A soil conditioner coated material, soil conditioner coated soil amendment and method of making same

Abstract

This invention belongs to the field of functional coating technology for soil conditioner particles, specifically relating to a soil loosening agent coating material, a soil loosening agent-coated soil conditioner, and its preparation method. The soil loosening agent coating material comprises the following raw materials: polyacrylamide, a high-temperature resistant binder and stabilizer, and sodium carbonate. This soil loosening agent coating material exhibits excellent high-temperature resistance. After coating the soil conditioner, the polyacrylamide activity retention rate is high. The resulting coated soil conditioner demonstrates excellent performance, with a high polyacrylamide activity retention rate after high-temperature drying. The coating layer adhesion reaches the highest level in the industry, with extremely low powder loss. The particles do not crack, clump, or pulverize. After application to the soil, it can quickly break up compaction, forming a stable granular structure. Simultaneously, it has the functions of water retention, soil stabilization, and water purification, enabling simultaneous fertilization and soil improvement. It is compatible with various soil conditioners and suitable for large-scale agricultural application.

Description

Technical Field

[0001] This invention belongs to the field of functional coating technology for soil conditioner particles, specifically relating to a soil loosening agent coating material, a soil loosening agent coated soil conditioner, and its preparation method. Background Technology

[0002] With the development of modern agriculture towards large-scale and intensive operations, problems such as soil compaction, declining fertility, and weakened water and fertilizer retention capacity are becoming increasingly prominent. Soil loosening agents, as highly efficient soil conditioners, have polyacrylamide as their core functional component. Polyacrylamide, with its excellent flocculation, water retention, and soil loosening properties, is widely used in the field of functional coating for soil amendments. By coating the surface of soil amendment particles with a soil loosening agent functional layer, fertilization and soil improvement can be carried out simultaneously, significantly improving agricultural production efficiency. However, existing soil loosening agent-coated soil amendment products and traditional preparation processes face many insurmountable technical bottlenecks, failing to meet the demands of industrial-scale high-temperature continuous production, severely restricting the product's promotion and application.

[0003] The main drawbacks of existing soil conditioner technologies are as follows: First, polyacrylamide, as the main functional material of the soil conditioner's functional layer, has poor molecular structure stability. Its molecular chains are prone to thermal degradation and chain breakage at high temperatures, directly leading to a decline in the soil conditioner's core properties of loosening soil, retaining water, and binding. Currently, industrial soil conditioner coatings commonly employ high-temperature drying processes. Traditional soil conditioner functional layers prepared from single anionic or cationic polyacrylamide cannot withstand prolonged high-temperature baking. After high-temperature drying, the immediate activity retention rate of polyacrylamide is low, and after three days of storage at room temperature, its activity drops sharply, essentially losing its core functions of loosening soil, retaining water, and preventing soil compaction, rendering the product unusable in practical applications. Secondly, existing soil conditioner coating processes generally require preheating of the soil conditioner granules. This increases the investment in preheating equipment and energy consumption, raising overall production costs and failing to meet the requirements of low-carbon and high-efficiency production. Furthermore, preheating reduces the structural stability of the soil conditioner granules, making them prone to pulverization and breakage. Subsequent coating processes can lead to cracking and detachment of the coating layer, resulting in poor appearance and low yield of the finished granules, failing to meet commercial requirements. Thirdly, traditional soil conditioner coatings use only a single polyacrylamide component without supporting high-temperature resistant protective and binding reinforcement components. This results in poor high-temperature resistance and weak adhesion to the soil conditioner granules. Stable coating cannot be achieved with either fast-acting fertilizers like urea and compound fertilizers, or slow-release fertilizers like organic and mineral fertilizers. During industrial screening, mechanical transportation, and field application, the functional layer is easily detached and powdered, wasting raw materials and failing to achieve long-term soil improvement effects.

[0004] In summary, existing soil conditioner products and preparation processes cannot simultaneously achieve high-temperature resistance, particle integrity, accurate moisture content, and long-lasting functionality, thus failing to achieve long-term soil improvement. Therefore, developing a functional soil conditioner granule that does not require preheating of soil conditioner particles, can withstand high-temperature drying, has a firm coating, and is compatible with multiple types of soil conditioners has become an urgent need to promote the soil conditioner industry. Summary of the Invention

[0005] Based on the above technical background, the main objective of this invention is to provide a soil loosening and coating material, a soil loosening and coating soil conditioner, and a method for preparing the same, so as to overcome the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0007] The first aspect of this invention is to provide a soil conditioner coating material, the soil conditioner coating material comprising the following raw materials in parts by weight: 10-30 parts by weight of polyacrylamide, 8-18 parts by weight of high-temperature adhesive stabilizer, and 2-5 parts by weight of sodium carbonate.

[0008] The components of the above-mentioned loosening and coating material are used in combination according to the above-mentioned weight proportions and coated on the surface of the soil conditioner. They can synergistically achieve the functions of high temperature resistance, firm coating, water retention, loosening soil and anti-caking, and have excellent compatibility with various soil conditioner particles.

[0009] Preferably, the soil loosening and coating material comprises the following raw materials in parts by weight: 20 parts by weight of polyacrylamide, 13 parts by weight of high-temperature adhesive stabilizer, and 3 parts by weight of sodium carbonate.

[0010] Preferably, the soil loosening and coating material comprises the following raw materials in parts by weight: 10 parts by weight of polyacrylamide, 8 parts by weight of high-temperature adhesive stabilizer, and 2 parts by weight of sodium carbonate.

[0011] Preferably, the soil loosening and coating material comprises the following raw materials in parts by weight: 30 parts by weight of polyacrylamide, 18 parts by weight of high-temperature adhesive stabilizer, and 5 parts by weight of sodium carbonate.

[0012] Sodium carbonate has the functions of high-temperature buffering, anti-caking and dispersing modification. It can stabilize the high-temperature drying environment, prevent particles from sticking together and clumping, and at the same time adjust the microstructure of the soil conditioner coating layer, improving the overall density and uniformity of the soil conditioner particles coated with soil conditioner.

[0013] Optionally, the soil loosening coating material further includes 1 to 3 parts by weight of industrial fine salt.

[0014] The soil loosening and coating material also includes 2 parts by weight of industrial fine salt.

[0015] Industrial fine salt can be used as a natural soil conditioner. It can strengthen the adhesion between the loosening agent coating layer and the soil conditioner particles, reduce the cracking and peeling of the coating, increase the soil organic matter content, promote the formation of soil aggregate structure, and take into account the effects of fertilizer and water retention and nutrient enhancement.

[0016] The high-temperature resistant adhesive stabilizer includes a primary stabilizer and a secondary stabilizer.

[0017] The main stabilizer is selected from one or two of modified starch and silicone phenyl glycidyl ether epoxy resin.

[0018] Preferably, the main stabilizer is modified starch.

[0019] The stabilizer is selected from one or more fatty alcohols.

[0020] Preferably, the stabilizer is polyethylene glycol (PEG, preferably with a molecular weight of 400-600) or glycerol.

[0021] More preferably, the stabilizer is polyethylene glycol. Experiments have shown that using polyethylene glycol as a stabilizer is more beneficial for improving the high-temperature adhesion of the loosening agent.

[0022] According to a preferred embodiment of the present invention, the high-temperature resistant adhesive stabilizer is obtained by mixing modified starch and polyethylene glycol in a mass ratio of (1-2):1.

[0023] Preferably, the high-temperature resistant adhesive stabilizer is obtained by mixing modified starch and polyethylene glycol in a mass ratio of 1.6:1.

[0024] This invention uses polyethylene glycol and modified starch in the above mass ratio to obtain a high-temperature resistant adhesive stabilizer, which can form a protective layer on the outside of the polyacrylamide molecular chain, effectively inhibiting its thermal degradation at high temperatures, while improving the adhesion between the soil loosening agent functional layer and various soil conditioner particles, effectively avoiding powdering and falling off during drying, storage and transportation.

[0025] The soil loosening and coating material also includes 400 to 600 parts by weight of water.

[0026] Preferably, the soil loosening coating material further includes 500 parts by weight of water.

[0027] The soil loosening agent coating material can coat the surface of a single soil conditioner particle, which can be one type of agricultural soil conditioner. The soil loosening agent coating material can adhere tightly to the surface of the soil conditioner particle without changing the original properties of the soil conditioner particle or affecting its fertilizer efficiency.

[0028] A second aspect of the present invention is to provide a soil conditioner coated with a soil loosening agent, wherein the soil conditioner is prepared from the soil loosening agent coating material and the soil conditioner described in the first aspect of the present invention.

[0029] The soil loosening coating material is uniformly coated on the surface of the soil conditioner particles, forming a soil loosening coating layer on the surface of the soil conditioner particles.

[0030] The thickness of the loosening soil coating layer is 50–100 μm.

[0031] Preferably, the thickness of the loosening soil coating layer is 70 μm.

[0032] The particle size of the soil conditioner is 1–5 mm.

[0033] The mass ratio of the soil loosening coating material to the soil conditioner particles is 536:(15000~30000).

[0034] Preferably, the mass ratio of the soil loosening coating material to the soil conditioner particles is 536:20000.

[0035] The soil conditioner includes one of the following: organic fertilizer, inorganic fertilizer, mineral fertilizer, and inorganic mineral soil remediation materials.

[0036] The organic fertilizer includes animal-derived organic fertilizer, plant-derived organic fertilizer, and commercial organic fertilizer.

[0037] The inorganic fertilizers include nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, compound fertilizer, and soil conditioners containing trace elements.

[0038] Preferably, the inorganic fertilizer is one of nitrogen fertilizer and compound fertilizer.

[0039] The nitrogen fertilizer mentioned includes urea.

[0040] The compound fertilizer includes diamine fertilizer.

[0041] The inorganic mineral soil remediation material is selected from bentonite, attapulgite, and lime.

[0042] A third aspect of the present invention is to provide a method for preparing the soil conditioner with soil loosening and coating as described in the second aspect of the present invention, the preparation method comprising the following steps: Step 1: Mix the weighed polyacrylamide, high-temperature resistant adhesive stabilizer and sodium carbonate evenly to obtain the loosening agent coating material; Step 2: Using the coating method, the soil loosening agent coating material is coated onto the surface of the soil conditioner particles to obtain soil loosening agent coated wet particles. Step 3: Dry the wet granules coated with soil loosening agent with high-temperature hot air to obtain soil loosening agent coated soil conditioner.

[0043] The steps described above are described in detail below.

[0044] In step 1, the soil loosening agent coating material can be prepared in the form of soil loosening agent coated dry powder or soil loosening agent coated liquid.

[0045] The preparation method of the soil loosening agent coated dry powder includes the following steps: The weighed polyacrylamide, high-temperature resistant adhesive stabilizer and sodium carbonate are mixed evenly to obtain a dry powder coated with loosening agent.

[0046] The preparation method of the soil loosening and coating liquid includes the following steps: Weigh out water, high-temperature resistant adhesive stabilizer, sodium carbonate and polyacrylamide. Add the high-temperature resistant adhesive stabilizer to the water, then add sodium carbonate and stir for 5-10 minutes until the mixture is uniform. Then, under stirring conditions, evenly sprinkle in the polyacrylamide and stir until the mixture is uniform to obtain the soil loosening agent coating solution.

[0047] In step 2, the coating method is spraying, powder spraying, or rolling. When the soil loosening agent coating material is dry soil loosening agent powder, the rolling method or spraying method is used for coating. When the soil loosening agent coating material is liquid soil loosening agent, the spraying method is used for coating.

[0048] The rolling conditions for the rolling method are as follows: the soil conditioner particles are placed in the soil loosening powder coating dry powder and rolled so that the soil loosening powder is evenly coated on the surface of the soil conditioner particles.

[0049] In step 3, the high-temperature hot air drying is preferably carried out in a 12 m drum dryer.

[0050] The process is fully compatible with industrial 12-meter drum hot air drying continuous production line. The drying process is standardized, and drying can be completed in just 20 minutes with high-temperature hot air blowing. It has high production efficiency, simple operation process, no need for complicated process control, and is suitable for large-scale and continuous industrial production. It fully meets the industrialization needs of modern agricultural soil conditioner processing.

[0051] The conditions for high-temperature hot air drying are as follows: use high-temperature hot air at 60℃~180℃ to continuously blow for 10~30 minutes, and dry until the moisture content of the loose soil-coated wet particles is ≤5%.

[0052] Preferably, the conditions for high-temperature hot air drying are: using high-temperature hot air at 65-150℃ for continuous blowing for 20 minutes, drying until the moisture content of the loose soil-coated wet particles is 5%.

[0053] If the soil conditioner granules are not thoroughly dried after the soil loosening agent's functional layer coats them, excessive moisture content will cause the granules to clump together. During storage, these granules are prone to moisture absorption, deterioration, and bacterial growth, affecting the soil conditioner's fertilizer efficacy and lifespan. Conversely, excessive drying, resulting in a moisture content below 5%, will cause stress imbalance within the soil conditioner granules, leading to cracking and breakage. This also damages the structure of the soil loosening agent's functional layer, further exacerbating powdering and detachment issues. Furthermore, excessively low moisture content will also affect the product's soil-loosening and water-retaining effects after application. Experiments have shown that at a moisture content of 5%, the surface of the soil loosening agent-coated granules remains crack-free and does not clump, ensuring both industrial production efficiency and granule quality.

[0054] The beneficial effects of this invention are as follows: (1) The soil conditioner coating material of the present invention mainly uses polyacrylamide as the main raw material, and adds a high-temperature resistant adhesive stabilizer and sodium carbonate. The high-temperature resistant adhesive stabilizer gives polyacrylamide good high-temperature resistant adhesive stability; sodium carbonate has a high-temperature buffering effect, which can improve the anti-caking and dispersion modification effect of the soil conditioner coating material. The polyacrylamide, the high-temperature resistant adhesive stabilizer and sodium carbonate work together to make the soil conditioner coating material, after coating the soil conditioner particles, have excellent properties such as high polyacrylamide activity retention rate, no cracking and no clumping.

[0055] (2) This invention uses a compound of polyethylene glycol and modified starch as a high-temperature resistant adhesive stabilizer for the coating material of the soil loosening agent. This high-temperature resistant adhesive stabilizer can form a dense high-temperature resistant protective film around the polyacrylamide molecular chain, effectively blocking the thermal degradation damage of the polyacrylamide molecular chain caused by high-temperature hot air, and solving the problem of easy high-temperature deactivation of traditional single polyacrylamide formulations. By adding the high-temperature resistant adhesive stabilizer, even after high-temperature drying, the activity retention rate of polyacrylamide in the soil loosening agent coating material is still as high as 80%~90%, thereby greatly improving the high-temperature resistance of the soil loosening agent coating material. After being stored at room temperature for 3 days, the activity retention rate of polyacrylamide is still ≥75%, which is much higher than the activity retention rate of traditional formulations (the activity retention rate of polyacrylamide in traditional formulations is below 10%). This achieves long-term stability of the core function of the soil loosening agent coating layer, greatly extends the product shelf life, and has high storage stability.

[0056] (3) The soil loosening agent coating material of the present invention has excellent coating firmness, is compatible with a variety of soil conditioner particles, and has wide compatibility. It can individually coat various conventional agricultural soil conditioner particles such as urea, compound fertilizer, diammonium phosphate, organic fertilizer, and mineral fertilizer. Moreover, the soil loosening agent coating material has extremely strong adhesion to the surface of the soil conditioner particles, and the adhesion can reach the highest level in the industry. It can ensure that the soil conditioner particles coated with soil loosening agent maintain a complete coating state from production to field application, and can stably release the efficacy of the soil conditioner.

[0057] (4) All raw materials used in the soil loosening agent functional material are environmentally friendly agricultural adjuvants, without toxic or harmful components, and will not cause pollution to soil or water. After being applied to the soil, it can be naturally degraded without residue. The coating layer formed by the soil loosening agent functional material on the surface of the soil conditioner particles can tightly coat the surface of the soil conditioner particles, without changing the original nutrient content, release pattern and basic properties of the soil conditioner, and will not interfere with the original fertilizer effect release of the soil conditioner. It can realize the simultaneous application of fertilizer and soil improvement, saving time and effort, and is suitable for the simplified and efficient planting mode of modern agriculture.

[0058] (5) The method for preparing soil conditioner granules coated with loosening agent described in this invention can precisely and stably control the moisture content of the soil conditioner granules to ≤5% by optimizing the drying process parameters and formula ratio, thus perfectly balancing drying efficiency and granule quality. Compared with the problem of large moisture content fluctuation (3%~8%) in traditional processes, the product obtained by this invention has a uniform and stable moisture content. It will not cause the granules to stick together and agglomerate or deteriorate due to excessive moisture content, nor will it cause the soil conditioner granules to crack or the functional layer to break due to excessive moisture content. This results in soil conditioner granules with loosening agent coating that have good integrity, regular appearance, no powdering, no falling off, and no cracking, making them easy to mechanically screen, package, store, transport, and apply in the field by mechanization.

[0059] (6) The preparation method described in this invention does not preheat the soil conditioner particles, but directly coats the soil conditioner particles at room temperature. This not only reduces the energy consumption of preheating, but also significantly reduces the production cost. More importantly, it avoids the problems of soil conditioner particles being powdered, broken, or ineffective due to preheating. This not only improves the qualified rate of the finished product, but also does not affect the fertilizer effect of the soil conditioner.

[0060] (7) After the soil conditioner particles coated with the loosening agent of the present invention are applied to the soil, the loosening agent coating layer can quickly play its role, efficiently decomposing dry and compacted soil into a fine sand-like stable aggregate structure, breaking up soil compaction, clearing soil pores, and improving soil aeration and water permeability; at the same time, the soil conditioner particles coated with the loosening agent have excellent soil fixing, water retention and water purification effects, strong water locking ability, which can effectively reduce soil moisture loss and improve water and fertilizer utilization. When the soil conditioner particles coated with the loosening agent are mixed with conventional soil conditioners, they can greatly improve the soil nutrient absorption efficiency, improve seedling uniformity and lodging resistance, and achieve the dual effects of soil improvement and crop yield and quality improvement, which is suitable for large-scale planting of various field crops and cash crops. Detailed Implementation

[0061] The present invention will now be described in detail, and its features and advantages will become clearer and more apparent from these descriptions.

[0062] Example The present invention is further illustrated below with specific examples. These embodiments are merely illustrative and not intended to limit the scope of the invention. All raw materials used in the embodiments of the present invention are commercially available.

[0063] Example 1 A soil loosening agent coating material, the soil loosening agent coating material comprising the following raw materials in parts by weight: 20 parts by weight of polyacrylamide, 13 parts by weight of high temperature resistant adhesive stabilizer, 3 parts by weight of sodium carbonate, and 500 parts by weight of water.

[0064] The high-temperature resistant adhesive stabilizer is obtained by mixing modified starch and polyethylene glycol in a mass ratio of 1.6:1.

[0065] Mix the above-mentioned parts by weight of raw materials evenly to obtain the soil loosening coating material.

[0066] Example 2 A soil loosening coating material, the soil loosening coating material comprising the following raw materials in parts by weight: 10 parts by weight of polyacrylamide, 8 parts by weight of high temperature resistant adhesive stabilizer, 2 parts by weight of sodium carbonate, and 400 parts by weight of water.

[0067] The high-temperature resistant adhesive stabilizer is obtained by mixing modified starch and polyethylene glycol in a mass ratio of 1:1.

[0068] Mix the above-mentioned parts by weight of raw materials evenly to obtain the soil loosening coating material.

[0069] Example 3 A soil loosening agent coating material, the soil loosening agent coating material comprising the following raw materials in parts by weight: 30 parts by weight of polyacrylamide, 18 parts by weight of high temperature resistant adhesive stabilizer, and 5 parts by weight of sodium carbonate.

[0070] The high-temperature resistant adhesive stabilizer is obtained by mixing modified starch and polyethylene glycol in a mass ratio of 2:1.

[0071] Mix the above-mentioned parts by weight of raw materials evenly to obtain the soil loosening coating material.

[0072] This embodiment is applicable to dry powder coating process; spray coating process requires the addition of 400-600 parts by weight of water.

[0073] Example 4 A soil loosening agent coating material, the soil loosening agent coating material comprising the following raw materials in parts by weight: 20 parts by weight of polyacrylamide, 13 parts by weight of high temperature resistant adhesive stabilizer, 3 parts by weight of sodium carbonate, and 500 parts by weight of water.

[0074] The high-temperature resistant adhesive stabilizer is glycerin.

[0075] Mix the above-mentioned parts by weight of raw materials evenly to obtain the soil loosening coating material.

[0076] Example 5 A soil conditioner with a loosening agent coating is disclosed. The soil conditioner is prepared from the loosening agent coating material described in Example 1 and a soil conditioner. The loosening agent coating material uniformly coats the surface of the soil conditioner particles, forming a loosening agent coating layer on the surface of the soil conditioner particles. The thickness of the loosening agent coating layer is 70 μm, and the soil conditioner particles are bentonite.

[0077] A method for preparing a soil conditioner with a loosening agent coating, the method comprising the following steps: Weigh each raw material according to the weight proportions described in Example 1, add a high-temperature resistant adhesive stabilizer to water, then add sodium carbonate in sequence, stir for 5-10 minutes until the mixture is uniform, and then, under stirring conditions, evenly sprinkle in polyacrylamide and stir until the mixture is uniform to obtain the soil loosening agent coating liquid.

[0078] The loosening agent coating liquid was uniformly coated onto the surface of bentonite particles using a spraying method, forming a uniform loosening agent coating layer with a thickness of 70 μm, thus obtaining loosening agent coated wet particles.

[0079] The wet granules coated with soil loosening agent were fed into a 12-meter drum dryer for high-temperature drying. They were continuously purged with 70°C hot air for 20 minutes until the moisture content of the wet granules coated with soil loosening agent was 5%, thus obtaining the soil loosening agent coated soil conditioner.

[0080] Example 6 A soil conditioner with a loosening agent coating is disclosed. The soil conditioner is prepared from the loosening agent coating material and soil conditioner described in Example 4. The loosening agent coating material uniformly coats the surface of the soil conditioner particles, forming a loosening agent coating layer on the surface of the soil conditioner particles. The thickness of the loosening agent coating layer is 70 μm, and the soil conditioner particles are bentonite.

[0081] A method for preparing a soil conditioner with a loosening agent coating, the method comprising the following steps: Weigh each raw material according to the weight proportions described in Example 4, add a high-temperature resistant adhesive stabilizer to water, then add sodium carbonate in sequence, stir for 5-10 minutes until the mixture is uniform, and then, under stirring conditions, evenly sprinkle in polyacrylamide and stir until the mixture is uniform to obtain the soil loosening agent coating liquid.

[0082] The loosening agent coating liquid was uniformly coated onto the surface of bentonite particles using a spraying method, forming a uniform loosening agent coating layer with a thickness of 70 μm, thus obtaining loosening agent coated wet particles.

[0083] The wet granules coated with soil loosening agent were fed into a 12-meter drum dryer for high-temperature drying. They were continuously purged with 70°C hot air for 20 minutes until the moisture content of the wet granules coated with soil loosening agent was 5%, thus obtaining the soil loosening agent coated soil conditioner.

[0084] Example 7 The soil conditioner coated with loosening agent was prepared in a manner similar to that in Example 5, except that the loosening agent coating liquid was uniformly coated on the surface of the attapulgite particles to form a uniform loosening agent coating layer on the surface of the attapulgite particles. The thickness of the loosening agent coating layer was 70 μm, and loosening agent coated wet particles were obtained.

[0085] Example 8 The soil conditioner coated with loosening agent was prepared in a manner similar to that in Example 5, except that the loosening agent coating liquid was uniformly coated on the surface of lime particles to form a uniform loosening agent coating layer on the surface of lime particles. The thickness of the loosening agent coating layer was 70 μm, resulting in loosening agent coated wet particles.

[0086] Comparative Example Comparative Example 1 A soil conditioner with a loosening agent coating is disclosed. The soil conditioner is prepared from anionic polyacrylamide and a soil conditioner. The single anionic polyacrylamide uniformly coats the surface of the soil conditioner particles, forming a loosening agent coating layer on the surface of the soil conditioner particles. The thickness of the loosening agent coating layer is 70 μm, and the soil conditioner particles are compound fertilizer.

[0087] A method for preparing a soil conditioner with a loosening agent coating, the method comprising the following steps: The weighed anionic polyacrylamide was mixed with water to obtain an anionic polyacrylamide coating solution.

[0088] Anionic polyacrylamide coating liquid was applied to the surface of soil conditioner particles using a spraying method. The thickness of the soil conditioner coating layer was 70 μm, resulting in soil conditioner coated wet particles.

[0089] The wet granules coated with soil loosening agent were fed into a 12-meter drum dryer for high-temperature drying. They were continuously blown with 150°C hot air for 20 minutes until the moisture content of the wet granules coated with soil loosening agent was 5%, thus obtaining the soil loosening agent coated soil conditioner.

[0090] Comparative Example 2 The preparation of the soil conditioner with soil loosening agent coating was carried out in a similar manner to Comparative Example 1, except that the anionic polyacrylamide was replaced with cationic polyacrylamide.

[0091] Experimental Example Experimental Example 1: Activity Retention Rate and Moisture Content Test The activity retention rate and moisture content of the soil conditioner coating layer prepared in Examples 5, 6, Comparative Example 1 and Comparative Example 2 were tested. The test method was as follows: the activity retention rate of polyacrylamide (PAM) in the soil conditioner functional layer was tested immediately after high temperature discharge and after being placed at room temperature for 3 days, and the actual moisture content of the particles after drying were tested. The test results are shown in Table 1.

[0092] Table 1

[0093] As shown in Table 1, Examples 5 and 6 used the soil loosening agent coating materials described in Examples 1 and 4, respectively, to coat the soil conditioner particles. After high-temperature drying, the polyacrylamide activity retention rate of the soil loosening agent coating layer on the surface of the soil conditioner particles prepared in Examples 5 and 6 was above 88%. After three days of storage, the polyacrylamide activity retention rate of the soil loosening agent coating layer was still above 79%. The moisture content of the soil conditioner particles was about 5%, and the soil loosening agent coating layer showed no cracking or clumping. This indicates that the soil loosening agent coating material and coating method described in this invention can significantly retain the activity of polyacrylamide after coating the soil conditioner, and the polyacrylamide still has high activity after three days of storage at room temperature. In addition, the moisture content of the dried soil loosening agent coated soil conditioner particles was about 5%, and the soil loosening agent coating layer showed no cracking or clumping.

[0094] Compared with Comparative Examples 1 and 2, Examples 5 and 6 show significantly better polyacrylamide activity retention rates, moisture content, and other properties on the surface of the soil conditioner particles coated with loosening agents in Examples 5 and 6. These results indicate that the loosening agent coating material of this invention can withstand long-term industrial-grade high-temperature drying, and the activity stability of the polyacrylamide after drying is significantly better than that of single anionic and single cationic polyacrylamide. Furthermore, the preparation method described in this invention can precisely control the particle moisture content to an optimal 5% after 20 minutes of drying, balancing drying efficiency and particle quality, and solving the shortcomings of uneven moisture content, easy cracking, and clumping in soil conditioner particles prepared by traditional processes.

[0095] Experiment Example 2: Test on the Coating Firmness of Loose Soil Coating Layer The adhesion strength of the soil conditioner particles coated with loosening agent prepared in Examples 5 and 6 was tested. The test methods were as follows: industrial standard sieving test, manual rubbing test, and storage and transportation simulation test were used to detect the adhesion strength between the loosening agent coating layer and various soil conditioner particles (the moisture content of the test sample was 5%). Sieving test: 100 g of the soil conditioner particles coated with loosening agent prepared in Example 5 and Example 6 were taken and placed in a 40-mesh standard sieve and vibrated vertically for 5 minutes. The powder loss rate of the loosening agent coating layer in Example 5 and Example 6 was ≤0.5%. Rub test: When the soil conditioner particles coated with loosening agent are rubbed vigorously with fingers, there is no peeling or falling off of the loosening agent coating on the surface of the soil conditioner particles, and no powder sticks to the fingers. The adhesion level of the loosening agent coating is level 1 (the highest level). Storage and transportation simulation: The soil conditioner granules coated with loosening agent were placed in a shaker and vibrated for 30 minutes. The loosening agent coating did not fall off and the soil conditioner granules did not pulverize or crack.

[0096] The above results show that the soil loosening functional layer prepared by the present invention has excellent bonding strength with various soil conditioner particles. Under the optimal moisture content of 5%, it can withstand mechanical collisions during industrial screening, storage and transportation without powdering, falling off or cracking.

[0097] Experiment Example 3: Field Simulation of Soil Improvement Effects The soil improvement effects of the soil conditioner granules coated with the soil conditioner prepared in Examples 5 and 6 were tested in a field simulation. Test method: Naturally dried compacted soil was collected from the field. A mineral water bottle was used to simulate an aqueous solution environment. 50g of compacted soil was mixed with 10g of the soil conditioner granules coated with the soil conditioner of this invention (5% moisture content). After adding water and shaking well, the mixture was allowed to stand, and the soil improvement effect of the functional layer was measured. The test results are shown in Table 2.

[0098] Table 2

[0099] As shown in Table 2, the soil conditioner granules coated with loosening agent prepared in Examples 5 and 6 can rapidly decompose dry, compacted soil into fine sand without large clumps. These granules achieve efficient water purification and have a strong water-locking effect on the soil. The above results indicate that the soil conditioner granules coated with loosening agent prepared in this invention have a significant soil improvement effect, can rapidly decompose compacted soil and form a stable granular structure, and simultaneously possess water purification, soil stabilization, and water retention functions. Furthermore, a moisture content of 5% for the soil conditioner granules ensures stable soil conditioning effects.

[0100] Experimental Example 4: Field Application Test (Corn Planting, Application of the Soil Loosening Agent Coated Organic Fertilizer Granules of this Invention) In this field experiment, the soil-loosening agent-coated bentonite granules (5% moisture content) prepared in Example 6 were used as the test object. They were mixed with conventional compound fertilizer / diammonium phosphate granules and applied to test the effect on improving corn growth. Core application parameters (precisely quantified, suitable for large-scale agriculture): Application area: Apply 160 catties of bentonite granules coated with the soil loosening agent of this invention to one shoal (15 mu). Mixing ratio: Mix with conventional compound fertilizer / diammonium granules (the mass ratio of conventional compound fertilizer to diammonium granules is 9:1), and mix conventional compound fertilizer / diammonium granules with bentonite granules coated with soil loosening agent in Example 6 at a mass ratio of 8:2 (as the experimental group). Application method: Mix the two thoroughly and apply together. Apply about two bags of the mixed granules per acre. No separate operation is required. It is suitable for large-scale agricultural fertilization processes.

[0101] Comparative experimental results (field measurements in the main maize-producing area of ​​North China, same plot / same field management). Two field comparison experiments were set up. Under the same plot of land, the same water and fertilizer conditions, and the same field management measures, only the fertilization method was changed, and the differences in maize growth were detected. The results are shown in Table 3.

[0102] Table 3

[0103] As shown in Table 3, compared with the application of conventional compound fertilizer, the corn plants treated with the soil conditioner granules coated with the loosening agent described in Example 6 exhibited significantly higher plant height, thicker stems, and darker, glossier leaves. Emergence uniformity was greatly improved, lodging resistance was significantly enhanced, and overall growth was far superior to the control group. These results indicate that the application of the soil conditioner granules coated with the loosening agent described in this invention, in combination with conventional compound fertilizer / diammonium phosphate granules, can effectively improve the utilization efficiency of nutrients in the soil, significantly improve corn growth, and is suitable for large-scale corn cultivation.

[0104] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A soil loosening and coating material, characterized in that, The loosening and coating material comprises the following raw materials in parts by weight: 10-30 parts by weight of polyacrylamide, 8-18 parts by weight of high-temperature adhesive stabilizer, and 2-5 parts by weight of sodium carbonate.

2. The soil loosening and coating material according to claim 1, characterized in that, 20 parts by weight of polyacrylamide, 13 parts by weight of high-temperature adhesive stabilizer, and 3 parts by weight of sodium carbonate.

3. The soil loosening and coating material according to claim 1, characterized in that, 10 parts by weight of polyacrylamide, 8 parts by weight of high-temperature adhesive stabilizer, and 2 parts by weight of sodium carbonate.

4. The soil loosening and coating material according to claim 1, characterized in that, 30 parts by weight of polyacrylamide, 18 parts by weight of high-temperature adhesive stabilizer, and 5 parts by weight of sodium carbonate.

5. The soil loosening and coating material according to claim 1, characterized in that, The high-temperature resistant adhesive stabilizer includes a primary stabilizer and a secondary stabilizer; The main stabilizer is selected from one or two of modified starch and silicone phenyl glycidyl ether epoxy resin. The stabilizer is selected from one or more fatty alcohols.

6. The soil loosening and coating material according to claim 5, characterized in that, The main stabilizer is modified starch; The stabilizer is polyethylene glycol.

7. The soil loosening and coating material according to claim 1, characterized in that, The soil loosening and coating material also includes 400 to 600 parts by weight of water.

8. A soil conditioner with a loosening agent coating, characterized in that, The soil conditioner with loosening agent coating is prepared from the soil conditioner coating material and soil conditioner as described in any one of claims 1 to 7. The soil loosening coating material is uniformly coated on the surface of the soil conditioner particles, forming a soil loosening coating layer on the surface of the soil conditioner particles. The thickness of the loosening soil coating layer is 50–100 μm.

9. A method for preparing the soil conditioner with soil loosening agent coating as described in claim 8, characterized in that, The preparation method includes the following steps: Step 1: Mix the weighed polyacrylamide, high-temperature resistant adhesive stabilizer and sodium carbonate evenly to obtain the loosening agent coating material; Step 2: Using the coating method, the soil loosening agent coating material is coated onto the surface of the soil conditioner particles to obtain soil loosening agent coated wet particles. Step 3: Dry the wet granules coated with soil loosening agent with high-temperature hot air to obtain soil loosening agent coated soil conditioner.

10. The preparation method according to claim 9, characterized in that, In step 3, The conditions for high-temperature hot air drying are as follows: use high-temperature hot air at 60℃~180℃ to continuously blow for 10~30 minutes, and dry until the moisture content of the loose soil-coated wet particles is ≤5%.

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