Composite soil conditioner and preparation method thereof

Abstract

The invention provides a composite soil conditioner and a preparation method thereof, and the composite soil conditioner comprises the following components by mass: 20-50 parts of an organic fertilizer, 1-5 parts of gypsum, 1-5 parts of aluminum sulfate, 1-10 parts of lignin, 1-5 parts of a lime compound, and 1-5 parts of charcoal. According to the composite soil conditioner, the water retention capacity and porosity of soil are improved through the synergistic effect of the lignin and the biochar, the lignin and the biochar are wide in source and cheap in raw material, biological resources can be utilized in a friendly mode, and the biochar material can improve the porosity and the surface area of the soil; the tensile strength of the soil is reduced, so that the physical properties of the soil are improved; the growth of plant root systems and the permeation of water are facilitated. Lignin can fix nutrient elements in soil through complexation to form a long-acting slow-release fertilizer, so that the utilization efficiency of plants on the nutrients is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of soil conditioners, and particularly relates to a composite soil conditioner and a preparation method thereof. Background Art

[0002] Soil degradation refers to the deterioration or loss of soil quality, resulting in a decline in land productivity or the inability to support certain agricultural production and ecosystem functions. Soil degradation is generally considered to be the combined result of multiple factors such as agriculture, urbanization, ecological environment damage, and climate change. The impact of soil degradation is significant, not only affecting agricultural production and food safety, but also having a profound impact on the ecological environment, such as causing desertification, soil erosion, climate change and other problems. Therefore, land resource protection and management should be strengthened, land resources should be rationally utilized, factors causing soil degradation should be reduced, and sustainable management and utilization of land should be promoted.

[0003] Soil conditioners have functions such as improving soil, controlling desertification, retaining water and drought resistance, enhancing the disease resistance of crops, increasing crop yields, improving the quality of agricultural products, and restoring the original ecology of crops. However, the functions of current soil conditioners are relatively single.

[0004] Lignin is abundant in nature. Lignin is a phenolic macromolecule composed of different monomer structural units. They are rigid biopolymers and are part of the plant cell wall, causing the lignification of plant cells. Approximately 20% to 30% of the dry mass of plants is composed of lignin. It fills the volume in the cell wall established by cellulose, hemicellulose, and pectin components, especially filling the volume in xylem tracheids. As a biomass material, the second largest resource in the plant kingdom after cellulose, the global annual output of lignin is about 50 million tons, of which lignin derived from agricultural residues accounts for about 10% - 20%, and lignin derived from forest biomass materials accounts for about 20% - 30%. The sources are very wide and the output is huge.

[0005] Biochar is a type of charcoal used as a soil conditioner that can help plant growth. Therefore, improving the physical and chemical properties of the soil and enhancing the water retention capacity and porosity of the soil are one of the important problems that need to be solved urgently. Summary of the Invention

[0006] In view of this, the present invention proposes a composite soil conditioner that can not only make full use of resources but also effectively solve the physical and chemical properties of the soil. Using lignin and biochar as raw materials, the two act synergistically to solve the soil porosity and water retention capacity.

[0007] The technical solution of the present invention is realized as follows: The present invention provides a composite soil conditioner. Calculated by mass components, the composite soil conditioner comprises the following components:

[0008] 20 - 50 parts of organic fertilizer, 1 - 5 parts of gypsum, 1 - 5 parts of aluminum sulfate, 1 - 10 parts of lignin, 1 - 5 parts of lime compounds, 1 - 5 parts of biochar.

[0009] Based on the above technical solutions, preferably, by mass components, the compound soil conditioner comprises the following components:

[0010] 35 parts of organic fertilizer, 3 parts of gypsum, 3 parts of aluminum sulfate, 6 parts of lignin, 3 parts of lime compounds, 3 parts of biochar.

[0011] Based on the above technical solutions, preferably, the lime compounds are selected from at least one of calcium carbonate, calcium oxide, and calcium hydroxide.

[0012] According to another aspect of the present invention, the present invention provides a preparation method of the above - mentioned compound soil conditioner, and the preparation method comprises the following steps:

[0013] Step S1: Crush the lignin and sieve it to obtain pretreated lignin;

[0014] Step S2: Stir the raw materials containing gypsum and aluminum sulfate for 1, add the organic fertilizer and pretreated lignin and mix them, stir for 2, add the lime compounds and biochar, stir for 3, and extrude and granulate to obtain the compound soil conditioner.

[0015] Based on the above technical solutions, preferably, in step S1, the mesh number of the sieving is 100 - 120 meshes.

[0016] Based on the above technical solutions, preferably, in step S1, the temperature of stirring 1 is 40 - 50 °C, the time of stirring 1 is 3 - 6 h, and the rotation speed of stirring 1 is 150 - 300 rpm.

[0017] Based on the above technical solutions, preferably, the temperature of stirring 2 is 40 - 60 °C, the time of stirring 2 is 2 - 8 h, and the rotation speed of stirring 2 is 100 - 250 rpm.

[0018] Based on the above technical solutions, preferably, the temperature of stirring 3 is 30 - 70 °C, the time of stirring 3 is 1 - 5 h, and the rotation speed of stirring 3 is 50 - 400 rpm.

[0019] In the compound soil conditioner of the present invention, gypsum can undergo a displacement reaction with sodium ions in the soil, thereby reducing the alkalinity and salt content of the soil; further improving the soil structure and increasing the permeability of the soil. As an acidic compound, aluminum sulfate can react with alkaline substances in the soil to form water - insoluble salts and aluminum hydroxides, thereby reducing the pH value and alkalinity of the soil.

[0020] Organic fertilizers are rich in organic matter and microorganisms. During the decomposition process of organic matter, alkaline substances such as carbonate ions (CO 3 2 -) and hydroxide ions (OH-) are produced, which can neutralize acidic substances in the soil, further improve the soil structure, and enhance soil fertility. At the same time, the microorganisms in organic fertilizers can also decompose harmful substances in the soil and purify the soil environment.

[0021] Lime compounds can react with acidic substances in the soil to neutralize them and increase the pH value of the soil.

[0022] Biochar is a porous carbon material produced by pyrolyzing biomass under anaerobic conditions. It has good adsorption performance and buffering capacity. It can adsorb acidic substances in the soil, and at the same time provide a rich pore structure to improve soil aeration and water retention.

[0023] Lignin has a complex three-dimensional network structure and can bind to soil particles to promote the formation and stability of soil aggregate structures, thereby improving soil aeration and water retention; the addition of lignin can promote the formation of soil aggregates, reduce soil bulk density, increase soil porosity, and play a role in preventing soil compaction, retaining water and fertilizer, and enhancing plant stress resistance. When the soil porosity is low, the soil is prone to compaction, which is not conducive to the penetration of air and water. Therefore, the present invention solves the problems of poor water retention effect and low porosity of the soil through the synergistic effect between biochar and lignin.

[0024] The composite soil conditioner provided by the present invention has the following beneficial effects compared with the prior art:

[0025] The composite soil conditioner provided by the present invention improves the water retention capacity and porosity of the soil through the synergistic effect of lignin and biochar. The sources of lignin and biochar are extensive, and the raw materials are cheap, which can make friendly use of biological resources. Its biochar material can increase soil porosity and surface area, and reduce the tensile strength of the soil, thereby improving the physical properties of the soil; it is beneficial to the growth of plant roots and the penetration of water. Lignin can fix nutrient elements in the soil through complexation to form a long-acting slow-release fertilizer. At the same time, it can also reduce the adsorption and fixation capacity of the soil for nutrients such as phosphorus and potassium, and has a certain synergistic effect on urea, forming compounds that are beneficial for plant absorption, thereby improving the utilization efficiency of plants for these nutrients. Specific embodiments

[0026] The following will describe the technical solutions in the embodiments of the present invention clearly and completely in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] Example 1

[0028] Weigh 1 g of lignin, crush it with a pulverizer, and sieve it through a 100-mesh sieve to obtain pretreated lignin. Weigh 1 g of gypsum and 1 g of aluminum sulfate as raw materials, stir at 40 °C and 150 rpm for 6 h, add 20 g of organic fertilizer and pretreated lignin and mix them, stir at 40 °C and 100 rpm for 8 h, add 1 g of calcium carbonate and 1 g of biochar, stir at 30 °C and 50 rpm for 5 h, and extrude and granulate to obtain compound soil conditioner 1#.

[0029] Example 2

[0030] Weigh 6 g of lignin, crush it with a pulverizer, and sieve it through a 100-mesh sieve to obtain pretreated lignin. Weigh 3 g of gypsum and 3 g of aluminum sulfate as raw materials, stir at 45 °C and 200 rpm for 4 h, add 35 g of organic fertilizer and pretreated lignin and mix them, stir at 50 °C and 150 rpm for 6 h, add 3 g of calcium carbonate and 3 g of biochar, stir at 50 °C and 200 rpm for 3 h, and extrude and granulate to obtain compound soil conditioner 2#.

[0031] Example 3

[0032] Weigh 10 g of lignin, crush it with a pulverizer, and sieve it through a 120-mesh sieve to obtain pretreated lignin. Weigh 5 g of gypsum and 5 g of aluminum sulfate as raw materials, stir at 50 °C and 300 rpm for 3 h, add 50 g of organic fertilizer and pretreated lignin and mix them, stir at 60 °C and 250 rpm for 2 h, add 5 g of calcium carbonate and 5 g of biochar, stir at 70 °C and 400 rpm for 1 h, and extrude and granulate to obtain compound soil conditioner 3#.

[0033] Example 4

[0034] Weigh 10 g of lignin, crush it with a pulverizer, and sieve it through a 100-mesh sieve to obtain pretreated lignin. Weigh 1 g of gypsum and 1 g of aluminum sulfate as raw materials, stir at 40 °C and 150 rpm for 6 h, add 20 g of organic fertilizer and pretreated lignin and mix them, stir at 40 °C and 100 rpm for 8 h, add 1 g of calcium carbonate and 5 g of biochar, stir at 30 °C and 50 rpm for 5 h, and extrude and granulate to obtain compound soil conditioner 4#.

[0035] Comparative Example 1

[0036] Weigh 1 g of lignin, crush it with a pulverizer, and sieve it through a 100-mesh sieve to obtain pretreated lignin. Weigh 1 g of gypsum and 1 g of aluminum sulfate as raw materials, stir at 40 °C and 150 rpm for 6 h, add 20 g of organic fertilizer and pretreated lignin, stir at 40 °C and 100 rpm for 8 h, add 1 g of calcium carbonate, and stir at 30 °C and 50 rpm for 5 h, then extrude and granulate to obtain Compound Soil Conditioner No. 5.

[0037] Comparative Example 2

[0038] Weigh 1 g of gypsum and 1 g of aluminum sulfate as raw materials, stir at 40 °C and 150 rpm for 6 h, add 20 g of organic fertilizer and mix, stir at 40 °C and 100 rpm for 8 h, add 1 g of calcium carbonate and 1 g of biochar, stir at 30 °C and 50 rpm for 5 h, then extrude and granulate to obtain Compound Soil Conditioner No. 6.

[0039] Comparative Example 3

[0040] Weigh 0.5 g of lignin, crush it with a pulverizer, and sieve it through a 100-mesh sieve to obtain pretreated lignin. Weigh 1 g of gypsum and 1 g of aluminum sulfate as raw materials, stir at 40 °C and 150 rpm for 6 h, add 20 g of organic fertilizer and pretreated lignin, stir at 40 °C and 100 rpm for 8 h, add 1 g of calcium carbonate and 1 g of biochar, stir at 30 °C and 50 rpm for 5 h, then extrude and granulate to obtain Compound Soil Conditioner No. 7.

[0041] Comparative Example 4

[0042] Weigh 11 g of lignin, crush it with a pulverizer, and sieve it through a 100-mesh sieve to obtain pretreated lignin. Weigh 1 g of gypsum and 1 g of aluminum sulfate as raw materials, stir at 40 °C and 150 rpm for 6 h, add 20 g of organic fertilizer and pretreated lignin, stir at 40 °C and 100 rpm for 8 h, add 1 g of calcium carbonate and 1 g of biochar, stir at 30 °C and 50 rpm for 5 h, then extrude and granulate to obtain Compound Soil Conditioner No. 8.

[0043] Comparative Example 5

[0044] Weigh 1 g of lignin, crush it with a pulverizer, and sieve it through a 100-mesh sieve to obtain pretreated lignin. Weigh 1 g of gypsum and 1 g of aluminum sulfate as raw materials, stir them at 40 °C and 150 rpm for 6 h, add 20 g of organic fertilizer and pretreated lignin and mix them, stir at 40 °C and 100 rpm for 8 h, add 1 g of calcium carbonate and 0.5 g of biochar, stir at 30 °C and 50 rpm for 5 h, and extrude and granulate to obtain compound soil conditioner No. 9.

[0045] Comparative Example 6

[0046] Weigh 1 g of lignin, crush it with a pulverizer, and sieve it through a 100-mesh sieve to obtain pretreated lignin. Weigh 1 g of gypsum and 1 g of aluminum sulfate as raw materials, stir them at 40 °C and 150 rpm for 6 h, add 20 g of organic fertilizer and pretreated lignin and mix them, stir at 40 °C and 100 rpm for 8 h, add 1 g of calcium carbonate and 6 g of biochar, stir at 30 °C and 50 rpm for 5 h, and extrude and granulate to obtain compound soil conditioner No. 10.

[0047] Test Example

[0048] Take 10 g of the compound soil conditioners No. 1-10 prepared in Examples 1-4 and Comparative Examples 1-6 with the same importance and put them into a soil sample volumetric flask with a known volume. Under the same room temperature environmental conditions, measure the water potential value and porosity of the soil every 24 hours and continuously record for 7 days. Record the water potential value and porosity in the original soil sample as 100%. The specific experimental results are shown in Table 1 and Table 2.

[0049] Table 1 Influence of compound soil conditioner on soil water retention capacity

[0050]

[0051]

[0052] As can be seen from Table 1, when the compound soil conditioner contains lignin and biochar, in Examples 1 to 4, the water potential value in the soil did not change in the first three days, and there was a slight downward trend starting from the fourth day. Until the 7th day, the water retention capacity of the soil conditioned with the compound soil conditioner containing lignin and biochar had good effects. Biochar was not added in Comparative Example 1, lignin was not added in Comparative Example 2, the amount of lignin was less in Comparative Example 3, the amount of lignin was more in Comparative Example 4, the amount of biochar was less in Comparative Example 5, and the amount of biochar was more in Comparative Example 6. By comparing Examples 1 to 4 with Comparative Examples 1 to 6, it can be found that when the amount of lignin or biochar is less or more, it cannot achieve good water retention capacity for the soil, and too much amount is also a waste of raw materials. Thus, it can be seen that through the synergistic effect between lignin and biochar, the soil can have good water retention capacity. Due to the complex three-dimensional network structure in lignin, it can bind to soil particles, promote the formation and stability of soil aggregate structure, thereby improving the water retention of the soil; in addition, biochar has good adsorption performance and buffering capacity, it can adsorb acidic substances in the soil, and at the same time provide a rich pore structure, thereby improving the water retention of the soil.

[0053] Table 2 Influence of Compound Soil Conditioner on Soil Porosity

[0054]

[0055]

[0056] As can be seen from Table 2, when the compound soil conditioner contains lignin and biochar, in Examples 1 to 4, the porosity value in the soil did not change in the first four days, and there was a slight downward trend starting from the fifth day until the porosity change in the soil was not very obvious on the 7th day; while in Comparative Example 1, biochar was not added, in Comparative Example 2, lignin was not added, in Comparative Example 3, the amount of lignin was less, in Comparative Example 4, the amount of lignin was more, in Comparative Example 5, the amount of biochar was less, and in Comparative Example 6, the amount of biochar was more. By comparing Examples 1 to 4 with Comparative Examples 1 to 6, it can be found that when the amount of lignin or biochar is less or more, the pores of the soil cannot be improved well. Among them, the porosity of the soil conditioned with the compound soil conditioner containing lignin and biochar has better effects. Thus, through the synergistic effect between lignin and biochar, the soil can have better porosity. Since the addition of lignin can promote the formation of soil aggregates, reduce soil bulk density, increase soil porosity, and play a role in preventing soil compaction, retaining water and fertilizer, and enhancing plant stress resistance. Biochar has good adsorption performance and buffering capacity. It can adsorb acidic substances in the soil, while providing a rich pore structure, thereby improving soil aeration, reducing soil compaction, further increasing soil porosity, preventing soil compaction and water loss, and improving soil water retention capacity.

[0057] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A composite soil conditioner, characterized in that: The composite soil conditioner comprises the following components by mass: 20-50 parts of organic fertilizer, 1-5 parts of gypsum, 1-5 parts of aluminum sulfate, 1-10 parts of lignin, 1-5 parts of lime compounds, and 1-5 parts of biochar.

2. The composite soil conditioner according to claim 1, characterized in that: The composite soil conditioner comprises the following components by mass: 35 parts of organic fertilizer, 3 parts of gypsum, 3 parts of aluminum sulfate, 6 parts of lignin, 3 parts of lime compounds, and 3 parts of biochar.

3. The composite soil conditioner according to claim 1, characterized in that: The lime compound is selected from at least one of calcium carbonate, calcium oxide and calcium hydroxide.

4. The method for preparing the composite soil conditioner according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: Step S1: crushing and sieving lignin to obtain pretreated lignin; Step S2: Stir 1 the raw materials containing gypsum and aluminum sulfate, add organic fertilizer and pretreated lignin to mix, stir 2, add lime compounds and biochar, stir 3, extrude and granulate to obtain the composite soil conditioner.

5. The preparation method according to claim 4, characterized in that: In the step S1, the mesh size of the sieving is 100 to 120 meshes.

6. The preparation method according to claim 4, characterized in that: In the step S1, the temperature of the stirring 1 is 40-50°C, the time of the stirring 1 is 3-6 hours, and the rotation speed of the stirring 1 is 150-300 rpm.

7. The preparation method according to claim 4, characterized in that: The stirring temperature of the stirring 2 is 40-60° C., the stirring time of the stirring 2 is 2-8 hours, and the stirring speed of the stirring 2 is 100-250 rpm.

8. The preparation method according to claim 4, characterized in that: The temperature of the stirring 3 is 30-70° C., the time of the stirring 3 is 1-5 hours, and the rotation speed of the stirring 3 is 50-400 rpm.

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