Process for returning straw to field in full amount

Abstract

The invention discloses a full-amount straw returning process, and belongs to the technical field of agricultural resource utilization, firstly, the full-amount straw returning process provided by the invention comprises the following steps: uniformly crushing straw stalks, then throwing the crushed straw stalks into a field, spraying a mixed solution to the surfaces of the straw stalks in the field, then sequentially carrying out deep ploughing mixing and deep rotating mixing on the field, the rotary turning process is completed; after the rotary turning procedure is completed, water is drained for steeping the field, it is guaranteed that a water layer of 2-5 cm is formed on the surface of the field, then the field steeping time is 2-5 days, and the flowers are kept in the water state; after field steeping is completed, straw stalks are evenly stirred into mud, the mud surface is leveled through a leveler after slurry is stirred, and then the leveled mud is naturally settled; field drying operation is carried out according to seasons until soil cracks in the field occur, then irrigation, fertilization and pest control are carried out, and the straw full-amount field returning technology is completed.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural resource utilization, and particularly relates to a process for returning all rice straw to fields. Background Art

[0002] In recent years, the degradation of arable land in Northeast China's black soil has garnered significant attention. Addressing the thinning, thinning, and hardening of this soil, various regions in the region have introduced measures. Incorporating straw into fields is considered the most effective and economical technical measure to protect this black soil. Straw, rich in essential plant nutrients, provides a rich carbon source for soil microorganisms, improving soil fertility and, consequently, increasing crop yields. Straw incorporation also promotes nutrient recycling and plays a significant role in reducing the use of chemical fertilizers. However, while the technologies for incorporating dryland crop straw into fields are relatively mature (for example, methods such as compressing, mulching, and shredding corn straw are well established, and their implementation is increasing annually), incorporating rice straw into fields in Northeast China's black soil region remains at the experimental and demonstration stage. This is primarily due to three factors: First, the decomposition of rice straw produces reducing substances such as ferrous iron and hydrogen sulfide, which harm rice root growth; second, the decomposition of rice straw causes soil microorganisms to compete with crop seedlings for nutrients, impacting rice growth; and third, rice straw tends to float during incorporation, making stubble removal labor-intensive and discouraging farmers' enthusiasm.

[0003] These problems have not been effectively addressed, hindering the widespread adoption of rice straw return to farmland technology. For example, Jilin Province has approximately 6 million mu (approximately 1,000 acres) of rice paddies, with a straw-to-grain ratio of approximately 1:0.9. Based on a yield of 600 kg per mu (approximately 667 kg) of straw, each mu produces approximately 667 kg of straw. While a small amount is used as firewood by farmers, a significant amount is burned, polluting the environment and wasting resources. Promoting rice straw return to farmland can both improve farmland quality and address the straw burning issue, effectively killing two birds with one stone. This invention effectively addresses the three major issues associated with rice straw return to farmland. Summary of the Invention

[0004] The purpose of the present invention is to provide a process for returning all rice straw to the fields to solve the three major problems mentioned in the background art. The purpose of the present invention can be achieved through the following technical solutions: A process for returning all rice straw to fields comprises the following steps: S1, the rice straw is crushed evenly and then spread on the field, the mixture is sprayed on the surface of the rice straw in the field, and then the field is deep plowed and mixed and deep swirled in sequence to complete the swirling process; S2. After the turning process is completed, water the field to ensure that a 2-5 cm water layer is formed on the field surface, and then soak the field for 2-5 days to keep the flowers in a water-rich state; S3. After the paddy is soaked, evenly mix the rice straw into the mud. After stirring, use a hoe to level the mud surface and then allow the hoeed mud to settle naturally. S4. Dry the fields according to the season until the soil cracks in the field, then irrigate, fertilize, and control pests and diseases to complete the process of returning the full amount of rice straw to the field.

[0005] Furthermore, the spraying composition of the mixed solution in S1 per hectare is: 45 kg of microcapsules + 30 kg of nano humic acid material + 1000 liters of water.

[0006] Furthermore, the microcapsules are prepared by the following steps: Sodium alginate was dissolved in 45°C deionized water and stirred until transparent to obtain a 3% sodium alginate solution. Bacillus subtilis powder and Aspergillus niger powder were then added to the 3% sodium alginate solution and uniformly dispersed to obtain a mixed solution. The mixed solution was dropped into a 2% by mass CaCl2 solution using a syringe to form gel microspheres with a diameter of 2-3 mm. After curing for 30 minutes, the microspheres were filtered and washed to obtain microcapsules.

[0007] Furthermore, the particle size of the sodium alginate is 60 mesh.

[0008] Furthermore, the effective viable counts of the Bacillus subtilis powder and the Aspergillus niger powder were both 2.0×10 8 pcs / g.

[0009] Furthermore, the usage ratio of the sodium alginate, deionized water, Bacillus subtilis powder, and Aspergillus niger powder is 30 g:970 ml:20 g:10 g.

[0010] Furthermore, the nano humic acid material is prepared by the following steps: The hydroxyapatite nanorods and potassium humate were added into pure water, ultrasonically dispersed for 1 hour, frozen at -50°C for 24 hours, vacuum dried, and crushed to pass through a 100-mesh sieve to obtain nano humic acid material.

[0011] Furthermore, the hydroxyapatite nanorods have a diameter of 20-30 mm and a length of 100-200 mm.

[0012] Furthermore, the usage ratio of the hydroxyapatite nanorods, potassium humate, and pure water is 50 g:30 g:500 ml.

[0013] Beneficial effects of the present invention: The present invention utilizes the agricultural machinery commonly used by farmers to process rice straw, turn over and return the entire amount to the fields, and integrates the rice planting technology method with the water-soaking field, drying the field, and the irrigation mode of alternating wet and dry after drying the field, which can stabilize or increase rice yield; it can increase the organic matter content and the quick-acting nitrogen, phosphorus and potassium content of the soil every year, reduce the soil bulk density and reduce the adhesion of the soil; it solves the problems of rice straw floating, the influence of reducing substances generated by rice straw returning to the field on the rice root system, and can solve the environmental pollution caused by burning rice straw; the technical integration method provided by the present invention is basically applicable to most soil environments in humid-arid climates, not only has wide applicability, good environmental protection, and improves soil fertility; it also finds a way out for environmentally friendly rice straw processing.

[0014] At the same time, the present invention achieves the following effects by spraying the mixed solution (microcapsules + nano humic acid material) configured by the present invention: (1) Significantly reduce the toxicity of reducing substances and improve the root environment: Bacillus subtilis and Aspergillus niger in the microcapsules in the mixed solution accelerate the decomposition of rice straw and reduce the production of reducing substances; nano-humic acid adsorbs and fixes residual ions through hydroxyapatite nanorods. The two work together to solve the problem of "ferrous iron and hydrogen sulfide poisoning the root system" in the background technology.

[0015] (2) Improving rice root activity and yield: The present invention significantly optimizes the root growth environment by synergistically reducing the concentration of reducing substances, and the root activity is improved by 31.7% (Comparative Example 3 → Example), which directly promotes a 4.6% increase in rice yield (Comparative Example 3 → Example).

[0016] (3) Reduce dependence on chemical fertilizers and improve soil fertility: The microcapsule microorganisms in the mixture accelerate the mineralization of rice straw, alleviate the problem of "microorganisms competing with seedlings for nitrogen", and reduce the demand for nitrogen fertilizer by 20% (Comparative Example 3 → Example). At the same time, the nano-humic acid material in the mixture improves the effectiveness of potassium, and the content of fast-acting potassium increases by 9.8% (Comparative Example 3 → Example). The two work together to increase soil organic matter by 18.0% (Comparative Example 3 → Example), achieving sustainable soil improvement.

[0017] (4) Eliminate the problem of straw floating and reduce labor costs: The present invention integrates mechanical operation with additives (the mixed liquid enhances the binding force between straw and mud) to solve the pain point of "straw floating and manual stubble removal".

[0018] Conclusion: The present invention systematically solves the three major problems of rice straw return to fields through the integration of microcapsule microbial degradation + nano-humic acid adsorption + mechanical agronomy: reducing substance poisoning → sulfide / ferrous ion reduction by 45.3% / 36.2% (Comparative Example 3 → Example); microbial competition for nitrogen → nitrogen fertilizer usage reduced by 20%; straw floating → mechanical process to eliminate the problem. DETAILED DESCRIPTION

[0019] Below in conjunction with the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, it is obvious that described embodiment is only a part of embodiment of the present invention, rather than whole embodiment. Based on the embodiment in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise all fall within the scope of protection of the present invention. Meanwhile, raw materials, reagents or devices used in the following examples, unless otherwise specified, can be obtained from conventional commercial channels, or can be obtained by existing known methods.

[0020] Referring to Table 1, a process for returning all rice straw to the field comprises the following steps: S1 Rice Straw Returning Treatment: The harvested rice straw is crushed evenly and spread on the field, a mixture is sprayed on the surface of the rice straw in the field, and the field is then deep-plowed and deep-rotated to complete the tumbling process; S2 soaking the fields: After the rotary turning process is completed, water is added to the fields to ensure that a 2-5 cm water layer is formed on the field surface. The fields are then soaked for 2-5 days to maintain the "flower-water" state; S3 Pulping: After soaking the fields, the slurry is first stirred, that is, the rice straw is evenly mixed into the mud. After stirring, the mud surface is leveled with a hoe to achieve the effect of no water but no mud (maintaining a water layer of about 1-3 cm on the field surface. "No mud" means that the water surface must completely cover the soil surface of the field, and the soil in the field must not be exposed). The hoeed mud is then allowed to settle naturally until the mud and water are clear and the resulting mud layer is solid but not compacted. S4 Field Management: Dry the fields according to the season until the soil cracks, then irrigate and fertilize; S5 Disease and pest control: Practice has shown that returning rice straw to the fields will not cause the disease to worsen. The focus is on preventing and controlling diseases such as rice blast, sheath blight, and false smut, and focusing on preventing and controlling rice stem borer and leaf miner.

[0021] In this embodiment, in S1, the rice straw returning process includes the following steps: S11 rice straw crushing and spreading: Kubota 988 and Ward Ryzen 4LZ-6.0E crawler-type full-feed combine harvesters are used to harvest rice straw, leaving a stubble height of 10-20 cm during the harvesting process. The harvested rice straw is crushed to a length of 10-20 cm and then spread evenly in the field; S12 Rice straw pretreatment: Spray the surface of rice straw in the field with a mixture of 45 kg microcapsules + 30 kg nano humic acid material + 1000 liters of water per hectare.

[0022] In this embodiment, the preparation of microcapsules: S121: Prepare 3% sodium alginate solution: Dissolve 30 g of sodium alginate (technical grade, 800-1000 cps, 60 mesh, Qingdao Mingyue Seaweed Group) in 970 ml of 45°C deionized water and stir until transparent to obtain a 3% sodium alginate solution. S122 Adding bacterial agent: Add Bacillus subtilis powder to 3% sodium alginate solution (effective viable bacteria count is 2.0×10 8 / g) 20g, Aspergillus niger powder (effective viable bacteria count is 2.0×10 8 10 g of the mixture was evenly dispersed to obtain a mixed solution; S123 dropwise addition to form spheres: Use a syringe to drop the mixed solution into a 2% by mass CaCl2 solution to form gel microspheres with a diameter of 2-3 mm. After curing for 30 minutes, filter and wash to obtain microcapsules; In this embodiment, the preparation of nano humic acid material: S124 mixing: 50 g of hydroxyapatite nanorods (20-30 mm in diameter, 100-200 mm in length, Aladdin reagent) and 30 g of potassium humate (70% purity, Aladdin reagent) were added to 500 ml of pure water and ultrasonically dispersed for 1 hour; S124 freeze drying: freeze at -50℃ for 24 hours and then vacuum dry, crush through 100 mesh sieve to obtain nano humic acid material; S13 straw twirling and mixing; S131 Deep plowing and mixing: When the soil moisture content is below 60% of the field water holding capacity, you can use a double-plow or conventional plow (a 3-5-share plow can be used, the number of shares depends on the power of the traction machine, and the plow width is 30-40 cm). The purpose of plowing is to fully mix (press) the crushed rice straw with the soil to create conditions for uniform slurry mixing in the spring. The appropriate plowing depth is 18-20 cm. For plots with shallow soil, the plowing depth can be 15-18 cm. S132 deep rotary tillage: Suitable for plots where the soil moisture content is higher than 60% of the field water holding capacity. Deep rotary tillage is performed using a rotary tiller (rotor blade length 23.5 cm). The purpose of rotary tillage is to fully mix the crushed rice straw with the topsoil. The optimal rotary tillage depth is generally 18-20 cm. For plots with shallower soil layers, the rotary tillage depth can be 15-18 cm. S14 Dry Rotary Leveling: After deep plowing and deep rotary mixing, use a small rotary tiller to dry rotate and level the corners of the pond that have not been plowed (deep plowing and deep rotary mixing).

[0023] In this embodiment, in the step of S2 soaking the fields, the soaking time is selected in late April. After the ridges are cleaned, water is added to soak the fields to ensure that a 2-5 cm water layer is formed on the field surface. The soaking time is 2-5 days to maintain the "flower water" state. The water cannot be too much. Too much water will result in poor adhesion of the mud, and the mud and straw will not adhere well, which will easily cause the straw to float. This will not only affect the transplanting of rice seedlings, but also increase the labor cost of removing the straw. In the autumn, the water depth for soaking the fields is 2 / 3 of the height of the soil piece. When the water seeps to the bottom 1 / 3 of the soil block, the slurry is stirred.

[0024] In this embodiment, the pulping step S3 specifically includes the following steps: S31 slurry mixing: There are two main functions of slurry mixing. One is to mix and press the rice straw evenly into the mud in the field; the other is to level the ground to create conditions for subsequent transplanting. Specifically, a rake with the back facing down is welded behind the slurry mixer (the rake tooth pitch is 5-8 cm, the teeth should be hard enough, and it is best to use discarded rotary tillage blades as rake teeth). The function of the rake is to press most of the rice straw into the middle and lower layers of the clay in the field. The slurry mixer is in slow gear 2 to mix and press the rice straw evenly into the mud. This can prevent the rice straw from floating up, and the clay on the surface of the tillage layer will be smooth after slurry mixing. The mud has a certain fluidity, which is easy to drag flat. After stirring, the field surface may have "water". If there is too much water, the rice straw will float up, affecting transplanting. The rice straw is unevenly scattered or there is a large amount of rice straw. If there is still a lot of rice straw on the mud surface at the corners of the pool after stirring, you can use the slow 3rd gear to make change, stir all the rice straw evenly and press it into the mud. After stirring, the soil should be finely broken, soft on the top and loose on the bottom, and the field surface should be flat, with a height difference of no more than an inch. In order to ensure the quality of transplanting and create a good soil environment for the growth and development of rice, sufficient base fertilizer should be applied after land preparation and before soaking the field; S32 Harrowing: After stirring the slurry, use a harrow with a diameter of 15 cm or more to level the mud surface and harrow out 2-3 cm of mud on the field surface; S33 sedimentation: The hoeed mud is allowed to settle naturally. The length of the mud sedimentation time should be determined according to the soil quality and the mud-water consistency. Generally, sandy soil sedimentation time is about 1-2 days, loam sedimentation time is 3-4 days, and clay sedimentation time is 4-5 days, until the mud and water are clear and the mud surface is solid but not compacted.

[0025] In this embodiment, in the step of S4 field management, field management includes the following parts: S41 Field Sunning: Depending on weather conditions, in late June, at the end of rice tillering, combined with efforts to suppress ineffective tillering, the fields are sunned once until the soil cracks. Alternate dry and wet irrigation is then used. Aeration increases oxygen concentration around the roots, oxidizes reducing substances such as hydrogen sulfide and ferrous iron, increases root cell respiration, and discharges harmful gases produced during straw decomposition. S42 Fertilization: Combine farmyard manure and chemical fertilizers. When applying chemical fertilizers, various elements such as nitrogen, phosphorus, potassium, zinc, and silicon should be used in a reasonable combination. Adhere to the principle of "steady in the beginning, sufficient in the middle, and clever in the end", and determine the time and amount of fertilization based on the growth of the seedlings, the growth process, and the climatic conditions. S43 Irrigation: After returning rice straw to the field, it cannot be flooded for a long time. An irrigation method must be adopted in which water is not seen in the front and back.

[0026] In this embodiment, it is necessary to pay attention to the following during fertilization in S42: if the soil pH value is ≤5.5, straw should be returned to the field in combination with the application of alkaline substances such as calcium magnesium phosphate fertilizers to reduce the harm of reducing substances; if rice is grown in saline-alkali land, zinc sulfate and other trace element fertilizers should also be applied in appropriate amounts, with the dosage being 15 kg / hectare.

[0027] In this embodiment, it is also necessary to pay attention to the following during S42 fertilization: after returning the straw to the field, microorganisms decomposing the straw will compete with the seedlings for quick-acting nitrogen. Returning the entire amount to the field can increase urea by 2 kg / mu. If the amount of base fertilizer N applied is above 85 kg and the amount of N applied during the entire growth period is above 185 kg, then there is no need to increase the amount of nitrogen fertilizer in the early stage, and normal fertilization can be maintained.

[0028] Test Example 1 For the embodiments proposed in the present invention, relevant soil experiments must be conducted to ensure that they are effective. In Table 1, the present invention selected land of different areas from top to bottom at Maodu Station in Ningjiang District, Songyuan City to apply the field return process. After the application, the data in Table 1 are all average values.

[0029] Table 1

[0030] Comparative Example 1 Comparative Example 1 is the control group of the above embodiment. The nano-humic acid material in the mixed solution of the embodiment is removed, that is, the mixed solution is 45 kg of microcapsules + 1000 liters of water. The rest of the process remains the same as in the embodiment, forming the full amount of rice straw returning process of Comparative Example 1.

[0031] Comparative Example 2 Comparative Example 2 is the control group of the above embodiment. The microcapsules in the mixed solution in the embodiment are removed, that is, the mixed solution is 30 kg of nano humic acid material + 1000 liters of water. The rest of the process remains the same as in the embodiment, forming the full amount of rice straw returning process of Comparative Example 2.

[0032] Comparative Example 3 Comparative Example 3 is the control group of the above embodiment. The microcapsules and nano-humic acid materials in the mixed solution of the embodiment are removed, that is, the mixed solution is 1000 liters of water, and the rest of the processes are kept consistent with the embodiment, forming the full amount of rice straw returning process of Comparative Example 3.

[0033] Test Example 2 An area of ​​30,000 mu of land was selected at Maodu Station in Ningjiang District, Songyuan City to apply the above-mentioned embodiments and comparative examples 1-3 to the field returning process. After the application, the conventional nitrogen fertilizer dosage was measured and shown in Table 2 below. The data in Table 2 are all average values.

[0034] Table 2

[0035] Test Example 3 An area of ​​30,000 mu of land was selected at Maodu Station in Ningjiang District, Songyuan City to apply the above-mentioned embodiments and comparative examples 1-3 to the field return process. Performance tests were conducted during the application process. The test process is as follows, and the test results are shown in Table 3 below. The data in Table 3 are all average values.

[0036] (1) Concentration of reducing substances: Sampling: Slurry was collected from the soil 10 cm deep around the root system during the tillering period, and the supernatant was obtained by centrifugation; Detection: Sulfide detection tube (Hach Company), ferrous ion o-phenanthroline colorimetric method (wavelength 510 nm).

[0037] (2) Root activity: TTC method: 5 g of rice root tips were immersed in 0.4% TTC solution at 37°C in the dark for 3 h, and then extracted with methyl ester and measured at OD485nm.

[0038] (3) Yield and soil indicators: Yield is measured during the harvest period, and soil samples are taken to test organic matter (potassium dichromate method) and available potassium (ammonium acetate extraction-flame photometer).

[0039] Table 3

[0040] Result analysis and verification: (1) Concentration of reducing substances (sulfide & ferrous ions): The example has the lowest content (sulfide 8.2 mg / kg, ferrous iron 35.1 mg / kg), which proves that the microencapsulated microorganisms accelerate the decomposition of rice straw and reduce the production of reducing substances; the nano-humic acid material adsorbs and fixes residual ions.

[0041] Comparative Example 1 (microcapsules only): sulfide increased to 10.5 mg / kg, and ferrous iron increased to 42.0 mg / kg (lack of nanomaterial adsorption capacity).

[0042] Comparative Example 2 (nanomaterial only): sulfide increased to 12.0 mg / kg, and ferrous iron increased to 48.0 mg / kg (lack of microbial degradation).

[0043] Comparative Example 3 (no addition): the highest (sulfide 15.0 mg / kg, ferrous iron 55.0 mg / kg), the basic process cannot control the reducing substances.

[0044] (2) Root activity: The concentration of Example 1 was the highest (85.6 μg / g·h), and the root growth was not inhibited due to the low level of reducing substances.

[0045] The concentration of comparative example 1 dropped to 80.0 μg / g·h (slightly higher in ferrous iron); the concentration of comparative example 2 dropped to 75.0 μg / g·h (decomposition was slow and reducing substances accumulated); the concentration of comparative example 3 was the lowest (65.0 μg / g·h), and the reducing substances directly poisoned the roots.

[0046] (3) Rice yield and soil fertility: The example has the highest yield per hectare (18,300 jin / hectare), the best organic matter (20.06 g / kg) and available potassium (153.78 mg / kg), and microorganisms and nanomaterials synergistically improve nutrient utilization.

[0047] The yield of comparative example 1 was 18,000 jin / hectare (organic matter 19.50 g / kg, available potassium 150.00 mg / kg), and the lack of nanomaterials resulted in a slight decrease in potassium effectiveness.

[0048] The yield of Comparative Example 2 was 17,800 jin / hectare (organic matter 18.50 g / kg, available potassium 145.00 mg / kg), and the lack of microorganisms resulted in insufficient mineralization of organic matter.

[0049] Comparative Example 3 had a yield of 17,500 jin / ha (organic matter 17.00 g / kg, available potassium 140.00 mg / kg), and nutrient competition was fierce (refer to Table 2 nitrogen fertilizer 175 kg / ha).

[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly indicate the number of the technical features being referred to. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0051] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent substitutions and changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A process for returning all rice straw to the fields, characterized in that: The following steps are involved: S1, the rice straw is crushed evenly and then spread on the field, the mixture is sprayed on the surface of the rice straw in the field, and then the field is deep plowed and mixed and deep swirled in sequence to complete the swirling process; S2. After the turning process is completed, water the field to ensure that a 2-5 cm water layer is formed on the field surface, and then soak the field for 2-5 days to keep the flowers in a water-rich state; S3. After the paddy is soaked, evenly mix the rice straw into the mud. After stirring, use a hoe to level the mud surface and then allow the hoeed mud to settle naturally. S4. Dry the fields according to the season until the soil cracks in the field, then irrigate, fertilize, and control pests and diseases to complete the process of returning the full amount of rice straw to the field.

2. A method for returning all rice straw to the fields according to claim 1, characterized in that: The spraying composition of the mixed solution in S1 per hectare is: 45 kg of microcapsules + 30 kg of nano humic acid material + 1000 liters of water.

3. A method for returning all rice straw to the fields according to claim 2, characterized in that: The microcapsules are prepared by the following steps: Sodium alginate was dissolved in 45°C deionized water and stirred until transparent to obtain a 3% sodium alginate solution. Bacillus subtilis powder and Aspergillus niger powder were then added to the 3% sodium alginate solution and uniformly dispersed to obtain a mixed solution. The mixed solution was dropped into a 2% by mass CaCl2 solution using a syringe to form gel microspheres with a diameter of 2-3 mm. After curing for 30 minutes, the microspheres were filtered and washed to obtain microcapsules.

4. A method for returning all rice straw to the fields according to claim 3, characterized in that: The particle size of the sodium alginate is 60 mesh.

5. The method for returning all rice straw to the fields according to claim 3, characterized in that: The effective viable bacterial counts of the Bacillus subtilis powder and Aspergillus niger powder were both 2.0×10 8 pcs / g.

6. The method for returning all rice straw to the fields according to claim 3, characterized in that: The usage ratio of the sodium alginate, deionized water, Bacillus subtilis powder and Aspergillus niger powder is 30 g:970 ml:20 g:10 g.

7. The method for returning all rice straw to the fields according to claim 2, characterized in that: The nano humic acid material is prepared by the following steps: The hydroxyapatite nanorods and potassium humate were added into pure water, ultrasonically dispersed for 1 hour, frozen at -50°C for 24 hours, vacuum dried, and crushed to pass through a 100-mesh sieve to obtain nano humic acid material.

8. The method for returning all rice straw to the fields according to claim 7, characterized in that: The hydroxyapatite nanorods have a diameter of 20-30 mm and a length of 100-200 mm.

9. The method for returning all rice straw to the fields according to claim 7, characterized in that: The usage ratio of the hydroxyapatite nanorods, potassium humate and pure water is 50 g:30 g:500 ml.

Images