Microbial slow-release bacterial fertilizer, preparation method and application thereof

Abstract

The present application relates to a kind of microbial slow-release bacterial fertilizer and its preparation method and application, belong to microbial bacterial fertilizer technical field.The microbial slow-release bacterial fertilizer described in the present application contains composite microorganism 15-18 parts, soybean root powder 8-10 parts, β-cyclodextrin 20-23 parts, grasswood ash 15-20 parts, humic acid 5-8 parts, tea saponin 5-8 parts, potassium fulvate 13-15 parts, carboxymethyl chitosan 18-20 parts by weight;Wherein composite microorganism contains round brown nitrogen-fixing bacteria, bacillus subtilis, streptomyces microflavus.The microbial composite bacterial fertilizer of the present application can effectively reduce soil acidity, improve soil structure, release nutrient components, increase soil fertility, be conducive to promoting crop growth and improving crop yield.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial fertilizers and relates to a microbial slow-release fertilizer and a preparation method and application thereof. Background Art

[0002] Land is the economic source for farmers and the foundation for crop survival. Soil acidification refers to the process by which soil absorptive complexes accept a certain amount of exchangeable hydrogen or aluminum ions, leading to the leaching of alkaline (basic) ions from the soil. The main causes of soil acidification are: 1) Natural acidification. Natural acidification is primarily caused by intense weathering, acidic sulfate soils, a deficiency of alkaline cations in the parent material, and rainfall. Soil acidification itself is a continuous natural process. Influenced by the parent rock, rainfall leaches and erodes basic calcium ions. Rainfall causes a significant leaching of basic compounds (primarily calcium and magnesium) from the soil, significantly increasing the exchangeable hydrogen and aluminum content, and causing the soil to become acidic. Furthermore, organic acids and CO2 produced by microbial decomposition of organic matter in the soil, acidic substances secreted by plant roots as they absorb nutrients, and organic acids produced by the metabolic activities of soil microorganisms themselves can all contribute to natural soil acidification. 2) Anthropogenic acidification. Anthropogenic factors primarily include acid deposition caused by human activities and inappropriate agricultural practices. Improper agricultural practices, including excessive use of chemical fertilizers, incorrect fertilization methods, continuous cropping, and the cultivation of acidogenic crops, all contribute to soil acidification. Physiologically acidic fertilizers such as ammonium chloride and ammonium sulfate are absorbed by plants after oxidation of ammonium ions, leading to increased exchangeable acid and aluminum content in the soil and increased soil acidity.

[0003] Soil acidification causes a rapid increase in hydrogen ion concentration, which is related to Ca 2+ Mg 2+ , K + The competition between basic nutrient cations and cations for exchange sites leads to the leaching of these ions. When the acidity increases, the migration rate of certain heavy metal elements and their ionic forms in the soil also increases, posing a huge threat to the entire ecosystem.

[0004] Soil acidification can have several apparent impacts on plants, including slowed growth, yellowing leaves, reduced yields, and increased susceptibility to disease. Increased acidity also impacts phosphorus utilization and availability, primarily because the increased variable negative charge on the soil surface affects phosphorus adsorption and, consequently, its availability.

[0005] Numerous beneficial microorganisms exist in the soil, playing a vital role in crop growth. However, most beneficial microorganisms thrive only in a neutral pH range of 6.5 to 7.5. As soil pH decreases, the diversity and activity of these microorganisms decrease, hindering nitrogen fixation and organic matter mineralization in the soil. Nutrient conversion is also severely hindered, resulting in low crop yields. Summary of the Invention

[0006] The main purpose of the present invention is to provide a microbial slow-release fertilizer, which can effectively improve soil acidification and increase crop yield.

[0007] The present invention adopts the following technical solutions to achieve the above-mentioned purpose:

[0008] A microbial slow-release fertilizer contains, by weight, 15-18 parts of composite microorganisms, 8-10 parts of soybean root powder, 20-23 parts of beta-cyclodextrin, 15-20 parts of wood ash, 5-8 parts of humic acid, 5-8 parts of tea saponin, 13-15 parts of potassium fulvic acid, and 18-20 parts of carboxymethyl chitosan.

[0009] The present invention provides a method for preparing the composite microorganism, which specifically comprises the following steps:

[0010] Composite biochar, sodium caseinate, yeast extract powder, potato starch, fucoidan, soy peptone, agar and water are added to prepare a culture medium; to the prepared culture medium, nitrogen-fixing bacteria, Bacillus subtilis and Streptomyces tenuifolius are added, the culture medium is incubated at 25-30° C. for 1.5-2 days, dried and crushed to obtain composite microorganisms.

[0011] Preferably, the weight ratio of each component in the culture medium of the composite microorganism preparation method is: composite biochar 30-40g / L, sodium caseinate 6-8g / L, yeast extract 5-7g / L, potato starch 12-15g / L, fucoidan 3-5g / L, soy peptone 12-15g / L, and agar 1.5-2.0g / L.

[0012] Preferably, the addition amount of each microorganism in the composite microorganism preparation method is: 3-5 g / L of Azotobacter rotundifolia, 6-8 g / L of Bacillus subtilis, and 4-5 g / L of Streptomyces tenuifolius.

[0013] Among them, the aforementioned nitrogen-fixing bacteria, Bacillus subtilis, and Streptomyces tenuifolius are all currently commercially available products, and the effective viable bacterial count is 10 billion / g.

[0014] The present invention provides a method for preparing composite biochar in the culture medium, which specifically comprises the following steps:

[0015] Activation: Soak rapeseed meal in hydrochloric acid solution for 20-30 minutes, then add sodium silicate to react, dry, and activate the product for later use;

[0016] First calcination: calcine the activated product obtained in step 1 at 200-230°C for 1-1.5h in a nitrogen environment, then cool to room temperature and set aside;

[0017] Second calcination: Add shell powder and rape straw to the calcined product obtained in step 2 in a nitrogen environment and calcine at 600-650° C. for 1-1.5 hours to obtain composite biochar.

[0018] Preferably, in the activation step of the composite biochar preparation method, the mass-volume ratio of rapeseed meal, sodium silicate, and hydrochloric acid solution is 1:(3-5):(1.5-3) in terms of kg / kg / L.

[0019] Preferably, the hydrochloric acid solution has a mass fraction of 30-35%.

[0020] Preferably, in the second calcination step of the composite biochar preparation method, the amount of shell powder added is 3-5 times the weight of rapeseed meal, and the amount of rapeseed straw added is 0.3-0.5 times the weight of rapeseed meal.

[0021] The present invention provides a method for preparing the microbial slow-release fertilizer, which specifically comprises the following steps: step A, adding water to β-cyclodextrin to form a paste, then adding the composite microorganism, mixing, and obtaining a mixture I for standby use;

[0022] Step B, adding water to soybean root powder, wood ash, humic acid, tea saponin, potassium fulvic acid, and carboxymethyl chitosan to form a paste to obtain mixture II for later use;

[0023] Step C, adding mixture I to mixture II, mixing evenly, and drying to obtain a microbial slow-release fertilizer.

[0024] The present invention has the following beneficial effects:

[0025] 1. The present invention uses a culture medium containing composite biochar to cultivate the desired microorganisms. The rich pores in the biochar allow the microorganisms to enter the pores during microbial cultivation, providing a certain degree of protection. At the same time, the adsorption effect of the biochar is utilized to effectively adsorb components in the soil for microbial digestion and decomposition. In the preparation process of composite biochar, rapeseed meal is used as the main raw material. Rapeseed meal contains rich components such as crude fiber and minerals. Hydrochloric acid is used to activate the rapeseed meal. Sodium silicate is then added. Hydrochloric acid and sodium silicate react to generate silicic acid. The activated rapeseed meal is calcined with the silicic acid. The silicic acid decomposes into silicon dioxide and water. The water forms water vapor at high temperature. The water vapor can enter the rapeseed meal and etch it, thereby generating different pores. Shell powder and soybean straw are added during the secondary calcination process. The main component of shell powder is calcium carbonate, which decomposes into calcium oxide and carbon dioxide at high temperature. The carbon dioxide gas enters the rapeseed meal and soybean straw and etches it, further enriching the pores. The biochar prepared by this method has abundant pores and strong adsorption. At the same time, calcium oxide is produced in the preparation method. When calcium oxide meets water, it forms calcium hydroxide, which can neutralize acidic substances in the soil and reduce soil acidity.

[0026] 2. The microbial slow-release fertilizer of the present invention creatively adds soybean root powder, and utilizes the residual endophytes therein to decompose the acidic components in the soil. In the microbial fertilizer of the present invention, soybean root powder, wood ash, humic acid, tea saponin, potassium fulvate, and carboxymethyl chitosan are first used as the first slow-release layer. The soybean root powder, wood ash, and potassium fulvate components are used to improve the soil. Composite microorganisms are used as the second slow-release layer. The pore adsorption effect of biochar and the decomposition effect of microorganisms are utilized to improve the soil, thereby achieving long-term and sustainable soil improvement.

[0027] 3. The use of the microbial composite fertilizer of the present invention can effectively reduce soil acidity, improve soil structure, release nutrients, increase soil fertility, and is conducive to promoting crop growth and increasing crop yields. DETAILED DESCRIPTION

[0028] The present invention is further illustrated below with reference to specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. After reading this invention, modifications of various equivalent forms of the present invention made by those skilled in the art fall within the scope of protection of the claims of this application. The rapeseed straw used in the present invention is the discarded straw of the oil-bearing cruciferous crop rapeseed after deseeding, the rapeseed meal is a by-product of rapeseed oil extraction, and the soybean root is the discarded soybean plant root, which is dried and crushed into powder before use.

[0029] Example 1

[0030] Preparation of composite biochar:

[0031] Activation: Grind 1 kg of rapeseed meal, add 3 L of 35% hydrochloric acid solution and soak for 30 minutes, then add 1.5 kg of sodium silicate to react. After the reaction is complete, dry it and use the activated product for later use;

[0032] First calcination: calcine the activated product obtained in step 1 at 230°C for 1 hour in a nitrogen environment, then cool to room temperature and set aside;

[0033] Second calcination: Add 5 kg of shell powder and 0.3 kg of rape straw to the calcined product obtained in step 2 in a nitrogen environment and calcine at 650° C. for 1 h to obtain composite biochar.

[0034] Preparation of composite microorganisms:

[0035] A culture medium was prepared according to 40 g / L composite biochar, 6 g / L sodium caseinate, 5 g / L yeast extract powder, 15 g / L potato starch, 3 g / L fucoidan, 15 g / L soy peptone, and 2.0 g / L agar; 5 g / L of Azotobacter rotundifolia, 6 g / L of Bacillus subtilis, and 5 g / L of Streptomyces tenuifolius were added to the culture medium, and the culture was carried out at 30° C. for 1.5 days, dried, and crushed to obtain a composite microorganism.

[0036] Preparation of microbial slow-release fertilizer:

[0037] Step A, add 23 kg of β-cyclodextrin to water to form a paste, then add 18 kg of composite microorganisms and mix well to obtain mixture I for later use;

[0038] Step B, adding water to 10 kg of soybean root powder, 15 kg of wood ash, 8 kg of humic acid, 5 kg of tea saponin, 15 kg of potassium fulvic acid, and 18 kg of carboxymethyl chitosan to form a paste to obtain mixture II for later use;

[0039] Step C, adding mixture I to mixture II, mixing evenly, and drying to obtain a microbial slow-release fertilizer.

[0040] Example 2

[0041] Preparation of composite biochar:

[0042] Activation: Grind 1 kg of rapeseed meal, add 5 L of 30% hydrochloric acid solution and soak for 20 minutes, then add 3 kg of sodium silicate to react. After the reaction is complete, dry it and use the activated product for later use;

[0043] First calcination: calcine the activated product obtained in step 1 at 200°C for 1.5 h in a nitrogen environment, then cool to room temperature and set aside for later use;

[0044] Second calcination: Add 3 kg of shell powder and 0.5 kg of rape straw to the calcined product obtained in step 2 in a nitrogen environment and calcine at 600° C. for 1.5 h to obtain composite biochar.

[0045] Preparation of composite microorganisms:

[0046] A culture medium was prepared according to 30 g / L composite biochar, 8 g / L sodium caseinate, 7 g / L yeast extract powder, 12 g / L potato starch, 5 g / L fucoidan, 12 g / L soy peptone, and 1.5 g / L agar; 4 g / L Azotobacter rotundifolia, 7 g / L Bacillus subtilis, and 5 g / L Streptomyces tenuifolius were added to the culture medium, and the culture was incubated at 25° C. for 2 days, dried, and crushed to obtain a composite microorganism.

[0047] Preparation of microbial slow-release fertilizer:

[0048] Step A, adding water to β-cyclodextrin 20 to form a paste, then adding the composite microorganism 15, mixing well, and obtaining a mixture I for later use;

[0049] Step B, adding water to 8g of soybean root powder, 20g of wood ash, 5g of humic acid, 8g of tea saponin, 13g of potassium fulvic acid, and 20g of carboxymethyl chitosan to form a paste to obtain mixture II for later use;

[0050] Step C, adding mixture I to mixture II, mixing evenly, and drying to obtain a microbial slow-release fertilizer.

[0051] Example 3

[0052] Preparation of composite biochar:

[0053] Activation: Grind 1 kg of rapeseed meal, add 4 L of 33% hydrochloric acid solution and soak for 25 minutes, then add 2 kg of sodium silicate to react. After the reaction is complete, dry it and use the activated product for later use;

[0054] First calcination: calcine the activated product obtained in step 1 at 230°C for 1.5h in a nitrogen environment, then cool to room temperature and set aside;

[0055] Second calcination: Add 4 kg of shell powder and 0.4 kg of rape straw to the calcined product obtained in step 2 in a nitrogen environment and calcine at 650° C. for 1 h to obtain composite biochar.

[0056] Preparation of composite microorganisms:

[0057] A culture medium was prepared according to 35 g / L composite biochar, 7 g / L sodium caseinate, 6 g / L yeast extract powder, 13 g / L potato starch, 4 g / L fucoidan, 13 g / L soy peptone, and 1.8 g / L agar; 3 g / L Azotobacter rotundifolia, 8 g / L Bacillus subtilis, and 4 g / L Streptomyces tenuifolius were added to the culture medium, the culture was incubated at 30°C for 2 days, dried, and crushed to obtain a composite microorganism.

[0058] Preparation of microbial slow-release fertilizer:

[0059] Step A, add 22 kg of β-cyclodextrin to water to form a paste, then add 16 kg of composite microorganisms and mix well to obtain mixture I for later use;

[0060] Step B, adding water to 9 kg of soybean root powder, 18 kg of wood ash, 7 kg of humic acid, 6 kg of tea saponin, 14 kg of potassium fulvic acid, and 19 kg of carboxymethyl chitosan to form a paste to obtain mixture II for later use;

[0061] Step C, adding mixture I to mixture II, mixing evenly, and drying to obtain a microbial slow-release fertilizer.

[0062] Comparative Example 1

[0063] Preparation of composite microorganisms:

[0064] A culture medium was prepared according to 7 g / L sodium caseinate, 6 g / L yeast extract powder, 13 g / L potato starch, 4 g / L fucoidan, 13 g / L soy peptone, and 1.8 g / L agar; 3 g / L Azotobacter rotundifolia, 8 g / L Bacillus subtilis, and 4 g / L Streptomyces tenuifolius were added to the culture medium, the culture was incubated at 30° C. for 2 days, dried, and crushed to obtain a composite microorganism.

[0065] Preparation of microbial slow-release fertilizer:

[0066] Step A, add 22 kg of β-cyclodextrin to water to form a paste, then add 16 kg of composite microorganisms and mix well to obtain mixture I for later use;

[0067] Step B, adding water to 9 kg of soybean root powder, 18 kg of wood ash, 7 kg of humic acid, 6 kg of tea saponin, 14 kg of potassium fulvic acid, and 19 kg of carboxymethyl chitosan to form a paste to obtain mixture II for later use;

[0068] Step C, adding mixture I to mixture II, mixing evenly, and drying to obtain a microbial slow-release fertilizer.

[0069] Comparative Example 2

[0070] Preparation of composite biochar:

[0071] Activation: Grind 1 kg of rapeseed meal, add 4 L of 33% hydrochloric acid solution and soak for 25 minutes, then dry and activate the product for later use;

[0072] Calcination: The activated product obtained in step 1 was added to 0.4 kg of rape straw in a nitrogen environment and calcined at 650° C. for 1 h to obtain composite biochar.

[0073] Preparation of composite microorganisms:

[0074] A culture medium was prepared according to 35 g / L composite biochar, 8 g / L silicon dioxide, 7 g / L sodium caseinate, 6 g / L yeast extract powder, 13 g / L potato starch, 4 g / L fucoidan, 13 g / L soy peptone, and 1.8 g / L agar; 3 g / L of Azotobacter rotundifolia, 8 g / L of Bacillus subtilis, and 4 g / L of Streptomyces tenuifolius were added to the culture medium, the culture was incubated at 30° C. for 2 days, dried, and crushed to obtain a composite microorganism.

[0075] Preparation of microbial slow-release fertilizer:

[0076] Step A, add 22 kg of β-cyclodextrin to water to form a paste, then add 16 kg of composite microorganisms and mix well to obtain mixture I for later use;

[0077] Step B, adding water to 18 kg of wood ash, 7 kg of humic acid, 14 kg of potassium fulvic acid, and 19 kg of carboxymethyl chitosan to form a paste to obtain mixture II for later use;

[0078] Step C, adding mixture I to mixture II, mixing evenly, and drying to obtain a microbial slow-release fertilizer.

[0079] Comparative Example 3

[0080] Preparation of composite biochar:

[0081] Activation: Grind 1 kg of rapeseed meal, add 4 L of 33% hydrochloric acid solution and soak for 25 minutes, then add 2 kg of sodium silicate to react. After the reaction is complete, dry it and use the activated product for later use;

[0082] First calcination: calcine the activated product obtained in step 1 at 230°C for 1.5h in a nitrogen environment, then cool to room temperature and set aside;

[0083] Second calcination: Add 4 kg of shell powder and 0.4 kg of rape straw to the calcined product obtained in step 2 in a nitrogen environment and calcine at 650° C. for 1 h to obtain composite biochar.

[0084] Preparation of composite microorganisms:

[0085] 35 g of composite biochar, 3 g of round brown nitrogen-fixing bacteria, 8 g of Bacillus subtilis, and 4 g of Streptomyces tenuifolius were mixed to obtain a composite microorganism.

[0086] Preparation of microbial slow-release fertilizer:

[0087] Mix 22 kg of β-cyclodextrin, 16 kg of composite microorganisms, 9 kg of soybean root powder, 18 kg of wood ash, 7 kg of humic acid, 6 kg of tea saponin, 14 kg of potassium fulvic acid, and 19 kg of carboxymethyl chitosan to obtain a microbial slow-release fertilizer.

[0088] 1. Effect of the microbial slow-release agent of the present invention on citrus orchard soil

[0089] 1.1 Test materials and methods

[0090] The citrus orchard used in this experiment is our company's cooperative "Yichang Mandarin" orchard. Testing revealed a soil pH of approximately 4.3, an organic matter content of approximately 18.1 g / kg, exchangeable hydrogen of approximately 0.53 cmol / kg, exchangeable magnesium of approximately 2.39 cmol / kg, and exchangeable calcium of approximately 4.27 cmol / kg.

[0091] Usage: The fruit trees were divided into 8 groups, with 10 trees in each group. Among them, 6 groups were added with the microbial slow-release fertilizers (0.8 kg / mu) prepared by Examples 1-3 of the present invention and Comparative Examples 1-3 when applying autumn and winter fertilizers, and then conventional field management was performed and spring fertilizer and summer fertilizer were applied in the following year; 1 group was conventionally applied with autumn and winter fertilizers and spring and summer fertilizers in the following year, serving as a blank group; 1 group was added with the soil conditioner produced by our company when applying autumn and winter fertilizers, and then conventional field management was performed and spring fertilizer and summer fertilizer were applied in the following year, serving as a control group.

[0092] Soil was collected before applying autumn and winter fertilizers (Phase I), before applying summer fertilizers in the following year (Phase II), and when fruits were picked (Phase III) to test pH, organic matter content, exchangeable hydrogen content, exchangeable Mg content, and exchangeable Ca content.

[0093] 1.2 Results and Analysis

[0094] As can be seen from the results in Table 1 and Table 2, the use of the microbial slow-release fertilizer of the present invention can significantly improve the acidification of the soil in the citrus orchard, increase the soil pH, reduce the acidity, reduce the exchange hydrogen content of harmful substances in the soil, increase the content of organic matter and trace elements in the soil, and improve the soil structure.

[0095] Table 1 Effects of different treatments on soil pH and

[0096]

[0097] Table 2 Effects of different treatments on nutrient components in citrus orchard soil

[0098]

[0099] 2. Improvement effect of the microbial slow-release agent of the present invention on acidified paddy soil

[0100] 2.1 Test materials and methods

[0101] This experiment used our company's slightly acidified experimental rice field base (soil pH of approximately 5.03) and set up eight test plots (5m×5m). Seven days before transplanting rice seedlings, conventional fertilizers were applied with Examples 1-3 (5kg / mu), Comparative Examples 1-3 (5kg / mu), and our company's soil conditioner, followed by broadcast application. The fields were then plowed and mixed. Conventional fertilizer served as a blank control group. Rice seedlings were then transplanted and field management was performed according to conventional farming practices. After the rice was harvested, soil samples were collected to measure pH, organic matter, and nutrient content.

[0102] 2.2 Results and Analysis

[0103] As can be seen from the results in Tables 3 and 4, the microbial slow-release fertilizer prepared by the present invention has a good effect of improving soil acidification and increasing rice yield. The microbial slow-release fertilizer prepared by the embodiment of the present invention can significantly increase the pH value of the soil, increase the organic matter content in the soil, and significantly increase the total nitrogen, total phosphorus, total potassium, available phosphorus, and available potassium content in the soil, thereby improving the fertilizer efficiency of the soil. During the rice planting period, it can continuously regulate the soil pH and release effective components such as nitrogen, phosphorus, and potassium in the soil, continuously providing nutrition for rice, thereby promoting the growth of rice plants and increasing rice yield.

[0104] Table 3 Effects of different treatments on soil properties

[0105]

[0106] Table 4 Effects of different treatments on rice yield

[0107]

[0108]

Claims

1. A microbial slow-release fertilizer, characterized in that: The invention comprises, by weight, 15-18 parts of composite microorganisms, 8-10 parts of soybean root powder, 20-23 parts of beta-cyclodextrin, 15-20 parts of wood ash, 5-8 parts of humic acid, 5-8 parts of tea saponin, 13-15 parts of potassium fulvic acid, and 18-20 parts of carboxymethyl chitosan; the composite microorganisms comprise Azotobacter rotundus, Bacillus subtilis, and Streptomyces tenuifolius; The preparation method of the composite microorganism is as follows: A culture medium is prepared by adding water to the raw materials according to a ratio of 30-40 g / L composite biochar, 6-8 g / L sodium caseinate, 5-7 g / L yeast extract powder, 12-15 g / L potato starch, 3-5 g / L fucoidan, 12-15 g / L soy peptone, and 1.5-2.0 g / L agar; 3-5 g / L Azotobacter rotundifolia, 6-8 g / L Bacillus subtilis, and 4-5 g / L Streptomyces tenuifolius are added to the prepared culture medium, culturing at 25-30° C. for 1.5-2 days, drying, and crushing to obtain a composite microorganism; The preparation method of the composite biochar comprises the following steps: Activation: Soak rapeseed meal in a 30-35% hydrochloric acid solution for 20-30 minutes, then add sodium silicate to react, dry, and activate the product for later use; the mass-to-volume ratio of rapeseed meal, sodium silicate, and hydrochloric acid solution is 1:(3-5):(1.5-3) in kg / kg / L; First calcination: calcining the activated product obtained in the activation step at 200-230°C for 1-1.5h in a nitrogen environment, then cooling to room temperature and setting aside for later use; Second calcination: The calcined product obtained in the first calcination step is added with shell powder and rape straw in a nitrogen environment and calcined at 600-650°C for 1-1.5 hours to obtain composite biochar; the amount of shell powder added is 3-5 times the weight of rapeseed meal, and the amount of rape straw added is 0.3-0.5 times the weight of rapeseed meal; The preparation method of the microbial slow-release fertilizer comprises the following steps: Step A, adding β-cyclodextrin to water to form a paste, then adding the composite microorganism and mixing to obtain a mixture I for later use; Step B, adding water to soybean root powder, wood ash, humic acid, tea saponin, potassium fulvic acid, and carboxymethyl chitosan to form a paste to obtain mixture II for later use; Step C, adding mixture I to mixture II, mixing evenly, and drying to obtain a microbial slow-release fertilizer.

2. Use of the microbial slow-release fertilizer as claimed in claim 1 in improving soil acidification.

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