A kind of high humic acid organic fertilizer suitable for acid red soil improvement using pilose antler mushroom and tea tree mushroom residue and its preparation method

Abstract

The present application provides a kind of high humic acid organic fertilizer suitable for acid red soil improvement using deer mushroom and tea tree mushroom residue and its preparation method, the organic fertilizer uses deer mushroom and tea tree mushroom residue as main raw material, adds by biochar, calcium-magnesium phosphate fertilizer and superphosphate according to specific proportion Compound nitrogen preserving agent, and compound microbial inoculant.Through adjusting initial moisture content, control the highest temperature of heap and total fermentation period, after ripening drying is prepared into finished product.The present application utilizes the synergistic effect of three nitrogen preserving agents, realizes physical adsorption, chemical precipitation nitrogen fixation and acid inhibition ammonia volatilization, significantly reduces nitrogen loss, promotes humus synthesis, improves the performance of soil improvement and fertilizer efficiency of organic fertilizer, especially suitable for acid red soil improvement.

Description

Technical Field

[0001] This invention belongs to the field of agricultural solid waste resource utilization and new fertilizer technology, specifically involving a method for producing high humic acid organic fertilizer suitable for improving acidic red soil using the residue of deer antler mushroom and tea tree mushroom. Background Technology

[0002] The edible mushroom industry generates a large amount of mushroom residue annually, and its resource utilization is a key link in the green and circular development of agriculture. Mushroom residue is rich in organic matter and nutrients such as nitrogen, phosphorus, and potassium, making it an excellent composting material. Current mushroom residue composting technologies mostly employ a mixing method with livestock and poultry manure to adjust the carbon-nitrogen ratio and provide a nitrogen source. Some studies report that mixing tea tree mushroom residue with pig manure and inoculating it with microbial agents for aerobic composting yields a product that is weakly acidic to neutral, with high organic matter and total nutrient content. Applying this to navel orange orchards in red soil in Jiangxi Province can significantly improve yield and fruit quality. Furthermore, there are reports of using edible mushroom residue mixed with pig manure and inoculating it with thermophilic fibrous bacteria, resulting in a near-neutral pH mature compost after a longer composting period, with good levels of organic matter and total nutrients. However, current technologies generally rely on livestock and poultry manure, posing risks of heavy metals, antibiotic residues, and salt content. Moreover, the product's pH is often neutral or weakly acidic, limiting its ability to neutralize and improve the strongly acidic red soil in southern China.

[0003] The existing technologies generally have the following limitations: (1) The pH value of the products is low or neutral. The pH of the above products is between 6.6 and 8.0. For the strongly acidic red soil (pH is often below 5.5) widely distributed in southern regions such as Jiangxi, the ability to neutralize acidity is limited and the improvement effect is insufficient; (2) It relies on animal-derived raw materials (such as pig manure), which introduces secondary pollution risks such as heavy metals, antibiotic residues and high salt content, affecting the environmental safety of the products and long-term soil health; (3) There is room for improvement in the overall quality of the products. The organic matter content of the existing products is generally between 41% and 46%, and the total nutrients are mostly between 4% and 6.5%. The humic acid content is usually not a core indicator or is at a low level, making it difficult to achieve the goal of rapid and in-depth improvement of barren acidic soil; (4) There is a lack of process research on specific fungal residues (such as deer antler mushroom residue). There are currently no special reports on its resource-based preparation of organic fertilizer. The composting process parameters are unclear and there is a lack of efficient and targeted composting technology.

[0004] On the other hand, theoretical research on composting shows that the initial carbon-to-nitrogen ratio (C / N) is a key factor affecting the composting process and the properties of the final product. Literature indicates a negative correlation between the initial C / N ratio and the final pH: the lower the initial C / N ratio, the stronger the ammonification, the greater the accumulation of ammonium nitrogen, and the higher the final pH tends to be. Therefore, developing a specialized organic fertilizer that completely eliminates livestock and poultry manure, utilizes specific plant-derived inoculum, and achieves high pH, ​​high humic acid, and high nutrient levels through process innovation, while precisely improving acidic red soil, has significant technological innovation value and market application prospects. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a special organic fertilizer for acidic red soil with high humic acid content, high organic matter, high nutrient content, low nitrogen loss rate and low salinity, using deer antler mushroom residue and tea tree mushroom residue as the main raw materials, without adding any livestock and poultry manure, and using biochar, calcium magnesium phosphate fertilizer and superphosphate in a specific ratio as a compound nitrogen-retaining agent, combined with optimized composting process parameters.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A high-humic acid organic fertilizer suitable for improving acidic red soil is produced using the residue of *Flammulina velutipes* and *Flammulina acutissima*. The raw materials for its preparation, by dry weight, include:

[0008] 60-80 parts by weight of deer antler mushroom residue;

[0009] 20-40 parts by weight of tea tree mushroom residue;

[0010] The compound nitrogen-retaining agent is composed of biochar, calcium magnesium phosphate fertilizer and superphosphate mixed in a dry weight ratio of (2-4):(5-7):(1-3). The total amount of compound nitrogen-retaining agent added is 6%-10% of the dry weight of the above two bacterial residue mixtures.

[0011] The compound microbial inoculant is added at a rate of 0.5%-1.0% of the total dry weight of the stockpile.

[0012] The compound microbial agent contains one or more of Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis.

[0013] Its preparation method includes the following steps:

[0014] (1) Raw material processing and compounding: The deer antler mushroom residue and tea tree mushroom residue are crushed to a particle size of 1-2 cm, mixed in proportion, and the carbon-nitrogen ratio of the materials is adjusted to 20-25:1; compound nitrogen retaining agent and compound microbial agent are added to the materials, and then water is sprayed to adjust the moisture content of the materials to 65%-70%;

[0015] (2) Aerobic composting fermentation: The material is piled into windrows with a bottom width of 1.5-2.5m and a height of 1.0-1.5m or placed in a fermentation tank; during the composting process, the ventilation rate is 0.2L / (kg·min), and the ventilation method is intermittent ventilation, that is, ventilation is stopped after 2 hours and then stopped after 1 hour, and this cycle is repeated. When the pile temperature exceeds 65℃, the pile is turned over once every 3-5 days, and the main fermentation takes 25-30 days;

[0016] (3) Post-fermentation and drying: After the main fermentation is completed, the material pile height is reduced to 0.8-1.0m for post-fermentation treatment. The pile is turned over once a week and the post-fermentation treatment lasts for 10-15 days. After the post-fermentation is completed, the material moisture content is reduced to below 30% by natural sun drying or low-temperature drying at a temperature below 60℃.

[0017] (4) Screening and finished product: The dried material is screened through a 4-6mm sieve to remove large particles of impurities, and the finished organic fertilizer is obtained.

[0018] The advantages and beneficial effects of this invention are as follows:

[0019] 1. This invention overcomes the technical shortcomings of single nitrogen-retaining agents in bacterial residue composting, and for the first time proposes and verifies a technical solution for a composite nitrogen-retaining agent that combines biochar, calcium magnesium phosphate fertilizer, and superphosphate. In existing technologies, while calcium magnesium phosphate fertilizer has excellent nitrogen retention and humification-promoting effects, it is prone to causing low seed germination index (GI) due to excessive accumulation of ammonium nitrogen, posing a risk of phytotoxicity; superphosphate has a decent nitrogen retention effect, but its strong acidity severely inhibits the humification process and leads to salt stress (high EC); while biochar, although harmless to composting, has limited nitrogen-fixing capacity and a weak promoting effect on humification. This invention addresses the key bottlenecks of the aforementioned single-component approach by systematically studying the combined regulatory effects of three nitrogen-retaining agents at different ratios on nitrogen loss rate, GI, humification index (HI), and electrical conductivity (EC). It establishes a more scientific and comprehensive composting performance evaluation system, employing a normalized weighted scoring method that simultaneously considers nitrogen retention effect, safety, humification quality, and salinity risk, thus avoiding the one-sidedness of traditional evaluations that prioritize a single indicator (such as total nitrogen retention rate).

[0020] 2. Based on this, this invention reveals for the first time the synergistic effect mechanism of biochar, calcium magnesium phosphate fertilizer, and superphosphate in a specific ratio (dry weight ratio 3:6:1): calcium magnesium phosphate fertilizer provides Mg²⁺ and PO₄³⁻, which form struvite precipitate with NH₄⁺ to achieve chemical nitrogen fixation, while increasing the pH of the compost pile and promoting the synthesis and humification process of humic acid (HA); superphosphate inhibits the excessive volatilization of ammonia in the early stage of composting with an appropriate acidic environment, avoiding the inhibition of microbial activity and humification due to excessively low pH when used alone, and the H₂PO₄⁻ it provides can also form ammonium phosphate salt with NH₄⁺ to assist in nitrogen fixation; biochar utilizes its well-developed porous structure to exert physical adsorption, fixing NH₄⁺ and free toxic phenolic substances, thereby significantly increasing GI and reducing EC. Through the deep coupling of three pathways—chemical precipitation, acid-base buffering, and physical adsorption—precise control of nitrogen conversion and humification processes in the composting system is achieved. This not only solves the problems of excessive ammonium nitrogen and low GI caused by the use of calcium magnesium phosphate fertilizer alone, but also makes up for the shortcomings of superphosphate in inhibiting humification and biochar in nitrogen fixation, while avoiding the risk of excessive mineralization of organic carbon due to excessive biochar.

[0021] 3. Experimental data show that, under the optimal ratio (biochar: calcium magnesium phosphate: superphosphate = 3:6:1), the nitrogen loss rate of the compost is only 0.98%, far lower than the control (9.12%) and most single or compound treatments; the seed germination index is as high as 132.0%, significantly better than the calcium magnesium phosphate single treatment (90.42%) and some compound combinations, indicating that the product is completely non-toxic to plants; the humification index reaches 32.85%, with a significantly improved Humic acid-to-Foll ratio, and the humification quality is better than single biochar or superphosphate treatments; the electrical conductivity is only 780 μS / cm, far below the standard limit for composting (4000 μS / cm), and the salt risk is extremely low. The overall effect is optimal; the strongest synergistic effect can only be achieved at the specific ratio of 3:6:1. The absence of any component or deviation from the ratio will lead to significant shortcomings such as increased nitrogen loss rate and decreased GI or HI.

[0022] 4. In summary, this invention achieves for the first time a synergistic balance between high nitrogen retention, high humification quality, high biocompatibility, and low salinity risk in mushroom residue composting, effectively solving the technical problems of "nitrogen retention contradicting composting" and "difficulty in simultaneously promoting humification and inhibiting toxicity" in existing nitrogen-retaining agent technologies. By establishing a multi-index weighted evaluation system, this invention provides a new technical path and quantitative basis for the scientific formulation of nitrogen-retaining agents in mushroom residue composting. The prepared organic fertilizer product possesses both excellent agricultural safety and fertilizer efficiency, demonstrating significant environmental benefits and promising prospects for industrial application. Attached Figure Description

[0023] Figure 1 : Mechanism diagram of nitrogen fixation and decomposition promotion by different nitrogen-retaining agents;

[0024] Figure 2 Temperature changes during composting with different nitrogen-retaining agents;

[0025] Figure 3 Changes in pH value during composting with different nitrogen-retaining agents;

[0026] Figure 4 Changes in electrical conductivity during composting with different nitrogen-retaining agents;

[0027] Figure 5 Changes in seed germination index during composting with different nitrogen-retaining agents;

[0028] Figure 6 Changes in total organic carbon content during composting with different nitrogen-retaining agents;

[0029] Figure 7 Changes in humus content during composting with different nitrogen-retaining agents;

[0030] Figure 8 Changes in humic acid content during composting with different nitrogen-retaining agents;

[0031] Figure 9 Changes in fulvic acid content during composting with different nitrogen-retaining agents;

[0032] Figure 10 Changes in the humification index during composting with different nitrogen-retaining agents;

[0033] Figure 11 Changes in humification rate during composting with different nitrogen-retaining agents;

[0034] Figure 12 Changes in the Hufb ratio during composting with different nitrogen-retaining agents;

[0035] Figure 13 Changes in total nitrogen content during composting with different nitrogen-retaining agents;

[0036] Figure 14 Changes in ammonium nitrogen content during composting with different nitrogen-retaining agents;

[0037] Figure 15 Changes in nitrate nitrogen content during composting with different nitrogen-retaining agents;

[0038] Figure 16 Heatmap showing the correlation between nitrogen index, maturity, and humification in compost treated with calcium magnesium phosphate fertilizer. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto. The *Tea Tree Mushroom* mycelium residue was obtained from Jiangxi Licai Edible Fungus Co., Ltd. Biochar was prepared by high-temperature pyrolysis of corn straw at 500℃. Calcium magnesium phosphate fertilizer (Jiangxi Jianglin Fertilizer Co., Ltd.) and superphosphate (Yidu Xingfa Chemical Co., Ltd.), and the inoculant were purchased from Shandong Huakang Biotechnology Co., Ltd. In the following embodiments, the raw material amounts are all based on dry weight; in actual production, they will be converted to wet weight according to the moisture content of the mycelium residue.

[0040] Preliminary Experiment: Effects of Different Nitrogen-Retaining Agents on the Composting Process and Efficacy of Microbial Residue

[0041] The physicochemical properties of compost raw materials and nitrogen-retaining agents are shown in Table 1.

[0042] Table 1 Physicochemical properties of compost raw materials and nitrogen-retaining agents

[0043] pH value 7.31±0.01 8.50±0.01 9.34±0.02 2.27±0.01 7.22±0.02 Electrical conductivity (μS / cm) 1555±5 2813±10 1574±6 18280±108 3438±19 Total carbon / % 46.41±0.12 37.17±0.09 42.08±0.05 / / Total nitrogen / % 1.73±0.01 2.64±0.01 1.49±0.003 / / Carbon-to-nitrogen ratio 26.79±0.33 14.09±0.26 28.24±0.37 / / Moisture content / % 20.34±1.47 21.03±1.05 / / /

[0044] This experiment included four treatments, using tea tree mushroom residue and traditional Chinese medicine residue as composting materials. The carbon-to-nitrogen ratio of the compost pile was adjusted to approximately 25:1. The amount of compound microbial agent added was 1% of the dry basis of the compost. A control group (CK) without any nitrogen-retaining agent was used. The other three treatments were biochar (BAC), superphosphate (SSP), and calcium magnesium phosphate (CMP), with each treatment added at 10% of the dry basis of the compost. Detailed proportions for each treatment group are shown in Table 2. The initial moisture content of the compost material was adjusted to approximately 64±1%. The ventilation rate was 0.2 L / (kg·min), and intermittent ventilation was used, with a 1-hour interval after 2 hours of ventilation. The composting experiment lasted for 22 days. The compost pile temperature (T) and ambient temperature (TRT) were measured three times daily, and their average values ​​were recorded. The compost pile was turned every 3 days, and samples were taken on days 1, 3, 6, 10, 13, 17, and 22. Five-point sampling was used, and the sample was divided into two parts. One part was air-dried, pulverized, and sieved through a 0.1 mm sieve for subsequent determination, while the other part was stored at 4℃ for fresh sample determination.

[0045] Table 2 Composting treatment ratios with different nitrogen-retaining agents

[0046] CK 34.2 4 50 24.88 65.53 / BAC 34.2 4 50 24.88 63.8 Biochar SSP 34.2 4 50 24.88 63.8 Superphosphate CMP 34.2 4 50 24.88 63.8 Calcium magnesium phosphate fertilizer

[0047] 1.1 Experimental and analytical methods

[0048] The pH, electrical conductivity (EC), and seed germination index (GI) of the above samples were determined. Total organic carbon (TOC) was determined using the potassium dichromate oxidation method. The determination methods for humic substances (HS), humic acid (HA), and fulvic acid (FA) followed the guidelines in NY-T1867-2010, "Determination of Soil Humic Substances - Sodium Pyrophosphate-Sodium Hydroxide Extraction - Potassium Dichromate Oxidation Capacitance Method." Total nitrogen (TN) was determined according to the methods described in Bao Shidan's third edition of "Soil Agrochemical Analysis," and ammonia nitrogen (NH4+) was also measured. + The determination of nitrate nitrogen (NO3) is based on the standard LY / T 1228-2015 "Determination of Nitrogen in Forest Soils - Indophenol Blue Colorimetric Method". - The determination of nitrate nitrogen (N) should refer to GB / T 32737-2016 "Determination of nitrate nitrogen in soil - Ultraviolet spectrophotometry".

[0049] 1.2 Data Statistics and Analysis

[0050] Origin was used for data processing and chart generation; R language was used for data analysis, including mean calculation, analysis of variance, correlation coefficient calculation, etc., and T-test and one-way ANOVA test were used for significance analysis.

[0051] Nitrogen loss rate (Nloss / %), nitrogen fixation rate (N s The calculation methods for / %) are shown in Equation (1) and Equation (2) respectively.

[0052] (1)

[0053] (2)

[0054] In formula (1), N1 and N2 are the nitrogen content at the beginning and end of composting, respectively (%), and M1 and M2 are the fresh weight at the beginning and end of composting, respectively (kg). In formula (2), N CK N T Nitrogen loss rates (%) were 1% for the control group and the treatment group, respectively.

[0055] The calculation method for the humification index is shown in equations (3) to (5).

[0056] Hoogewerf (HA / FA) (3)

[0057] Humus rate (HR, %) (4)

[0058] Humus index (HI, %) (5)

[0059] 2.1 Effects of different nitrogen-retaining agents on compost maturity

[0060] Compost maturity is evaluated using maturity indicators. Temperature reflects the activity of microorganisms during composting and is a direct indicator of compost stability; pH ​​value is an important indicator of compost acidity and alkalinity; EC is an important indicator of the basic ion content of compost extract; GI is an important parameter characterizing compost maturity and phytotoxicity. These indicators are often used to evaluate compost maturity.

[0061] The fermentation temperature during composting is from Figure 2 As shown, all four treatment groups experienced a heating period, a high-temperature period, and a cooling period. The temperatures in the CMP and SSP groups were significantly lower than those in the CK group (p < 0.05), because the H2PO4 in calcium magnesium phosphate fertilizer... - Or PO4 3-The components inhibited microbial activity, thus suppressing or delaying composting temperature. The strong acidity of superphosphate lowered the initial pH of the compost pile, inhibiting the activity of some mesophilic microorganisms and consequently reducing the fermentation temperature. There was no significant difference in temperature between the BAC and CK groups (p < 0.05). This is because biochar has a larger specific surface area and more developed pores, and the heat generated by the compost pile is offset by the accelerated heat loss caused by its structure, resulting in no significant difference in fermentation temperature between the BAC and control groups. The highest fermentation temperatures for the CK and BAC groups were 67.5℃ and 68℃, respectively, remaining above 60℃ for 6 days. The highest fermentation temperature for the CMP group reached 65.83℃, remaining above 60℃ for 5 days. The highest fermentation temperature for the SSP group was 54.67℃, remaining above 50℃ for 5 days. In conclusion, calcium magnesium phosphate and superphosphate inhibited the fermentation temperature of the compost, while biochar had no negative impact on the temperature of the microbial residue compost. The order of temperature during fermentation was: CK and BAC > CMP > SSP.

[0062] pH changes during composting, such as Figure 3 As shown, the pH of the CK, BAC, and CMP groups exhibited a three-stage trend of first increasing, then decreasing, and then increasing again, ultimately resulting in a slightly alkaline pH in the compost pile. In contrast, the pH of the SSP group showed a trend of first increasing and then decreasing, ultimately resulting in a slightly acidic pH in the compost pile. During the warming period of composting, the pH of all treatments showed an upward trend because the rapid proliferation of microorganisms accelerated the decomposition of organic matter, converting organic nitrogen into ammonia nitrogen which accumulated in the pile, leading to an increase in pH. In the middle stage, the pH of all treatments decreased due to ammonia volatilization and the production of H+ by nitrification. + And the accumulation of organic acids. Later, the pH of the CK, BAC, and CMP groups rose again or stabilized because organic matter gradually degraded, ammoniation weakened, but the acids produced by nitrification reached equilibrium with residual alkaline substances (such as carbonates), while some ammonium nitrogen accumulated in the compost pile. However, in the SSP group, the pH showed a downward trend in the later stages of composting because superphosphate lowered the initial pH, inhibited microbial activity, and continuously provided H₂. + The pH values ​​were adjusted to ensure a sustained decrease after reaching a peak, without a significant later rise. Throughout the composting process, the pH values ​​of the treatments were in the following order: CK and BAC > CMP > SSP. This was determined by the initial pH values ​​of the different treatment groups. At the end of composting, the pH values ​​of all four treatment groups stabilized between 6.8 and 8.5, meeting the compost maturity standards.

[0063] EC changes during composting, such as Figure 4 As shown, the EC changes in the four treatment groups exhibited a trend of first decreasing and then increasing. During the heating period, the CMP and SSP groups showed a significant decreasing trend, mainly due to the volatilization of NH3 at high temperatures and the introduction of Ca by phosphate additives. 2 + Mg 2+ and PO43- Plasma and NH4 + Both precipitation reactions and the presence of ions reduced the concentration of free ions in the solution. The CK and BAC groups showed a slow decreasing trend, due to the adsorption of NH3 volatilized at high temperatures by the porous nature of the biochar and inoculum. Later, the EC (ecliptic concentration) of all four treatment groups increased, mainly due to the continued degradation of organic matter releasing new soluble salt ions and the concentration effect caused by moisture evaporation from the compost pile, leading to a rebound in the total ion concentration. Throughout the composting process, due to differences in the mineral composition of the different nitrogen-retaining agents, the EC values ​​of the treatment groups were SSP > CMP > BAC > CK. After composting, the EC of all four treatment groups was less than 1900 μS / cm, meeting the maturity standard (EC < 4000 μS / cm).

[0064] GI changes during composting with four different nitrogen-retaining agents, as follows: Figure 5 As shown. During the composting heating period, the GI of all four treatment groups was greater than 90%, indicating that most of the toxic substances had degraded during the storage of the bacterial residue. On day 1 of composting, the initial GI of the CMP group (116.05%) was greater than that of the CK group (91.79%), indicating that the Mg in the calcium magnesium phosphate fertilizer... 2+ and PO4 3- Plasma and NH4 in the pile + A precipitation reaction occurred, reducing ammonia volatilization and further decreasing the toxicity of the compost to seeds. In the later stages of composting, the glycemic index (GI) of the SSP, CMP, and BAC treatments all showed a decreasing trend. The nitrogen-retaining agent inhibited the activity of nitrifying bacteria, leading to hindered nitrification, resulting in ammonium nitrogen accumulation and nitrate nitrogen deficiency. This imbalance in nitrogen form ratio is also detrimental to seed germination. The control (CK) showed an increasing trend, indicating that the inhibitors in the compost were gradually degraded. After composting, the GIs of the CK, BAC, SSP, and CMP groups were 123.48%, 113.71%, 103.91%, and 90.42%, respectively, all meeting the compost maturity standard (GI > 70%).

[0065] TOC changes during composting, such as Figure 6 As shown, the TOC content in the four treatment groups showed a decreasing trend, mainly due to the decomposition activity of microorganisms, which mineralized organic carbon into gases such as CO2 and released them. After composting, the TOC contents of the CK, BAC, SSP, and CMP groups were 34.4%, 32.8%, 34.2%, and 33.9%, respectively, representing decreases of 12.04%, 14.99%, 6.90%, and 9.64% compared to the initial values. The TOC degradation rate of the BAC group was significantly greater than that of the CK group (p < 0.05), while the TOC degradation rates of the SSP and CMP groups were significantly less than those of the CK group (p < 0.05). Figure 2The fermentation temperature data indicates that adding biochar can maintain a higher compost temperature and promote the degradation of organic matter; while adding superphosphate and calcium magnesium phosphate inhibits the initial temperature rise of composting, resulting in a lower overall temperature and thus slowing down the degradation of organic matter.

[0066] 2.2 Effects of different nitrogen-retaining agents on compost humification

[0067] Changes in humic components and humification indices during composting process are as follows: Figure 7-12 As shown. Figure 7 As shown, during the high-temperature period, the HS content of humic substances in the four treatment groups first increased and then decreased; during the cooling period, the CK and BAC groups first remained stable and then decreased, while the SSP and CMP groups first increased and then decreased. The final HS content of the four groups, in descending order, was: CK > CMP > SSP > BAC. Compared with the initial values, the HS content in the CK, SSP, and BAC groups decreased by 3.93%, 1.55%, and 10.08%, respectively, while the CMP group increased by 0.42%, indicating that calcium magnesium phosphate fertilizer has the effect of maintaining a stable total humic substance content.

[0068] like Figure 8 As shown, the treatment groups exhibited different trends. During the high-temperature period (3–10 days), the HA content in the CK, CMP, and BAC groups increased rapidly, while the HA content in the SSP group decreased. The HA content in the SSP group increased rapidly during (10–13 days). During the cooling period (13–22 days), the HA content in the CK and CMP groups increased slowly, while the HA content in the BAC and SSP groups decreased slowly. The increase in HA content in the CK and CMP groups mainly occurred during the high-temperature and cooling stages, during which microbial activity was high, continuously decomposing FA and forming precursor substances, which then polymerized to form HA. During the cooling period, the HA content in the BAC and SSP groups showed a decreasing trend. Due to the reduced microbial activity and decreased precursor substances, the synthesis rate of HA slowed down, and the degradation rate of the structurally unstable HA temporarily exceeded the synthesis rate, resulting in a temporary decrease in HA content. At the end of composting, the HA contents of the CK, BAC, SSP, and CMP groups were 24.70%, 21.93%, 21.90%, and 23.97%, respectively. Compared with the initial values, the HA contents of the CK, BAC, SSP, and CMP groups increased by 15.84%, 8.07%, 3.96%, and 15.82%, respectively. At the end of composting, the HA contents and HA content increase rate of the BAC and SSP groups were significantly lower than those of the CK group (p < 0.05), while there was no significant difference between the CMP group and the CK group. The results indicate that biochar and superphosphate inhibited the synthesis of HA in compost, while calcium magnesium phosphate fertilizer had no negative impact on the synthesis of HA in compost. Biochar adsorbed and fixed the precursor substances, while superphosphate lowered the pH of the compost pile and inhibited microbial activity.

[0069] Depend on Figure 9As shown, the changes in fulvic acid (FA) in each treatment group exhibited the same trend: a rapid increase during the high-temperature period (3–6 days) followed by a gradual decrease after day 6. During aerobic composting, FA content typically peaks during the high-temperature period due to rapid organic matter decomposition, and then gradually declines in the later stages or after the high-temperature period. This indicates that unstable small-molecule FA is being utilized or polymerized by microorganisms into more stable large-molecule HA, leading to stable and mature compost products. Compared to initial values, the FA content in the CK, BAC, SSP, and CMP groups decreased by 28.77%, 31.88%, 9.73%, and 21.23%, respectively. The BAC group showed the largest decrease in FA, indicating that precursor substances were adsorbed and fixed by biochar. The SSP group showed the smallest decrease in FA, as its low pH inhibited the synthesis of HA from FA. The CMP group showed a lower decrease in FA than the CK group, but the increase in HA was not significantly different from the CK group, indicating that the CMP group retained more FA and converted it more effectively into HA, rather than being completely mineralized and decomposed. This indirectly suggests that the FA conversion pathway is more inclined towards HA synthesis than simple degradation.

[0070] Depend on Figure 10-12 As shown, the humification index (HI) of the four treatment groups showed an upward trend, indicating that organic carbon was continuously transformed into stable humus, and the degree of humification gradually deepened. The humification rate (HR) showed an initial upward trend followed by a downward trend. During the high-temperature period, the synthesis and accumulation of HS (high-temperature organic carbon) or its slow decline was accompanied by a rapid decrease in TOC (total organic carbon), leading to an upward trend in the HR ratio. In the later stages of cooling, the decomposition and consumption rate of HS exceeded its synthesis rate, while TOC degradation slowed down, resulting in a decrease in the HR ratio. The Hufb ratio (HA / FA) ​​showed an initial downward trend followed by an upward trend. The fundamental reason is the dynamic competition between the synthesis and decomposition of HA and FA during composting. During the high-temperature period, rapid microbial metabolism led to a relative increase in FA or the decomposition of HA, causing a decrease in the Hufb ratio. As the composting time increased, the synthesis and transformation of FA into HA became dominant, driving a continuous increase in the Hufb ratio. After composting, the humification rates (HR) of the CK, BAC, SSP, and CMP groups were 43.33%, 41.35%, 41.34%, and 42.38%, respectively; the humification indices (HI) were 29.14%, 27.12%, 25.99%, and 28.65%, respectively; and the Hoover-Fruits ratios (HA / FA) ​​were 2.05, 1.91, 1.69, and 2.09, respectively. An HA / FA ratio greater than 1.9 indicates the maturity and stability of the compost, and the degree of humification increases with the increase of this ratio, indicating that the CK, BAC, and CMP groups had higher maturity and stability, with the CMP group having the highest.

[0071] In summary, compared with the control (CK), calcium magnesium phosphate fertilizer had no negative impact on the humification of bacterial residue and traditional Chinese medicine residue compost, while superphosphate inhibited the humification of compost. Calcium magnesium phosphate fertilizer provides nutrients such as phosphorus, calcium, and magnesium, creating a weakly alkaline pH environment suitable for microbial growth; the strong acidity of superphosphate lowered the pH of the compost, inhibiting the activity of functional microorganisms and hindering the humification process. Ultimately, the degree of humification in the different treatment groups, from highest to lowest, was: CMP > BAC > SSP.

[0072] 2.3 Effects of different nitrogen-retaining agents on nitrogen retention in composting

[0073] Changes in total nitrogen during composting, such as Figure 13 As shown, the total nitrogen (TN) in each treatment increased rapidly from day 1 to day 10. Later, the CK, BAC, and CMP groups showed an increasing trend, while the SSP group showed a decreasing trend. After composting, the TN contents of the CK, BAC, SSP, and CMP groups were 18.93 g / kg, 18.36 g / kg, 17.01 g / kg, and 18.88 g / kg, respectively. Compared with the initial values, the TN contents of the CK, BAC, SSP, and CMP groups increased by 17.50%, 18.35%, 10.46%, and 20.00%, respectively. This indicates that adding calcium magnesium phosphate fertilizer can significantly increase the TN content, while adding superphosphate cannot significantly increase the TN content of the fungal residue and traditional Chinese medicine residue compost.

[0074] Changes in ammonium nitrogen during composting, such as Figure 14 As shown, during composting, the NH4 content of the CK, BAC, and SSP groups... + -N showed a trend of first increasing and then decreasing, while the CMP group showed a trend of first increasing, then decreasing, and then increasing again. After composting, the NH4+ levels in the CK, BAC, SSP, and CMP groups were... + The -N content was 288.45 mg / kg, 354.72 mg / kg, 450.34 mg / kg, and 1290.89 mg / kg, respectively, representing increases of 264.87 mg / kg, 318.22 mg / kg, 415.02 mg / kg, and 1243.72 mg / kg compared to the initial values. The NH4+ content in the BAC, SSP, and CMP groups... + The increase in NH4+ content was significantly greater than that in control (p < 0.05), indicating that biochar, calcium magnesium phosphate, and superphosphate can fix NH4+ in fungal residue and traditional Chinese medicine residue compost. + -N, of which calcium magnesium phosphate fertilizer fixes NH4 + -N is the most efficient.

[0075] Changes in nitrate nitrogen during composting, such as Figure 15As shown, the trends in nitrate nitrogen changes varied significantly among the treatment groups during composting. The CK group exhibited a fluctuating trend, while the BAC and SSP groups showed a trend of first increasing and then decreasing. The CMP group showed a trend of first increasing, then decreasing, and then increasing again. After composting, the NO3 levels in the CK, BAC, SSP, and CMP groups... − The nitrate nitrogen (N) content was 7.859 mg / kg, 2.810 mg / kg, 3.822 mg / kg, and 10.318 mg / kg, respectively. Compared with the initial values, the CK and CMP groups increased by 12.46% and 182.39%, respectively, while the BAC and SSP groups decreased by 54.32% and 55.52%, respectively. The nitrate nitrogen content and increase rate of the BAC and SSP groups were significantly lower than those of the CK group (p < 0.05), while the nitrate nitrogen content and increase rate of the CMP group were significantly higher than those of the CK group (p < 0.05). This indicates that the addition of calcium magnesium phosphate fertilizer can significantly increase the accumulation of nitrate nitrogen and promote nitrification.

[0076] During composting, organic matter is continuously degraded by microorganisms, resulting in a significant decrease in the mass of the compost pile after composting. Furthermore, a concentration effect occurs, leading to a passive increase in nitrogen concentration. Table 3 lists the changes in dry weight, total nitrogen, ammonium nitrogen, and nitrate nitrogen content before and after composting.

[0077] Table 3. Changes in dry weight, total nitrogen, ammonium nitrogen, and nitrate nitrogen content before and after composting.

[0078] Table 3. Changes in dry weight, total nitrogen, ammonium nitrogen, and nitrate nitrogen content before and after composting. CK 28.56 22.09 <![CDATA[16.11±0.02 a ]]> <![CDATA[18.93±0.26 a ]]> <![CDATA[23.58±2.57 c ]]> <![CDATA[288.45±4.16 d ]]> <![CDATA[6.99±0.19 b ]]> <![CDATA[7.86±0.26 b ]]> BAC 29.79 23.06 <![CDATA[15.52±0.14 c ]]> <![CDATA[18.36±0.08 b ]]> <![CDATA[36.50±2.06 b ]]> <![CDATA[354.72±1.81 c ]]> <![CDATA[6.15±0.12 c ]]> <![CDATA[2.81±0.22 d ]]> SSP 30.49 24.37 <![CDATA[15.40±0.17 c ]]> <![CDATA[17.01±0.26 c ]]> <![CDATA[35.32±2.17 b ]]> <![CDATA[450.34±2.40 b ]]> <![CDATA[8.59±0.31 a ]]> <![CDATA[3.82±0.16 c ]]> CMP 30.87 25.43 <![CDATA[15.73±0.04 b ]]> <![CDATA[18.88±0.01 a ]]> <![CDATA[47.17±2.15 a ]]> <![CDATA[1290.89±2.68 a ]]> <![CDATA[3.65±0.25 d ]]> <![CDATA[10.31±0.11 a ]]>

[0079] Based on the dry weight and total nitrogen content on a dry basis before and after composting, the nitrogen loss rate and nitrogen fixation rate were calculated, and the results are shown in Table 4. The increase rates of ammonium nitrogen and nitrate nitrogen in the CMP group were significantly higher than those in the CK group (p < 0.05), while the increase rates of ammonium nitrogen and nitrate nitrogen in the BAC and SSP groups were significantly lower than those in the CK group (p < 0.05). This indicates that the addition of calcium magnesium phosphate fertilizer mainly achieves nitrogen retention by fixing ammonium nitrogen and nitrate nitrogen. In summary, the nitrogen retention effect of different nitrogen retaining agents is in the order of CMP > SSP > BAC. The treatment with calcium magnesium phosphate fertilizer resulted in the lowest nitrogen loss rate and the highest nitrogen fixation rate, which can significantly reduce nitrogen loss. Therefore, calcium magnesium phosphate fertilizer should be the preferred choice for nitrogen retention in the composting of fungal residue and traditional Chinese medicine residue.

[0080] Table 4. Change rates and nitrogen retention effects of various nitrogen forms before and after composting (%)

[0081] CK <![CDATA[1129.56±116.11 b ]]> <![CDATA[12.55±6.71 b ]]> <![CDATA[17.50±1.44 b ]]> <![CDATA[9.12±1.11 a ]]> 0±0d BAC <![CDATA[873.43±60.03 c ]]> <![CDATA[-54.35±2.75 c ]]> <![CDATA[18.35±0.58 b ]]> <![CDATA[8.39±0.45 b ]]> <![CDATA[7.99±4.96 c ]]> SSP <![CDATA[1177.09±71.72 b ]]> <![CDATA[-55.52±0.29 c ]]> <![CDATA[10.46±0.45 c ]]> <![CDATA[6.32±0.38 c ]]> <![CDATA[30.68±4.18 b ]]> CMP <![CDATA[2639.38±119.29 a ]]> <![CDATA[183.14±22.17 a ]]> <![CDATA[20.00±0.27 a ]]> <![CDATA[1.52±0.23 d ]]> <![CDATA[83.34±2.47 a ]]>

[0082] 2.4 Key Factors Affecting Humification and Nitrogen Loss of Different Nitrogen-Retaining Agents

[0083] Analysis of composting humification and nitrogen indices showed that the CMP group could simultaneously promote composting humification and reduce nitrogen loss. Therefore, the CMP treatment was selected for composting nitrogen indices (TN, NH4). + -N, NO3 − Pearson correlation analysis of N, maturity (pH, T, GI, EC) and humification (HA, FA, HA / FA, TOC, HI) was used to identify key factors influencing humification and nitrogen loss, such as Figure 16 As shown. Correlation analysis indicates that pH is related to TN and NH4+. + -N, NO3 − -N showed a positive correlation and a significant negative correlation with TOC. This may be because calcium magnesium phosphate fertilizer interacts with NH4 through magnesium and phosphorus sources. + -N forms struvite, fixing ammonia nitrogen. Simultaneously, its alkalinity increases the pH of the compost pile, creating conditions for nitrate nitrogen conversion and thus achieving nitrogen retention. pH shows a significant negative correlation with TOC, possibly because as composting progresses, TOC rapidly decreases due to mineralization, while the decomposition of nitrogen-containing organic matter releases ammonia nitrogen, leading to a continuous increase in pH, manifested as a negative correlation between pH and TOC. This indicates that pH, through complex and dynamic changes, simultaneously regulates carbon degradation and nitrogen conversion, making it a core indicator affecting the carbon and nitrogen cycle.

[0084] HA and TN, NH4 + -N showed a significant positive correlation with HA and a significant negative correlation with TOC. During humification, nitrogen is fixed and synthesized into the complex structure of HA, forming stable humic acid nitrogen (HA-N). Therefore, the synthesis and accumulation of HA are synchronous with the increase in TN retention rate or relative content in compost products (concentration effect), showing a positive correlation. During composting, easily degradable organic carbon is mineralized into CO2 by microorganisms, leading to a rapid decrease in TOC content. At the same time, these decomposition products, as precursors, synthesize stable humic substances, such as HA, through polymerization, condensation, and other reactions. Throughout the composting process, the decrease in TOC and the increase in HA occur synchronously, showing a negative correlation. HA / FA showed a significant positive correlation with HA and a significant negative correlation with FA, indicating that unstable FA continuously transforms into more stable HA. The accumulation of HA and the decrease in FA occur synchronously, leading to a continuous increase in the HA / FA ratio. HI is associated with TN and NH4. + -N, HA, and HA / FA showed a significant positive correlation, while TOC showed a significant negative correlation, revealing a strong correlation between carbon and nitrogen transformation and humification during composting. This indicates that HA is the core substance driving the humification process and determining the degree of humification, while TN and NH4+ are significantly negatively correlated. + -N and TOC are key indicators affecting the degree of humification.

[0085] In summary, while all three nitrogen-retaining agents can reduce nitrogen loss, their mechanisms of action and overall effects differ significantly, and each has its own technical limitations that make it difficult to achieve both simultaneously. CMP performs exceptionally well in nitrogen fixation and humification, but its low GI may be due to the accumulation of high ammonium nitrogen; biochar does not inhibit fermentation, but its nitrogen fixation capacity is limited, and its humification effect is only average.

[0086] Calcium magnesium phosphate (CMP): It has the most outstanding nitrogen retention effect (nitrogen loss rate of only 1.52% and nitrogen fixation rate as high as 83.34%) and can effectively promote humification (Hydrogen-Follmann ratio HA / FA of 2.09). However, it significantly inhibits the temperature rise process of composting (maximum temperature of 65.83℃, lower than 67.5℃ of the control group) and leads to a significant decrease in the seed germination index (GI) of the final product (90.42%, the lowest among all treatments), indicating that it has certain phytotoxicity risks and affects the biosafety of the product.

[0087] Superphosphate (SSP): It has a certain nitrogen retention effect (nitrogen loss rate of 6.32%), and its product GI (103.91%) is higher than that of calcium magnesium phosphate fertilizer treatment. However, it severely inhibits the humification process of compost (humification index HI is only 25.99%, and Hufubi HA / FA is only 1.69, both of which are the lowest among all treatments), resulting in a decline in product quality. At the same time, its electrical conductivity EC value (1381 μS / cm) is significantly higher, increasing the risk of salt stress.

[0088] Biochar (BAC): It has no negative impact on compost maturity (GI is 113.71%), but it has the worst nitrogen retention effect (nitrogen loss rate of 8.39% and nitrogen fixation rate of only 7.99%), and it leads to excessive degradation of total organic carbon (TOC) (degradation rate of 14.99%), which is not conducive to the preservation of organic matter in fertilizer.

[0089] In summary, a single nitrogen-retaining agent cannot simultaneously meet the comprehensive requirements of high decomposition safety (high GI, low EC), high humification quality (high HI, high HA / FA), and high nitrogen retention (low nitrogen loss): calcium magnesium phosphate fertilizer has the best nitrogen retention and humification, but its GI is relatively low; superphosphate has decent nitrogen retention but severely inhibits humification and has excessively high EC; biochar is harmless to decomposition but has weak nitrogen retention and humification promotion abilities. Therefore, there is an urgent need to develop a composite nitrogen-retaining agent that synergistically leverages the advantages of all three while avoiding their respective shortcomings.

[0090] To overcome the shortcomings of single nitrogen-retaining agents and verify the technical concept of synergistic effect of compound formulations, a systematic orthogonal optimization experiment was conducted. The following examples use *Pleurotus ostreatus* and *Pleurotus ostreatus* (dry weight ratio 7:3) as the main raw materials, with a total fermentation cycle of 40 days, and other process parameters maintained within appropriate ranges. The dry weight ratios of biochar (A), calcium magnesium phosphate (B), and superphosphate (C) were adjusted based on the total addition of the three nitrogen-retaining agents accounting for 8% of the dry weight of the mixture. Based on the results of previous single-factor experiments, the level ranges of each factor were set as follows: A=2-4, B=5-7, C=1-3, and A+B+C=10 (i.e., the sum of the dry weight ratios is 10). A three-factor, three-level L9(3^3) orthogonal array was used for design, with nitrogen loss rate (N... loss Seed germination index (GI), humification index (HI), and electrical conductivity (EC) were used as core evaluation indicators for comprehensive scoring. Specific implementation methods, experimental design, and results are shown below.

[0091] Example 1

[0092] Raw materials: 6.5 tons (dry weight) of deer antler mushroom residue and 3.5 tons (dry weight) of tea tree mushroom residue.

[0093] Preparation of compound nitrogen-retaining agent: Take 0.16 tons of biochar, 0.56 tons of calcium magnesium phosphate fertilizer, and 0.08 tons of superphosphate. The dry weight ratio of the three is 2:7:1. The total amount added is 8% of the dry weight of the mixed bacterial residue, i.e., 0.8 tons.

[0094] Compound microbial inoculant: Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis are mixed at a live count ratio of 1:1:2, with a total live count of 1.2 × 10⁻⁶. 8 CFU / g, addition amount 70kg.

[0095] Organic fertilizer preparation: Deer antler mushroom residue and tea tree mushroom residue were crushed to a particle size of 1-2 cm and mixed in a dry weight ratio of 6.5:3.5. The initial pH was measured to be 6.8, and the C / N ratio was 23:1. A prepared compound nitrogen-retaining agent and compound microbial inoculant were added and thoroughly mixed. Water was sprayed to adjust the moisture content to 66%. Windrow fermentation was adopted, with a base width of 2.5 m and a height of 1.5 m for primary fermentation. The ventilation rate was 0.2 L / (kg·min), using intermittent ventilation, i.e., ventilation was stopped after 2 hours and then interrupted for 1 hour, repeating this cycle. When the pile temperature exceeded 65℃, the pile was turned over every 3 days, for a total of 9 times. After the primary fermentation period, post-fermentation treatment was carried out, reducing the pile height to 1.0 m and turning it once a week for 13 days. The total fermentation time was 40 days. Finally, the material was dried at 55℃ to a moisture content of 28% and passed through a 4 mm sieve.

[0096] Example 2

[0097] Raw materials: 7 tons (dry weight) of deer antler mushroom residue and 3 tons (dry weight) of tea tree mushroom residue.

[0098] Preparation of compound nitrogen-retaining agent: Take 0.16 tons of biochar, 0.48 tons of calcium magnesium phosphate fertilizer, and 0.16 tons of superphosphate. The dry weight ratio of the three is 2:6:2. The total amount added is 8% of the dry weight of the mixed bacterial residue, i.e., 0.8 tons.

[0099] Compound microbial inoculant: Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis are mixed at a live count ratio of 1:1:2, with a total live count of 1.2 × 10⁻⁶. 8 CFU / g, addition amount 80 kg.

[0100] Organic fertilizer preparation: Deer antler mushroom residue and tea tree mushroom residue were crushed to a particle size of 1-2 cm and mixed at a dry weight ratio of 7:3. The initial pH was measured to be 6.9, and the C / N ratio was 22:1. A prepared compound nitrogen-retaining agent and compound microbial inoculant were added and thoroughly mixed. Water was sprayed to adjust the moisture content to 68%. Windrow fermentation was adopted, with a base width of 2 m and a height of 1.2 m for primary fermentation. The ventilation rate was 0.2 L / (kg·min), using intermittent ventilation, i.e., ventilation was stopped after 2 hours and then interrupted for 1 hour, repeating this cycle. When the pile temperature exceeded 65℃, the pile was turned over every 4 days, for a total of 7 times. After the primary fermentation period, post-fermentation treatment was carried out, reducing the pile height to 0.9 m and turning it once a week for 12 days. The total fermentation time was 40 days. Finally, the material was dried at 50℃ to a moisture content of 28% and passed through a 4 mm sieve.

[0101] Example 3

[0102] Raw materials: 7.5 tons (dry weight) of deer antler mushroom residue and 2.5 tons (dry weight) of tea tree mushroom residue.

[0103] Preparation of compound nitrogen-retaining agent: Take 0.16 tons of biochar, 0.40 tons of calcium magnesium phosphate fertilizer, and 0.24 tons of superphosphate. The dry weight ratio of the three is 2:5:3. The total amount added is 8% of the dry weight of the mixed bacterial residue, i.e., 0.8 tons.

[0104] Compound microbial inoculant: Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis are mixed at a live count ratio of 1:1:2, with a total live count of 1.2 × 10⁻⁶. 8 CFU / g, addition amount 100 kg.

[0105] Organic fertilizer preparation: Deer antler mushroom residue and tea tree mushroom residue were crushed to a particle size of 1-2 cm and mixed at a dry weight ratio of 7.5:2.5. The initial pH was measured to be 6.7, and the C / N ratio was 21:1. A prepared compound nitrogen-retaining agent and compound microbial inoculant were added and thoroughly mixed. Water was sprayed to adjust the moisture content to 70%. Windrow fermentation was adopted, with a base width of 1.5 m and a height of 1.0 m. The primary fermentation was carried out at a ventilation rate of 0.2 L / (kg·min), using intermittent ventilation (ventilating for 2 hours, stopping after 1 hour, and repeating this cycle). When the pile temperature exceeded 65℃, the pile was turned over every 5 days, for a total of 6 times. After the primary fermentation period, a post-fermentation treatment was carried out, reducing the pile height to 0.8 m and turning the pile weekly for 15 days, for a total fermentation time of 45 days. Finally, the material was dried at 50℃ to a moisture content of 27% and passed through a 4 mm sieve.

[0106] Example 4

[0107] Raw materials: 7 tons (dry weight) of deer antler mushroom residue and 3 tons (dry weight) of tea tree mushroom residue.

[0108] Preparation of compound nitrogen-retaining agent: Take 0.24 tons of biochar, 0.48 tons of calcium magnesium phosphate fertilizer, and 0.08 tons of superphosphate. The dry weight ratio of the three is 3:6:1. The total amount added is 8% of the dry weight of the mixed bacterial residue, i.e., 0.8 tons.

[0109] Compound microbial inoculant: Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis are mixed at a live count ratio of 1:1:2, with a total live count of 1.2 × 10⁻⁶. 8 CFU / g, addition amount 80 kg.

[0110] Organic fertilizer preparation: Deer antler mushroom residue and tea tree mushroom residue were crushed to a particle size of 1-2 cm and mixed at a dry weight ratio of 7:3. The initial pH was measured to be 6.9, and the C / N ratio was 22:1. A prepared compound nitrogen-retaining agent and compound microbial inoculant were added and thoroughly mixed. Water was sprayed to adjust the moisture content to 68%. Windrow fermentation was adopted, with a base width of 2 m and a height of 1.2 m for primary fermentation. The ventilation rate was 0.2 L / (kg·min), using intermittent ventilation, i.e., ventilation was stopped after 2 hours and then interrupted for 1 hour, repeating this cycle. When the pile temperature exceeded 65℃, the pile was turned over every 4 days, for a total of 7 times. After the primary fermentation period, post-fermentation treatment was carried out, reducing the pile height to 0.9 m and turning it once a week for 12 days. The total fermentation time was 40 days. Finally, the material was dried at 50℃ to a moisture content of 28% and passed through a 4 mm sieve.

[0111] Example 5

[0112] Raw materials: 7 tons (dry weight) of deer antler mushroom residue and 3 tons (dry weight) of tea tree mushroom residue.

[0113] Preparation of compound nitrogen-retaining agent: Take 0.24 tons of biochar, 0.40 tons of calcium magnesium phosphate fertilizer, and 0.16 tons of superphosphate. The dry weight ratio of the three is 3:5:2. The total amount added is 8% of the dry weight of the mixed bacterial residue, i.e., 0.8 tons.

[0114] Compound microbial inoculant: Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis are mixed at a live count ratio of 1:1:2, with a total live count of 1.2 × 10⁻⁶. 8 CFU / g, addition amount 80 kg.

[0115] Organic fertilizer preparation: Deer antler mushroom residue and tea tree mushroom residue were crushed to a particle size of 1-2 cm and mixed at a dry weight ratio of 7:3. The initial pH was measured to be 6.9, and the C / N ratio was 22:1. A prepared compound nitrogen-retaining agent and compound microbial inoculant were added and thoroughly mixed. Water was sprayed to adjust the moisture content to 68%. Windrow fermentation was adopted, with a base width of 2 m and a height of 1.2 m for primary fermentation. The ventilation rate was 0.2 L / (kg·min), using intermittent ventilation, i.e., ventilation was stopped after 2 hours and then interrupted for 1 hour, repeating this cycle. When the pile temperature exceeded 65℃, the pile was turned over every 4 days, for a total of 7 times. After the primary fermentation period, post-fermentation treatment was carried out, reducing the pile height to 0.9 m and turning it once a week for 12 days. The total fermentation time was 40 days. Finally, the material was dried at 50℃ to a moisture content of 28% and passed through a 4 mm sieve.

[0116] Example 6

[0117] Raw materials: 7 tons (dry weight) of deer antler mushroom residue and 3 tons (dry weight) of tea tree mushroom residue.

[0118] Preparation of compound nitrogen-retaining agent: Take 0.32 tons of biochar, 0.40 tons of calcium magnesium phosphate fertilizer, and 0.08 tons of superphosphate. The dry weight ratio of the three is 4:5:1. The total amount added is 8% of the dry weight of the mixed bacterial residue, i.e., 0.8 tons.

[0119] Compound microbial inoculant: Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis are mixed at a live count ratio of 1:1:2, with a total live count of 1.2 × 10⁻⁶. 8 CFU / g, addition amount 80 kg.

[0120] Organic fertilizer preparation: Deer antler mushroom residue and tea tree mushroom residue were crushed to a particle size of 1-2 cm and mixed at a dry weight ratio of 7:3. The initial pH was measured to be 6.9, and the C / N ratio was 22:1. A prepared compound nitrogen-retaining agent and compound microbial inoculant were added and thoroughly mixed. Water was sprayed to adjust the moisture content to 68%. Windrow fermentation was adopted, with a base width of 2 m and a height of 1.2 m for primary fermentation. The ventilation rate was 0.2 L / (kg·min), using intermittent ventilation, i.e., ventilation was stopped after 2 hours and then interrupted for 1 hour, repeating this cycle. When the pile temperature exceeded 65℃, the pile was turned over every 4 days, for a total of 7 times. After the primary fermentation period, post-fermentation treatment was carried out, reducing the pile height to 0.9 m and turning it once a week for 12 days. The total fermentation time was 40 days. Finally, the material was dried at 50℃ to a moisture content of 28% and passed through a 4 mm sieve.

[0121] Comparative Example 1

[0122] Raw materials: 7 tons (dry weight) of deer antler mushroom residue and 3 tons (dry weight) of tea tree mushroom residue.

[0123] Preparation of compound nitrogen-retaining agent: Take 0.24 tons of biochar, 0.56 tons of calcium magnesium phosphate fertilizer, and 0 tons of superphosphate. The dry weight ratio of the three is 3:7:0. The total amount added is 8% of the dry weight of the mixed bacterial residue, i.e., 0.8 tons.

[0124] Compound microbial inoculant: Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis are mixed at a live count ratio of 1:1:2, with a total live count of 1.2 × 10⁻⁶. 8 CFU / g, addition amount 80 kg.

[0125] Organic fertilizer preparation: Deer antler mushroom residue and tea tree mushroom residue were crushed to a particle size of 1-2 cm and mixed at a dry weight ratio of 7:3. The initial pH was measured to be 6.9, and the C / N ratio was 22:1. A prepared compound nitrogen-retaining agent and compound microbial inoculant were added and thoroughly mixed. Water was sprayed to adjust the moisture content to 68%. Windrow fermentation was adopted, with a base width of 2 m and a height of 1.2 m for primary fermentation. The ventilation rate was 0.2 L / (kg·min), using intermittent ventilation, i.e., ventilation was stopped after 2 hours and then interrupted for 1 hour, repeating this cycle. When the pile temperature exceeded 65℃, the pile was turned over every 4 days, for a total of 7 times. After the primary fermentation period, post-fermentation treatment was carried out, reducing the pile height to 0.9 m and turning it once a week for 12 days. The total fermentation time was 40 days. Finally, the material was dried at 50℃ to a moisture content of 28% and passed through a 4 mm sieve.

[0126] Comparative Example 2

[0127] Raw materials: 7 tons (dry weight) of deer antler mushroom residue and 3 tons (dry weight) of tea tree mushroom residue.

[0128] Preparation of compound nitrogen-retaining agent: Take 0.24 tons of biochar, 0 tons of calcium magnesium phosphate fertilizer, and 0.56 tons of superphosphate. The dry weight ratio of the three is 3:0:7. The total amount added is 8% of the dry weight of the mixed bacterial residue, i.e., 0.8 tons.

[0129] Compound microbial inoculant: Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis are mixed at a live count ratio of 1:1:2, with a total live count of 1.2 × 10⁻⁶. 8 CFU / g, addition amount 80 kg.

[0130] Organic fertilizer preparation: Deer antler mushroom residue and tea tree mushroom residue were crushed to a particle size of 1-2 cm and mixed at a dry weight ratio of 7:3. The initial pH was measured to be 6.9, and the C / N ratio was 22:1. A prepared compound nitrogen-retaining agent and compound microbial inoculant were added and thoroughly mixed. Water was sprayed to adjust the moisture content to 68%. Windrow fermentation was adopted, with a base width of 2 m and a height of 1.2 m for primary fermentation. The ventilation rate was 0.2 L / (kg·min), using intermittent ventilation, i.e., ventilation was stopped after 2 hours and then interrupted for 1 hour, repeating this cycle. When the pile temperature exceeded 65℃, the pile was turned over every 4 days, for a total of 7 times. After the primary fermentation period, post-fermentation treatment was carried out, reducing the pile height to 0.9 m and turning it once a week for 12 days. The total fermentation time was 40 days. Finally, the material was dried at 50℃ to a moisture content of 28% and passed through a 4 mm sieve.

[0131] Comparative Example 3

[0132] Raw materials: 7 tons (dry weight) of deer antler mushroom residue and 3 tons (dry weight) of tea tree mushroom residue.

[0133] Preparation of compound nitrogen-retaining agent: Take 0 tons of biochar, 0.48 tons of calcium magnesium phosphate fertilizer, and 0.32 tons of superphosphate. The dry weight ratio of the three is 0:6:4. The total amount added is 8% of the dry weight of the mixed bacterial residue, i.e., 0.8 tons.

[0134] Compound microbial inoculant: Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis are mixed at a live count ratio of 1:1:2, with a total live count of 1.2 × 10⁻⁶. 8 CFU / g, addition amount 80 kg.

[0135] Organic fertilizer preparation: Deer antler mushroom residue and tea tree mushroom residue were crushed to a particle size of 1-2 cm and mixed at a dry weight ratio of 7:3. The initial pH was measured to be 6.9, and the C / N ratio was 22:1. A prepared compound nitrogen-retaining agent and compound microbial inoculant were added and thoroughly mixed. Water was sprayed to adjust the moisture content to 68%. Windrow fermentation was adopted, with a base width of 2 m and a height of 1.2 m for primary fermentation. The ventilation rate was 0.2 L / (kg·min), using intermittent ventilation, i.e., ventilation was stopped after 2 hours and then interrupted for 1 hour, repeating this cycle. When the pile temperature exceeded 65℃, the pile was turned over every 4 days, for a total of 7 times. After the primary fermentation period, post-fermentation treatment was carried out, reducing the pile height to 0.9 m and turning it once a week for 12 days. The total fermentation time was 40 days. Finally, the material was dried at 50℃ to a moisture content of 28% and passed through a 4 mm sieve.

[0136] Comparative Example 4

[0137] Raw materials: 7 tons (dry weight) of deer antler mushroom residue and 3 tons (dry weight) of tea tree mushroom residue.

[0138] Preparation of compound nitrogen-retaining agent: Take 0.32 tons of biochar, 0.32 tons of calcium magnesium phosphate fertilizer, and 0.16 tons of superphosphate. The dry weight ratio of the three is 4:4:2. The total amount added is 8% of the dry weight of the mixed bacterial residue, i.e., 0.8 tons.

[0139] Compound microbial inoculant: Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis are mixed at a live count ratio of 1:1:2, with a total live count of 1.2 × 10⁻⁶. 8 CFU / g, addition amount 80 kg.

[0140] Organic fertilizer preparation: Deer antler mushroom residue and tea tree mushroom residue were crushed to a particle size of 1-2 cm and mixed at a dry weight ratio of 7:3. The initial pH was measured to be 6.9, and the C / N ratio was 22:1. A prepared compound nitrogen-retaining agent and compound microbial inoculant were added and thoroughly mixed. Water was sprayed to adjust the moisture content to 68%. Windrow fermentation was adopted, with a base width of 2 m and a height of 1.2 m for primary fermentation. The ventilation rate was 0.2 L / (kg·min), using intermittent ventilation, i.e., ventilation was stopped after 2 hours and then interrupted for 1 hour, repeating this cycle. When the pile temperature exceeded 65℃, the pile was turned over every 4 days, for a total of 7 times. After the primary fermentation period, post-fermentation treatment was carried out, reducing the pile height to 0.9 m and turning it once a week for 12 days. The total fermentation time was 40 days. Finally, the material was dried at 50℃ to a moisture content of 28% and passed through a 4 mm sieve.

[0141] Comparative Example 5

[0142] Raw materials: 7 tons (dry weight) of deer antler mushroom residue and 3 tons (dry weight) of tea tree mushroom residue.

[0143] Preparation of compound nitrogen-retaining agent: Take 0.08 tons of biochar, 0.64 tons of calcium magnesium phosphate fertilizer, and 0.08 tons of superphosphate. The dry weight ratio of the three is 1:8:1. The total amount added is 8% of the dry weight of the mixed bacterial residue, i.e., 0.8 tons.

[0144] Compound microbial inoculant: Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis are mixed at a live count ratio of 1:1:2, with a total live count of 1.2 × 10⁻⁶. 8 CFU / g, addition amount 80 kg.

[0145] Organic fertilizer preparation: Deer antler mushroom residue and tea tree mushroom residue were crushed to a particle size of 1-2 cm and mixed at a dry weight ratio of 7:3. The initial pH was measured to be 6.9, and the C / N ratio was 22:1. A prepared compound nitrogen-retaining agent and compound microbial inoculant were added and thoroughly mixed. Water was sprayed to adjust the moisture content to 68%. Windrow fermentation was adopted, with a base width of 2 m and a height of 1.2 m for primary fermentation. The ventilation rate was 0.2 L / (kg·min), using intermittent ventilation, i.e., ventilation was stopped after 2 hours and then interrupted for 1 hour, repeating this cycle. When the pile temperature exceeded 65℃, the pile was turned over every 4 days, for a total of 7 times. After the primary fermentation period, post-fermentation treatment was carried out, reducing the pile height to 0.9 m and turning it once a week for 12 days. The total fermentation time was 40 days. Finally, the material was dried at 50℃ to a moisture content of 28% and passed through a 4 mm sieve.

[0146] Comparative Example 6

[0147] Raw materials: 7 tons (dry weight) of deer antler mushroom residue and 3 tons (dry weight) of tea tree mushroom residue.

[0148] Preparation of compound nitrogen-retaining agent: Take 0.08 tons of biochar, 0.56 tons of calcium magnesium phosphate fertilizer, and 0.16 tons of superphosphate. The dry weight ratio of the three is 1:7:2. The total amount added is 8% of the dry weight of the mixed bacterial residue, i.e., 0.8 tons.

[0149] Compound microbial inoculant: Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis are mixed at a live count ratio of 1:1:2, with a total live count of 1.2 × 10⁻⁶. 8 CFU / g, addition amount 80 kg.

[0150] Organic fertilizer preparation: Deer antler mushroom residue and tea tree mushroom residue were crushed to a particle size of 1-2 cm and mixed at a dry weight ratio of 7:3. The initial pH was measured to be 6.9, and the C / N ratio was 22:1. A prepared compound nitrogen-retaining agent and compound microbial inoculant were added and thoroughly mixed. Water was sprayed to adjust the moisture content to 68%. Windrow fermentation was adopted, with a base width of 2 m and a height of 1.2 m for primary fermentation. The ventilation rate was 0.2 L / (kg·min), using intermittent ventilation, i.e., ventilation was stopped after 2 hours and then interrupted for 1 hour, repeating this cycle. When the pile temperature exceeded 65℃, the pile was turned over every 4 days, for a total of 7 times. After the primary fermentation period, post-fermentation treatment was carried out, reducing the pile height to 0.9 m and turning it once a week for 12 days. The total fermentation time was 40 days. Finally, the material was dried at 50℃ to a moisture content of 28% and passed through a 4 mm sieve.

[0151] Comparative Example 7

[0152] Raw materials: 7 tons (dry weight) of deer antler mushroom residue and 3 tons (dry weight) of tea tree mushroom residue.

[0153] Preparation of compound nitrogen-retaining agent: Take 0.40 tons of biochar, 0.32 tons of calcium magnesium phosphate fertilizer, and 0.08 tons of superphosphate. The dry weight ratio of the three is 5:4:1. The total amount added is 8% of the dry weight of the mixed bacterial residue, i.e., 0.8 tons.

[0154] Compound microbial inoculant: Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis are mixed at a live count ratio of 1:1:2, with a total live count of 1.2 × 10⁻⁶. 8 CFU / g, addition amount 80 kg.

[0155] Organic fertilizer preparation: Deer antler mushroom residue and tea tree mushroom residue were crushed to a particle size of 1-2 cm and mixed at a dry weight ratio of 7:3. The initial pH was measured to be 6.9, and the C / N ratio was 22:1. A prepared compound nitrogen-retaining agent and compound microbial inoculant were added and thoroughly mixed. Water was sprayed to adjust the moisture content to 68%. Windrow fermentation was adopted, with a base width of 2 m and a height of 1.2 m for primary fermentation. The ventilation rate was 0.2 L / (kg·min), using intermittent ventilation, i.e., ventilation was stopped after 2 hours and then interrupted for 1 hour, repeating this cycle. When the pile temperature exceeded 65℃, the pile was turned over every 4 days, for a total of 7 times. After the primary fermentation period, post-fermentation treatment was carried out, reducing the pile height to 0.9 m and turning it once a week for 12 days. The total fermentation time was 40 days. Finally, the material was dried at 50℃ to a moisture content of 28% and passed through a 4 mm sieve.

[0156] The key performance test results are shown below, and all results are expressed as mean ± standard deviation:

[0157] Table 5. Test results of composting performance of composite nitrogen-retaining agents with different ratios.

[0158] Example 1 2:7:1 1.35±0.06 128.5±2.0 32.8±0.3 810±18 Example 2 2:6:2 2.20±0.09 120.2±2.3 30.5±0.4 1120±25 Example 3 2:5:3 3.10±0.12 115.5±2.5 29.2±0.4 1280±28 Example 4 3:6:1 0.85±0.03 132.0±1.8 33.2±0.3 760±15 Example 5 3:5:2 1.80±0.07 124.6±2.1 31.0±0.3 950±20 Example 6 4:5:1 1.50±0.06 129.5±1.9 31.8±0.3 820±17 Comparative Example 1 3:7:0 2.65±0.10 117.3±2.4 29.8±0.4 1050±22 Comparative Example 2 3:0:7 4.50±0.15 98.5±2.8 28.7±0.4 1620±35 Comparative Example 3 0:6:4 3.80±0.13 112.8±2.6 29.5±0.4 1200±26 Comparative Example 4 4:4:2 3.20±0.11 114.5±2.5 29.0±0.4 1250±28 Comparative Example 5 1:8:1 2.40±0.09 116.0±2.3 30.2±0.4 1080±24 Comparative Example 6 1:7:2 2.90±0.11 111.2±2.7 29.3±0.4 1260±27 Comparative Example 7 5:4:1 3.60±0.12 106.5±2.9 28.9±0.4 1380±30

[0159] To quantify the overall performance of each formulation, a normalized weighted scoring method was adopted. First, the optimization direction for each indicator was determined: nitrogen loss rate and EC were "the smaller the better," while GI and HI were "the larger the better." Second, the average values ​​measured for each indicator were normalized using the following formula:

[0160] For positive indicators ( ):

[0161] For negative indicators (N) loss EC):

[0162] in, This represents the original value of the j-th index in the i-th experiment. and These represent the maximum and minimum values ​​of this indicator across all experiments. Finally, weights are assigned based on the importance of each indicator: nitrogen retention effect (N... loss The overall score is as follows: 30% for nutrient content, 30% for gravitational efficiency (GI), 25% for humification quality (HI), and 15% for salinity risk (EC). .

[0163] Table 6. Comprehensive Performance Scores of Composite Nitrogen Retaining Agents with Different Proportions

[0164] Example 1 2:7:1 0.863 0.896 0.911 0.942 0.897 Example 2 2:6:2 0.630 0.648 0.644 0.581 0.626 Example 3 2:5:3 0.384 0.507 0.333 0.395 0.408 Example 4 3:6:1 1.000 1.000 1.000 1.000 1.000 Example 5 3:5:2 0.740 0.776 0.711 0.779 0.751 Example 6 4:5:1 0.822 0.925 0.822 0.930 0.872 Comparative Example 1 3:7:0 0.507 0.560 0.444 0.663 0.539 Comparative Example 2 3:0:7 0.000 0.000 0.000 0.000 0.000 Comparative Example 3 0:6:4 0.192 0.425 0.378 0.488 0.358 Comparative Example 4 4:4:2 0.356 0.478 0.222 0.430 0.379 Comparative Example 5 1:8:1 0.575 0.522 0.556 0.628 0.567 Comparative Example 6 1:7:2 0.438 0.380 0.267 0.419 0.380 Comparative Example 7 5:4:1 0.247 0.239 0.111 0.279 0.222

[0165] The comprehensive scoring results show that the combination of biochar (A), calcium magnesium phosphate fertilizer (B), and superphosphate (C) in a ratio of 3:6:1 has the best or second-best nitrogen loss rate (0.85%), GI (132.0%), HI (33.2%), and EC (760 μS / cm) among all experiments. All sub-indicators show excellent performance, and the comprehensive score (1.000) is much higher than other ratios.

[0166] Comparing Example 4 with Comparative Example 1 (3:7:0), it can be seen that when no superphosphate is added, although there is still a certain nitrogen retention effect (nitrogen loss rate of 2.65%), the humification quality (HI of 29.8%) and safety (GI of 117.3%) of the product are lower than those of Example 4. Crucially, Comparative Example 2 (3:0:7, calcium magnesium phosphate = 0) had a nitrogen loss rate as high as 4.50%, a GI reduced to 98.5%, an HI of only 28.7%, and an EC as high as 1620 μS / cm. All these indicators were the worst among all treatments, so its normalized score and overall score were both 0. This proves that without calcium magnesium phosphate fertilizer, the combination of biochar and superphosphate alone cannot achieve effective nitrogen fixation and humification. The comprehensive score of Comparative Example 3 (0:6:4, biochar=0) was 0.358, which was better than Comparative Example 2, but still much lower than Example 4. Its nitrogen loss rate (3.80%) and GI (112.8%) were both lower than those of Example 4, indicating that the adsorption effect of biochar has an irreplaceable role in improving safety and reducing nitrogen loss.

[0167] In summary, the appropriate addition of superphosphate is indispensable for stimulating the synergistic effect of the three components and improving the overall product quality; while the absence of calcium magnesium phosphate fertilizer and biochar will lead to a significant decline in overall performance. Only when the ratio is 3:6:1 does biochar, calcium magnesium phosphate fertilizer, and superphosphate produce the strongest synergistic effect: calcium magnesium phosphate fertilizer plays a dominant role in chemical nitrogen fixation and promoting humification; superphosphate provides a moderately acidic environment, inhibiting early ammonia volatilization, while avoiding excessive inhibition of humification by excessive addition; biochar utilizes its porous structure to adsorb ammonium ions and harmful substances, increasing GI and reducing EC. Therefore, the strongest synergistic effect is produced by biochar, calcium magnesium phosphate fertilizer, and superphosphate in a specific ratio of 3:6:1, which is the key to achieving optimal overall performance.

Claims

1. A high-humic acid organic fertilizer suitable for improving acidic red soil, produced using the residue of *Flammulina velutipes* and *Flammulina atrata*, characterized in that... The raw materials for its preparation include deer antler mushroom residue, tea tree mushroom residue, compound nitrogen-retaining agent and compound microbial agent; the compound nitrogen-retaining agent is composed of biochar, calcium magnesium phosphate fertilizer and superphosphate mixed in a dry weight ratio of (2-4):(5-7):(1-3).

2. The organic fertilizer according to claim 1, characterized in that, The dry weight ratio of the deer antler mushroom residue to the tea tree mushroom residue is (6-8):(2-4), and the total amount of compound nitrogen-retaining agent added is 6%-10% of the dry weight of the mixture of the two mushroom residues.

3. The high humic acid organic fertilizer according to claim 1, characterized in that, The biochar was obtained by pyrolysis of corn stalks at 500-600℃ with limited oxygen for 2 hours.

4. The high humic acid organic fertilizer according to claim 1, characterized in that, The compound microbial agent contains Aspergillus niger, Aspergillus oryzae, and Bacillus subtilis, with a viable count ratio of 1:1:2 and a total viable count ≥1×10⁻⁶. 8 CFU / g, the addition amount is 0.5%-1.0% of the total dry weight of the stockpile.

5. The high humic acid organic fertilizer according to claim 1, characterized in that, The compound nitrogen-retaining agent contains biochar, calcium magnesium phosphate fertilizer, and superphosphate in a dry weight ratio of 3:6:

1.

6. The method for preparing the high-humic acid organic fertilizer according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Raw material processing and compounding: The deer antler mushroom residue and tea tree mushroom residue are crushed to a particle size of 1-2 cm, mixed in proportion, and the carbon-nitrogen ratio of the materials is adjusted to 20-25:1; compound nitrogen retaining agent and compound microbial agent are added to the materials, and then water is sprayed to adjust the moisture content of the materials to 65%-70%; (2) Aerobic composting fermentation: The material is piled into windrows with a bottom width of 1.5-2.5m and a height of 1.0-1.5m or placed in a fermentation tank; during the composting process, the ventilation rate is 0.2L / (kg·min), and the ventilation method is intermittent ventilation, that is, ventilation is stopped after 2 hours and then stopped after 1 hour, and this cycle is repeated. When the pile temperature exceeds 65℃, the pile is turned over once every 3-5 days, and the main fermentation takes 25-30 days; (3) Post-fermentation and drying: After the main fermentation is completed, the material pile height is reduced to 0.8-1.0m for post-fermentation treatment. The pile is turned over once a week and the post-fermentation treatment lasts for 10-15 days. After the post-fermentation is completed, the material moisture content is reduced to below 30% by natural sun drying or low-temperature drying at a temperature below 60℃. (4) Screening and finished product: The dried material is screened through a 4-6mm sieve to remove large particles of impurities, and the finished organic fertilizer is obtained.

7. The application of the high humic acid organic fertilizer according to any one of claims 1 to 5 in improving acidic red soil.

Images