A high-efficiency green improver for acidic soil

Abstract

The present invention relates to a high-efficiency green improver for acidic soil, which comprises modifying biochar and using the biochar in improving the acidic soil to improve various physical and chemical properties of the acidic soil.

Description

Technical Field

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

[0002] Soil acidification not only affects the solubility of mineral elements in the soil and the balanced absorption of nutrients by plants, but also significantly alters the structure of soil microbial communities, directly affecting plant yield and quality. Researchers have used physical, chemical, and biological methods to explore ways to improve acidic soils, finding that amendments such as alkali residue, biochar, and lime are effective in improving acidic tobacco field soils, significantly increasing soil pH and metal elements such as calcium and magnesium. Amendments can effectively increase the pH of acidic soils and promote crop yields, achieving both nutritional and soil-improving benefits. They also have a significantly improved effect 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 this invention. Summary of the Invention

[0004] The purpose of the present 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 by mass of a 2% acetic acid solution, 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 the mixture is added dropwise to 900 parts by mass of a 1.2% NaOH solution and allowed to stand for 12 hours, 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, then crushed, and passed through a 100-mesh sieve for later 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 60-mesh nylon in a muffle furnace at 500°C for 2 hours, then crush the biochar again, pass it through a 100-mesh sieve, and then wash the sieved biochar powder 2-3 times with deionized water to remove impurities such as ash, and then place the biochar sample at 80°C for drying to obtain the original biochar.

[0009] The application of the above acidic soil conditioner in acidic soil improvement is as follows: the above 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 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 nutrients such as phosphorus, potassium, calcium, etc. These nutrients can be directly input into the soil to improve soil fertility. At the same time, the 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.

[0011] Carboxymethylated tuckahoe polysaccharide is an important natural polymer compound whose chemical structure contains multiple carboxymethyl and polysaccharide groups. Carboxymethylated tuckahoe polysaccharide has excellent electrical conductivity. When it fills the pores of biochar, it not only improves the material's conductivity but also enhances its interfacial adhesion, improving the biochar's conductive pathways.

[0012] 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 soil's adsorption of basic ions and further increase the EC of the soil.

[0013] The abundant functional groups within carboxymethyl tuckahoe polysaccharide molecules effectively enhance the adsorption properties of biochar. In particular, these functional groups interact with ions in the soil, enhancing the adsorption capacity for trace elements such as amino groups, copper, zinc, and iron, thereby improving the availability of nutrients in the soil. Biochar modified with carboxymethyl tuckahoe polysaccharide effectively reduces ammonia volatilization and helps reduce the loss of nutrients such as nitrogen and phosphorus from the soil. Its abundant surface functional groups provide attachment sites for ions such as NH₄, NO₃, and PO₄ in the soil, promoting nutrient retention. Biochar modified with carboxymethyl tuckahoe polysaccharide can increase soil nitrogen content, improve soil nitrogen balance, and promote the growth of beneficial microorganisms. Furthermore, carboxymethyl tuckahoe polysaccharide exhibits antibacterial properties, effectively inhibiting the growth of some pathogens. This provides a better environment for beneficial microorganisms, further enhancing enzyme activity and microbial diversity in the soil. The porous structure of biochar provides a rich habitat and substrates for soil microorganisms, increasing their biomass. Through filling and modification, carboxymethyl tuckahoe polysaccharide not only enhances the physical properties of biochar, but also promotes the circulation of soil nutrients and the improvement of soil fertility. DETAILED DESCRIPTION

[0014] The present invention will be further described in detail below with reference to the embodiments. Example

[0015] Preparation of raw biochar: Prepare dry rice husks and crush them into powder using a grinder. The biomass powder sieved through a 60-mesh nylon sieve is pyrolyzed at 500°C in a muffle furnace for 2 hours. The biochar is then crushed again and passed through a 100-mesh sieve. The sieved biochar powder is then washed three times with deionized water to remove impurities such as ash. The biochar sample is then dried at 80°C to obtain raw biochar.

[0016] The biochar was modified by the in situ precipitation method: first, 3 parts of carboxymethyl tuckahoe polysaccharide 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 minutes, and then added dropwise to 900 parts of 1.2% NaOH solution and allowed to stand for 12 hours. The mixture was then washed with deionized water to remove excess NaOH. The modified biochar mixture was then spread on a ceramic tray and dried in an oven at 70°C for 24 hours. It was then crushed and passed through a 100-mesh sieve for later use. Example

[0017] Preparation of raw biochar: Prepare dry rice husks and crush them into powder using a grinder. The biomass powder sieved through a 60-mesh nylon sieve is pyrolyzed at 500°C in a muffle furnace for 2 hours. The biochar is then crushed again and passed through a 100-mesh sieve. The sieved biochar powder is then washed twice with deionized water to remove impurities such as ash. The biochar sample is then dried at 80°C to obtain raw biochar.

[0018] The biochar was modified by the in-situ precipitation method: first, 1 part of carboxymethyl tuckahoe polysaccharide 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 minutes, and then added dropwise to 900 parts of 1.2% NaOH solution and allowed to stand for 12 hours. Then, the excess NaOH was washed with deionized water to remove the modified biochar mixture. The modified biochar mixture was then spread on a ceramic tray and dried in an oven at 70°C for 24 hours. It was then crushed and passed through a 100-mesh sieve for later use. Example

[0019] Preparation of raw biochar: Prepare dry rice husks and crush them into powder using a grinder. The biomass powder sieved through a 60-mesh nylon sieve is pyrolyzed at 500°C in a muffle furnace for 2 hours. The biochar is then crushed again and passed through a 100-mesh sieve. The sieved biochar powder is then washed three times with deionized water to remove impurities such as ash. The biochar sample is then dried at 80°C to obtain raw biochar.

[0020] The biochar was modified by the in-situ precipitation method: first, 5 parts of carboxymethyl tuckahoe polysaccharide 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 minutes, and then added dropwise to 900 parts of 1.2% NaOH solution and allowed to stand for 12 hours. Then, the excess NaOH was washed with deionized water to remove the modified biochar mixture. The modified biochar mixture was then spread on a ceramic tray and dried in an oven at 70°C for 24 hours. It was then crushed and passed through a 100-mesh sieve for later use.

[0021] Comparative Example 1

[0022] 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.

[0023] Comparative Example 2

[0024] 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.

[0025] Comparative Example 3

[0026] 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. The rest is the same as in Example 1.

[0027] Comparative Example 4

[0028] 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 a speed of 250 rpm for 30 minutes, and then 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.

[0029] Comparative Example 5

[0030] 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 a speed of 250 rpm for 30 minutes, and then 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.

[0031] Test 1: Soil Testing

[0032] 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 periodically during incubation, and water was added every 2-3 days to maintain the soil moisture at 60% of its maximum field capacity. The control group consisted of the experimental group with zero application of the conditioner, i.e., the original acidified soil to be improved. Soil pH was determined using the HJ962-2018 water extraction method (soil-to-water mass ratio of 1:2.5). The results are shown in Table 1.

[0033] Table 1

[0034]

[0035] Test 2: Detection of soil activity

[0036] (1) Soil EC was determined using the HJ802-2016 water extraction method (soil-water mass ratio of 1:5).

[0037] (2) Soil organic matter was determined using the potassium dichromate dilution calorimetry method (NY / T85-1988).

[0038] (3) Soil enzyme activity: Urease was measured using the sodium phenolate-sodium hypochlorite colorimetric method, and soil sucrase was measured using the nitrosalicylic acid colorimetric method. The control group was the experimental group with zero applied amendment, i.e., the original acidified soil to be amended. The results are shown in Table 2.

[0039] Table 2

[0040]

Claims

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

2. The high-efficiency green improver for acidic soil according to claim 1, characterized in that: The raw biochar also includes a preparation method: preparing dried rice husks, using a grinder to crush them into powder, pyrolyzing the biomass powder through a 60-mesh nylon sieve at 500°C in a muffle furnace for 2 hours, then crushing the biochar again, passing it through a 100-mesh sieve, and then washing the sieved biochar powder with deionized water 2-3 times to remove impurities such as ash, and then placing the biochar sample at 80°C for drying to obtain the raw biochar.

3. Use of the acidic soil conditioner obtained by the preparation method according to any one of claims 1 to 2 in acidic soil improvement: mixing the acidic soil conditioner into acidic soil at a mass ratio of 0.5% to 5% of the acidic soil conditioner to the acidic soil.

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