Efficient green improver for acid soil

Abstract

The invention relates to an efficient green improver for acid soil, which is used for modifying biochar and applying the biochar to improvement of the acid soil to improve various physicochemical properties of the acid soil.

Description

Technical Field

[0001] The invention belongs to the technical field of acidic soil remediation, and in particular relates to a high-efficiency green improver for acidic soil. Background Art

[0002] The phenomenon of agricultural soil acidification is common in southern my country. After the soil is acidified, it not only affects the solubility of mineral elements in the soil and the balance of plant absorption of nutrients, but also the structure of soil microbial communities has changed significantly, directly affecting the yield and quality of plants. In this regard, researchers have used physical, chemical, and biological methods to explore the improvement of acidic soils, and found that improvers such as alkali residue, biochar, and lime have a good effect on improving acidic tobacco field soils, and the soil pH value and metal elements such as calcium and magnesium have been significantly improved. Improvers can effectively increase the pH value of acidic soils and promote the increase of crop yields. They have the dual effects of nutrition and soil improvement. They have better improvement effects on the physical and chemical properties of acidic soils.

[0003] Among them, the raw materials of biochar are very abundant, including agricultural waste (such as straw, rice straw, corn stalks), forestry waste (such as sawdust, sycamore wood chips), etc. These wastes are usually easy to obtain and can be converted into valuable biochar resources. Although biochar has the ability to remove heavy metal pollutants, unmodified biochar is easily affected by raw materials, production methods and production environment, and due to the surface charge and active sites of biochar, the adsorption capacity of biochar for ions is limited. Therefore, compared with biochar, modified biochar may have a stronger removal rate for soil heavy metal cadmium and a better soil improvement effect. Therefore, how to modify biochar and apply it to improve acidic soil is the research focus of the present invention. Summary of the invention

[0004] The purpose of the invention is to provide a high-efficiency green improver for acidic soil.

[0005] In order to solve the above technical problems, the specific process of the present invention is as follows:

[0006] A highly efficient green improver for acidic soil, wherein biochar is modified by an in-situ precipitation method: first, 1-5 parts of a modified substance are dissolved in 180 parts of an acetic acid solution with a mass fraction of 2%, then 3 parts of original biochar are added to the solution, the mixture is stirred at a rotation speed of 200-300 rpm for 30 minutes, then it is added dropwise to 900 parts of a NaOH solution with a mass fraction of 1.2% and allowed to stand for 12 hours, then it is washed with deionized water to remove excess NaOH, and then the modified biochar mixed material is spread on a ceramic tray and dried in an oven at 70°C for 24 hours, then crushed, and passed through a 100-mesh sieve for standby use.

[0007] Wherein, the modified substance is carboxymethyl pachymaran.

[0008] Among them, the original biochar also includes a preparation method: prepare dry rice husks, use a grinder to crush them into powder, pyrolyze the biomass powder sieved through a 60-mesh nylon screen at 500°C in a muffle furnace for 2 hours, and then crush the biochar again, pass it through a 100-mesh sieve, and then wash the sieved biochar powder with deionized water 2-3 times to remove impurities such as ash, and then place the biochar sample at 80° to dry to obtain the original biochar.

[0009] The application of the above-mentioned acidic soil conditioner in acidic soil improvement is as follows: the above-mentioned acidic soil conditioner is mixed into acidic soil at a mass ratio of 0.5% to 5% of the acidic soil conditioner to the acidic soil.

[0010] The beneficial effects of the present invention are:

[0011] 1. The acidic soil conditioner of the present invention has significant advantages. First, the porous structure and high specific surface area of ​​the modified biochar can improve the physical properties of the soil, increase the water retention capacity and porosity of the soil, and thus provide a good environment for plant growth. Secondly, it can increase the pH value of the soil, alleviate soil acidification, and promote crop growth. In addition, biochar itself is rich in nutrient elements, such as phosphorus, potassium, calcium, etc. These nutrients can be directly input into the soil to improve soil fertility. At the same time, modified biochar can improve the structure of soil microbial communities, increase the number and activity of beneficial microorganisms, and thus improve the overall health of the soil.

[0012] 2. Carboxymethyl tuckahoe polysaccharide is an important natural polymer compound, and its chemical structure contains multiple carboxymethyl and polysaccharide groups. Biochar itself is alkaline, and carboxymethyl tuckahoe polysaccharide contains abundant carboxymethyl and polysaccharide groups, which can enhance the alkalinity of biochar. Carboxymethyl tuckahoe polysaccharide has good electrical conductivity. When it fills the pores of biochar, it not only improves the conductivity of the material, but also enhances the interfacial adhesion of the material and improves the conductive pathway of biochar.

[0013] 3. Biochar itself increases the EC value of soil through lime effect, etc., and after modification with carboxymethyl tuckahoe polysaccharide, the conductivity of biochar is further enhanced, which can more effectively promote the adsorption of basic ions by the soil and further improve the EC of the soil.

[0014] 4. The rich functional groups in the carboxymethyl tuckahoe polysaccharide molecules can effectively enhance the adsorption performance of biochar. In particular, these functional groups can interact with ions in the soil to enhance the adsorption capacity of trace elements such as amino, copper, zinc, and iron, which helps to improve the effectiveness of nutrients in the soil. Biochar modified with carboxymethyl tuckahoe polysaccharide can effectively reduce the volatilization of ammonia and help reduce the loss of nutrients such as N and P in the soil. Its rich surface functional groups provide attachment points for ions such as NH4, NO3, and PO4 in the soil, promoting nutrient retention. Biochar modified with carboxymethyl tuckahoe polysaccharide can increase the nitrogen content in the soil, improve the CN balance of the soil, and promote the growth of beneficial microorganisms. In addition, carboxymethyl tuckahoe polysaccharide also has certain antibacterial properties, which can effectively inhibit the growth of some pathogens, thereby providing a better growth environment for beneficial microorganisms and further improving the enzyme activity and microbial diversity in the soil. The porous structure of biochar itself provides a rich habitat and reaction substrate for soil microorganisms, enhancing the biomass of microorganisms. Through filling and modification, carboxymethyl pachymaran not only enhances the physical properties of biochar, but also promotes the circulation of soil nutrients and the improvement of soil fertility. DETAILED DESCRIPTION

[0015] The present invention is further described in detail below with reference to the embodiments.

[0016] Example 1

[0017] Preparation of original biochar: prepare dry rice husks, use a grinder to grind them into powder, pyrolyze the biomass powder sieved through a 60-mesh nylon sieve at 500°C in a muffle furnace for 2 h, and then grind the biochar again, pass through a 100-mesh sieve, and wash the sieved biochar powder three times with deionized water to remove impurities such as ash. Finally, the biochar sample is placed at 80° to dry to obtain original biochar.

[0018] The biochar was modified by in-situ precipitation method: first, 3 parts of carboxymethyl pachymaran were dissolved in 180 parts of 2% acetic acid solution, and then 3 parts of original biochar were added to the solution. The mixture was stirred at 250 rpm for 30 min, and then added dropwise to 900 parts of 1.2% NaOH solution and allowed to stand for 12 h. Then, the excess NaOH was removed by washing with deionized water. The modified biochar mixed material was then spread on a ceramic tray and dried in an oven at 70°C for 24 h, then crushed and sieved through a 100-mesh sieve for later use.

[0019] Example 2

[0020] Preparation of original biochar: prepare dry rice husks, use a grinder to grind them into powder, pyrolyze the biomass powder sieved through a 60-mesh nylon sieve at 500°C in a muffle furnace for 2 h, then grind the biochar again, pass through a 100-mesh sieve, and wash the sieved biochar powder twice with deionized water to remove impurities such as ash. Finally, dry the biochar sample at 80° to obtain original biochar.

[0021] The biochar was modified by in-situ precipitation method: first, 1 part of carboxymethyl pachymaran was dissolved in 180 parts of 2% acetic acid solution, and then 3 parts of original biochar were added to the solution. The mixture was stirred at 200 rpm for 30 min, and then added dropwise to 900 parts of 1.2% NaOH solution and allowed to stand for 12 h. Then, the excess NaOH was removed by washing with deionized water. The modified biochar mixed material was then spread on a ceramic tray and dried in an oven at 70°C for 24 h, then crushed and sieved through a 100-mesh sieve for later use.

[0022] Example 3

[0023] Preparation of original biochar: prepare dry rice husks, use a grinder to grind them into powder, pyrolyze the biomass powder sieved through a 60-mesh nylon sieve at 500°C in a muffle furnace for 2 h, and then grind the biochar again, pass through a 100-mesh sieve, and wash the sieved biochar powder three times with deionized water to remove impurities such as ash. Finally, the biochar sample is placed at 80° to dry to obtain original biochar.

[0024] The biochar was modified by in-situ precipitation method: first, 5 parts of carboxymethyl pachymaran were dissolved in 180 parts of 2% acetic acid solution, and then 3 parts of original biochar were added to the solution. The mixture was stirred at 300 rpm for 30 min, and then added dropwise to 900 parts of 1.2% NaOH solution and allowed to stand for 12 h. Then, the excess NaOH was removed by washing with deionized water. The modified biochar mixed material was then spread on a ceramic tray and dried in an oven at 70°C for 24 h, then crushed and sieved through a 100-mesh sieve for later use.

[0025] Comparative Example 1

[0026] The difference between this comparative example and Example 1 is that the biochar in this comparative example is not modified, and the rest is the same as Example 1.

[0027] Comparative Example 2

[0028] The difference between this comparative example and Example 1 is that the carboxymethyl pachymaran in this comparative example is chitosan, and the rest is the same as Example 1.

[0029] Comparative Example 3

[0030] The difference between this comparative example and Example 1 is that in this comparative example, the biochar is physically modified: the original biochar is placed in an ozone atmosphere and activated at 700° C. for 1 hour to obtain the biochar, and the rest is the same as Example 1.

[0031] Comparative Example 4

[0032] The difference between this comparative example and Example 1 is that the amount of carboxymethyl tuckahoe polysaccharide in this comparative example is different, specifically: the biochar is modified by the in-situ precipitation method: first, 10 parts of carboxymethyl tuckahoe polysaccharide are dissolved in 180 parts of 2% acetic acid solution by mass, and then 3 parts of original biochar are added to the solution, the mixture is stirred at 250 rpm for 30 minutes, and then it is added dropwise to 900 parts of 1.2% NaOH solution by mass and allowed to stand for 12 hours, and then washed with deionized water to remove excess NaOH, and then the modified biochar mixed material is spread on a ceramic tray and dried in an oven at 70°C for 24 hours, and then crushed and sieved through a 100-mesh sieve for use; the rest is the same as Example 1.

[0033] Comparative Example 5

[0034] The difference between this comparative example and Example 1 is that the amount of carboxymethyl tuckahoe polysaccharide in this comparative example is different, specifically: the biochar is modified by the in-situ precipitation method: first, 0.5 parts of carboxymethyl tuckahoe polysaccharide is dissolved in 180 parts of 2% acetic acid solution by mass, and then 3 parts of original biochar are added to the solution, the mixture is stirred at 250 rpm for 30 minutes, and then it is added dropwise to 900 parts of 1.2% NaOH solution by mass for 12 hours, and then washed with deionized water to remove excess NaOH, and then the modified biochar mixed material is spread on a ceramic tray and dried in an oven at 70°C for 24 hours, and then crushed and sieved through a 100-mesh sieve for use; the rest is the same as Example 1.

[0035] Test 1: Soil Testing

[0036] The acidic soil conditioner prepared above was applied to the acidic soil to be improved at a weight ratio of 1%. After incubation at room temperature, the exchangeable acidity, exchangeable magnesium content and exchangeable calcium content were measured on the 7th and 28th days respectively. The soil was stirred irregularly during the incubation process, and water was replenished every 2-3 days to maintain the moisture in the soil at 60% of the maximum field water holding capacity. Among them, the control group was the experimental group when the applied conditioner was 0, that is, the original acidified soil to be improved. The soil pH value was measured by the HJ962-2018 water extraction method (soil-water mass ratio was 1:2.5), and the results are shown in Table 1.

[0037] Table 1

[0038]

[0039]

[0040] Test 2: Detection of soil activity

[0041] (1) Soil EC was determined using the HJ802-2016 water extraction method (soil-water mass ratio of 1:5).

[0042] (2) Soil organic matter was determined using the potassium dichromate dilution calorimetry method (NY / T85-1988).

[0043] (3) Soil enzyme activity: Urease was determined by sodium phenol-sodium hypochlorite colorimetric method, and soil sucrase was determined by nitrosalicylic acid colorimetric method. The control group was the experimental group when the applied amendment was 0, that is, the original acidified soil to be improved. The results are shown in Table 2.

[0044] Table 2

[0045]

Claims

1. An efficient green improver for acidic soil, characterized by: The preparation method includes: modifying biochar by in-situ precipitation method: first dissolving 1-5 parts of modified substance in 180 parts of 2% acetic acid solution by mass, then adding 3 parts of original biochar to the solution, stirring the mixture at 200-300rpm for 30min, then dropping it into 900 parts of 1.2% NaOH solution by mass and letting it stand for 12h, then washing with deionized water to remove excess NaOH, then spreading the modified biochar mixed material on a ceramic tray and drying it in an oven at 70°C for 24h, then crushing it and passing it through a 100-mesh sieve for later use.

2. The high-efficiency green improver for acidic soil according to claim 1, characterized in that: The modified substance is carboxymethyl pachymaran.

3. The high-efficiency green improver for acidic soil according to claim 1, characterized in that: The original biochar also includes a preparation method: prepare dry rice husks, use a grinder to crush them into powder, pyrolyze the biomass powder sieved through a 60-mesh nylon screen at 500°C in a muffle furnace for 2 hours, then crush the biochar again, pass it through a 100-mesh screen, and then wash the sieved biochar powder with deionized water 2-3 times to remove impurities such as ash, and then place the biochar sample at 80° for drying to obtain the original biochar.

4. An acidic soil conditioner obtained by the preparation method according to any one of claims 1 to 3 for acidic soil improvement Application: The acidic soil conditioner is mixed into the acidic soil at a mass ratio of 0.5% to 5% of the acidic soil conditioner to the acidic soil.

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