A hydrogel composition for soil improvement, its preparation method and application

Abstract

The present invention relates to the technical field of soil conditioner preparation, and particularly relates to a hydrogel composition for soil improvement, a preparation method thereof, and an application thereof. The present invention provides a hydrogel composition for soil improvement, which is prepared from components including the following parts by mass: 10-14 parts of polyacrylamide, 10-14 parts of polyacrylic acid, 8-12 parts of hectorite, 12-18 parts of mixed bacterial agents, and 4-8 parts of nutritional supplements. In the present invention, probiotics are encapsulated in the hydrogel, and the hydrogel can provide a good colonization and reproduction environment for the probiotics, so that the beneficial bacteria can improve the saline-alkali land environment and promote the growth of crops in a short time.

Description

Technical Field

[0001] The present invention relates to the technical field of soil conditioner preparation, and particularly relates to a hydrogel composition for soil improvement, a preparation method thereof, and an application thereof. Background Art

[0002] The problems of soil salinization and secondary salinization exist widely worldwide, especially in arid and semi-arid regions, where the problems are more serious. Soil salinization not only harms the soil conditions on which crops depend for survival, but also inhibits the growth and development of crops, resulting in lack of seedlings, reduced yields, and death, thus hindering the development of agricultural production. In areas with severe soil salinization, large areas of farmland are abandoned and deserted, wasting a large amount of land resources.

[0003] In the process of using saline-alkali land, simply speaking, it can be divided into light saline-alkali land, medium saline-alkali land, and heavy saline-alkali land. Currently, the measures for treating saline-alkali land mainly include four aspects: water conservancy improvement measures (irrigation, drainage, silting, rice planting, anti-seepage, etc.), agricultural improvement measures (land leveling, tillage improvement, applying foreign soil, fertilization, sowing, crop rotation, intercropping, etc.), biological improvement measures (planting salt-tolerant plants and forages, green manure, afforestation, etc.), and chemical improvement measures (applying improvement substances such as gypsum, phosphogypsum, calcium sulfite, etc.). Since each measure has a certain scope of application and conditions, and cannot fundamentally solve the spread and development of soil salinization. Therefore, the above measures all have great limitations.

[0004] Hydrogel is a class of extremely hydrophilic three-dimensional network structure gels. It swells rapidly in water and can maintain a large volume of water in this swollen state without dissolving. Due to the existence of a cross-linked network, hydrogels can swell and retain a large amount of water. In agriculture, hydrogels are mainly used as water-retaining agents in aspects such as seed coating, drought resistance and water retention, and slow release of chemical fertilizers. Using water-retaining agents can inhibit soil water evaporation, increase the saturated water content of the soil, reduce the saturated hydraulic conductivity of the soil, reduce the soil water release rate, and increase the leaf water retention rate, etc. However, there are few reports on the application of hydrogels in the improvement of saline-alkali soil or heavy metal contaminated soil.

[0005] Therefore, how to utilize the water-retaining characteristics of hydrogels and apply hydrogels in the improvement of soil salinization or the treatment of heavy metal pollution is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of the present invention is to provide a hydrogel composition for soil improvement, using a composite hydrogel material as a carrier for attaching beneficial bacteria, enabling the beneficial bacteria to rapidly proliferate by means of the hydrogel microenvironment, and further achieving the technical effect of soil improvement.

[0007] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0008] The present invention provides a hydrogel composition for soil improvement, which is prepared from components including the following parts by mass: 10 - 14 parts of polyacrylamide, 10 - 14 parts of polyacrylic acid, 8 - 12 parts of hectorite, 12 - 18 parts of mixed bacterial agents, and 4 - 8 parts of nutritional supplements.

[0009] Preferably, the mixed bacterial agents include: Lactobacillus casei, Lactobacillus plantarum, Azotobacter chroococcum, Trichoderma viride, Bacillus megaterium, Bacillus licheniformis, Klebsiella, and Rhodospirillum.

[0010] Preferably, the bacterial concentrations of Lactobacillus casei, Lactobacillus plantarum, Azotobacter chroococcum, Trichoderma viride, Bacillus megaterium, Bacillus licheniformis, Klebsiella, and Rhodospirillum in the mixed bacterial liquid are all 2 - 4×10 7 CFU / mL.

[0011] Preferably, the nutritional supplements include: yeast extract, peanut cake powder, cottonseed powder, starch, and molasses; the mass ratio of the yeast extract, peanut cake powder, cottonseed powder, starch, and molasses is 7 - 11:6 - 10:6 - 10:8 - 12:8 - 12.

[0012] The present invention also provides a preparation method of the hydrogel composition for soil improvement, including the following steps:

[0013] (1) Mix the nutritional supplements with water to obtain material 1;

[0014] (2) Mix the material 1 with the mixed bacterial agents to obtain material 2;

[0015] (3) Mix polyacrylamide, polyacrylic acid, and hectorite with water and stir once to obtain material 3;

[0016] (4) Mix the material 2 with the material 3 and stir twice to obtain the hydrogel composition for soil improvement.

[0017] Preferably, the mass ratio of the nutritional supplements to water in step (1) is 1:6 - 10.

[0018] Preferably, the mass ratio of the sum of the masses of polyacrylamide, polyacrylic acid, and hectorite to water in step (3) is 4 - 8:1000.

[0019] Preferably, the time for the first stirring in step (3) is 40 - 60 min.

[0020] Preferably, the time for the second stirring in step (4) is 30 - 50 min.

[0021] The present invention also provides the application of the soil-improving hydrogel composition prepared by the preparation method of the soil-improving hydrogel composition in the improvement of saline-alkali soil or cadmium-polluted soil.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The beneficial bacteria provided by the present invention are coordinated with each other. Lactobacillus casei, Lactobacillus plantarum, and Azotobacter chroococcum have the functions of nitrogen fixation and phosphorus release, etc., and secrete a variety of cell enzymes to promote the absorption and growth of plant trace elements. And yeast extract has a particularly good promoting effect on the growth of these microorganisms.

[0024] The present invention uses Trichoderma viride, Bacillus megaterium, and Bacillus licheniformis to activate the soil and promote the exchange of salt ions, which is beneficial to the absorption of salt ions by plants or the downward movement of salt ions to the deep layer of the soil with water. On the other hand, Klebsiella and Rhodospirillum are used to activate soil nutrients and promote the growth of crop roots, which is beneficial to plant growth. Among them, Bacillus licheniformis, as a beneficial microorganism in the rhizosphere of plants, can induce plants to produce resistance and promote plant growth, and at the same time has the function of preventing diseases and inhibiting bacteria, and can protect the rhizosphere environment of plants;

[0025] Therefore, the addition of beneficial bacteria in the present invention starts from multiple aspects. The combined use of various beneficial bacteria can improve the soil, release nutrient elements, improve the rhizosphere environment of plants, reduce the inhibitory effect of salt on the growth of crops, and further improve the resistance of crops to saline-alkali environments.

[0026] 2. The present invention adds nitrogen sources such as peanut cake powder and cottonseed powder, and carbon sources such as starch and molasses as nutritional supplements, which helps the colonization of beneficial bacteria.

[0027] 3. The present invention wraps probiotics in the hydrogel. The hydrogel can provide a good colonization and reproduction environment for the probiotics, enabling the beneficial bacteria to improve the saline-alkali land environment in a short time and significantly promoting the growth of crops.

[0028] 4. Among the gel components added in the present invention, the gel has a porous structure and good adsorption performance itself. Acrylic acid is negatively charged and can adsorb positively charged cadmium ions. There is a carboxyl group on acrylic acid, which can bind to cadmium ions through coordination. Lithium saponite is introduced into the system. Lithium saponite is a nanomaterial with a high specific surface area, which can enhance the adsorption effect. Lithium saponite has a disc-like structure with a positive charge on the edge, which can bind to acrylic acid. Moreover, it is a physical cross-linking agent itself, which can enhance the strength of the gel. Its layered surface is negatively charged, which can increase the electrostatic interaction with cadmium ions. Detailed implementation manners

[0029] The present invention provides a hydrogel composition for soil improvement, which is prepared from components including the following parts by mass: 10 - 14 parts of polyacrylamide, 10 - 14 parts of polyacrylic acid, 8 - 12 parts of hectorite, 12 - 18 parts of mixed bacteria agent, and 4 - 8 parts of nutrient supplement; preferably, it is prepared from components including the following parts by mass: 11 - 13 parts of polyacrylamide, 11 - 13 parts of polyacrylic acid, 9 - 11 parts of hectorite, 13 - 17 parts of mixed bacteria agent, and 5 - 7 parts of nutrient supplement; more preferably, it is prepared from components including the following parts by mass: 12 parts of polyacrylamide, 12 parts of polyacrylic acid, 10 parts of hectorite, 14 - 16 parts of mixed bacteria agent, and 6 parts of nutrient supplement; still more preferably, it is prepared from components including the following parts by mass: 12 parts of polyacrylamide, 12 parts of polyacrylic acid, 10 parts of hectorite, 15 parts of mixed bacteria agent, and 6 parts of nutrient supplement.

[0030] In the present invention, the mixed bacteria agent includes: Lactobacillus casei, Lactobacillus plantarum, Azotobacter chroococcum, Trichoderma viride, Bacillus megaterium, Bacillus licheniformis, Klebsiella sp., and Rhodospirillum sp.

[0031] In the present invention, the bacterial concentrations of Lactobacillus casei, Lactobacillus plantarum, Azotobacter chroococcum, Trichoderma viride, Bacillus megaterium, Bacillus licheniformis, Klebsiella sp., and Rhodospirillum sp. in the mixed bacteria liquid are all 2 - 4×10 7 CFU / mL; preferably 3×10 7 CFU / mL.

[0032] In the present invention, the nutrient supplement includes: yeast extract, peanut cake powder, cottonseed powder, starch, and molasses; the mass ratio of the yeast extract, peanut cake powder, cottonseed powder, starch, and molasses is 7 - 11:6 - 10:6 - 10:8 - 12:8 - 12; preferably 8 - 10:7 - 9:7 - 9:9 - 11:9 - 11; more preferably 9:8:8:10:10.

[0033] The present invention also provides a preparation method of the hydrogel composition for soil improvement as described above, including the following steps:

[0034] (1) Mix the nutrient supplement with water to obtain material 1;

[0035] (2) Mix the material 1 with the mixed bacteria agent to obtain material 2;

[0036] (3) Mix polyacrylamide, polyacrylic acid, and hectorite with water and stir once to obtain material 3;

[0037] (4) Mix the material 2 with the material 3 and stir twice to obtain the hydrogel composition for soil improvement.

[0038] In the present invention, the mass ratio of the nutritional supplement described in step (1) to water is 1:6 to 10; preferably 1:7 to 9; more preferably 1:8.

[0039] In the present invention, the mass ratio of the sum of the masses of polyacrylamide, polyacrylic acid and hectorite described in step (3) to water is 4 to 8:1000; preferably 5 to 7:1000; more preferably 6:1000.

[0040] In the present invention, the time for the first stirring described in step (3) is 40 to 60 min; preferably 44 to 56 min; more preferably 48 to 52 min; even more preferably 50 min.

[0041] In the present invention, the time for the second stirring described in step (4) is 30 to 50 min; preferably 34 to 46 min; more preferably 38 to 42 min; even more preferably 40 min.

[0042] The present invention also provides an application of the soil-improving hydrogel composition prepared by the preparation method of the soil-improving hydrogel composition in the improvement of saline-alkali soil or cadmium-polluted soil.

[0043] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0044] Example 1

[0045] A soil-improving hydrogel composition is prepared from the following components in parts by mass: 10 parts of polyacrylamide, 10 parts of polyacrylic acid, 8 parts of hectorite, 12 parts of a mixed bacterial agent, and 4 parts of a nutritional supplement.

[0046] The mixed bacterial agent includes: Lactobacillus casei, Lactobacillus plantarum, Azotobacter chroococcum, Trichoderma viride, Bacillus megaterium, Bacillus licheniformis, Klebsiella, and Rhodospirillum; the bacterial concentration is 2×10 7 CFU / mL.

[0047] The nutritional supplement includes: yeast extract, peanut cake powder, cottonseed powder, starch, and molasses; the mass ratio is 7:6:6:8:8.

[0048] The preparation method of the soil-improving hydrogel composition is as follows:

[0049] (1) Mix the nutritional supplement and water at a mass ratio of 1:6 to obtain Material 1;

[0050] (2) Mix Material 1 with the mixed bacterial agent to obtain Material 2;

[0051] (3) Mix polyacrylamide, polyacrylic acid and lithium saponite with water at a mass ratio of 4:1000 and stir for 40 min to obtain Material 3;

[0052] (4) Mix the said Material 2 and Material 3 and stir for 30 min to obtain the hydrogel composition for soil improvement, and it can be used after standing for 24 h.

[0053] Example 2

[0054] A hydrogel composition for soil improvement is prepared from the following components in parts by mass: 14 parts of polyacrylamide, 14 parts of polyacrylic acid, 12 parts of lithium saponite, 18 parts of mixed bacterial agent and 8 parts of nutritional supplement.

[0055] The said mixed bacterial agent includes: Lactobacillus casei, Lactobacillus plantarum, Azotobacter chroococcum, Trichoderma viride, Bacillus megaterium, Bacillus licheniformis, Klebsiella and Rhodospirillum; the bacterial concentration is all 4×10 7 CFU / mL.

[0056] The said nutritional supplement includes: yeast extract, peanut cake powder, cottonseed powder, starch and molasses; the mass ratio is 11:10:10:12:12.

[0057] The preparation method of the said hydrogel composition for soil improvement comprises the following steps:

[0058] (1) Mix the nutritional supplement and water at a mass ratio of 1:10 to obtain Material 1;

[0059] (2) Mix the said Material 1 and the mixed bacterial agent to obtain Material 2;

[0060] (3) Mix polyacrylamide, polyacrylic acid and lithium saponite with water at a mass ratio of 8:1000 and stir for 60 min to obtain Material 3;

[0061] (4) Mix the said Material 2 and Material 3 and stir for 50 min to obtain the hydrogel composition for soil improvement, and it can be used after standing for 24 h.

[0062] Example 3

[0063] A hydrogel composition for soil improvement is prepared from the following components in parts by mass: 12 parts of polyacrylamide, 12 parts of polyacrylic acid, 10 parts of lithium saponite, 15 parts of mixed bacterial agent and 6 parts of nutritional supplement.

[0064] The said mixed bacterial agent includes: Lactobacillus casei, Lactobacillus plantarum, Azotobacter chroococcum, Trichoderma viride, Bacillus megaterium, Bacillus licheniformis, Klebsiella and Rhodospirillum; the bacterial concentration is all 3×10 7 CFU / mL.

[0065] The nutritional supplement includes: yeast extract, peanut cake powder, cottonseed powder, starch and molasses; with a mass ratio of 9:8:8:10:10.

[0066] The preparation method of the water gel composition for soil improvement is as follows:

[0067] (1) Mix the nutritional supplement and water at a mass ratio of 1:8 to obtain Material 1;

[0068] (2) Mix the Material 1 with the mixed microbial agent to obtain Material 2;

[0069] (3) Mix polyacrylamide, polyacrylic acid and hectorite with water at a mass ratio of 6:1000 and stir for 50 min to obtain Material 3;

[0070] (4) Mix the Material 2 and Material 3 and stir for 40 min to obtain the water gel composition for soil improvement, and it can be used after standing for 24 h.

[0071] Experimental Example 1

[0072] Comparative experiment:

[0073] Select a saline-alkali land as the test plot (salt content 0.35%, active organic matter content 1.30%, water-stable aggregate content 8.7%, pH 8.57).

[0074] Divide the test plot into 21 equal areas on average, randomly plant three areas in each group, and the test crop is corn.

[0075] Use the water gel combination obtained in Example 3 as the experimental group.

[0076] Control Group 1: Follow the method of Example 3, the only difference is that hectorite is replaced by polymethacrylic acid.

[0077] Control Group 2: Follow the method of Example 3, the only difference is that hectorite is not added.

[0078] Control Group 3: Follow the method of Example 3, the only difference is that the mixed microbial agent is not added.

[0079] Control Group 4: Follow the method of Example 3, the only difference is that the nutritional supplement is not added.

[0080] Control Group 5: Follow the method of Example 3, the only difference is that the Material 2 obtained in step (2) is directly used as the final product.

[0081] Existing technology group: Zhitu saline-alkali soil remediation liquid (Shandong Zhitu Ecological Environment Research Institute Co., Ltd.) is used according to the method described in the instruction manual.

[0082] The usage methods for the experimental group and control groups 1 - 5 are as follows: Apply it after mixing with the base fertilizer before planting crops, and the application rate is 300 kg per mu.

[0083] Except for the different use of the modifier, the other corn growth management methods for each experimental group are the same. After the corn is harvested, the main technical and economic indicators before and after the use of the modifier in each experimental group are measured, and the yield and quality indicators of the corn are measured and averaged. The results are shown in Tables 1 and 2.

[0084] Table 1

[0085]

[0086]

[0087] Table 2

[0088] Yield (kg / mu) 100-seed weight (g) Seed setting rate (%) Experimental group 499 26.5 78.3 Control group 1 474 26.0 77.4 Control group 2 448 25.6 74.1 Control group 3 368 21.1 59.0 Control group 4 463 25.4 75.2 Control group 5 378 21.6 62.5 Prior art group 451 25.2 74.6

[0089] As can be seen from Tables 1 and 2, the modifier provided by the present invention can significantly reduce the pH and soil salt content of saline - alkali land, and increase the water - stable aggregates and the content of soil active organic matter. Although the soil modifier is added, in the first - year improvement and repair, the yield of corn is still significantly affected, but the experimental group still maintains a high yield. From the data of the control group, it can be known that the components of the present invention are used in combination. If one or some of the components are discarded, the use effect of the composition will be significantly affected.

[0090] Experimental Example 2

[0091] Select a cadmium - polluted farmland and divide it into 21 areas on average. Three areas are randomly planted in each group, and the experimental crop is corn. Before the experiment, the cadmium ion concentration of the cadmium - polluted farmland is measured to be 0.704 mg / kg.

[0092] The experimental group, the control group and the prior - art group are the same as in Experimental Example 1.

[0093] Prior - art group: Use it with reference to the modifier and application method of CN201810265704.X.

[0094] The experiment lasts for two years. After the corn is harvested in the second year, the cadmium ion content in the soil is measured again three times and averaged. The results are shown in Table 3.

[0095] Among them, the determination of cadmium content in the soil adopts the dithizone colorimetric method.

[0096] Table 3

[0097] Content mg / kg Experimental group 0.315 Control group 1 0.368 Control group 2 0.392 Control group 3 0.498 Control group 4 0.377 Control group 5 0.584 Prior art group 0.387

[0098] As can be seen from Table 3, the hydrogel composition of the present invention not only has the effect of improving saline-alkali soil, but also can be applied to the remediation of cadmium pollution in soil, and its use effect is significantly better than that of the products of the prior art. From the data of the control group, it can be seen that the present invention also further degrades and controls heavy metal ions through the action of microorganisms. Therefore, the addition of beneficial bacteria also plays a promoting role in the remediation of cadmium ions.

[0099] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A hydrogel composition for improving saline-alkali soil or cadmium-polluted soil, characterized in that, It is prepared from components including the following parts by mass: 10 - 14 parts of polyacrylamide, 10 - 14 parts of polyacrylic acid, 8 - 12 parts of lithium saponite, 12 - 18 parts of mixed bacterial agent, and 4 - 8 parts of nutritional supplement; The mixed bacterial agent includes: Lactobacillus casei, Lactobacillus plantarum, Azotobacter chroococcum, Trichoderma viride, Bacillus megaterium, Bacillus licheniformis, Klebsiella, and Rhodospirillum; The bacterial concentrations of Lactobacillus casei, Lactobacillus plantarum, Azotobacter chroococcum, Trichoderma viride, Bacillus megaterium, Bacillus licheniformis, Klebsiella and Rhodospirillum in the mixed bacterial agent are all 2 - 4×10 7 CFU / mL; The nutritional supplement includes: yeast extract, peanut cake powder, cottonseed powder, starch, and molasses; the mass ratio of the yeast extract, peanut cake powder, cottonseed powder, starch, and molasses is 7 - 11:6 - 10:6 - 10:8 - 12:8 - 12.

2. The preparation method of a hydrogel composition for improving saline-alkali soil or cadmium-polluted soil according to claim 1, characterized in that, It includes the following steps: (1) Mix the nutritional supplement with water to obtain Material 1; (2) Mix the Material 1 with the mixed bacterial agent to obtain Material 2; (3) Mix polyacrylamide, polyacrylic acid, and lithium saponite with water and stir once to obtain Material 3; (4) Mix the Material 2 with the Material 3 and stir twice to obtain the hydrogel composition for soil improvement.

3. The preparation method according to claim 2, characterized in that, In step (1), the mass ratio of the nutritional supplement to water is 1:6 - 10.

4. The preparation method according to claim 2, wherein, In step (3), the mass ratio of the sum of the masses of polyacrylamide, polyacrylic acid, and lithium saponite to water is 4 - 8:1000.

5. The preparation method according to claim 2, characterized in that, The time for the first stirring in step (3) is 40 - 60 min.

6. The preparation method according to claim 2, characterized in that, The time for the second stirring in step (4) is 30 - 50 min.

7. Application of the hydrogel composition for improving saline - alkali soil or cadmium - polluted soil, which is prepared by the preparation method of the hydrogel composition for improving saline - alkali soil or cadmium - polluted soil according to any one of claims 2 - 6, in improving saline - alkali soil or cadmium - polluted soil.

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