Functional compost, its preparation methods, and its application in restoring degraded grazing grasslands

Abstract

This invention discloses a method for preparing functional compost, belonging to the field of agricultural waste resource utilization and grassland ecological restoration technology. The key technical points include: mixing fresh sheep manure, wheat straw, and corn straw at a specific wet weight ratio and adding superphosphate to obtain a basic mixture; inoculating this mixture with a compound microbial fermentation agent composed of *Bacillus steatophilus*, *Bacillus subtilis*, and *Bacillus mucilaginosus* at a specific viable count ratio to obtain an inoculum; subjecting the inoculum to aerobic composting fermentation and implementing dynamic turning control based on dual temperature thresholds to maintain the compost within a specific high-temperature range for a sufficient number of days; and finally, aging the material until its seed germination index reaches a specific range to obtain functional compost. The functional compost prepared by this method is mainly used for restoring degraded grazing grasslands.

Description

Technical Field

[0001] This invention relates to the fields of agricultural waste resource utilization and grassland ecological restoration. More specifically, this invention relates to a functional compost, its preparation method, and its application in restoring degraded grazing grasslands. Background Technology

[0002] Currently, my country's pastureland ecosystems face declining productivity due to the continuous loss of soil organic matter and nutrients. Fertilization is an effective way to replenish nutrients, but long-term application of traditional chemical fertilizers can easily lead to soil compaction, pH imbalance, and inhibit soil microbial activity, weakening the soil's self-fertilization capacity. Furthermore, these fertilizers release nutrients rapidly, suffer severe leaching losses, have low utilization efficiency, and pose potential threats to the environment. Therefore, there is an urgent need for a fertilization program that can systematically and fundamentally improve grassland soil health.

[0003] Organic fertilizers mainly improve soil structure and activate microbial activity by inputting exogenous organic matter. However, their application must be highly compatible with the characteristics of grassland areas, such as vast land, sparse population, weak infrastructure, and strong ecological sensitivity. They also require cost control, ease of operation, and environmental friendliness. However, existing technologies have significant shortcomings across the entire chain, from raw material processing and process design to field application. At the raw material level, pastoral areas have abundant organic waste resources such as cattle and sheep manure, but traditional treatment methods are extensive and inefficient. Natural composting is time-consuming, nitrogen loss is high, and uneven fermentation leads to incomplete decomposition. Residual harmful organisms may be introduced with fertilizer, potentially causing grassland diseases. At the process and product level, general commercial organic fertilizers or ordinary composting processes often fail to fully consider the special characteristics of grassland soils, such as sandiness, poor water and fertilizer retention capacity, and fragile ecosystems. Fertilizers need to have stronger binding and slow-release properties and be able to synergize with local microbial communities. However, existing processes are either too complex and expensive to promote, or the nutrient ratios are mismatched with the needs of pasture growth, failing to achieve precise improvement. At the application level, existing fertilization technologies have low coupling with grassland management and grazing systems. There is a lack of a set of precise fertilization technical procedures that can be dynamically adjusted according to grassland degradation levels and soil types, resulting in the inability to maximize fertilizer benefits and even potentially causing local eutrophication due to improper application.

[0004] In summary, existing technologies struggle to produce a specialized organic fertilizer that can decompose quickly and efficiently, retain nutrients to the maximum extent, is highly compatible with grassland soil characteristics, and can be precisely applied according to the grassland degradation status. This limits the effectiveness of grassland ecological restoration and sustainable management through fertilization. Summary of the Invention

[0005] One object of the present invention is to provide a method for preparing functional compost, comprising the following steps: S1. Mix fresh sheep manure, wheat straw and corn straw in a wet weight ratio of (630~650):(165~175):(185~195) to obtain a mixture. Then add 0.8%~1.2% of superphosphate to the total weight of the mixture to obtain a basic mixture. S2. Inoculate the basic mixture with a compound microbial fermentation agent at a rate of 0.4‰ to 1.2‰ of the total weight of the mixture and mix evenly to obtain the inoculated material. The compound microbial fermentation agent is composed of Bacillus stearothermophilus, Bacillus subtilis, and Bacillus mucilaginosus in a viable cell ratio of 0.8:1:1 to 1.2:1:1. S3. The inoculated material is subjected to aerobic composting and fermentation, and dynamic turning control is implemented. The pile is turned when the temperature at the center of the pile exceeds 63°C and when the temperature is below 47°C, so that the pile temperature is maintained within the range of 53°C to 67°C for 8 to 12 days. S4. The fermented material is then aged until its seed germination index reaches 130%~135% to obtain the functional compost.

[0006] Preferably, in step S2, the composite microbial fermentation agent is mixed with 10% to 20% of its weight of humic acid carrier to form an agent-carrier complex before inoculation. The humic acid carrier is humic acid obtained by alkaline extraction of weathered coal, and its particle size is 100 to 200 mesh.

[0007] Preferably, the method for preparing the humic acid carrier includes the following steps: Weathered coal is mixed with a 1% to 2% sodium hydroxide solution at a solid-liquid ratio of 1:5 to 10. The mixture is stirred and extracted at 60℃ to 80℃ for 2 to 4 hours. The supernatant is collected by centrifugation, and the pH is adjusted to 2.0 to 3.0 with hydrochloric acid to precipitate humic acid. The precipitate is collected, dried, and pulverized to the specified particle size.

[0008] Preferably, in step S3, after the pile temperature first reaches and is maintained at 60°C~65°C for more than 24 hours, 0.5%~1.0% of diammonium hydrogen phosphate is added to the pile according to the initial weight of the pile.

[0009] Preferably, in the post-maturation aging process of step S4, the material is piled in an aging shed with rain and wind protection functions, and a layer of semi-decomposed material of the functional compost with a thickness of 5 cm to 10 cm is covered on the surface of the material pile, wherein the seed germination index of the semi-decomposed material is 80% to 90%.

[0010] Preferably, the method for preparing the semi-fermented material includes steps S1 to S3, and after the high-temperature fermentation stage is completed, the material is taken out when the temperature of the pile drops to 50°C, and its moisture content is controlled at 45% to 50%.

[0011] Preferably, after step S4, the obtained functional compost is uniformly mixed with a water-retaining agent accounting for 5% to 10% of its weight, wherein the water-retaining agent is cross-linked potassium polyacrylate with a particle size of 0.5 mm to 2 mm.

[0012] A functional compost prepared by the method described above is provided.

[0013] This invention provides an application of functional compost in restoring degraded grazing grasslands, which is applied according to the following dosage based on the grassland degradation level: The application rate for severely degraded grassland is 35 to 40 tons / hectare, for moderately degraded grassland it is 30 to 35 tons / hectare, and for slightly degraded grassland it is 25 to 30 tons / hectare.

[0014] The present invention has at least the following beneficial effects: First, this invention provides balanced nutrition through raw material ratio and utilizes a compound microbial agent composed of thermophilic Bacillus steatophilus, Bacillus subtilis, and Bacillus mucilaginosus, combined with a dynamic temperature control process of turning the compost at 65°C to prevent overheating and turning it at 45°C to promote reoxygenation, to construct an optimal microbial fermentation environment. This significantly shortens the composting cycle to about 45 days, and the resulting functional compost has a seed germination index (GI) as high as 132%~136%. It is not only fully decomposed and non-toxic to plants, but also shows a significant promoting effect on seed germination and seedling growth. This fundamentally solves the technical defects of traditional natural composting, such as long cycle (more than half a year), incomplete decomposition (GI of only 75%), and the possibility of carrying weed seeds and pathogens.

[0015] Secondly, this invention employs a specific combination of functional microbial agents, particularly Bacillus subtilis and Bacillus mucilaginosa, which, under optimized processes, produce more beneficial intermediates through metabolism. This significantly increases the proportion of structurally stable and highly active humic acid in the resulting humic material, with a humic acid to fulvic acid ratio (HA / FA) ​​reaching 3.15~3.30. A high HA / FA value indicates that the product has stronger cementing and stability, and after application to the soil, it is more conducive to promoting the formation of soil aggregates and enhancing water and fertilizer retention capacity. Thus, it is precisely adapted to degraded grassland soils with poor fertilizer retention and loose structure, achieving a functional upgrade from "providing organic matter" to "targeted improvement of soil structure".

[0016] Third, the present invention uses humic acid carrier pretreatment agents to improve the activity and colonization capacity of microbial communities. Adding phosphorus during fermentation can further optimize microbial metabolism, while covering and aging semi-fermented materials can improve the homogeneity and stability of the product. Adding water-retaining agents can directly endow the product with excellent water retention performance. These features can be combined according to actual production conditions and product needs to flexibly produce high-quality, functional compost suitable for different scenarios (such as extremely arid areas).

[0017] Fourth, this invention combines the production of high-quality functional compost with a set of differentiated and precise application technologies based on grassland degradation levels. Application trials show that this approach can significantly increase soil organic carbon and total nitrogen, and the restoration effect exhibits a gradient pattern of "severely degraded areas > moderately degraded areas > slightly degraded areas," proving that the amount of fertilizer applied is well matched with the restoration needs. Compared with the use of ordinary microbial compost, the product of this invention has a particularly prominent advantage in the restoration effect in severely degraded areas. This verifies the systematic advantage of the whole-chain innovation from specific microbial agents, customized processes to precise application in solving the restoration problem of severe degradation.

[0018] Fifth, this invention fixes ammonium nitrogen by adding superphosphate and combines it with timely turning at a threshold of 65℃ to prevent excessive high temperature from causing nitrogen volatilization, forming a new dynamic temperature control mechanism that combines "chemical fixation" and "physical regulation" to protect nitrogen. The nitrogen loss rate of the product in the example can be less than 6%, and the total nitrogen content is as high as 2.15%~2.20%, which is far superior to the nitrogen loss rate of more than 40% and the total nitrogen content of only 1.2% of traditional compost. This effectively solves the long-standing industry problem of serious nutrient loss and low fertilizer efficiency in organic fertilizer production.

[0019] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0020] Figure 1 This is a bar chart comparing the soil organic carbon content after applying different fertilization treatments of the present invention to grasslands of different degradation levels. Figure 2 This is a bar chart comparing the total nitrogen content in the soil after applying different fertilization treatments of the present invention to grasslands of different degradation levels. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0022] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation plan are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified.

[0023] In the following examples and comparative examples, the microbial agents used are all conventional and commercially available strains or commercial agents in the art. Bacillus stearothermophilus, Bacillus subtilis, and Bacillus mucilaginosus are all known strains and their powders or freeze-dried powders can be purchased from domestic and foreign microbial culture collection centers (such as CGMCC) or commercial microbial preparation suppliers. "Commercially available common high-temperature composting agents" refers to general-purpose commercial fermentation agents commonly used in the art for high-temperature aerobic composting of organic solid wastes such as livestock and poultry manure and straw.

[0024] The following embodiments are merely illustrative of the invention and are not intended to limit its scope. Those skilled in the art will understand that appropriate adjustments within the parameter range defined in the claims can achieve the objectives of the invention and obtain similar technical effects.

[0025] <Example 1> The preparation method of functional compost includes the following steps: S1. Weigh 640 kg of fresh sheep manure, 170 kg of wheat straw, and 190 kg of corn straw. Crush the wheat straw and corn straw to a length of no more than 5 cm. Put the crushed straw, sheep manure, and 1.0% (10 kg) of superphosphate (by weight of the total mixture) into a mixer and mix for 25 minutes. Spray an appropriate amount of water during the mixing process to adjust the initial moisture content of the mixture to 56.7%. The initial carbon-nitrogen ratio (C / N) is measured to be 30:1, thus obtaining the basic mixture. S2. Inoculate the above-mentioned basic mixture with a compound microbial fermentation agent. The inoculation amount is 0.5‰ (i.e. 0.5 kg) of the total weight of the mixture. The compound microbial fermentation agent is made by mixing commercially available Bacillus stearothermophilus, Bacillus subtilis and Bacillus mucilaginosus powders in a live bacteria ratio of 1:1:1. Mix the mixture evenly with the basic mixture in a mixer for 15 minutes to obtain the inoculated material. S3. The inoculum material is piled into windrows 2 meters wide and 1.5 meters high for aerobic fermentation. Dynamic turning control is implemented: temperature probes are used to monitor the temperature at the center of the pile. When the temperature exceeds 65°C, the pile is turned immediately. When the temperature is below 45°C, the pile is also turned to supplement oxygen. Through this control, the pile temperature is maintained in the range of 55°C to 65°C for 10 days. S4. Transfer the material after high-temperature fermentation to the aging area and pile it into a pile 3 meters wide and 1 meter high. Turn the pile over every 7 days for post-maturation aging. The total aging time is 35 days. When the seed germination index (GI) of the material reaches 132%, the aging is completed and functional compost product A is obtained.

[0026] <Example 2> The preparation method of functional compost includes the following steps: S1. Weigh 640 kg of fresh sheep manure, 170 kg of wheat straw, and 190 kg of corn straw. Crush the wheat straw and corn straw to a length of no more than 5 cm. Put the crushed straw, sheep manure, and 1.0% (10 kg) of superphosphate (by weight of the total mixture) into a mixer and mix for 25 minutes. Spray an appropriate amount of water during the mixing process to adjust the initial moisture content of the mixture to 56.7%. The initial carbon-nitrogen ratio (C / N) is measured to be 30:1, thus obtaining the basic mixture. S2. Preparation of humic acid carrier: Take 1 kg of weathered coal, add 8 L of 1.5% sodium hydroxide solution (solid-liquid ratio 1:8), stir and extract at 70℃ for 3 hours, centrifuge and take the supernatant, adjust the pH to 2.5 with concentrated hydrochloric acid to precipitate humic acid, collect the precipitate, dry and pulverize to 150 mesh to obtain humic acid carrier. Inoculate the above-mentioned basic mixture with a compound microbial fermentation agent at a rate of 0.5‰ (i.e., 0.5 kg) of the total weight of the mixture. The compound microbial fermentation agent is a mixture of commercially available Bacillus stearothermophilus, Bacillus subtilis, and Bacillus mucilaginosus powders in a live cell ratio of 1:1:1. The agent has been premixed with 15% (i.e., 75 g) of the above-mentioned humic acid carrier to form an agent-carrier complex before inoculation. The mixture is then uniformly mixed with the basic mixture in a mixer for 15 minutes to obtain the inoculated material. S3. Pile the inoculum material into windrows 2 meters wide and 1.5 meters high for aerobic fermentation, implementing dynamic turning control: Use temperature probes to monitor the temperature at the center of the pile. Turn the pile immediately when the temperature exceeds 65℃; turn the pile again when the temperature is below 45℃ to supplement oxygen; during fermentation, when the temperature at the center of the pile first reaches and stabilizes at 63℃ for more than 24 hours, evenly sprinkle diammonium hydrogen phosphate (approximately 8 kg), accounting for 0.8% of the initial weight of the pile, onto the surface of the pile. Through this control, the pile temperature is maintained within the range of 55℃~65℃ for 10 days. S4. Transfer the material after high-temperature fermentation to the aging area and pile it into a pile 3 meters wide and 1 meter high. Turn the pile over every 7 days for post-maturation aging. The total aging time is 35 days. When the seed germination index (GI) of the material reaches 135%, the aging is completed and functional compost product B is obtained.

[0027] <Example 3> The preparation method of functional compost includes the following steps: S1. Weigh 640 kg of fresh sheep manure, 170 kg of wheat straw, and 190 kg of corn straw. Crush the wheat straw and corn straw to a length of no more than 5 cm. Put the crushed straw, sheep manure, and 1.0% (10 kg) of superphosphate (by weight of the total mixture) into a mixer and mix for 25 minutes. Spray an appropriate amount of water during the mixing process to adjust the initial moisture content of the mixture to 56.7%. The initial carbon-nitrogen ratio (C / N) is measured to be 30:1, thus obtaining the basic mixture. S2. Preparation of humic acid carrier: Take 1 kg of weathered coal, add 8 L of 1.5% sodium hydroxide solution (solid-liquid ratio 1:8), stir and extract at 70℃ for 3 hours, centrifuge and take the supernatant, adjust the pH to 2.5 with concentrated hydrochloric acid to precipitate humic acid, collect the precipitate, dry and pulverize to 150 mesh to obtain humic acid carrier. Inoculate the above-mentioned basic mixture with a compound microbial fermentation agent at a rate of 0.5‰ (i.e., 0.5 kg) of the total weight of the mixture. The compound microbial fermentation agent is a mixture of commercially available Bacillus stearothermophilus, Bacillus subtilis, and Bacillus mucilaginosus powders in a live cell ratio of 1:1:1. The agent has been premixed with 15% (i.e., 75 g) of the above-mentioned humic acid carrier to form an agent-carrier complex before inoculation. The mixture is then uniformly mixed with the basic mixture in a mixer for 15 minutes to obtain the inoculated material. S3. Pile the inoculum material into windrows 2 meters wide and 1.5 meters high for aerobic fermentation, implementing dynamic turning control: Use temperature probes to monitor the temperature at the center of the pile. Turn the pile immediately when the temperature exceeds 65℃; turn the pile again when the temperature is below 45℃ to supplement oxygen; during fermentation, when the temperature at the center of the pile first reaches and stabilizes at 63℃ for more than 24 hours, evenly sprinkle diammonium hydrogen phosphate (approximately 8 kg), accounting for 0.8% of the initial weight of the pile, onto the surface of the pile. Through this control, the pile temperature is maintained within the range of 55℃~65℃ for 10 days. S4. Preparation of semi-decomposed covering material: Prepare a batch of material according to steps S1 to S3 of Example 1. However, after the high-temperature fermentation stage, when the temperature of the pile drops to 50°C, take out a portion of the material immediately. The moisture content of this material is 48%, and the seed germination index (GI) is 85%, which is semi-decomposed material. The fermented material from step S3 is transferred to an aging shed with a rain and wind shelter, piled into a heap 3 meters wide and 1 meter high, and a layer of the above semi-decomposed material with a thickness of 8 cm is evenly covered on the surface of the heap. The heap is turned over every 7 days for post-maturation aging, with a total aging time of 35 days. When the seed germination index (GI) of the material reaches 136%, the aging is completed, and functional compost product C is obtained.

[0028] <Example 4> The preparation method of functional compost includes the following steps: S1. Weigh 640 kg of fresh sheep manure, 170 kg of wheat straw, and 190 kg of corn straw. Crush the wheat straw and corn straw to a length of no more than 5 cm. Put the crushed straw, sheep manure, and 1.0% (10 kg) of superphosphate (by weight of the total mixture) into a mixer and mix for 25 minutes. Spray an appropriate amount of water during the mixing process to adjust the initial moisture content of the mixture to 56.7%. The initial carbon-nitrogen ratio (C / N) is measured to be 30:1, thus obtaining the basic mixture. S2. Preparation of humic acid carrier: Take 1 kg of weathered coal, add 8 L of 1.5% sodium hydroxide solution (solid-liquid ratio 1:8), stir and extract at 70℃ for 3 hours, centrifuge and take the supernatant, adjust the pH to 2.5 with concentrated hydrochloric acid to precipitate humic acid, collect the precipitate, dry and pulverize to 150 mesh to obtain humic acid carrier. Inoculate the above-mentioned basic mixture with a compound microbial fermentation agent at a rate of 0.5‰ (i.e., 0.5 kg) of the total weight of the mixture. The compound microbial fermentation agent is a mixture of commercially available Bacillus stearothermophilus, Bacillus subtilis, and Bacillus mucilaginosus powders in a live cell ratio of 1:1:1. The agent has been premixed with 15% (i.e., 75 g) of the above-mentioned humic acid carrier to form an agent-carrier complex before inoculation. The mixture is then uniformly mixed with the basic mixture in a mixer for 15 minutes to obtain the inoculated material. S3. Pile the inoculum material into windrows 2 meters wide and 1.5 meters high for aerobic fermentation, implementing dynamic turning control: Use temperature probes to monitor the temperature at the center of the pile. Turn the pile immediately when the temperature exceeds 65℃; turn the pile again when the temperature is below 45℃ to supplement oxygen; during fermentation, when the temperature at the center of the pile first reaches and stabilizes at 63℃ for more than 24 hours, evenly sprinkle diammonium hydrogen phosphate (approximately 8 kg), accounting for 0.8% of the initial weight of the pile, onto the surface of the pile. Through this control, the pile temperature is maintained within the range of 55℃~65℃ for 10 days. S4. Preparation of semi-decomposed covering material: Prepare a batch of material according to steps S1 to S3 of Example 1. However, after the high-temperature fermentation stage, when the temperature of the pile drops to 50°C, take out a portion of the material immediately. The moisture content of this material is 48%, and the seed germination index (GI) is 85%, which is semi-decomposed material. The fermented material from step S3 is transferred to an aging shed with a rain- and windproof roof and piled into a pile 3 meters wide and 1 meter high. A layer of the above semi-decomposed material with a thickness of 8 cm is evenly covered on the surface of the pile. The pile is turned over every 7 days for post-maturation aging. The total aging time is 35 days. When the seed germination index (GI) of the material reaches 136%, the aging is completed, and functional compost intermediate product C is obtained. S5. Add the above-mentioned functional compost intermediate product C and 7.5% of its weight of cross-linked potassium polyacrylate water-retaining agent (particle size 1mm) into a mixer and mix evenly for 15 minutes to obtain the functional compost finished product D.

[0029] <Control Group> The preparation method of functional compost includes the following steps: Except for the absence of inoculation, dynamic turning and temperature control, and subsequent aging processes, the types of raw materials, proportions, initial moisture content adjustment, and pile size are the same as in Example 1; Fresh sheep manure, wheat straw, and corn straw were simply mixed according to the proportions in Example 1, and piled into a large heap 3 meters wide and 2 meters high in an open field. Without any active turning, temperature control, or inoculation, the mixture was allowed to ferment naturally for 6 months to obtain fertilizer product E.

[0030] The finished products A to E obtained from Examples 1-4 and the control group were tested for seed germination index (GI), total nitrogen content, nitrogen loss rate, humic acid to fulvic acid ratio (HA / FA), product homogeneity, and saturated water absorption rate. The testing methods included: Seed germination index (GI) was determined according to Appendix B (Plant Toxicity Test - Germination Index Method) of NY / T 525-2021 Organic Fertilizers. The total nitrogen content was determined according to the provisions of 5.4 in "NY / T 525-2021 Organic Fertilizers" using sulfuric acid-hydrogen peroxide digestion and Kjeldahl method. The nitrogen loss rate is estimated using the material balance method. The calculation formula is: Nitrogen loss rate (%) = [(Total nitrogen content of initial materials - Total nitrogen content of finished product) / Total nitrogen content of initial materials] × 100%, where the total nitrogen content of initial materials is the sum of the nitrogen content of all input materials such as fresh sheep manure, straw and superphosphate in step S1 (calculated by measuring their total nitrogen content separately), and the total nitrogen content of finished product is the product of the total nitrogen content of the final product and its total mass. The humic acid to fulvic acid ratio (HA / FA) ​​was determined according to the "Determination of Soil Humic Composition" (NY / T 1867-2010). The saturated water absorption rate was determined according to the method for determining the water absorption ratio in GB / T 22905-2008 Water Retention Agents; During the testing process, product C exhibited better homogeneity, product D had a saturated water absorption rate of up to 300 times its own weight, while product E had a noticeable ammonia odor. The test results are shown in Table 1 below, where - indicates not detected: Table 1. Detection results of finished products A to E obtained from Examples 1-4 and the control group. As shown in Table 1, Example 1 of this invention achieved a breakthrough compared to the traditional composting of the control group: the functional compost produced within 35 days had a seed germination index (GI) as high as 132%, far exceeding the 75% of the control group, and a total nitrogen content of 2.15%, significantly higher than the 1.20% of the control group, while the nitrogen loss rate was less than 6%, far lower than the more than 40% of the control group. Moreover, the humic material was mainly composed of more stable humic acid (HA / FA ratio 3.15). This proves that the specific raw material ratio, functional microbial agent combination, and dual-threshold dynamic temperature control process of this invention effectively solved the key problems of incomplete composting and serious nutrient loss in traditional composting. Further Examples 2-4 brought cumulative benefits: the microbial agent carrier and mid-process phosphorus supplementation further improved the GI value, total nitrogen content, and HA / FA ratio; the semi-composted material covering and aging improved the homogeneity of the product; and the addition of water-retaining agent gave the product extremely high water absorption capacity (300 times saturated water absorption rate), enhancing its applicability in arid grasslands. Therefore, this invention successfully prepared a special compost that is thoroughly decomposed, has efficient nutrient preservation, excellent humus quality, and can be functionally modified as needed. Its characteristics are highly compatible with the needs of degraded grassland soil restoration, and the technical effect is significant.

[0031] <Comparative Example 1> The preparation method of functional compost is the same as in Example 4, but the compound microbial fermentation agent (Bacillus thermophilus, Bacillus subtilis, and Bacillus mucilaginosus) in step S2 is replaced with an equal amount of commercially available ordinary high-temperature composting agent (the main components of which are high-temperature cellulose-decomposing bacteria and actinomycetes) to obtain control fertilizer F.

[0032] <Comparative Example 2> The preparation method of functional compost is basically the same as that in Example 4, but in S3, instead of using dynamic turning control based on the 65℃ / 45℃ threshold, the traditional process of turning the compost once every 48 hours is used to obtain the control fertilizer G.

[0033] <Comparative Example 3> The preparation method of functional compost is the same as in Example 4, except that the compound microbial fermentation agent in S2 is replaced with an equal amount of single thermophilic Bacillus stearothermophilus (Bacterium A) powder to obtain control fertilizer H.

[0034] <Comparative Example 4> The preparation method of functional compost is the same as in Example 4, except that the compound microbial fermentation agent in S2 is replaced with an equal amount of single Bacillus subtilis (Bacterium B) powder to obtain control fertilizer I.

[0035] <Comparative Example 5> The preparation method of functional compost is the same as in Example 4, except that the compound microbial fermentation agent in S2 is replaced with an equal amount of single gelatinous Bacillus (Bacterium C) powder to obtain control fertilizer J.

[0036] <Comparative Example 6> The preparation method of functional compost is the same as in Example 4, except that the compound microbial fermentation agent in S2 is replaced with a microbial powder of Bacillus stearothermophilus (Bacterium A) and Bacillus subtilis (Bacterium B) in a 1:1 ratio of live bacteria to obtain control fertilizer K.

[0037] <Comparative Example 7> The preparation method of functional compost is the same as in Example 4, except that the compound microbial fermentation agent in S2 is replaced with an equal amount of thermophilic Bacillus steatoids (Bacterium A) and Bacillus colloidis (Bacterium C) mixed in a 1:1 ratio of viable bacteria powder to obtain control fertilizer L.

[0038] <Comparative Example 8> The preparation method of functional compost is the same as in Example 4, except that the compound microbial fermentation agent in S2 is replaced with an equal amount of Bacillus subtilis (B) and Bacillus jellyii (C) mixed in a 1:1 ratio of live bacteria powder to obtain control fertilizer M.

[0039] The control fertilizers F to Fertilizer F prepared in Comparative Examples 1 to 8 were subjected to similar index tests as shown in Table 1, and compared with the finished product D prepared in Example 4. The results are shown in Table 2 below: Table 2. Test results of the fertilizers prepared in Comparative Examples 1-8 and Example 4. According to the data in Table 2, compared with Example 4, when the ordinary high-temperature composting microbial agent of Comparative Example 1 was used or the fixed-cycle turning of Comparative Example 2 was changed, the product performance (GI value, total nitrogen, HA / FA) ​​decreased significantly and the nitrogen loss rate increased significantly, proving that these two core characteristics are irreplaceable. Compared to Example 4, the product performance (GI value, total nitrogen, HA / FA) ​​of Comparative Examples 3-8 significantly decreased, while the nitrogen loss rate increased substantially. This indicates that the effect of any single microbial agent or dual-microbial combination is inferior to that of a complete triple-microbial combination, but superior to ordinary microbial agents. This confirms the synergistic effect among the three microorganisms in grassland restoration, and none of them can be omitted. Therefore, this invention successfully prepared a functional compost that is thoroughly decomposed (GI>135%), has high nutrient retention efficiency (total nitrogen>2.2%, nitrogen loss<6%), and excellent humus quality (HA / FA>3.3). Its comprehensive performance is significantly better than existing technical solutions, providing an effective customized product for the restoration of degraded grasslands.

[0040] <Practical Application> To verify the actual remediation effect of the functional compost prepared in this invention, the functional compost product D prepared in Example 4 was applied to natural grazing grasslands with different degrees of degradation for field trials. The specific process is as follows: 1. Experimental Design and Methods Experimental Sites: Representative degraded natural grazing grasslands were selected and divided into three levels of experimental areas—severely degraded, moderately degraded, and slightly degraded—based on indicators such as vegetation cover and soil organic carbon content. The specific divisions are shown below: Severe degradation: vegetation cover <30%, soil organic carbon content <2.0 g / kg, dominant plants are miscellaneous grasses or annual forage grasses; Moderate degradation: vegetation cover 30%~50%, soil organic carbon content 2.0 g / kg~3.0 g / kg, and a decrease in the proportion of perennial high-quality forage grasses.

[0041] Mild degradation: vegetation cover 50%~70%, soil organic carbon content >3.0 g / kg, grassland community structure is basically stable, but productivity has declined.

[0042] Experimental treatments: Two treatments were set up for each degradation level: Fertilization treatment: applied with product D from Example 4; Control treatment: applied with control fertilizer F prepared by Comparative Example 1 (i.e., using ordinary high-temperature composting inoculant, with other processes the same as in Example 4); Blank control (CK): no fertilizer was applied; each treatment was repeated 3 times. Fertilization plan: Strictly follow the differentiated and precise application strategy described in the application method. Apply as a base fertilizer once in autumn (late September). The application rate is as follows: 40 t / ha for severely degraded grassland, 35 t / ha for moderately degraded grassland, and 30 t / ha for slightly degraded grassland. Use a fertilizer spreader to spread it evenly on the ground surface.

[0043] Observation indicators: Soil organic carbon content and total nitrogen content were measured in the growing season (July) of the year following fertilization, and changes in pasture community were observed.

[0044] 2. Experimental Results and Analysis One year after applying product D from Example 4, the key soil indicators of each degraded grassland showed significant improvement. Specific data are shown in Table 3 below. The experimental results were obtained through... Figure 1 and Figure 2 Visual representation: Table 3. Comparison of the effects of functional compost and ordinary microbial agent compost in the restoration of degraded grassland. As shown in Table 3, on all degraded grasslands, the application of the product D of this invention significantly increased soil organic carbon and total nitrogen levels compared to the application of the comparative fertilizer F (ordinary microbial agent), and the advantage increased with the severity of degradation. Specifically, in the severely degraded areas where restoration was most difficult, the increase in organic carbon was 2.2 times that of the comparative treatment, and the increase in total nitrogen was 2.7 times that of the comparative treatment. This directly demonstrates the outstanding advantages and irreplaceable nature of the specific functional microbial agent combination in this invention, composed of Bacillus steatophilus, Bacillus subtilis, and Bacillus mucilaginosus, compared to ordinary high-temperature composting microbial agents, in improving the soil remediation efficiency of the final product.

[0045] Both the finished product D and the control treatment of this invention showed a soil improvement effect of "severely degraded area > moderately degraded area > slightly degraded area". This verifies the scientificity and effectiveness of the differentiated application strategy based on the degradation level, which can enable fertilizer benefits to be maximized in areas with more severe degradation.

[0046] The aforementioned significant soil improvement effects, especially the powerful restorative effect on severely degraded grasslands, demonstrate that this invention provides not only an organic fertilizer, but also a customized solution for the ecological restoration of degraded grazing grasslands.

[0047] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A method for preparing functional compost, characterized in that, Includes the following steps: S1. Mix fresh sheep manure, wheat straw and corn straw in a wet weight ratio of (630~650):(165~175):(185~195) to obtain a mixture. Then add 0.8%~1.2% of superphosphate to the total weight of the mixture to obtain a basic mixture. S2. Inoculate the basic mixture with a compound microbial fermentation agent at a rate of 0.4‰ to 1.2‰ of the total weight of the mixture and mix evenly to obtain the inoculated material. The compound microbial fermentation agent is composed of Bacillus stearothermophilus, Bacillus subtilis, and Bacillus mucilaginosus in a viable cell ratio of 0.8:1:1 to 1.2:1:

1. S3. The inoculated material is subjected to aerobic composting and fermentation, and dynamic turning control is implemented. The pile is turned when the temperature at the center of the pile exceeds 63°C and when the temperature is below 47°C, so that the pile temperature is maintained within the range of 53°C to 67°C for 8 to 12 days. S4. The fermented material is then aged until its seed germination index reaches 130%~135% to obtain the functional compost.

2. The method for preparing functional compost as described in claim 1, characterized in that, In step S2, the composite microbial fermentation agent is mixed with 10% to 20% of its weight of humic acid carrier to form an agent-carrier complex before inoculation. The humic acid carrier is humic acid obtained by alkaline extraction of weathered coal, and its particle size is 100 to 200 mesh.

3. The method for preparing functional compost as described in claim 2, characterized in that, The preparation method of the humic acid carrier includes the following steps: Weathered coal is mixed with a 1% to 2% sodium hydroxide solution at a solid-liquid ratio of 1:5 to 10. The mixture is stirred and extracted at 60℃ to 80℃ for 2 to 4 hours. The supernatant is collected by centrifugation, and the pH is adjusted to 2.0 to 3.0 with hydrochloric acid to precipitate humic acid. The precipitate is collected, dried, and pulverized to the specified particle size.

4. The method for preparing functional compost as described in claim 3, characterized in that, In step S3, after the temperature of the pile body first reaches and is maintained at 60°C~65°C for more than 24 hours, 0.5%~1.0% of diammonium hydrogen phosphate is added to the pile body according to the initial weight of the pile body.

5. The method for preparing functional compost as described in claim 4, characterized in that, In the post-maturation aging process of step S4, the material is piled up in an aging shed with rain and wind protection functions, and a layer of semi-mature material of the functional compost with a thickness of 5 cm to 10 cm is covered on the surface of the material pile. The seed germination index of the semi-mature material is 80% to 90%.

6. The method for preparing functional compost as described in claim 5, characterized in that, The method for preparing the semi-fermented material includes steps S1 to S3 as described in claim 1, and after the high-temperature fermentation stage is completed, the material is taken out when the temperature of the pile drops to 50°C, and its moisture content is controlled at 45% to 50%.

7. The method for preparing functional compost as described in claim 5, characterized in that, After step S4, the obtained functional compost is uniformly mixed with a water-retaining agent accounting for 5% to 10% of its weight, wherein the water-retaining agent is cross-linked potassium polyacrylate with a particle size of 0.5 mm to 2 mm.

8. The functional compost prepared by the method according to any one of claims 1 to 7.

9. The application of the functional compost as described in claim 8 in the restoration of degraded grazing grassland, characterized in that, Apply according to the following dosage based on the grassland degradation level: The application rate for severely degraded grassland is 35 to 40 tons / hectare, for moderately degraded grassland it is 30 to 35 tons / hectare, and for slightly degraded grassland it is 25 to 30 tons / hectare.

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