, the germination rates of the groups did not show significant differences. As time goes by, the soil water retaining agent provides moisture to the soil, promoting seed germination.

[0064] Therefore, the present invention adopts the above-mentioned multifunctional farmland water-retaining agent and its preparation method and use method. The three-dimensional network structure of the farmland water-retaining agent provided by the present invention contains temperature-sensitive monomers, which can automatically adjust the water supply according to the soil moisture content and crop water demand.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A multifunctional farmland water-retaining agent, characterized in that: The components include, by weight, 30-60 parts of a temperature-sensitive monomer, 20-40 parts of a polymer monomer, 1-10 parts of a crosslinking agent, 5-20 parts of a functional filler, 1-5 parts of a surfactant and 0.1-5 parts of an initiator.

2. A multifunctional farmland water-retaining agent according to claim 1, characterized in that: The temperature-sensitive monomer includes one or more of N-isopropylacrylamide, N,N-diethylacrylamide and N-vinylcaprolactam.

3. A multifunctional farmland water-retaining agent according to claim 1, characterized in that: The polymer monomers include one or more of aspartic acid, glutamic acid, hydroxymethyl cyclodextrin, hydroxypropyl cyclodextrin, sodium alginate and chitosan.

4. The multifunctional farmland water-retaining agent according to claim 1, characterized in that: The cross-linking agent includes one or more of glutaraldehyde, divinylbenzene and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide.

5. The multifunctional farmland water-retaining agent according to claim 1, characterized in that: The functional filler includes one or more of lignin, cellulose nanocrystals, nano-silicon dioxide, graphene and carbon nanotubes.

6. A method for preparing a multifunctional farmland water-retaining agent according to any one of claims 1 to 5, characterized in that: The following steps are included: S1. Weigh 30-60 parts of temperature-sensitive monomer, 20-40 parts of polymer monomer, 1-10 parts of crosslinking agent, 5-20 parts of functional filler, 1-5 parts of surfactant and 0.1-5 parts of initiator by mass; S2, adding the temperature-sensitive monomer and the polymer monomer to the solvent in sequence, stirring at 200-500 rpm / min at room temperature until the mixture is uniformly mixed, to obtain a first component; S3, mixing the functional filler with the surfactant and the solvent, stirring them evenly and then ultrasonically dispersing them to obtain a second component; S4, mixing the first component in S2 and the second component in S3, stirring, slowly adding an initiator, and continuing stirring until the reaction is complete to obtain a product; S5. Wash the product obtained in S4 with ethanol, dry it, and then crush and granulate it to obtain a farmland water-retaining agent.

7. The method for preparing a multifunctional farmland water-retaining agent according to claim 6, characterized in that: In S4, stirring is performed at a temperature of 60-70° C., a time of 12-24 h, and a speed of 300 rpm / min.

8. The method for preparing a multifunctional farmland water-retaining agent according to claim 6, characterized in that: In S5, the drying temperature is 60-120° C., and the drying time is 6-12 hours.

9. A method for using a multifunctional farmland water-retaining agent according to any one of claims 1 to 5, characterized in that: The following steps are included: S1, mixing the farmland water retaining agent with soil, stirring until the mixture is uniform to obtain a mixture 1 for standby use, mixing the farmland water retaining agent with fertilizer, stirring until the mixture is uniform to obtain a mixture 2 for standby use; S2, after digging 50-60cm into the farmland, evenly spread the second mixture, and spread the soil layer on the second mixture; S3. Spreading mixture 1 on the soil layer in S2 and planting crops in mixture 1.

10. The method for using the multifunctional farmland water-retaining agent according to claim 1, characterized in that: In S1, the mixing mass ratio of the farmland water retaining agent to the soil is 1:50-80, and the mixing mass ratio of the farmland water retaining agent to the fertilizer is 1:15-20.

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