A method for improving saline-alkali soil

Abstract

The application relates to a saline-alkali soil improvement method, and relates to the field of saline-alkali soil improvement.The application provides the saline-alkali soil improvement method, which can reduce the soil salt content of saline-alkali soil, improve soil nutrients, effectively improve soil salinization, alleviate the problem of ecological environment deterioration, overcome the bottleneck of agricultural utilization of saline-alkali soil, increase arable land area, promote sustainable utilization of valuable resources of saline-alkali soil, has remarkable effects, can be applied on a large scale, and has important significance.The liquid microbial fertilizer prepared by the application can not only provide trace elements required by crop growth, but also increase soil organic matter and active beneficial microorganisms.The nutrient release speed of the slow-release urea gel fertilizer prepared by the application can be controlled to a certain extent for continuous absorption and utilization of crops, so that the slow-release and controlled-release purposes are achieved.The application can obtain a saline-alkali soil improvement method.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of saline-alkali soil improvement, in particular to a saline-alkali soil improvement method. BACKGROUND

[0002] The saline-alkali soil is a kind of salt accumulation, which refers to the salt contained in the soil affects the normal growth of crops, according to the incomplete statistics of UNESCO and FAO, the area of saline-alkali soil in the world is 954.38 million hectares, and the area of saline-alkali soil in China is larger, because of the high salt content and strong alkalinity, it is not conducive to the growth of crops, therefore, the development and utilization of saline-alkali soil is a problem to be solved in agricultural production. Overcoming the bottleneck of saline-alkali soil agricultural utilization, increasing the cultivated land area, and promoting the sustainable development of saline-alkali soil resources have far-reaching significance.

[0003] At present, the methods for improving saline-alkali soil mainly include chemical improvement method, physical improvement method, biological improvement method and water conservancy improvement method, wherein the physical improvement method mainly uses the method of replacing soil, which has large engineering quantity, high cost and high economic cost, the water conservancy improvement method uses underground seepage pipe to discharge salt, combined with ditch and deep well drainage to prevent salt return, which also has large engineering quantity, high cost and long improvement time, and slow effect. The chemical improvement method mainly uses chemical improver, including gypsum, sulfur and humic acid, which is added to the saline-alkali soil to reduce the soil salinity, and generally needs to be used in combination with other methods to achieve good effect, the microbial improvement in the biological improvement method can promote the movement of salt in the soil and effectively convert the organic fertilizer in the soil into humic acid to improve the soil salinity, but the saline-alkali soil is generally poor in nutrients required for microbial growth and reproduction, therefore, the effect of microbial improvement has certain limitations.

[0004] In addition, the existing saline-alkali soil improvement method cannot effectively improve the physical and chemical properties and nutrient status of the soil, cannot positively affect the soil microorganisms, and the plants planted in the improved saline-alkali soil also have problems of blind fertilization, unbalanced nutrients, serious fertilizer loss in the late growth period, and poor salt-alkali adaptation. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a saline-alkali soil improvement method.

[0006] The present application provides a saline-alkali soil improvement method, which can reduce the salt content of the soil in the saline-alkali soil, improve the soil nutrients, effectively improve the soil salinization, alleviate the deterioration of the ecological environment, overcome the bottleneck of saline-alkali soil agricultural utilization, increase the cultivated land area, and promote the sustainable utilization of the valuable resources of saline-alkali soil, which has important significance and can be applied on a large scale.

[0007] A saline-alkali soil improvement method, characterized in that the saline-alkali soil improvement method is specifically completed according to the following steps:

[0008] I. Land leveling, fresh water washing salt, and salt water being collected to a collection pool through a buried pipe;

[0009] II. After supernatant overflow in the collection pool, the supernatant is concentrated through ultrafiltration, and the concentrated solution is recovered;

[0010] III. The improvement agent is rotary ploughed into the saline-alkali soil, and then liquid microbial fertilizer is sprayed;

[0011] IV. After the soil property is stabilized, plants are planted.

[0012] Advantages of the present application:

[0013] I. The effective viable bacteria number of the liquid microbial fertilizer prepared by the present application is greater than or equal to 0.5 billion / mL, the liquid microbial fertilizer prepared by the present application can not only provide trace elements required for crop growth after application, but also increase soil organic matter and active beneficial microorganisms; the beneficial microorganisms in the microbial fertilizer can improve soil fertility through nitrogen fixation, phosphorus solubilization and potassium solubilization, and soil function is strengthened; the activity of the beneficial microorganisms increases organic nutrients, which is beneficial to crop growth; in addition, the added polyglutamic acid can be used as a yield-increasing nutrient for tea trees; the polyglutamic acid has strong hydrophilicity and water retention capacity, excellent buffering capacity for acid and alkali, and can effectively balance the soil pH value to promote yield increase; the used Trichoderma harzianum has the effect of plant growth regulation, can stimulate plant growth and induce plant defense response, improve the microenvironment of the root system, enhance the growth and disease resistance of the plant, and improve yield and income;

[0014] II. The release speed of the slow-release urea gel fertilizer prepared by the present application can be controlled to a certain extent for continuous absorption and utilization by crops, achieving the purpose of slow release and controlled release; the use of the slow-release urea gel fertilizer prepared by the present application can reduce the loss of fertilizer nutrients, especially nitrogen, in the soil, improve fertilizer utilization rate, ensure the yield and nutrient substances of plants planted in saline-alkali soil, and solve the problems of blind fertilization, unbalanced nutrients, serious nutrient loss in the growth late stage, and poor salt-alkali adaptation ability;

[0015] Third, this invention recovers soluble organic components from saline solution through a combination of salt dissolution and ultrafiltration, returning them to the soil. This effectively removes salt components while preventing soil structure damage, which is beneficial for the organic improvement of saline-alkali land. The soil conditioner, combined with microbial fertilizer, provides long-term improvement to the soil's physical and chemical properties, increases soil aggregate structure, effectively cuts off soil capillary pores, constructs non-capillary pores and large fissures, slows down the accumulation of soluble salts to the soil surface, improves compaction, enhances soil permeability, and increases the efficiency of salt leaching and alkali reduction. Salt-absorbing plants gradually absorb salt from the soil, forming saline-alkali specialty products, achieving green improvement of saline-alkali land while also developing added value for saline-alkali land. The method of this invention can systematically and organically achieve soil improvement of saline-alkali land. Detailed Implementation

[0016] Specific Implementation Method 1: This implementation method is a method for improving saline-alkali land, which is specifically completed according to the following steps:

[0017] 1. The land is leveled, the salt is washed with fresh water, and the brine is collected in a collection pool through a buried pipe;

[0018] 2. After the supernatant overflows from the collection tank, it is concentrated by ultrafiltration, and then the ultrafiltration concentrate is recovered.

[0019] 3. Rotary till the soil conditioner into the saline-alkali soil, and then spray liquid microbial fertilizer.

[0020] Fourth, plants should be planted only after the soil properties have stabilized.

[0021] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: the salt content of the soil after salt washing in step two is below 0.5%; the pore size range of the ultrafiltration in step two is 2nm to 100nm, and the turbidity of the effluent is less than 3 NTU. Other steps are the same as in Specific Implementation Method One.

[0022] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: in step two, the precipitate other than the concentrated liquid is returned to the soil after solid-liquid separation; the concentrated liquid in step two can be recovered through reverse osmosis, electrodialysis, distillation, marine fish farming, etc., or it can be discharged after being rendered harmless. The other steps are the same as in Specific Implementation Method One or Two.

[0023] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the improver mentioned in step three is prepared from 3 to 5 parts of attapulgite clay, 3 to 10 parts of desulfurized gypsum, 1 to 10 parts of slow-release urea gel fertilizer, 2 to 5 parts of superphosphate, 1 to 3 parts of fish protein powder, 1 to 10 parts of polyglutamic acid, 1 to 5 parts of vermiculite, 40 to 60 parts of high-silica iron tailings, 5 to 10 parts of molasses powder, 5 to 10 parts of lignite powder, 10 to 20 parts of corn fermentation residue, 1 to 4 parts of ferrous sulfate, 35 to 50 parts of organic fermentation material, 10 to 15 parts of wheat straw, and 1 to 3 parts of microbial inoculant. The other steps are the same as in Specific Implementation Methods One to Three.

[0024] Specific Implementation Method 5: The difference between this implementation method and Specific Implementation Methods 1 to 4 is that: soybean meal, cow dung, and corn stalk powder are mixed evenly in a mass ratio of (5-7):(2-3):(1-2), and the moisture content of the mixture is adjusted to 55%-65%. The mixture is then transferred to a reactor and fermented at 50℃-65℃ for 7-15 days to obtain organic fermented product.

[0025] The organic fermented product has a fulvic acid content of 7%–25%, organic matter >40%, and total nutrients >6%. Other steps are the same as in specific embodiments one to four.

[0026] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the preparation method of the improver is completed according to the following steps:

[0027] I. This product is prepared by weighing 3-5 parts of attapulgite soil, 3-10 parts of desulfurized gypsum, 1-10 parts of slow-release urea gel fertilizer, 2-5 parts of superphosphate, 1-3 parts of fish protein powder, 1-10 parts of polyglutamic acid, 1-5 parts of vermiculite, 40-60 parts of high-silica iron tailings, 5-10 parts of molasses powder, 5-10 parts of lignite powder, 10-20 parts of corn fermentation residue, 1-4 parts of ferrous sulfate, 35-50 parts of organic fermentation material, 10-15 parts of wheat straw, and 1-3 parts of agricultural microbial agent.

[0028] 2. Mix the weighed fish protein powder, vermiculite, molasses powder, lignite powder, corn fermentation residue, organic fermentation material and wheat straw to obtain mixture I; adjust the moisture content of mixture I to 50%-60%, then spray with mixed bacterial solution and ferment for 10-30 days, then dry to obtain the regulator;

[0029] The mass ratio of the mixed bacterial solution to mixture I in step two is (0.3-1):100;

[0030] The mixed bacterial solution mentioned in step two is a mixture of Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium, and Bacillus laterosporus in a mass ratio of 1:1:1:1.

[0031] 3. Mix attapulgite, desulfurized gypsum, superphosphate, polyglutamic acid, high-silica iron tailings, ferrous sulfate, microbial inoculant and regulator, crush and pass through a 35-mesh sieve to obtain mixture II;

[0032] 4. Mix mixture II with the slow-release urea gel fertilizer until homogeneous to obtain the conditioner. The other steps are the same as in specific implementation methods one to five.

[0033] Specific Implementation Method Seven: The difference between this implementation method and Specific Implementation Methods One through Six is ​​that the slow-release urea gel fertilizer mentioned in step three is prepared according to the following steps:

[0034] First, tannic acid and chitosan oligosaccharide are added to hydrochloric acid with a concentration of 0.05 mol / L to 0.1 mol / L. Then, N,N'-methylenebisacrylamide is added, and the mixture is sonicated for 30 to 60 minutes. Next, ammonium persulfate is added, and the mixture is mechanically stirred for 30 to 90 minutes. Finally, urea is added, and FeCl3·6H2O solution is added dropwise. The mixture is then magnetically stirred, freeze-dried, and washed until neutral to obtain a slow-release urea gel fertilizer. The other steps are the same as in specific embodiments one to six.

[0035] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in the following ways: the volume ratio of tannic acid to hydrochloric acid with a concentration of 0.05–0.1 mol / L is (5 mg–10 mg):(1 mL–5 mL); the mass ratio of chitosan oligosaccharide to tannic acid is 1:(1–5); the molar ratio of N,N'-methylenebisacrylamide to chitosan oligosaccharide is (0.005–0.01):1; the molar ratio of ammonium persulfate to chitosan oligosaccharide is (0.2–0.5):1; the mass ratio of urea to hydrochloric acid with a concentration of 0.05–0.1 mol / L is (2 g–4 g):(20 mL–40 mL); the concentration of the FeCl3·6H2O solution is 0.01–0.05 mol / L; and the molar ratio of FeCl3·6H2O to chitosan oligosaccharide is (0.008–0.009):1. Other steps are the same as in Specific Implementation Methods One to Seven.

[0036] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the effective viable bacteria count in the liquid microbial fertilizer is ≥0.5 billion / mL, and the preparation method is completed according to the following steps:

[0037] Soybean residue, peanut bran, molasses powder, ultrafiltration concentrate and water are mixed in a mass ratio of (1-5):1:10:100:100 as the material. Fermentation agent is then added and fermented continuously for 5-20 days to obtain the fermentation product. Polyglutamic acid and Trichoderma harzianum dry powder are added to the fermentation product and mixed evenly to obtain liquid bio-fertilizer.

[0038] The mass ratio of the fermentation agent to the material is (0.1-0.5):10;

[0039] The fermentation agent is Bacillus subtilis, Saccharomyces cerevisiae, Bacillus laterosporus brevis, and Bacillus megaterium, wherein the mass ratio of Bacillus subtilis, Saccharomyces cerevisiae, Bacillus laterosporus brevis, and Bacillus megaterium is (1-2):(1-2):1:1;

[0040] The mass ratio of the dried Trichoderma harzianum powder to the fermentation product is (0.01-0.05):100;

[0041] The mass ratio of polyglutamic acid to fermentation product is (1-5):100. Other steps are the same as in specific embodiments one to eight.

[0042] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One through Nine in the following ways: the rotary tillage depth in step three is 30cm to 60cm; the dosage of the soil conditioner is 300kg / mu to 1000kg / mu, and the dosage of the liquid microbial fertilizer is 15kg / mu to 30kg / mu. The liquid microbial fertilizer is diluted 500 to 1000 times with water before spraying; the daily irrigation water after planting in step four is a diluted ultrafiltration concentrate, diluted 500 to 1500 times; the salt-absorbing plants mentioned in step four are: corn, soybean, wheat, barley, Salicornia glutinosa, Tamarix chinensis, Populus euphratica, Artemisia argyi, Suaeda salsa, Suaeda salsa, and Elm twig spinach. The other steps are the same as in Specific Implementation Methods One through Nine.

[0043] The beneficial effects of the present invention are verified using the following embodiments:

[0044] Example 1: A method for improving saline-alkali land, specifically completed according to the following steps:

[0045] 1. The land is leveled, the salt is washed with fresh water, and the brine is collected in a collection pool through a buried pipe;

[0046] 2. After the supernatant overflows from the collection tank, it is concentrated by ultrafiltration, and then the ultrafiltration concentrate is recovered.

[0047] 3. Rotary till the soil conditioner into the saline-alkali soil, and then spray liquid microbial fertilizer.

[0048] 4. Planting should only take place after the soil properties have stabilized;

[0049] In step two, the salt content of the soil after leaching is below 0.5%; the pore size range of the ultrafiltration in step two is 2nm to 100nm, and the turbidity of the effluent is less than 3NTU.

[0050] In step two, the precipitates other than the concentrate are returned to the soil after solid-liquid separation; the concentrate in step two can be recovered through reverse osmosis, electrodialysis, distillation, marine fish farming, etc., or it can be discharged after being rendered harmless.

[0051] The preparation method of the modifier described in step three is completed according to the following steps:

[0052] ① The following ingredients are weighed according to their weight fractions: 4 parts attapulgite soil, 6 parts desulfurized gypsum, 8 parts slow-release urea gel fertilizer, 3 parts superphosphate, 2 parts fish protein powder, 3 parts polyglutamic acid, 4 parts vermiculite, 50 parts high-silica iron tailings, 7 parts molasses powder, 7 parts lignite powder, 15 parts corn fermentation residue, 3 parts ferrous sulfate, 40 parts organic fermentation material, 10 parts wheat straw, and 2 parts agricultural microbial agent.

[0053] The agricultural microbial agent mentioned in step ① is a microbial agent produced by Shandong Hengsheng Biotechnology Co., Ltd.;

[0054] The organic fermentation product mentioned in step ① is prepared according to the following method:

[0055] Soybean meal, cow dung, and corn stalk powder were mixed evenly in a mass ratio of 6:3:1. The moisture content of the mixture was then adjusted to 60%, and the mixture was transferred to a reactor and fermented at 60°C for 10 days to obtain organic fermented product.

[0056] The organic fermented product has a fulvic acid content of 18%, organic matter >40%, and total nutrients >6%.

[0057] ② Mix the weighed fish protein powder, vermiculite, molasses powder, lignite powder, corn fermentation residue, organic fermentation material and wheat straw to obtain mixture I; adjust the moisture content of mixture I to 55%, then spray with mixed bacterial solution and ferment for 30 days, then dry to obtain regulator;

[0058] The mass ratio of the mixed bacterial solution to mixture I in step ② is 0.6:100;

[0059] The mixed bacterial solution mentioned in step ② is a mixture of Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium and Bacillus laterosporus in a mass ratio of 1:1:1:1.

[0060] ③ Mix attapulgite, desulfurized gypsum, superphosphate, polyglutamic acid, high-silica iron tailings, ferrous sulfate, microbial inoculant and regulator, crush and pass through a 35-mesh sieve to obtain mixture II;

[0061] ④ Mix mixture II with slow-release urea gel fertilizer evenly to obtain the modifier;

[0062] The slow-release urea gel fertilizer mentioned in step ① is prepared according to the following steps:

[0063] First, tannic acid and chitosan oligosaccharide were added to 0.05 mol / L hydrochloric acid, then N,N'-methylenebisacrylamide was added, and the mixture was sonicated for 30 min. Ammonium persulfate was then added, and the mixture was mechanically stirred for 60 min. Finally, urea was added, and FeCl3·6H2O solution was added dropwise. The mixture was then magnetically stirred, freeze-dried, and washed until neutral to obtain a slow-release urea gel fertilizer. The volume ratio of tannic acid to 0.05 mol / L hydrochloric acid was 8 mg:4 mL. The mass ratio of oligosaccharide to tannic acid is 1:3; the molar ratio of N,N'-methylenebisacrylamide to chitosan oligosaccharide is 0.01:1; the molar ratio of ammonium persulfate to chitosan oligosaccharide is 0.3:1; the mass ratio of urea to 0.05 mol / L hydrochloric acid is 3 g:30 mL; the concentration of FeCl3·6H2O solution is 0.05 mol / L; the molar ratio of FeCl3·6H2O to chitosan oligosaccharide is 0.008:1.

[0064] The liquid microbial fertilizer described in step three has an effective viable bacteria count ≥ 0.5 billion CFU / mL, and the preparation method is completed according to the following steps:

[0065] Soybean residue, peanut bran, molasses powder, ultrafiltration concentrate and water are mixed in a mass ratio of 3:1:10:100:100 as the material. Fermentation agent is then added and fermented continuously with aeration for 20 days to obtain the fermentation product. Polyglutamic acid and Trichoderma harzianum dry powder are added to the fermentation product and mixed evenly to obtain liquid bio-fertilizer.

[0066] The mass ratio of the fermentation agent to the material is 0.5:10;

[0067] The fermentation agent is Bacillus subtilis, Saccharomyces cerevisiae, Bacillus laterosporus brevis, and Bacillus megaterium, wherein the mass ratio of Bacillus subtilis, Saccharomyces cerevisiae, Bacillus laterosporus brevis, and Bacillus megaterium is 2:2:1:1.

[0068] The mass ratio of the dried Trichoderma harzianum powder to the fermentation product is 0.05:100;

[0069] The mass ratio of polyglutamic acid to fermentation product is 3:100;

[0070] The rotary tillage depth mentioned in step three is 50cm; the amount of soil conditioner used is 400kg / mu, and the amount of liquid microbial fertilizer used is 20kg / mu. The liquid microbial fertilizer is diluted 500 times with water before spraying; the daily irrigation water after planting in step four is the diluted ultrafiltration concentrate, diluted 500 times; the salt-absorbing plant mentioned in step four is Salicornia glutinosa.

[0071] Example 2: The difference between this example and Example 1 is that the preparation method of the improver described in step three is completed according to the following steps: 1. Weigh out 3 parts of attapulgite soil, 8 parts of desulfurized gypsum, 4 parts of slow-release urea gel fertilizer, 3 parts of superphosphate, 3 parts of fish protein powder, 3 parts of polyglutamic acid, 2 parts of vermiculite, 60 parts of high-silica iron tailings, 5 parts of molasses powder, 6 parts of lignite powder, 20 parts of corn fermentation residue, 2 parts of ferrous sulfate, 35 parts of organic fermentation material, 15 parts of wheat straw, and 1.5 parts of agricultural microbial agent according to the weight fraction. Other steps and parameters are the same as in Example 1.

[0072] Comparative Example 1: The difference between this comparative example and Example 1 is that the preparation of slow-release urea gel fertilizer and the use of slow-release urea gel fertilizer are omitted when preparing the modifier. All other steps and parameters are the same as in Example 1.

[0073] Comparative Example 2: The difference between this comparative example and Example 1 is that the preparation of organic fermentation material and the use of organic fermentation material are omitted when preparing the improver. All other steps and parameters are the same as in Example 1.

[0074] Comparative Example 3: The difference between this comparative example and Example 1 is that the preparation of liquid microbial fertilizer and the spraying of liquid microbial fertilizer are omitted in step three. All other steps and parameters are the same as in Example 1.

[0075] The experimental soils in Examples 1-2 and Control Examples 1-3 were severely saline-alkali lands. After being desalinated by fresh water in Step 1, they all became moderately saline-alkali lands with a pH of 8.8 and an electrical conductivity of 2.354 mS / cm.

[0076] The pH value of the soil was determined according to the method in NY / T1121.2-2006;

[0077] The conductivity of the soil was determined according to the method in HJ802-2016.

[0078] In Examples 1-2 and Control Examples 1-3, the soil conditioner was rotary tilled into saline-alkali soil for 90 days, and the changes in soil pH and electrical conductivity were measured. The results are shown in Table 1.

[0079] Table 1

[0080]

[0081] Table 1 shows that the soil conditioners prepared in Examples 1 and 2 can significantly reduce soil pH and electrical conductivity. Omitting the use of slow-release urea gel fertilizer, organic fermentation products, or liquid microbial fertilizer during the preparation of the conditioners can also reduce the pH of saline-alkali land, but the effect is less pronounced.

[0082] In Examples 1-2 and Control Examples 1-3, the soil conditioner was rotary tilled into saline-alkali soil for 180 days and 270 days, respectively. The pH value of the soil was then measured, and the results are shown in Table 2.

[0083] Table 2

[0084]

[0085]

[0086] As shown in Table 2, the soil conditioners prepared in Examples 1-2 can significantly inhibit the degree of soil reversibility compared to Control Examples 1-3.

[0087] Ninety days after the soil conditioner was rotary tilled into the saline-alkali soil, the soils improved in Examples 1-2 could be directly planted with plants, while the soils improved in Control Examples 1-3 required the planting of *Salix babylonica*. After planting *Salix babylonica* for one year, the pH values ​​of the soils in Control Examples 1-3 were 7.5, 7.8, and 7.6, respectively. This demonstrates that planting *Salix babylonica* can improve saline-alkali soil.

Claims

1. A method for improving saline-alkali land, characterized in that... The method for improving saline-alkali land is specifically carried out according to the following steps:

1. The land is leveled, the salt is washed with fresh water, and the brine is collected in a collection pool through a buried pipe; 2. After the supernatant overflows from the collection tank, it is concentrated by ultrafiltration, and then the ultrafiltration concentrate is recovered.

3. Rotary till the soil conditioner into the saline-alkali soil, and then spray liquid microbial fertilizer.

4. Planting should only take place after the soil properties have stabilized; The amendment mentioned in step three consists of 3-5 parts attapulgite clay, 3-10 parts desulfurized gypsum, 1-10 parts slow-release urea gel fertilizer, 2-5 parts superphosphate, 1-3 parts fish protein powder, 1-10 parts polyglutamic acid, 1-5 parts vermiculite, 40-60 parts high-silica iron tailings, 5-10 parts molasses powder, 5-10 parts lignite powder, 10-20 parts corn fermentation residue, 1-4 parts ferrous sulfate, 35-50 parts organic fermentation material, 10-15 parts wheat straw, and 1-3 parts microorganisms. The slow-release urea gel fertilizer is prepared by the following steps: First, tannic acid and chitosan oligosaccharide are added to hydrochloric acid with a concentration of 0.05 mol / L to 0.1 mol / L, then N,N'-methylenebisacrylamide is added, and the mixture is sonicated for 30 min to 60 min. Then ammonium persulfate is added, and the mixture is mechanically stirred for 30 min to 90 min. Finally, urea is added, and FeCl3·6H2O solution is added dropwise. The mixture is then magnetically stirred, freeze-dried, and washed until neutral to obtain the slow-release urea gel fertilizer. The liquid microbial fertilizer described in step three has an effective viable bacteria count ≥ 0.5 billion CFU / mL, and the preparation method is completed according to the following steps: Soybean residue, peanut bran, molasses powder, ultrafiltration concentrate and water are mixed in a mass ratio of (1~5):1:10:100:100 as the material. Fermentation agent is then added and fermented continuously for 5 to 20 days to obtain the fermentation product. Polyglutamic acid and Trichoderma harzianum dry powder are added to the fermentation product and mixed evenly to obtain liquid bio-fertilizer. The mass ratio of the fermentation agent to the material is (0.1~0.5):10; The fermentation agent is Bacillus subtilis, Saccharomyces cerevisiae, Bacillus laterosporus brevis, and Bacillus megaterium, wherein the mass ratio of Bacillus subtilis, Saccharomyces cerevisiae, Bacillus laterosporus brevis, and Bacillus megaterium is (1~2):(1~2):1:1; The mass ratio of the dried Trichoderma harzianum powder to the fermentation product is (0.01~0.05):100; The mass ratio of polyglutamic acid to fermentation product is (1~5):

100.

2. The method for improving saline-alkali land according to claim 1, characterized in that... In step one, the salt content of the soil after rinsing is below 0.5%; in step two, the pore size of the ultrafiltration is in the range of 2nm to 100nm, and the turbidity of the effluent is less than 3NTU.

3. The method for improving saline-alkali land according to claim 1, characterized in that... In step two, the precipitates other than the concentrate are returned to the soil after solid-liquid separation; the concentrate in step two is recovered through reverse osmosis, electrodialysis, distillation or marine fish farming, or discharged after being rendered harmless.

4. The method for improving saline-alkali land according to claim 1, characterized in that... The organic fermented product is prepared by the following method: Soybean meal, cow dung, and corn stalk powder are mixed evenly in a mass ratio of (5~7):(2~3):(1~2), and the moisture content of the mixture is adjusted to 55%~65%. The mixture is then transferred to a reactor and fermented at 50℃~65℃ for 7~15 days to obtain organic fermented product. The organic fermented product has a fulvic acid content of 7% to 25%, organic matter content of >40%, and total nutrients content of >6%.

5. A method for improving saline-alkali land according to claim 1, characterized in that... The preparation method of the aforementioned modifier is completed according to the following steps: I. This product is prepared by weighing 3-5 parts of attapulgite soil, 3-10 parts of desulfurized gypsum, 1-10 parts of slow-release urea gel fertilizer, 2-5 parts of superphosphate, 1-3 parts of fish protein powder, 1-10 parts of polyglutamic acid, 1-5 parts of vermiculite, 40-60 parts of high-silica iron tailings, 5-10 parts of molasses powder, 5-10 parts of lignite powder, 10-20 parts of corn fermentation residue, 1-4 parts of ferrous sulfate, 35-50 parts of organic fermentation material, 10-15 parts of wheat straw, and 1-3 parts of agricultural microbial agent.

2. Mix the weighed fish protein powder, vermiculite, molasses powder, lignite powder, corn fermentation residue, organic fermentation material and wheat straw to obtain mixture I; adjust the moisture content of mixture I to 50%~60%, then spray with mixed bacterial solution and ferment for 10-30 days, then dry to obtain the regulator; The mass ratio of the mixed bacterial solution to mixture I in step two is (0.3~1):100; The mixed bacterial solution mentioned in step two is a mixture of Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium, and Bacillus laterosporus in a mass ratio of 1:1:1:

1.

3. Mix attapulgite, desulfurized gypsum, superphosphate, polyglutamic acid, high-silica iron tailings, ferrous sulfate, microbial inoculant and regulator, crush and pass through a 35-mesh sieve to obtain mixture II; IV. Mix mixture II with slow-release urea gel fertilizer until homogeneous to obtain the improver.

6. A method for improving saline-alkali land according to claim 1, characterized in that... The volume ratio of tannic acid to hydrochloric acid with a concentration of 0.05~0.1mol / L is (5mg~10mg):(1mL~5mL); the mass ratio of chitosan oligosaccharide to tannic acid is 1:(1~5); the molar ratio of N,N'-methylenebisacrylamide to chitosan oligosaccharide is (0.005~0.01):1; the molar ratio of ammonium persulfate to chitosan oligosaccharide is (0.2~0.5):1; the mass ratio of urea to hydrochloric acid with a concentration of 0.05~0.1mol / L is (2g~4g):(20mL~40mL); the concentration of FeCl3·6H2O solution is 0.01~0.05mol / L; the molar ratio of FeCl3·6H2O to chitosan oligosaccharide is (0.008~0.009):

1.

7. A method for improving saline-alkali land according to claim 1, characterized in that... The rotary tillage depth mentioned in step three is 30cm~60cm; the dosage of the soil conditioner is 300kg / mu~1000kg / mu, and the dosage of the liquid microbial fertilizer is 15kg / mu~30kg / mu. When using the liquid microbial fertilizer, it should be diluted with water 500~1000 times before spraying; the daily irrigation water after planting in step four is the diluted ultrafiltration concentrate, with a dilution ratio of 500 times~1500 times; the plants mentioned in step four are: corn, soybean, wheat, barley, Salicornia glutinosa, Tamarix chinensis, Populus euphratica, Artemisia argyi, Suaeda salsa, Suaeda salsa, and Elm spinach.

Images