Improvement method for improving soil porosity of saline-alkali soil

Abstract

The invention provides an improvement method for improving soil porosity of saline-alkali soil, which comprises the following steps: (1) uniformly spreading a saline-alkali soil conditioner on the surface of saline-alkali soil to be improved, and uniformly mixing the saline-alkali soil conditioner with the saline-alkali soil; (2) ploughing the saline-alkali soil to obtain a plough layer; (3) flattening the surface of the saline-alkali soil, and thoroughly watering the saline-alkali soil with water; after watering is conducted for 15-20 days, the saline-alkali soil is turned over again, and a planting layer is obtained; the soil conditioner in the step (1) is prepared from 20 to 30 parts of attapulgite-polyacrylamide, 10 to 30 parts of charcoal, 20 to 30 parts of humic acid and 10 to 20 parts of ardealite. Through the mass ratio of the attapulgite-polyacrylamide to the biochar to the humic acid, the obtained soil conditioner can better repair soil and can better maintain the granular structure of the soil, and the water retention and fertilizer retention effects are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of soil improvement, and in particular relates to a method for improving the porosity of saline-alkali soil. Background Art

[0002] Soil aggregates are the basic units of soil structure. They are formed by many soil particles bonded together in a certain way. They have the characteristics of water stability, mechanical stability and porosity. When the soil has a good aggregate structure, the large pores between the aggregates are filled with air, aerobic microorganisms are active, organic matter is decomposed quickly, and nutrients are converted quickly for crops to absorb and utilize; there is more water and less air inside the aggregates, anaerobic microorganisms are active, organic matter is decomposed slowly, and the slow release is high. In soils with a stable structure, water and nutrients will be released layer by layer. While crops absorb and utilize them, they act as "soil reservoirs and waste reservoirs."

[0003] Soil structure is the key to soil fertility, and good soil structure is the basis for crop growth. For crops, soil structure is as important as nutrients. In areas with adverse climates and severe erosion, continuously adding organic matter to maintain good soil structure has become an indispensable measure.

[0004] As the environment for the growth and development of crop roots, soil provides the necessary water and air for crops to maintain normal physiological functions and the nutrients needed for crop growth. The basis for affecting soil fertility and soil physical, chemical and biological characteristics is soil structure. Soil conditioners are currently the most commonly used components for improving soil structure. They can protect the soil tillage layer, promote the formation of aggregates and provide their stability to improve soil structure, improve the continuous supply and water retention capacity of soil effective water to prevent soil erosion, repair soil contaminated by heavy metals through passivation, regulate and maintain a relatively good living environment for soil microorganisms, regulate unbalanced soil nutrient systems, improve saline-alkali soils, and promote the supply of effective nutrients. According to different sources, soil conditioners are divided into four types: natural, synthetic, natural-synthetic copolymers and biological conditioners. Natural improvers are divided into inorganic materials and organic materials; artificial synthetic improvers mainly include polyacrylamide, polyvinyl alcohol, urea-formaldehyde resin, etc.; natural-synthetic copolymers are commonly used for humic acid-polyacrylic acid, sulfonated lignin-vinyl acetate, cellulose-acrylamide, zeolite / attapulgite-acrylamide, etc.; biological improvers mainly include microbial inoculants, aerobic composting tea, earthworms, mycorrhizae, etc.

[0005] Chinese patent CN114051786A discloses a method for improving soil porosity, comprising the following steps: evenly spreading a soil conditioner on the soil surface at an amount of 300-800 kg per mu, then deep plowing, with a plowing depth of ≥40 cm, to obtain a tillage layer; after leveling the soil surface, watering it thoroughly; and planting plants after 5-15 days; wherein the soil conditioner is a three-dimensional shape processed by mixing modified phosphogypsum, bentonite and vermiculite, and the three-dimensional shape includes a column, a sphere, a cube, a cone or a cube, with a size of 3-7 cm. The invention uses modified phosphogypsum as a basic skeleton, and a small amount of bentonite and vermiculite are mixed and distributed on the basic skeleton and applied to the soil. The bentonite and vermiculite gradually fall from the basic skeleton, enter the soil, and gradually disperse into each soil layer, further improving the porosity of the soil and maintaining its porosity for a longer time, while playing the functions of increasing fertilizer, retaining fertilizer, retaining water and permeability.

[0006] Another example is a saline-alkali soil improvement method disclosed in Chinese patent CN108207157A, which comprises the following steps: (1) evenly spreading a saline-alkali soil improver on the surface of the saline-alkali soil to be improved, and evenly mixing the saline-alkali soil improver with the saline-alkali soil with a thickness of 5-10 cm, wherein the application amount of the saline-alkali soil improver is 6-10% of the mass of the saline-alkali soil, and the saline-alkali soil improver is composed of potassium humate, fly ash, 1-2 mol / L boric acid, konjac flour, calcium-based bentonite, aluminum sulfate, and water; (2) plowing the saline-alkali soil by 20-30 cm to obtain a tillage layer; (3) leveling the surface of the saline-alkali soil and watering it thoroughly; and then, after watering for 15-20 days, plowing the saline-alkali soil again by 20-30 cm to obtain a planting layer. The invention continuously adjusts the physical structure of the soil, reduces the soil salt content, reduces the soil bulk density, increases the effect of porosity, and increases the permeability of the soil, thereby significantly reducing the pH value of the soil.

[0007] However, the methods used in the prior art cannot maintain the soil with a good aggregate structure for a long time, so that the water and fertilizer retention effects of the soil cannot better meet the needs. Therefore, it is necessary to develop an improved method for increasing the porosity of saline-alkali soil. Summary of the invention

[0008] Based on the deficiencies in the prior art, the present invention aims to provide an improved method for increasing the porosity of saline-alkali soil, which can better maintain the soil aggregate structure and retain water and fertilizer.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] A method for improving the porosity of saline-alkali soil comprises the following steps:

[0011] (1) evenly spreading the saline-alkali soil conditioner on the surface of the saline-alkali soil to be improved, and evenly mixing the saline-alkali soil conditioner with the saline-alkali soil with a thickness of 0-10 cm;

[0012] (2) Plough the saline-alkali soil to 20-30 cm;

[0013] (3) Level the surface of the saline-alkali soil after plowing and irrigate it thoroughly with water; then, after 15-20 days of watering, till the saline-alkali soil again to a depth of 20-50 cm before planting;

[0014] The soil conditioner described in the above step (1) comprises 20-30 parts of attapulgite-polyacrylamide, 10-30 parts of biochar, 20-30 parts of humic acid and 10-20 parts of phosphogypsum.

[0015] Preferably, the soil conditioner comprises 22-28 parts of attapulgite-polyacrylamide, 15-25 parts of biochar, 22-28 parts of humic acid and 12-18 parts of phosphogypsum.

[0016] As a preferred implementation scheme, the mass ratio of attapulgite-polyacrylamide, biochar and humic acid is 1.25:1:1.25.

[0017] More preferably, the soil conditioner comprises 25 parts of attapulgite-polyacrylamide, 20 parts of biochar, 25 parts of humic acid and 15 parts of phosphogypsum.

[0018] The added amount of the soil conditioner is 50-100kg / mu.

[0019] in,

[0020] The preparation method of the attapulgite-polyacrylamide is:

[0021] (1) adding attapulgite to a dodecyltrimethylammonium bromide ethanol solution, reacting under constant temperature and stirring conditions, and filtering, washing, and drying to obtain organic attapulgite after the reaction is completed;

[0022] (2) Add acrylamide to a reaction container, add water to dissolve it, then add the organic attapulgite and N,N-methylenebisacrylamide obtained in step (1), add ammonium persulfate to react after heating, then add sodium hydroxide solution to saponify, and after the reaction is completed, wash, dry and crush to obtain the attapulgite-polyacrylamide.

[0023] The concentration of the dodecyltrimethylammonium bromide ethanol solution is 0.01-0.02 g / mL, preferably 0.015 g / mL.

[0024] The mass volume ratio of the attapulgite and the dodecyltrimethylammonium bromide ethanol solution is 1g:5-15mL;

[0025] Preferably, the mass volume ratio of the attapulgite and the dodecyltrimethylammonium bromide ethanol solution is 1g:8mL.

[0026] The reaction temperature in step (1) is 65-80°C; preferably 75°C.

[0027] The reaction time in step (1) is 8-10 hours, preferably 10 hours.

[0028] The drying temperature in step (1) is 40°C.

[0029] The mass ratio of acrylamide to organic attapulgite in step (2) is 4-6:1, preferably 5:1.

[0030] The added amount of the N,N-methylenebisacrylamide is 0.04-0.06% of acrylamide, preferably 0.04%.

[0031] The amount of ammonium persulfate added is 0.2-0.5% of acrylamide, preferably 0.4%.

[0032] The temperature after heating is 45°C.

[0033] The reaction time of adding ammonium persulfate in step (2) is 3-5 hours, preferably 4 hours.

[0034] The mass concentration of the sodium hydroxide is 5-10%. After the sodium hydroxide solution is added, the temperature needs to be raised to react, and the heating temperature is 90°C.

[0035] The saponification time is 1-1.5 hours, preferably 1.2 hours.

[0036] The drying temperature described in step (2) is 70°C.

[0037] The biochar is peanut shell biochar, which is prepared by slow thermal cracking in a tubular carbonization furnace.

[0038] Specific: 0.5℃·s -1 The peanut shell biochar was prepared by pyrolysis at a heating rate of 600°C and passed through a 90-mesh sieve.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The present invention uses biochar as a soil conditioner component. The raw materials for preparing biochar are widely available, which realizes the sustainable utilization of resources. The application of biochar to saline-alkali land can also improve the physical and chemical properties and biological activity of the soil and promote the growth of crops in the seedling stage. Biochar can increase the organic carbon content of the soil, reduce the water-soluble salt content, and reduce the degree of soil salinization; increase the cation exchange capacity and enzyme activity of the soil, improve the soil fertility and fertilizer retention capacity; increase the biomass and diversity of soil microorganisms, and improve the stability of the soil micro-ecosystem.

[0041] (2) The present invention uses a mixture of attapulgite-polyacrylamide, biochar and humic acid to improve soil porosity, wherein attapulgite is a hydrous magnesium-aluminum-rich layered chain silicate, which has good salt resistance, adsorption and colloidal properties compared to other clays, and the anti-inflammatory effect of polyacrylamide is significantly improved after being modified by attapulgite; biochar can not only be directly used as an improver to improve the soil's water and fertilizer retention capacity, reduce nutrient loss, and promote crop growth; it can also be used as a fertilizer carrier to increase the soil organic carbon content, improve soil microbial activity, and improve soil structure; humic acid can not only reduce the migration of pollutants in the soil to the environment or crops by changing the existence mode of pollutants in the soil or changing the combination form of pollutants in the soil and the soil, but also reduce the content of harmful substances in the soil, promote the proliferation of microorganisms in the soil, improve the decomposition effect of microorganisms, and achieve the repair of contaminated soil. The present invention uses the mass ratio of attapulgite-polyacrylamide to biochar and humic acid, so that the obtained soil improver can better repair the soil, and can better maintain the soil aggregate structure, water retention, and fertilizer retention effects. DETAILED DESCRIPTION

[0042] The above features mentioned in the present invention or the features mentioned in the embodiments can be combined in any way. All the features explained in the specification of this case can be used in combination with any method form, and each feature disclosed in the specification can be replaced by any alternative feature that can provide the same, equal or similar purpose. Therefore, unless otherwise specified, the disclosed features are only general examples of equal or similar features.

[0043] The present invention will be further described below in conjunction with specific examples. These examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In the following examples, the implementation methods for specifying specific conditions are usually based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, all percentages and fractions are by weight.

[0044] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those known to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein can be applied to the methods of the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only.

[0045] Basic Example 1:

[0046] The preparation method of attapulgite-polyacrylamide is:

[0047] (1) adding attapulgite to a 0.015 g / mL dodecyltrimethylammonium bromide ethanol solution, reacting for 10 hours under a constant temperature stirring condition of 75° C., filtering, washing, and drying at 40° C. after the reaction to obtain organic attapulgite; the mass volume ratio of the attapulgite to the dodecyltrimethylammonium bromide ethanol solution is 1 g:8 mL;

[0048] (2) Add acrylamide to a reaction container, add water to dissolve it, then add the organic attapulgite and N,N-methylenebisacrylamide (the amount added is 0.04% of acrylamide) obtained in step (1), add ammonium persulfate after heating for 4 hours, then add 8% sodium hydroxide solution and heat to 90°C for saponification for 1.2 hours. After the reaction is completed, wash, dry at 70°C, and crush to obtain the attapulgite-polyacrylamide; the mass ratio of acrylamide to organic attapulgite is 5:1.

[0049] Basic Example 2:

[0050] The preparation method of peanut shell biochar is as follows: -1 The peanut shell biochar was prepared by pyrolysis at a heating rate of 600°C and passed through a 90-mesh sieve.

[0051] Embodiment 1:

[0052] (1) Evenly spread the saline-alkali soil conditioner on the surface of the saline-alkali soil to be improved, and evenly mix the saline-alkali soil conditioner with the saline-alkali soil with a thickness of 8 cm;

[0053] (2) plowing the saline-alkali soil to 25 cm;

[0054] (3) After leveling the surface of the saline-alkali soil, water it thoroughly; then, 20 days after watering, till the saline-alkali soil again to a depth of 30 cm before planting.

[0055] The soil conditioner described in the above step (1) includes 20 parts of attapulgite-polyacrylamide prepared in Basic Example 1, 10 parts of biochar prepared in Basic Example 2, 20 parts of humic acid and 10 parts of phosphogypsum.

[0056] The added amount of the soil conditioner is 80kg / mu.

[0057] Embodiment 2:

[0058] (1) Evenly spread the saline-alkali soil conditioner on the surface of the saline-alkali soil to be improved, and evenly mix the saline-alkali soil conditioner with the saline-alkali soil with a thickness of 8 cm;

[0059] (2) plowing the saline-alkali soil to 25 cm;

[0060] (3) After the surface of the saline-alkali soil is leveled, water it thoroughly; then, 20 days after watering, the saline-alkali soil is rotary tilled again to a depth of 30 cm before planting.

[0061] The soil conditioner described in the above step (1) includes 30 parts of attapulgite-polyacrylamide prepared in Basic Example 1, 30 parts of biochar prepared in Basic Example 2, 30 parts of humic acid and 20 parts of phosphogypsum.

[0062] The added amount of the soil conditioner is 80kg / mu.

[0063] Embodiment 3:

[0064] (1) Evenly spread the saline-alkali soil conditioner on the surface of the saline-alkali soil to be improved, and evenly mix the saline-alkali soil conditioner with the saline-alkali soil with a thickness of 8 cm;

[0065] (2) plowing the saline-alkali soil to 25 cm;

[0066] (3) After leveling the surface of the saline-alkali soil, water it thoroughly; then, 20 days after watering, till the saline-alkali soil again to a depth of 30 cm before planting.

[0067] The soil conditioner described in the above step (1) includes 25 parts of attapulgite-polyacrylamide prepared in basic example 1, 20 parts of biochar prepared in example 2, 25 parts of humic acid and 15 parts of phosphogypsum.

[0068] The added amount of the soil conditioner is 80kg / mu.

[0069] Comparative Example 1

[0070] The difference from Example 3 is: 10 parts of attapulgite, 20 parts of polyacrylamide, 30 parts of biochar prepared in Basic Example 2, 30 parts of humic acid and 20 parts of phosphogypsum, and the rest is the same as Example 3.

[0071] Comparative Example 2

[0072] The difference from Example 3 is: 20 parts of attapulgite, 10 parts of polyacrylamide, 30 parts of biochar prepared in Basic Example 2, 30 parts of humic acid and 20 parts of phosphogypsum, and the rest is the same as Example 3.

[0073] Comparative Example 3

[0074] The difference from Example 3 is that the soil conditioner includes 10 parts of attapulgite-polyacrylamide prepared in Basic Example 1, 20 parts of biochar prepared in Example 2, 40 parts of humic acid and 15 parts of phosphogypsum, and the rest is the same as Example 3.

[0075] Comparative Example 4

[0076] The difference from Example 3 is that the soil conditioner includes 40 parts of attapulgite-polyacrylamide prepared in Basic Example 1, 5 parts of biochar prepared in Example 2, 35 parts of humic acid and 15 parts of phosphogypsum, and the rest is the same as Example 3.

[0077] Performance data

[0078] 1. Water absorption rate detection:

[0079] The water absorption rate refers to the ratio of the mass of a unit mass of soil conditioner absorbed to saturation to the mass of the soil conditioner before water absorption. The sieve filtration method is used, that is, 1g of soil conditioner (accurate value 0.01g), recorded as ma, is placed in a 2000mL beaker, and an excess of 0.9% NaCl solution is added, stirred for 5 minutes, and allowed to stand for 30 minutes. After it fully absorbs water and swells, it is naturally filtered for 10 minutes with a 0.18mm sieve, the test sieve is tilted, and filtered for another 10 minutes, and then the mass after water absorption is weighed, recorded as mb.

[0080] Calculate its water absorption rate Q, g / g according to the formula:

[0081] Q=(mb-ma) / ma

[0082] The test results are shown in Table 1 below.

[0083] Table 1

[0084] Water absorption rate, g / g Example 1 36.4 Example 2 35.8 Example 3 38.2 Comparative Example 1 25.4 Comparative Example 2 24.5 Comparative Example 3 28.2 Comparative Example 4 29.6

[0085] According to the test results in Table 1 above, the soil conditioner used in Examples 1-3 of the present invention has a better water absorption effect, and the salt water absorption rate is more than 35g / g, while in Comparative Examples 1-2, attapulgite and polyacrylamide are used as soil conditioner components, and the water absorption rate is significantly reduced; Comparative Examples 3-4 change the mass ratio of various components of the soil conditioner, and the water absorption rate is also significantly reduced compared with the embodiment.

[0086] 2. Soil porosity detection

[0087] The soil in the test site is saline-alkali soil with a bulk density of 1.52-1.58 g / cm 3 .

[0088] The saline-alkali soil was divided into 7 equal areas, each with an area of ​​50 cm 2, respectively adopt the improvement methods of Examples 1-3 and Comparative Examples 1-4. Soil samples were taken 0 and 90 days after improvement (3 samples were taken from each area), the soil bulk density was tested, and the soil porosity was calculated.

[0089] Soil bulk density test: ring knife method.

[0090] The porosity calculation formula is: total soil porosity = (1-bulk density / density) × 100%, density is 2.65g / cm 2 , keep one decimal place. The test results are shown in Table 2 below.

[0091] Table 2

[0092]

[0093]

[0094] According to the test data in Table 2 above, the improvement method of Examples 1-3 of the present invention can significantly improve the permeability of the soil, significantly increase the soil porosity, and thus improve the soil fertility, especially Example 3 has the best improvement effect; while in Comparative Examples 1-2, attapulgite and polyacrylamide are used as soil conditioner components, and the change in soil porosity is significantly reduced compared with the examples; Comparative Examples 3-4 change the mass ratio of various components of the soil conditioner, and the change in soil porosity is also reduced to a certain extent compared with the examples.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for improving the porosity of saline-alkali soil, characterized in that: The steps include: (1) evenly spreading the saline-alkali soil conditioner on the surface of the saline-alkali soil to be improved, and evenly mixing the saline-alkali soil conditioner with the saline-alkali soil with a thickness of 0-10 cm; (2) Plough the saline-alkali soil to 20-30 cm; (3) Level the surface of the saline-alkali soil after plowing and irrigate it thoroughly with water; then, after 15-20 days of watering, till the saline-alkali soil again to a depth of 20-50 cm before planting; The soil conditioner described in step (1) comprises 20-30 parts of attapulgite-polyacrylamide, 10-30 parts of biochar, 20-30 parts of humic acid and 10-20 parts of phosphogypsum.

2. The improved method according to claim 1, characterized in that: The soil conditioner comprises 22-28 parts of attapulgite-polyacrylamide, 15-25 parts of biochar, 22-28 parts of humic acid and 12-18 parts of phosphogypsum.

3. The improved method according to claim 1, characterized in that: The mass ratio of the attapulgite-polyacrylamide, biochar and humic acid is 1.25:1:1.

25.

4. The improved method according to claim 3, characterized in that: The soil conditioner comprises 25 parts of attapulgite-polyacrylamide, 20 parts of biochar, 25 parts of humic acid and 15 parts of phosphogypsum.

5. The improved method according to claim 1, characterized in that: The preparation method of the attapulgite-polyacrylamide is: (1) adding attapulgite to a dodecyltrimethylammonium bromide ethanol solution, reacting under constant temperature and stirring conditions, and filtering, washing, and drying to obtain organic attapulgite after the reaction is completed; (2) Add acrylamide to a reaction container, add water to dissolve it, then add the organic attapulgite and N,N-methylenebisacrylamide obtained in step (1), add ammonium persulfate to react after heating, then add sodium hydroxide solution to saponify, and after the reaction is completed, wash, dry and crush to obtain the attapulgite-polyacrylamide.

6. The improved method according to claim 5, characterized in that: The concentration of the dodecyltrimethylammonium bromide ethanol solution is 0.01-0.02 g / mL.

7. The improved method according to claim 5, characterized in that: The mass volume ratio of the attapulgite and the dodecyltrimethylammonium bromide ethanol solution is 1g:5-15mL.

8. The improved method according to claim 5, characterized in that: The mass ratio of acrylamide to organic attapulgite in step (2) is 4-6:

1.

9. The improved method according to claim 5, characterized in that: The added amount of the N,N-methylenebisacrylamide is 0.04-0.06% of the acrylamide; the added amount of the ammonium persulfate is 0.2-0.5% of the acrylamide.

10. The improved method according to claim 1, characterized in that: The biochar is peanut shell biochar, which is prepared by slow thermal cracking in a tubular carbonization furnace; specifically: -1 The peanut shell biochar was prepared by pyrolysis at a heating rate of 600°C and passed through a 90-mesh sieve.

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