Method for improving soda saline-alkali soil by artificially designing molecular sieve

Abstract

The invention discloses a method for improving soda saline-alkali soil by artificially designing a molecular sieve, which comprises the following steps: artificially designing a molecular sieve modifier with the main component of calcium ion exchange LTA type molecular sieve and the molecular formula of Ca6 [(AlO2) 12 (SiO2) 12]: 27H2O, and diagnosing and evaluating the soda saline-alkali soil; artificially designed molecular sieves are applied according to different pH indexes; a corresponding amount of the modifier is scattered on the surface of the soil, and rotary tillage is carried out to penetrate into the soil by 20 cm; irrigating the saline-alkali dry farmland to enable the 20cm soil layer to reach the field moisture capacity, naturally airing until the water content is below 20%, and starting to plant dry farmland crops; the saline-alkali paddy field is irrigated and steeped for 8-10 cm, slurry stirring and water raking are conducted after the field is steeped for 36 h, drainage is conducted after soil is precipitated, and rice transplanting is conducted after the second time of irrigation for 3 cm. The soil conditioner has a soil calcium and sodium replacement effect, and excessive sodium ions in soil can be permanently locked through one-time treatment; meanwhile, the problem of heavy metal ion pollution of soil can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural utilization of saline-alkali land, in particular to a method for improving soda saline-alkali soil with an artificially designed molecular sieve. Background Art

[0002] Soda saline-alkali soil has the special physical and chemical barrier characteristics of "three highs and two lows" of high exchangeable sodium, high pH and high salt content, low permeability and low nutrient effectiveness. Its treatment technologies mainly include water conservancy projects, agronomic measures, irrigation and leaching, chemical improvement, foreign soil improvement and rice planting in saline-alkali land. Compared with other improvement measures, chemical improvement, which is mainly an improvement method based on gypsum, is widely used because it can quickly reduce soil salinity and achieve the purpose of improvement. For severe soda saline-alkali soil, chemical improvement is an improvement measure that must be used due to the extreme deterioration of soil structure and high dispersion of soil clay particles. Chemical improvement replaces the sodium ions adsorbed in soil colloids through Ca-Na replacement, reduces soil clay dispersion, and improves soil structure. It is a fundamental measure for the improvement of soda saline-alkali soil. However, the chemical improvement material itself is also salt. After a certain period of time after application, it will cause a significant increase in soil salinity and salt damage. Therefore, chemical improvement must be carried out with a large amount of irrigation, salt washing and salt discharge, and salt damage control. However, the discharged salt water can cause environmental pollution, and it also requires a lot of water, resulting in a waste of water resources. Some chemical improvers are industrial wastes containing heavy metal ions that can pollute the soil. Therefore, the improvement and utilization of soda saline-alkali soil urgently requires a method that can improve saline-alkali soil without causing salt damage, while saving water resources and ensuring environmental safety.

[0003] Artificially designed molecular sieves are crystalline microporous aluminosilicates, the main component of which is calcium ion exchange LTA (Ca-LTA) type molecular sieve, with a molecular formula of Ca6[(AlO2) 12 (SiO2) 12 ]:27H2O. The pore size of Ca-LTA molecular sieve is 0.5nm, which can screen substances with molecular diameter less than 0.5nm. It has high adsorption capacity for small molecules and ion exchange capacity, and can achieve heavy metals (heavy metal ions with a diameter of 0.1-0.3 nanometers) and Na in aqueous solution. +(The diameter of sodium ions is about 0.204nm). The Ca-LTA molecular sieve crystal framework carries a negative charge, and calcium ions exist inside the artificially designed molecular sieve crystals as a balanced positive charge. Under the action of water molecules, calcium ions can migrate out of the artificially designed molecular sieve crystals and enter the environment, but two sodium ions must be obtained from the environment at the same time to enter the artificially designed molecular sieve crystals to meet the principle of electrical neutrality generally followed in nature, that is, the ion exchange of the artificial molecular sieve is completed, and the calcium ions entering the soil solution are replaced by the sodium ions adsorbed by the soil colloid particles. Therefore, the artificially designed molecular sieve can not only provide calcium ions to replace the sodium ions in the soil, but also fix the replaced sodium ions in the molecular sieve framework, and can also adsorb and store heavy metal ions. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and propose a method for improving soda saline-alkali soil by artificially designed molecular sieves. Artificially designed molecular sieves have special advantages as soil conditioners and will definitely play an important role in improving saline-alkali land in the future.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for improving soda saline-alkali soil by artificially designed molecular sieves, comprising an artificially designed molecular sieve improver, wherein the main components of the artificially designed molecular sieve improver are LTA type molecular sieves exchanged with calcium ions, and a molecular formula of Ca6[(AlO2) 12 (SiO2) 12 ]:27H2O, specifically comprising the following specific steps:

[0007] S1: Application process:

[0008] S1a: Diagnostic evaluation of moderate to severe soda saline-alkali soils: Select moderate to severe soda saline-alkali soils, measure the soil pH, and divide them into three levels, namely moderate soda saline-alkali soil, severe soda saline-alkali soil, and extremely severe soda saline-alkali soil;

[0009] S1b: According to different pH indexes, i.e. different degrees of soda saline-alkali soil, different artificially designed molecular sieve application rates were applied, and the application rates were 0.65 tons / mu, 1 ton / mu and 3 tons / mu respectively;

[0010] S1c: According to the soil pH level, evenly spread the corresponding amount of artificially designed molecular sieve improver on the soil surface and till the soil 20cm deep;

[0011] S2: Irrigation and drainage process:

[0012] S2a: After the saline-alkali dryland is treated with the amendment, irrigation is stopped until the moisture content of the 20cm soil layer reaches the field water holding capacity, and then the soil is naturally dried until the moisture content of the soil layer is below 20%, and then dryland crops are planted;

[0013] S2b: After applying the soil conditioner to the saline-alkali paddy field, flood the field and stop irrigation when the water level reaches 8 - 10 cm. After flooding for 36 hours, carry out stirring and puddling, drain the water after the soil has settled, then conduct the second irrigation until the water level reaches 3 cm, and then transplant rice seedlings.

[0014] As a further technical solution of the present invention, in S1a, for moderately saline-alkali soil with 9.0 < pH ≤ 9.5, severely saline-alkali soil with 9.5 < pH ≤ 10, and extremely severely saline-alkali soil with pH > 10.

[0015] As a further technical solution of the present invention, in S1b, when 9.0 < pH ≤ 9.5, that is, for moderately saline-alkali soil, the application rate of the artificially designed molecular sieve soil conditioner is 0.65 tons per mu.

[0016] As a further technical solution of the present invention, in S1b, when 9.5 < pH ≤ 10, that is, for severely saline-alkali soil, the application rate of the artificially designed molecular sieve soil conditioner is 1 ton per mu.

[0017] As a further technical solution of the present invention, in S1b, when pH > 10, that is, for extremely severely saline-alkali soil, the application rate of the artificially designed molecular sieve soil conditioner is 3 tons per mu.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. It has the function of calcium-sodium replacement in the soil, and can permanently lock the excess sodium ions in the soil with one-time treatment.

[0020] 2. It can achieve soil improvement without increasing soil salinity.

[0021] 3. The materials used have the same composition as the soil, and there is no problem of soil pollution.

[0022] 4. It can simultaneously solve the problem of heavy metal ion pollution in the soil.

[0023] 5. There is no need to wash the field, saving water resources. Description of the Drawings

[0024] Figure 1 It is the soil EC and pH diagram with different application rates of the artificially designed molecular sieve in Example 1;

[0025] Figure 2 It is the effect diagram of the artificially designed molecular sieve for improving saline-alkali paddy fields in Example 1;

[0026] Figure 3 It is the diagram showing the effects of different application rates of the soil conditioner on the germination rate, seedling height, and root length of wheat seeds in Example 2;

[0027] Figure 4Graph showing the effects of different dosages of the modifier on the dry and fresh weights of the roots and stems of wheat seedlings in Example 2;

[0028] Figure 5 Photo of wheat growth in Example 2;

[0029] Figure 6 Photo of wheat after harvest in Example 2;

[0030] Figure 7 Graph showing the effects of different dosages of the modifier on the germination rate, seedling height, and root length of wheat seeds in Example 3;

[0031] Figure 8 Graph showing the effects of different dosages of the modifier on the dry and fresh weights of the roots and stems of wheat seedlings in Example 3;

[0032] Fig. 9 Photo of wheat growth in Example 3;

[0033] Fig.10 Photo of wheat after harvest in Example 3;

[0034] Fig.11 Flow chart of a method for improving soda saline-alkali soil by artificially designed molecular sieves proposed by the present invention. Detailed implementation manners

[0035] To make the technical means, creative features, achieved purposes, and functions of the present invention easy to understand, the present invention will be further described below in conjunction with the detailed implementation manners.

[0036] Please refer to the appendix Fig.11 , a method for improving soda saline-alkali soil by artificially designed molecular sieves, including artificially designed molecular sieve modifiers. The main component of the artificially designed molecular sieve modifier is calcium ion-exchanged LTA-type molecular sieve, with the molecular formula Ca6[(AlO2) 12 (SiO2) 12 :27H2O, and specifically includes the following specific steps:

[0037] S1: Application process:

[0038] S1a: Diagnosis and evaluation of moderately and severely soda saline-alkali soil: Select moderately and severely soda saline-alkali soil, measure the soil pH, and divide it into 3 grades, namely moderately soda saline-alkali soil with 9.0 < pH ≤ 9.5, severely soda saline-alkali soil with 9.5 < pH ≤ 10, and extremely severely soda saline-alkali soil with pH > 10;

[0039] S1b: Apply different dosages of artificially designed molecular sieves according to different pH indicators, that is, different degrees of soda saline-alkali soil. When 9.0 < pH ≤ 9.5, that is, medium soda saline-alkali soil, the dosage of the artificially designed molecular sieve modifier is 0.65 tons per mu; when 9.5 < pH ≤ 10, that is, heavy soda saline-alkali soil, the dosage of the artificially designed molecular sieve modifier is 1 ton per mu; when pH > 10, that is, extremely heavy soda saline-alkali soil, the dosage of the artificially designed molecular sieve modifier is 3 tons per mu.

[0040] S1c: According to the grade of soil pH, spread the corresponding amount of the artificially designed molecular sieve modifier evenly on the soil surface and rotary till it into the soil by 20 cm.

[0041] S2: Irrigation and drainage process:

[0042] S2a: After applying the modifier to the saline-alkali dry land, irrigate until the water content in the 20-cm soil layer reaches the field water holding capacity, then stop irrigation, and then naturally dry until the water content in the soil layer is below 20%, and start planting dry land crops.

[0043] S2b: After applying the modifier to the saline-alkali paddy field, flood the field for paddy field preparation. Stop irrigation when the irrigation water surface is 8 - 10 cm. After flooding the field for 36 hours, carry out stirring and puddling. Drain the water after the soil has settled, and then carry out the second irrigation until the water surface is 3 cm, and then carry out rice transplanting.

[0044] Example 1

[0045] Experiment on the dosage of artificially designed molecular sieve in medium soda saline-alkali soil (9.0 < pH ≤ 9.5)

[0046] Experiment location: The experimental plot is located in Honggangzi Village, Honggangzi Township, Daan City, Jilin Province. Plot coordinates: 45°36′33″ N, 123°52′49″ E.

[0047] The soil is medium soda saline-alkali soil, with a pH of 9.34 and a conductivity of 0.36 mS / cm. The crop planted is rice, and it is a saline-alkali paddy field.

[0048] Test treatment: For 4 treatment plots, according to the weight ratios of 0.5% (0.65 tons per mu), 1.0% (1.3 tons per mu), and 1.5% (1.95 tons per mu) in 3 groups of dosages, the fourth group is the control with a dosage of 0. After spreading evenly, rotary till 20 cm and mix well with the soil.

[0049] The specific grouping is as follows:

[0050] The first group: The dosage of the artificially designed molecular sieve modifier in the soda saline-alkali soil is 0.5% (NM2).

[0051] The second group: The dosage of the artificially designed molecular sieve modifier in the soda saline-alkali soil is 1.0% (NM3).

[0052] Group 3: The dosage of artificially designed molecular sieve modifier for soda saline-alkali soil is 1.5% (NM3).

[0053] Group 4: The dosage of artificially designed molecular sieve modifier for soda saline-alkali soil is 0% (NM0).

[0054] Test results: After applying the artificially designed molecular sieve, the soil EC was significantly reduced, and the EC of the treatments with 0.5% and 1.5% application rates decreased the most, by 30% compared with the control. After applying the artificially designed molecular sieve, the soil pH decreased at 0.5% and 1% application rates, with 0.5% decreasing by 0.05 and 1% decreasing by 0.07, and there was no significant difference between the two treatments.

[0055] After different molecular sieve application rates, rice yield increased significantly, with 0.5% application rate increasing yield by 46.4%, and 1% and 1.5% increasing yield by 63.6%. Considering the soil improvement effect, yield and molecular sieve input, 0.5% application rate was the most appropriate.

[0056] Table 1 Rice yield under different artificially designed molecular sieve application rates

[0057]

[0058] Example 2

[0059] Experiment on the application rate of artificially designed molecular sieve in heavy soda saline-alkali soil (9.5≤pH≤10)

[0060] The soil is severe soda saline-alkali soil (9.5≤pH≤10) with a soil pH of 9.62. Five treatments with artificially designed molecular sieve amendment dosages of 1 ton / mu, 2 tons / mu, 3 tons / mu, 4 tons / mu and 5 tons / mu were selected. The test crop was wheat. The effects of different dosages of artificially designed molecular sieve amendments on severe soda saline-alkali soil and wheat growth were explored.

[0061] The specific groups are as follows:

[0062] Group 1: The dosage of artificially designed molecular sieve conditioner for soda saline-alkali land is 1t / mu (NM1).

[0063] Group 2: The dosage of artificially designed molecular sieve conditioner for soda saline-alkali land is 2t / mu (NM2).

[0064] Group 3: The dosage of artificially designed molecular sieve conditioner for soda saline-alkali land is 3t / mu (NM3).

[0065] Group 4: The dosage of artificially designed molecular sieve conditioner for soda saline-alkali land is 4t / mu (NM4).

[0066] Group 5: The dosage of artificially designed molecular sieve conditioner for soda saline-alkali land is 5t / mu (NM5).

[0067] Group 6 (comparison): The dosage of artificially designed molecular sieve conditioner for soda saline-alkali land is 0t / mu (NM0).

[0068] The test results show that Table 2 shows the effects of different amounts of modifiers on the pH, electrical conductivity (EC), total alkalinity and sodium adsorption ratio of heavy soda saline-alkali soil. It can be seen from Table 2 that the application of artificially designed molecular sieve modifiers can significantly reduce the total alkalinity. Compared with the control, the soil pH decreased by 0.04-0.06 units; the electrical conductivity EC decreased by 0.06-0.12 units; the total alkalinity decreased by 39.73-42.60%; there was no significant difference in soil pH and EC among the five application amounts of modifiers at different application amounts.

[0069] Figure 3 The effects of different dosages of improvers on wheat seed germination rate, seedling height and root length. Figure 3 It can be seen that the application of artificially designed molecular sieve modifiers can increase the germination rate of wheat. The germination rate of wheat in the first group of this embodiment is significantly higher than that in the control group. Compared with the control group, the germination rate is increased by 15.38%; the application of artificially designed molecular sieve modifiers can increase the height of wheat seedlings and the length of roots. The height of wheat seedlings in the first to fifth groups is higher than that in the control group, and the length of wheat roots is increased by about 1.33-4.00 cm.

[0070] Figure 4 Effects of different dosages of amendments on the dry weight and fresh weight of roots and stems of wheat seedlings. Figure 4 It can be seen that the application of artificially designed molecular sieve amendments in soda saline-alkali soil can increase the underground dry weight and fresh weight of wheat seedlings; the aboveground fresh weight of wheat in the first, fourth and fifth groups was significantly higher than that in the control group, and the aboveground dry weight of wheat in the fourth group was significantly higher than that in the control group.

[0071] The test results show that the artificially designed molecular sieve improver has a certain improvement effect on severe soda saline-alkali soil (9.5≤pH≤10). Considering factors such as the economic benefits of field application, the optimal application rate is 1t / mu.

[0072] Table 2 Effects of different amounts of modifiers on pH, conductivity and total alkalinity of heavy soda saline-alkali soil (9.5≤pH≤10)

[0073]

[0074] Example 3

[0075] Experiment on the application rate of artificially designed molecular sieve in extremely heavy soda saline-alkali soil (pH>10)

[0076] The soil is extremely heavy soda saline soil, the soil pH (soil-water ratio is 1:5) is 10.10, and the test crop is wheat.

[0077] The specific groups are as follows:

[0078] Group 1: The dosage of artificially designed molecular sieve conditioner for soda saline-alkali land is 1t / mu (NM1).

[0079] Group 2: The dosage of artificially designed molecular sieve conditioner for soda saline-alkali land is 2t / mu (NM2).

[0080] Group 3: The dosage of artificially designed molecular sieve conditioner for soda saline-alkali land is 3t / mu (NM3).

[0081] Group 4 (comparison): The dosage of artificially designed molecular sieve conditioner for soda saline-alkali land is 0t / mu (CK).

[0082] The results show that Table 3 shows the effects of different dosages of modifiers on pH, conductivity and total alkalinity of soda saline-alkali soil. It can be seen from Table 3 that the application of artificially designed molecular sieve modifiers has no significant effect on reducing the pH of severe soda saline-alkali soil, but can significantly reduce soil conductivity and total alkalinity. The soil conductivity and total alkalinity of the third group are the lowest, which are reduced by 33.33% and 27.90% compared with the control group.

[0083] Figure 7 The effects of different dosages of improvers on wheat seed germination rate, seedling height and root length are shown in Table 1. Figure 7 It can be seen that the application of artificially designed molecular sieve improvers can significantly increase the wheat germination rate, which is about 366.65% higher than that of the control group; the height and root length of wheat seedlings in the second and third groups are significantly higher than those in the control group, which are increased by about 133.36%-262.5% and 293%-295.21%.

[0084] Figure 8 Effects of different dosages of amendments on the dry weight and fresh weight of roots and stems of wheat seedlings. Figure 8 It can be seen that the application of artificially designed molecular sieve improvers can significantly increase the fresh weight and dry weight of the underground part of wheat; overall, the application of artificially designed molecular sieve improvers in soda saline-alkali soil has a promoting effect on the growth and development of wheat. The experimental results show that for severe soda saline-alkali soil (pH>10), the optimal application rate of artificially designed molecular sieve improvers is 3t / mu.

[0085] Table 3 Effects of different dosages of modifiers on pH, conductivity, total alkalinity and sodium adsorption ratio of soda saline-alkali soil

[0086]

[0087] Example 4

[0088] Verification of artificially designed molecular sieves in typical soda saline-alkali land areas

[0089]

[0090]

[0091] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0092] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for improving soda saline-alkali soil by artificially designed molecular sieves, characterized in that: The invention comprises an artificially designed molecular sieve modifier, wherein the main components of the artificially designed molecular sieve modifier are LTA type molecular sieves exchanged with calcium ions and having a molecular formula of Ca6[(AlO2) 12 (SiO2) 12 ]:27H2O, specifically comprising the following specific steps: S1: Application process: S1a: Diagnosis and evaluation of moderately and severely soda saline-alkali soil: Select moderately and severely soda saline-alkali soil, measure the soil pH, and divide it into 3 grades, namely moderately soda saline-alkali soil, severely soda saline-alkali soil, and extremely severely soda saline-alkali soil; S1b: For different pH indicators, that is, different degrees of soda saline-alkali soil, apply different dosages of artificially designed molecular sieves. The dosages are 0.65 tons per mu, 1 ton per mu, and 3 tons per mu respectively; S1c: According to the grade of soil pH, evenly spread the corresponding amount of artificially designed molecular sieve modifier on the soil surface and rotary till it into the soil by 20 cm; S2: Irrigation and drainage process: S2a: After applying the modifier to saline-alkali dry farmland, irrigate until the water content in the 20-cm soil layer reaches the field water holding capacity, then stop irrigation, and then naturally dry until the water content in the soil layer is below 20%, and start planting dry farmland crops; S2b: After applying the modifier to saline-alkali paddy field, flood the field for soaking. Stop irrigation when the irrigation water surface is 8 - 10 cm. After soaking the field for 36 hours, carry out stirring and puddling. After the soil settles, drain the water, and then carry out the second irrigation until the water surface is 3 cm, and then carry out rice transplanting.

2. The method for improving soda saline-alkali soil with artificially designed molecular sieve according to claim 1, characterized in that: In the above S1a, for moderately soda saline-alkali soil, 9.0 < pH ≤ 9.5; for severely soda saline-alkali soil, 9.5 < pH ≤ 10; for extremely severely soda saline-alkali soil, pH > 10.

3. The method for improving soda saline-alkali soil with artificially designed molecular sieve according to claim 2, characterized in that: In the above S1b, when 9.0 < pH ≤ 9.5, that is, for moderately soda saline-alkali soil, the dosage of the artificially designed molecular sieve modifier is 0.65 tons per mu.

4. The method for improving soda saline-alkali soil with artificially designed molecular sieve according to claim 3, characterized in that: In the above S1b, when 9.5 < pH ≤ 10, that is, for severely soda saline-alkali soil, the dosage of the artificially designed molecular sieve modifier is 1 ton per mu.

5. The method for improving soda saline-alkali soil with artificially designed molecular sieve according to claim 4, characterized in that: In the above S1b, when pH > 10, that is, for extremely severely soda saline-alkali soil, the dosage of the artificially designed molecular sieve modifier is 3 tons per mu.

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