A soil conditioner and preparation method thereof

Abstract

The present application relates to the field of soil improvement technology and specifically discloses a soil conditioner and its preparation method. The soil conditioner comprises the following raw materials in parts by weight: 40-50 parts of straw biomass, 10-20 parts of anionic polyacrylamide, 5-15 parts of hydroxyapatite, and 0-10 parts of a soil additive; the hydroxyapatite has a particle size of 15-50 nm, the anionic polyacrylamide has a linear structure and an average molecular weight of 600-2000,000, and the straw biomass is obtained by sequentially crushing and ammonifying air-dried straw raw materials. The soil conditioner of the present application can be used to improve soil with a moderate degree of acidification.

Description

Technical Field

[0001] The present application relates to the technical field of soil improvement, and more specifically, to a soil improver and a preparation method thereof. Background Art

[0002] Soil conditioners, also known as soil conditioners, are materials primarily used to improve the physical, chemical, and biological properties of soil, making it more suitable for plant growth and promoting nutrient absorption by crops, without providing nutrients themselves. Soil conditioners work by bonding many small particles together to form larger, water-stable aggregates, essentially forming aggregates of several individual soil particles. They are widely used to prevent soil erosion, reduce evaporation or excessive transpiration, conserve irrigation water, and promote healthy plant growth. They act as "air corridors," serving as small water reservoirs for crop roots and fertilizer reservoirs for crop growth, loosening the soil and improving tillage properties, thereby maintaining high soil biodiversity.

[0003] Soil conditioners have moisture-retaining and warming properties, effectively increasing soil moisture and ground temperature in the cultivated layer, advancing crop growth by 2-7 days and boosting soil moisture by approximately 5%. They also improve soil structure, harmonizing the relationships between water, fertilizer, air, heat, and biomass, preventing soil erosion, enhancing waterway seepage control, inhibiting secondary salinization, and improving the utilization of sandy wasteland. They are primarily suitable for arid and semi-arid areas in northern my country, areas with insufficient accumulated heat during the crop growth period, and areas with poor soil structure, particularly drylands, sloping sandy land, and saline-alkali lands with severe water shortages. Currently, polyacrylamide and gypsum, a desulfurization byproduct of coal-fired power plants, are primarily used internationally. Traditional soil conditioner methods, such as adding sand to clay or loam to sand, use substances known as natural soil conditioners. Currently, organic extracts or synthetic soil conditioners are more commonly used.

[0004] Straw is a general term for the stems, leaves, or ears of mature crops. It usually refers to the remaining part of rice, corn, potatoes, onions, sugarcane, and other crops after the seeds are harvested. More than half of the products of crop photosynthesis are found in straw. Straw is rich in nitrogen, phosphorus, potassium, calcium, magnesium, and other nutrients. It is a multi-purpose renewable biological resource and a crude fiber. It is characterized by a high crude fiber content (30%-40%) and contains lignin, etc. Therefore, straw is a major source of soil organic matter. Returning straw to the field is beneficial to improving soil moisture and increasing soil fertility, and is one of the recommended conservation tillage measures.

[0005] In the prior art, straw has been applied to soil conditioners. For example, straw is mixed with calcium sulfate inorganic soil conditioner to reduce the volume mass of the topsoil, increase soil porosity, and thus increase crop yields; or straw is carbonized and then mixed with phosphate rock or calcium magnesium phosphate fertilizer to make a soil conditioner, using the functional groups and alkaline components of biochar itself to neutralize and alleviate soil acidity. The above technologies all provide specific application directions for the reuse of straw resources. However, in the face of the broad application prospects and resource reuse space of straw, on the one hand, the proportion of straw raw materials in existing straw applications in soil conditioners is generally less than 20%, that is, there is still room for improvement in straw utilization. On the other hand, the research on the application technology of straw in the field of soil improvement that has been disclosed is still relatively small and shallow. Therefore, it is urgent to provide more different dimensions of straw applications in the field of soil improvement to provide more ideas for the resource reuse of straw. Summary of the Invention

[0006] Based on the above, in order to improve the utilization rate of straw, the present application provides a soil conditioner and a preparation method thereof.

[0007] In a first aspect, the present application provides a soil conditioner, which adopts the following technical solution:

[0008] A soil conditioner comprises the following raw materials in parts by weight: 40-50 parts of straw biomass, 10-20 parts of anionic polyacrylamide, 5-15 parts of hydroxyapatite, and 0-10 parts of a soil additive; the hydroxyapatite has a particle size of 15-50 nm, the anionic polyacrylamide has a linear structure and an average molecular weight of 6-20 million, and the straw biomass is a straw processed material obtained by sequentially subjecting air-dried straw raw materials to a pulverizing treatment and an ammoniation treatment.

[0009] By adopting the above technical scheme, the present application designs the straw processed material obtained after crushing treatment and ammoniation treatment as the basic raw material and designs that the weight of straw biomass accounts for nearly half of the total amount of soil improver, and utilizes ammoniation treatment to destroy the ester bond between lignin and polysaccharide, so that cellulose, hemicellulose and lignin are partially decomposed, and the grass seeds and most of the pathogens in the straw are killed. On the one hand, it can make full use of the trace elements and organic matter in the straw, and on the other hand, it provides a basis for the design of a higher proportion of straw as raw material, which can avoid the competition between grass seeds and pathogens in the straw and crop growth; secondly, the present application designs the use of high molecular raw material anionic polyacrylamide. The addition of this raw material can improve the water holding capacity of the soil, and because straw biomass is rich in trace elements and, adding straw biomass to the soil will increase soil microorganisms. Biological activity, and soil microbial activity can easily cause the decomposition of anionic polyacrylamide, thereby affecting the water-holding effect of polyacrylamide. For this reason, 15-50nm hydroxyapatite is added. With the help of the high specific surface performance of nano-hydroxyphosphorus under this particle size, anionic polyacrylamide is combined with nano-hydroxyapatite. When the soil improver is applied to the soil, it can form a "nano-hydroxyapatite-anionic polyacrylamide-water" relatively stable coordination system with the water in the soil, delaying the decomposition of anionic polyacrylamide. Among them, 15-50nm hydroxyapatite and linear anionic polyacrylamide are selected and their molecular weight is limited to 6-20 million, so as to obtain a relatively stable coordination system; preferably, linear anionic polyacrylamide can form a more stable coordination system. Then, when the soil improver of the present application is applied to the soil, water-stable aggregates can be formed in the soil, which can better play the role of straw biomass in improving the soil.

[0010] In the raw material ratio of the soil conditioner, the weight of the straw biomass raw material is 40-50 parts, for example, it can be any value among 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 ​​parts, 49 parts, and 50 parts. The weight of the anionic polyacrylamide is 10-20 parts, for example, it can be any value among 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, and 20 parts. The weight of hydroxyapatite is 5-15 parts, for example, it can be any value among 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, and 15 parts. The weight percentage of the soil additive is 0-10 parts, for example, any value among 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 parts. The soil additive can be selected from various known soil additives, such as nitrogen, phosphorus, and potassium fertilizers, according to actual needs. The particle size of the hydroxyapatite is 15-50 nm, and in principle, any value among 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, and 50 nm. The average molecular weight of the anionic polyacrylamide is 6-20 million, for example, in principle it can be any value among 6 million, 7 million, 8 million, 9 million, 10 million, 11 million, 12 million, 13 million, 14 million, 15 million, 16 million, 17 million, 18 million, 19 million, and 20 million.

[0011] Preferably, the type of the air-dried straw raw material is selected from at least one of corn straw, millet straw, wheat straw, sorghum straw, cotton straw and rice straw.

[0012] By adopting the above technical solution, in principle, the straw of various existing crops can be used as the raw material of the straw biomass of the soil conditioner of this application, especially corn straw, millet straw, wheat straw, sorghum straw, cotton straw and rice straw.

[0013] Preferably, the molecular weight of the anionic polyacrylamide is 6-10 million, and the particle size of the anionic polyacrylamide is less than 50 μm.

[0014] By adopting the above technical solution, the average molecular weight of the anionic polyacrylamide is preferably 6-10 million, for example, it can be any value among 6 million, 6.5 million, 7 million, 7.5 million, 8 million, 8.5 million, 9 million, 9.5 million, and 10 million. Its particle size is less than 40-50 μm, for example, it can be any value among 50 μm, 45 μm, 40 μm, 35 μm, 30 μm, 25 μm, 20 μm, 15 μm, 10 μm, 5 μm, 1 μm, 0.5 μm, etc. In principle, the smaller the particle size, the better, taking into account both process and cost considerations, and 5-50 μm is generally selected.

[0015] Preferably, the pulverization process is specifically: pulverizing the air-dried straw raw material to a length of less than 2 cm.

[0016] By adopting the above technical solution, the crushing treatment can adopt known means, such as chopping, crushing equipment, etc., to crush the air-dried straw raw material to a length of less than 2 cm, so as to facilitate the subsequent ammoniation treatment.

[0017] Preferably, the ammoniation treatment specifically comprises the following steps:

[0018] S1: Dissolving 0.5-1.5% of urea and 1-1.5% of ammonium bicarbonate, which account for 20-45% of the dry weight of the air-dried straw raw material, in water to obtain a mixed solution, wherein the weight of the mixed solution is 20-45% of the dry weight of the air-dried straw raw material, spraying the mixed solution on the air-dried straw raw material, and performing a first ammoniation treatment at 35-40° C. under sealed conditions after spraying to obtain pre-ammoniation straw, wherein the first ammoniation treatment lasts for 24-30 hours;

[0019] S2: Under vacuum, liquid ammonia is introduced into the pre-ammoniated straw for a second ammoniation treatment, wherein the amount of liquid ammonia added is 1-2% of the weight of the pre-ammoniated straw, the second ammoniation treatment lasts for 2-5 hours, and the temperature is controlled at 35-40° C. and the reaction pressure is controlled at 1.35-1.56 MPa by heating during the second ammoniation treatment;

[0020] S3: stopping heating and sequentially placing the straw after the second ammoniation treatment to stand and dry for 8-10 hours to obtain the straw biomass.

[0021] By adopting the above technical solution, and by coordinating the first ammoniation treatment in step S1, the second ammoniation treatment in step S2, and the static treatment in step S3, the difficulty of the ammoniation treatment process and the time required for the ammoniation treatment can be effectively reduced, while ensuring a good ammoniation treatment effect. Furthermore, the moisture content of the air-dried straw raw material is generally controlled at 10-15%.

[0022] Preferably, in step S1, the weight ratio of urea to ammonium bicarbonate is 1:2.

[0023] By adopting the above technical solution, the ammoniation effect can be taken into account and preparation can be made for the second ammoniation.

[0024] Preferably, in step S1, continuous stirring is maintained during the spraying process.

[0025] By adopting the above technical solution, continuous stirring can be maintained during the spraying process.

[0026] Preferably, in step S2, the moisture content of the pre-ammoniation straw obtained in S1 is first adjusted to 20-30%, and then the second ammoniation treatment is performed.

[0027] By adopting the above technical solution, the water content is adjusted before the second ammoniation treatment, specifically, the water content is adjusted to 20-30%.

[0028] Preferably, in step S3, cooling is performed first and then drying is performed, the cooling temperature is 20-25° C., and the moisture content of the straw biomass obtained after drying is controlled to be below 10%.

[0029] By adopting the above technical solution, cooling is performed after standing and before drying, and the cooling temperature is controlled at 20-25°C.

[0030] Preferably, the C / N value of the air-dried straw raw material after the pulverization treatment is first adjusted to 25 / 1, and then the ammoniation treatment is performed.

[0031] By adopting the above technical solution, the C / N value of 25 / 1 is the appropriate carbon-nitrogen ratio for microbial life in the soil. Therefore, it is prioritized to adjust the C / N value before ammoniation treatment. Specifically, the C / N value can be reduced by adding nitrogen fertilizer.

[0032] In a second aspect, the present application provides a method for preparing the above-mentioned soil conditioner, which adopts the following technical solution:

[0033] A method for preparing the soil conditioner comprises mixing straw biomass, anionic polyacrylamide and hydroxyapatite, granulating the mixture, and then cooling and sieving the mixture in sequence to obtain a soil conditioner with a particle size of 2-4 cm.

[0034] By adopting the above technical solution, the soil conditioner can be easily applied after granulation, and a sealing bagging step can be further added to facilitate transportation and storage.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. This application uses straw biomass as raw material, and the amount of straw biomass added is 40-50 parts, accounting for nearly half of the total amount of the soil conditioner, thereby improving the utilization rate of straw; the addition of anionic polyacrylamide can improve the water holding capacity of the soil, and at the same time utilizes the high specific surface area of ​​hydroxyapatite to form a relatively stable "nanohydroxyapatite-anionic polyacrylamide-water" coordination system with anionic polyacrylamide and water in the soil, which can delay the decomposition of anionic polyacrylamide. When the soil conditioner of this application is applied to the soil, it can form water-stable aggregates in the soil, which can better play the role of straw in improving the soil.

[0037] 2. In the present application, the coordinated design of the first ammoniation treatment in step S1, the second ammoniation treatment in step S2, and the static state in step S3 can effectively reduce the process difficulty of the ammoniation treatment and shorten the time of the ammoniation treatment, while ensuring a better ammoniation treatment effect.

[0038] 3. The soil conditioner of this application is weakly alkaline and is suitable for improving acidic soils with a moderate degree of acidification. DETAILED DESCRIPTION

[0039] The present application is further described in detail below with reference to the embodiments.

[0040] Ingredients

[0041] Unless otherwise specified, the raw materials or reagents used in this application can be purchased from the market or obtained through commissioned processing according to specified parameters, including anionic polyacrylamide and nano-hydroxyapatite.

[0042] Preparation Example

[0043] Preparation Example 1

[0044] The straw biomass of this preparation example was prepared by the following preparation steps:

[0045] (1) Wheat straw was selected as raw material, and the wheat straw was air-dried until the moisture content was 12% to obtain air-dried straw raw material;

[0046] (2) The air-dried straw raw material is crushed to a length of 1 cm, and nitrogen fertilizer (preferably physiologically neutral nitrogen fertilizer, such as urea or ammonium bicarbonate) is added to adjust the C / N value of the air-dried straw raw material to be close to 25 / 1;

[0047] (3) The crushed air-dried straw raw material is subjected to ammoniation treatment, which specifically includes the following steps:

[0048] S1: Dissolving 0.5% urea and 1% ammonium bicarbonate, which account for 30% of the dry weight of the air-dried straw raw material, in water to obtain a mixed solution, wherein the weight of the mixed solution is 30% of the dry weight of the air-dried straw raw material, spraying the mixed solution onto the air-dried straw raw material while continuously stirring the mixture, and performing a first ammoniation treatment at 38° C. under sealed conditions after spraying to obtain pre-ammoniation straw, wherein the first ammoniation treatment lasts for 26 hours;

[0049] S2: first adjusting the moisture content of the pre-ammoniated straw obtained in S1 to 25%, then passing liquid ammonia into the pre-ammoniated straw under vacuum for a second ammoniation treatment, wherein the amount of liquid ammonia added is 1% of the weight of the pre-ammoniated straw, the second ammoniation treatment lasts for 4 hours, and during the second ammoniation treatment, the temperature is controlled at 38° C. and the reaction pressure is controlled at 1.46-1.47 MPa by heating;

[0050] S3: Stop heating and sequentially allow the straw after the second ammoniation treatment to stand, cool, and dry. The standing time is 8 hours, the cooling temperature is 20° C., and the drying standard is to control the moisture content to be below 10%, thereby obtaining the straw biomass of this preparation example.

[0051] Preparation Example 2

[0052] The straw biomass of this preparation example was prepared by the following preparation steps:

[0053] (1) Wheat straw was selected as raw material, and the wheat straw was air-dried until the moisture content was 15% to obtain air-dried straw raw material;

[0054] (2) The air-dried straw raw material was crushed to a length of 2 cm, and nitrogen fertilizer was added to adjust the C / N value of the air-dried straw raw material to be close to 25 / 1;

[0055] (3) The crushed air-dried straw raw material is subjected to ammoniation treatment, which specifically includes the following steps:

[0056] S1: Dissolving 1.5% urea and 1% ammonium bicarbonate, which account for 45% of the dry weight of the air-dried straw raw material, in water to obtain a mixed solution, wherein the weight of the mixed solution is 45% of the dry weight of the air-dried straw raw material, spraying the mixed solution onto the air-dried straw raw material while continuously stirring the mixture, and performing a first ammoniation treatment at 35° C. under sealed conditions after spraying to obtain pre-ammoniation straw, wherein the first ammoniation treatment lasts for 28 hours;

[0057] S2: first adjusting the moisture content of the pre-ammoniated straw obtained in S1 to 30%, then passing liquid ammonia into the pre-ammoniated straw under vacuum for a second ammoniation treatment, wherein the amount of liquid ammonia added is 2% of the weight of the pre-ammoniated straw, the second ammoniation treatment lasts for 5 hours, and during the second ammoniation treatment, the temperature is controlled at 40° C. and the reaction pressure is controlled at 1.55-1.56 MPa by heating;

[0058] S3: Stop heating and sequentially place the straw after the second ammoniation treatment to stand, cool, and dry. The standing time is 10 hours, the cooling temperature is 25° C., and the drying standard is to control the moisture content to be below 10%, thereby obtaining the straw biomass of this preparation example.

[0059] Preparation Example 3

[0060] The straw biomass of this preparation example was prepared by the following preparation steps:

[0061] (1) Wheat straw was selected as raw material, and the wheat straw was air-dried until the moisture content was 10% to obtain air-dried straw raw material;

[0062] (2) The air-dried straw raw material was crushed to a length of 0.5 cm, and nitrogen fertilizer was added to adjust the C / N value of the air-dried straw raw material to be close to 25 / 1;

[0063] (3) The crushed air-dried straw raw material is subjected to ammoniation treatment, which specifically includes the following steps:

[0064] S1: Dissolving 1% urea and 1.5% ammonium bicarbonate, which account for 20% of the dry weight of the air-dried straw raw material, in water to obtain a mixed solution, wherein the weight of the mixed solution is 20% of the dry weight of the air-dried straw raw material, spraying the mixed solution onto the air-dried straw raw material while continuously stirring the mixture, and performing a first ammoniation treatment at 32° C. under sealed conditions after the spraying to obtain pre-ammoniation straw, wherein the first ammoniation treatment lasts for 30 hours;

[0065] S2: first adjusting the moisture content of the pre-ammoniated straw obtained in S1 to 25%, then passing liquid ammonia into the pre-ammoniated straw under vacuum for a second ammoniation treatment, wherein the amount of liquid ammonia added is 1.6% of the weight of the pre-ammoniated straw, the second ammoniation treatment lasts for 2-5 hours, and during the second ammoniation treatment, the temperature is controlled at 35° C. and the reaction pressure is controlled at 1.35-1.37 MPa by heating;

[0066] S3: Stop heating and sequentially place the straw after the second ammoniation treatment to stand, cool, and dry. The standing time is 10 hours, the cooling temperature is 25° C., and the drying standard is to control the moisture content to be below 10%, thereby obtaining the straw biomass of this preparation example.

[0067] Preparation Example 4

[0068] The straw biomass of this preparation example was prepared by the following preparation steps:

[0069] (1) Wheat straw was selected as raw material, and the wheat straw was air-dried until the moisture content was 11% to obtain air-dried straw raw material;

[0070] (2) The air-dried straw raw material was crushed to a length of 0.5 cm, and nitrogen fertilizer was added to adjust the C / N value of the air-dried straw raw material to be close to 25 / 1;

[0071] (3) The crushed air-dried straw raw material is subjected to ammoniation treatment, which specifically includes the following steps:

[0072] S1: Dissolving 0.7% urea and 1.4% ammonium bicarbonate, which account for 36% of the dry weight of the air-dried straw raw material, in water to obtain a mixed solution, wherein the weight of the mixed solution is 36% of the dry weight of the air-dried straw raw material, spraying the mixed solution onto the air-dried straw raw material while continuously stirring the mixture, and performing a first ammoniation treatment at 39° C. under sealed conditions after spraying to obtain pre-ammoniation straw, wherein the first ammoniation treatment lasts for 24 hours;

[0073] S2: first adjusting the moisture content of the pre-ammoniated straw obtained in S1 to 30%, then passing liquid ammonia into the pre-ammoniated straw under vacuum for a second ammoniation treatment, wherein the amount of liquid ammonia added is 2% of the weight of the pre-ammoniated straw, the second ammoniation treatment lasts for 5 hours, and during the second ammoniation treatment, the temperature is controlled at 36° C. and the reaction pressure is controlled at 1.38-1.39 MPa by heating;

[0074] S3: Stop heating and sequentially place the straw after the second ammoniation treatment to stand, cool, and dry. The standing time is 10 hours, the cooling temperature is 22° C., and the drying standard is to control the moisture content to be below 10%, thereby obtaining the straw biomass of this preparation example.

[0075] Preparation Example 5

[0076] The preparation steps of the straw biomass in this preparation example are basically the same as those in Preparation Example 1, with the only difference being that rice straw is selected as the raw material in step (1).

[0077] Preparation Example 6

[0078] The preparation steps of the straw biomass in this preparation example are basically the same as those in Preparation Example 1, with the only difference being that millet straw is selected as the raw material in step (1).

[0079] Preparation Example 7

[0080] The preparation steps of the straw biomass in this preparation example are basically the same as those in Preparation Example 1, with the only difference being that corn straw is selected as the raw material in step (1).

[0081] Preparation Example 8

[0082] The preparation steps of the straw biomass in this preparation example are basically the same as those in Preparation Example 1, with the only difference being that sorghum straw is selected as the raw material in step (1).

[0083] Preparation Example 9

[0084] The preparation steps of the straw biomass in this preparation example are basically the same as those in Preparation Example 1, with the only difference being that cotton straw is selected as the raw material in step (1). Example

[0085] Example 1

[0086] The soil conditioner of this embodiment comprises the following raw materials in parts by weight: 50 parts of the straw biomass obtained in Preparation Example 1, 20 parts of linear anionic polyacrylamide, and 15 parts of hydroxyapatite; the hydroxyapatite has a particle size of 50 nm, the anionic polyacrylamide has an average molecular weight of 10 million, and the anionic polyacrylamide has a particle size of 50 μm. The raw materials are mixed and granulated, and then cooled and sieved to obtain a soil conditioner with a particle size of 2-4 cm.

[0087] Example 2

[0088] The soil conditioner of this embodiment comprises the following raw materials in parts by weight: 40 parts of the straw biomass obtained in Preparation Example 1, 15 parts of linear anionic polyacrylamide, and 10 parts of hydroxyapatite; the hydroxyapatite has a particle size of 40 nm, the linear anionic polyacrylamide has an average molecular weight of 20 million, and the particle size of the anionic polyacrylamide is 40 μm. The raw materials are mixed, granulated, cooled, and sieved to obtain a soil conditioner with a particle size of 2-4 cm.

[0089] Example 3

[0090] The soil conditioner of this embodiment comprises the following raw materials in parts by weight: 45 parts of the straw biomass obtained in Preparation Example 1, 10 parts of linear anionic polyacrylamide, and 5 parts of hydroxyapatite; the hydroxyapatite has a particle size of 15 nm, the anionic polyacrylamide has an average molecular weight of 8 million, and the particle size of the anionic polyacrylamide is 50 μm or less. The raw materials are mixed and granulated, and then cooled and sieved to obtain a soil conditioner with a particle size of 2-4 cm.

[0091] Example 4

[0092] The soil conditioner of this embodiment comprises the following raw materials in parts by weight: 43 parts of the straw biomass obtained in Preparation Example 1, 12 parts of linear anionic polyacrylamide, and 6 parts of hydroxyapatite; the hydroxyapatite has a particle size of 20 nm, the anionic polyacrylamide has an average molecular weight of 7 million, and the anionic polyacrylamide has a particle size of 30 μm. The raw materials are mixed and granulated, and then cooled and sieved to obtain a soil conditioner with a particle size of 2-4 cm.

[0093] Example 5

[0094] The soil conditioner of this embodiment comprises the following raw materials in parts by weight: 47 parts of the straw biomass obtained in Preparation Example 1, 16 parts of linear anionic polyacrylamide, and 8 parts of hydroxyapatite; the hydroxyapatite has a particle size of 35 nm, the anionic polyacrylamide has a molecular weight of 9 million, and the anionic polyacrylamide has a particle size of 20 μm. The raw materials are mixed and granulated, and then cooled and sieved to obtain a soil conditioner with a particle size of 2-4 cm.

[0095] Example 6

[0096] The soil conditioner of this embodiment comprises the following raw materials in parts by weight: 44 parts of the straw biomass obtained in Preparation Example 1, 18 parts of linear anionic polyacrylamide, and 13 parts of hydroxyapatite; the hydroxyapatite has a particle size of 45 nm, the anionic polyacrylamide has a molecular weight of 10 million, and the particle size of the anionic polyacrylamide is 40 μm or less. The raw materials are mixed and granulated, and then cooled and sieved to obtain a soil conditioner with a particle size of 2-4 cm.

[0097] Example 7

[0098] The soil conditioner of this embodiment comprises the following raw materials in parts by weight: 41 parts of the straw biomass obtained in Preparation Example 1, 12 parts of linear anionic polyacrylamide, and 6 parts of hydroxyapatite; the hydroxyapatite has a particle size of 25 nm, the anionic polyacrylamide has a molecular weight of 7 million, and the anionic polyacrylamide has a particle size of 5 μm. The raw materials are mixed and granulated, and then cooled and sieved to obtain a soil conditioner with a particle size of 2-4 cm.

[0099] Example 8

[0100] The soil conditioner of this embodiment comprises the following raw materials in parts by weight: 45 parts of the straw biomass obtained in Preparation Example 2, 15 parts of linear anionic polyacrylamide, and 10 parts of hydroxyapatite; the hydroxyapatite has a particle size of 45 nm, the anionic polyacrylamide has a molecular weight of 10 million, and the anionic polyacrylamide has a particle size of 40 μm. The raw materials are mixed and granulated, and then cooled and sieved to obtain a soil conditioner with a particle size of 2-4 cm.

[0101] Example 9

[0102] The soil conditioner of this embodiment comprises the following raw materials in parts by weight: 45 parts of the straw biomass obtained in Preparation Example 3, 18 parts of linear anionic polyacrylamide, and 12 parts of hydroxyapatite; the hydroxyapatite has a particle size of 35 nm, the anionic polyacrylamide has a molecular weight of 10 million, and the anionic polyacrylamide has a particle size of 40 μm. The raw materials are mixed and granulated, and then cooled and sieved to obtain a soil conditioner with a particle size of 2-4 cm.

[0103] Example 10

[0104] The soil conditioner of this embodiment comprises the following raw materials in parts by weight: 46 parts of the straw biomass obtained in Preparation Example 5, 14 parts of linear anionic polyacrylamide, and 11 parts of hydroxyapatite; the hydroxyapatite has a particle size of 35 nm, the anionic polyacrylamide has a molecular weight of 10 million, and the anionic polyacrylamide has a particle size of 40 μm. The raw materials are mixed and granulated, and then cooled and sieved to obtain a soil conditioner with a particle size of 2-4 cm.

[0105] Performance testing

[0106] Detection method / test method

[0107] 1. The straw biomass obtained in Preparation Example 1-9 was subjected to ammoniated straw quality inspection, specifically identification based on texture, color, pH value and odor.

[0108] It was found that the straw biomass obtained in Preparation Examples 1-9 was soft and fluffy, and had no obvious prickly feeling when held tightly by hand.

[0109] In terms of color, the straw biomass obtained in Preparation Examples 1-4 was apricot yellow, the straw biomass obtained in Preparation Example 5 was brownish yellow, the straw biomass obtained in Preparation Example 6 was dark yellow, the straw biomass obtained in Preparation Examples 7-8 was brown, and the straw biomass obtained in Preparation Example 9 was light brown;

[0110] The pH value of the straw biomass obtained in Preparation Example 1-9 is about 8;

[0111] In terms of smell, the straw biomass obtained in Preparation Examples 1-9 all had a paste aroma and a pungent ammonia smell. The straw biomass obtained in Preparation Example 7 was slightly different from that in other Preparation Examples, and it also had a sour aroma of silage.

[0112] Therefore, it can be seen from the above sensory evaluation that the quality of the straw biomass obtained in Preparation Examples 1-9 of the present application is relatively good.

[0113] 2. The soil conditioner obtained in Examples 1-10 was applied to a moderately acidified soil (pH 4.5-5.5) in Quanzhou City, Fujian Province, resulting from excessive application of acidic fertilizers. A 20-mu area was designated, with 15 mu serving as a test plot and 5 mu serving as a control plot. Within the 15-mu test plot, each 5 mu was divided into a test plot group, specifically three test plot groups: Test Plot 1, Test Plot 2, and Test Plot 3. The 20 mu of land in the test and control plots was plowed (mechanical tillage was used) and flooded with equal amounts of water. After 10 days, the soil was plowed and flooded again. After two days, 3 tons / mu of the soil conditioner obtained in Example 1 was applied to test plot one, 3 tons / mu of the soil conditioner obtained in Example 8 was applied to test plot two, and 3 tons / mu of the soil conditioner obtained in Example 10 was applied to test plot three. No soil conditioner was applied to the control plot. After five days, the fields in both the test and control plots were harrowed until level (harrowing can be performed using a harrowing machine). Then, equal amounts of peanuts were planted per mu in each of the test and control plots. (Peanuts were chosen as the test crop because they have a relatively short average maturity period, typically 4-6 months. In principle, other crops suitable for acidic or acid-tolerant soils can also be used.)

[0114] Two months later, it was observed that the peanut seedlings in experimental area one, experimental area two and experimental area three were growing well, while the seedling mortality rate in the control area was more than one-third; 3.5 months later, it was observed that the peanuts in experimental area one, experimental area two and experimental area three were mature 20 days earlier, 4 months later, some peanuts in the control area began to mature, and after 6 months, basically all peanuts in the control area were mature.

[0115] Based on this, it can be seen that the application of the soil conditioner of the embodiment of the present application can successfully improve the moderately acidified soil with an original pH value of 4.5-5.5. By adjusting the dosage, the soil can be improved to a pH value of 6-7 suitable for peanut crops.

[0116] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A soil conditioner, characterized in that The preparation method comprises the following raw materials in parts by weight: 40-50 parts of straw biomass, 10-20 parts of anionic polyacrylamide, 5-15 parts of hydroxyapatite, and 0-10 parts of a soil additive; the hydroxyapatite has a particle size of 15-50 nm, the anionic polyacrylamide has a linear structure and an average molecular weight of 6-10 million, and the straw biomass is a straw processed material obtained by sequentially subjecting air-dried straw raw materials to pulverization and ammoniation treatment; The particle size of the anionic polyacrylamide is less than 50 μm; The pulverization process specifically comprises: pulverizing the air-dried straw raw material to a length of less than 2 cm; The ammoniation treatment specifically comprises the following steps: S1: Dissolving 0.5-1.5% of urea and 1-1.5% of ammonium bicarbonate, which account for 20-45% of the dry weight of the air-dried straw raw material, in water to obtain a mixed solution, wherein the weight of the mixed solution is 20-45% of the dry weight of the air-dried straw raw material, spraying the mixed solution on the air-dried straw raw material, and performing a first ammoniation treatment at 35-40° C. under sealed conditions after spraying to obtain pre-ammoniation straw, wherein the first ammoniation treatment lasts for 24-30 hours; S2: Under vacuum, liquid ammonia is introduced into the pre-ammoniated straw for a second ammoniation treatment, wherein the amount of liquid ammonia added is 1-2% of the weight of the pre-ammoniated straw, the second ammoniation treatment lasts for 2-5 hours, and the temperature is controlled at 35-40° C. and the reaction pressure is controlled at 1.35-1.56 MPa by heating during the second ammoniation treatment; S3: stopping heating and sequentially placing the straw after the second ammoniation treatment at rest and drying for 8-10 hours to obtain the straw biomass; The C / N value of the air-dried straw raw material after the pulverization treatment is first adjusted to 25 / 1, and then the ammoniation treatment is performed.

2. The soil conditioner according to claim 1, characterized in that The type of the air-dried straw raw material is selected from at least one of corn straw, millet straw, wheat straw, sorghum straw, cotton straw and rice straw.

3. The soil conditioner according to claim 1, characterized in that In step S1, the weight ratio of urea to ammonium bicarbonate is 1:

2.

4. The soil conditioner according to claim 1, characterized in that In step S2, the moisture content of the pre-ammoniation straw obtained in S1 is first adjusted to 20-30%, and then the second ammoniation treatment is performed.

5. The soil conditioner according to claim 1, characterized in that In step S3, cooling is performed first and then drying is performed. The cooling temperature is 20-25° C., and the moisture content of the straw biomass obtained after drying is controlled to be below 10%.

6. A method for preparing the soil conditioner according to any one of claims 1 to 5, characterized in that: The straw biomass, anionic polyacrylamide and hydroxyapatite are mixed and granulated, and then cooled and sieved in sequence to obtain a soil conditioner with a particle size of 2-4 cm.