An agricultural soil conditioner and its preparation method

Abstract

This invention discloses an agricultural soil conditioner and its preparation method, belonging to the technical field of soil conditioner. The agricultural soil conditioner provided by this invention, by weight, comprises the following raw materials: 30-40 parts soybean meal, 20-25 parts bagasse, 15-20 parts rice husk ash, 5-15 parts brewer's grains, 6-12 parts tea residue, 5-15 parts lotus root powder, 8-10 parts compound microbial agent, 2-5 parts trehalose, 15-25 parts bentonite, 6-8 parts turmeric powder, and 5-10 parts inorganic chelating agent. The compound microbial agent includes Bacillus, *Alcaligenes xylose-oxidizing* subsp. *denitrifying*, and *Alcaligenes foetida*. This invention utilizes waste from multiple industries as raw materials, reducing costs and simultaneously achieving both biological and chemical neutralization of acidity. The combination of different microbial species reduces the accumulation of nitrates and organic acids in the soil. The dual antibacterial system of turmeric powder and microbial antibacterial agents achieves a synergistic effect of rapid soil improvement and long-term maintenance of soil pH.

Description

Technical Field

[0001] This invention belongs to the field of soil conditioner technology, specifically relating to an agricultural soil conditioner and its preparation method. Background Technology

[0002] Soil acidification also exacerbates the harmful effects of heavy metal pollution. It increases the activity of heavy metals in the soil, leading to increased absorption of these harmful heavy metals by plants. These toxic heavy metals then enter the food chain, posing a threat to human health. Furthermore, soil acidification exacerbates plant diseases and negatively impacts plant diversity and soil microbial diversity.

[0003] A common method for improving acidic soils is to apply alkaline substances such as lime to directly neutralize soil acidity. This method is traditional and effective, but it also has some problems. Long-term, excessive application of lime can lead to soil compaction and nutrient imbalance because lime only provides calcium, and excessive calcium can cause deficiencies in magnesium (Mg) and potassium (K), as well as decreased phosphorus (P) availability. When lime application is stopped, the soil may experience re-acidification, meaning the soil acidity rises again, causing crops to suffer acid damage once more. Lime has poor mobility in the soil and typically only neutralizes the acidity of the topsoil (15-20 cm), with limited effect on improving deeper soil layers (below 20 cm). Summary of the Invention

[0004] The purpose of this invention is to provide an agricultural soil conditioner and its preparation method, which can achieve short-term and long-term pH adjustment of acidic soils.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] This invention provides an agricultural soil conditioner, comprising the following raw materials by weight:

[0007] 30-40 parts soybean meal, 20-25 parts bagasse, 15-20 parts rice husk ash, 5-15 parts brewer's grains, 6-12 parts tea residue, 5-15 parts lotus root powder, 8-10 parts compound microbial agent, 2-5 parts trehalose, 15-25 parts bentonite, 6-8 parts turmeric powder, and 5-10 parts inorganic chelating agent.

[0008] Bentonite is loaded with microbial inoculum, and mixed with lotus root powder, brewer's grains, and trehalose to form a compound microbial agent. Sugarcane bagasse, tea residue, soybean meal, rice husk ash, and turmeric powder are then mixed with the compound microbial agent and granulated to form a soil conditioner.

[0009] The compound microbial agent includes Bacillus, Alcaligenes xylose oxidizing subsp. denitrifying and alkali-producing bacteria.

[0010] Of the above raw materials, bagasse, brewer's grains, tea residue, soybean meal, and rice husk ash are all agricultural wastes. Currently, bagasse is often used by sugar mills as fuel for steam engines; brewer's grains are mostly discarded as waste or used as animal feed, but this poses a risk of acidosis; soybean meal is mainly used to make animal feed, but its further application in the feed industry is limited due to the presence of various anti-nutritional factors. When these wastes are used as raw materials for agricultural soil conditioners, bagasse, being a loose, porous, and lightweight solid, can promote soil loosening, reduce soil density, and improve permeability, thus promoting plant absorption of water and nutrients. It also reduces water evaporation and soil compaction, which is beneficial for microbial activity, thereby enhancing soil fertility and disease resistance. Furthermore, the lignin and cellulose it provides can serve as nutrients for microbial inoculants, promoting their growth in the soil and increasing their activity.

[0011] Brewer's grains contain protein, crude fiber, crude fat, ash, as well as vitamins, minerals, and enzymes. They also contain high levels of maltose, arabinose, xylose, and glucose, making them an excellent nutrient source for *Alcaligenes xylose-oxidizing* subsp. *denitrifying*. *Alcaligenes xylose-oxidizing* subsp. *denitrifying* can utilize nitrite as an electron acceptor for denitrification, thus avoiding soil acidification caused by the combination of nitrite and hydrogen ions in the soil.

[0012] In addition to fiber and protein, tea residue also contains tea polyphenols, caffeine, and lysine. Tea polyphenols and caffeine are alkaline, which can inhibit soil acidification, and are rich in nutrients such as nitrogen, phosphorus, and potassium needed by plants.

[0013] Rice husk ash is the residue left after burning rice husks, and its main component is silicon dioxide (SiO2). The content is typically between 80% and 95%, with the remainder consisting of unburned carbon and other trace metal oxides (such as potassium oxide). O, sodium oxide N Rice husk ash contains elements such as oxygen (O), magnesium oxide (MgO), etc. It has a high specific surface area (typically 50-100 m² / g) and a porous structure, which can improve soil compaction. Rice husk ash itself is alkaline, which can neutralize acidic substances in the soil, thereby increasing the soil pH and improving acidic soil environments. Simultaneously, rice husk ash can replenish potassium and magnesium elements in the soil, enriching the soil's elemental composition.

[0014] Furthermore, the ratio of viable colony counts of Bacillus, Alcaligenes xylose oxidizing subsp. denitrifying and Alcaligenes fecalis in the compound microbial agent is 2:1.2-1.5:0.8-1.

[0015] Bacillus decomposes organic matter, releasing nutrients and providing carbon and nitrogen sources for alkali-producing bacteria. Alkali-producing bacteria degrade organic acids (such as acetic acid and lactic acid), reducing the accumulation of acid ions. They also catalyze the decomposition of residual urea in the soil into carbon dioxide and ammonia via urease, releasing alkaline substances. Furthermore, they reduce nitrogen oxides to nitrogen gas through denitrification and utilize the generated energy for nitrogen fixation, thus providing nitrogen nutrition for plants. The combined action of *Alkali-producing xylose* subsp. *denitrifying* and alkali-producing bacteria continuously regulates pH, preventing long-term drastic fluctuations.

[0016] Furthermore, the Bacillus is at least one of Bacillus subtilis, Bacillus pumilus, and Bacillus jellyoidus.

[0017] Bacillus subtilis can utilize the cellulose and protein in brewer's grains as carbon and nitrogen sources to produce γ-polyglutamic acid (γ-PGA) and other bioactive substances, such as glutamic acid and amino acids. The molecular structure of γ-polyglutamic acid contains carboxyl and amino groups, which impart acidity and alkalinity to it. In acidic environments, the carboxyl group protonates, while in alkaline environments, it deprotonates, thereby regulating the pH of the soil.

[0018] Bacillus pumilus can break down complex organic molecules into smaller molecules by secreting various enzymes, such as proteases and cellulases. Proteases can break down proteins into amino acids, while cellulases break down cellulose into monosaccharides.

[0019] Bacillus mucilaginosus possesses phosphorus and potassium solubilizing properties, capable of converting unavailable phosphorus and potassium fixed in the soil into available phosphorus and potassium that can be absorbed and utilized by plants, thus improving the utilization rate of phosphorus and potassium. Bacillus mucilaginosus can also convert atmospheric nitrogen into its own bacterial protein, thereby contributing to soil fertility.

[0020] Bacillus subtilis can promote the growth of plant roots and above-ground parts, enhance plant resistance, and exhibit significant antibacterial activity by secreting plant hormones (such as auxins and gibberellins) and various enzymes (such as phytase and cellulase). It can also improve soil structure by fixing nitrogen, solubilizing phosphorus and potassium, providing a more suitable growing environment for plants. Bacillus pumilus is widely used in agriculture for the control of plant diseases. It can secrete antibacterial substances (such as chitinase and lipopeptides) to inhibit the growth of plant pathogenic fungi. Bacillus mucilage secretes polysaccharide capsules that can produce various antibiotics, inhibiting the growth of many harmful microorganisms.

[0021] Furthermore, the Bacillus species are Bacillus subtilis and Bacillus pumilus with a live colony count ratio of 1:1.

[0022] Furthermore, the mass ratio of lotus root starch to trehalose is 2-3:1. Trehalose can act as a stress protectant for microorganisms, maintaining their survival rate during the drying process. Lotus root starch contains starch, as well as abundant iron, calcium, phosphorus, vitamins, and various minerals. It swells and gelatinizes upon contact with water, forming a viscous, semi-transparent gel. Compared to corn starch, it contains a higher proportion of amylopectin, resulting in a higher viscosity after gelatinization. This allows it to both encapsulate the microorganisms with trehalose and serve as a slow-release carbon source, supporting the continuous proliferation of microorganisms in the soil. The minerals in the lotus root starch can also replenish the soil.

[0023] Furthermore, the bentonite is sodium-based bentonite with a particle size ≤100 mesh.

[0024] Furthermore, the inorganic chelating agent is nano-hydroxyapatite. Hydroxyapatite (HAP), also known as basic calcium phosphate, is weakly alkaline and can adjust the pH of soil. Due to its high specific surface area and porous structure, nano-hydroxyapatite has a large adsorption capacity and can achieve chelation adsorption of metals through processes such as chemical adsorption and ion exchange.

[0025] Furthermore, the nano-hydroxyapatite is prepared using seashells as raw material.

[0026] This invention also provides a method for preparing an agricultural soil conditioner, comprising the following steps:

[0027] Step 1: Inoculate Bacillus, *Alcaligenes xylose-oxidizing* subsp. *denitrifying*, and *Alcaligenes faecalis* separately into LB medium and culture until ≥1... CFU / g is mixed according to the colony count ratio to form a compound microbial agent;

[0028] Step 2: Mix the compound microbial inoculant with bentonite, add trehalose and gelatinized lotus root powder, and continue mixing until homogeneous. Dry at room temperature to achieve inoculum loading, obtaining the loaded inoculant. The triple protection of bentonite, trehalose, and lotus root powder—bentonite adsorbing and fixing the bacteria, trehalose stabilizing the cell membrane, and lotus root powder providing a slow-release carbon source—significantly improves the survival rate of the inoculant in processing and soil environments.

[0029] Step 3: Mix soybean meal, bagasse, rice husk ash, brewer's grains, tea residue, turmeric powder and inorganic chelating agent, then pulverize and sieve through a 100-mesh sieve. Mix the sieved material with the loaded microbial agent evenly and dry thoroughly to obtain an agricultural soil conditioner.

[0030] Furthermore, the gelatinized lotus root starch is prepared by dissolving lotus root starch in water, heating to gelatinize, and then cooling to room temperature. The concentration of lotus root starch in water is 5-10 wt%, and the heating temperature is 60-80°C. .

[0031] The beneficial effects of this invention are:

[0032] (1) The soil conditioner provided by the present invention combines microbial alkali production with chemical neutralization of rice husk ash to achieve a dual biological and chemical neutralization effect. It also utilizes the combination of different functional strains to reduce the accumulation of nitrates and organic acids in the soil, and to decompose phosphorus and fix nitrogen, thereby achieving a synergistic effect of rapid soil condition improvement and long-term maintenance of soil pH.

[0033] (2) The raw materials used in this invention have no pollution hazards, and can avoid the microplastic risks of synthetic modifiers. Industrial and agricultural waste (bagasse, brewer's grains, tea dregs, soybean meal, rice husk ash) can be transformed into treasures. By optimizing the ratio, it can form good nutrients for microorganisms in the soil, improve microbial activity, and combine waste from multiple industries to reduce costs.

[0034] (3) The microbial agent in this invention can produce antibacterial substances to inhibit pathogens. At the same time, turmeric powder contains natural antibacterial substances and can be used as a fast-acting antibacterial agent. The microbial agent can inhibit harmful pathogens for a long time, forming a dual antibacterial system. At the same time, it avoids the damage of chemical fungicides to beneficial bacteria and can reduce pesticide dependence.

[0035] (4) In the preparation process, the present invention uses bentonite to load the composite microbial agent and simultaneously uses trehalose and lotus root powder to encapsulate it, forming a protective structure for the microbial strain while forming a structure that softens and disintegrates when exposed to water. When applied, it can release the microbial strain when exposed to water, with a good release effect. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] Prepare the raw materials according to the following mass ratio: 35 parts soybean meal, 22 parts bagasse, 20 parts rice husk ash, 12 parts brewer's grains, 12 parts tea residue, 5 parts lotus root powder, 10 parts compound microbial agent, 5 parts trehalose, 25 parts sodium bentonite, 8 parts turmeric powder, and 10 parts nano hydroxyapatite.

[0039] Preparation of agricultural soil conditioners:

[0040] Step 1: Inoculate Bacillus subtilis, Bacillus pumilus, Alcaligenes xylose oxidizing subsp. denitrifying, and Alcaligenes feces into LB medium and culture until ≥1 CFU / g is mixed at a live colony count ratio of 1:1:1.5:0.8 to form a compound microbial agent;

[0041] Step 2: Dissolve lotus root starch in water at a concentration of 8 wt%, and heat to 70°C. Gelatinize the mixture, cool it to room temperature, mix the compound microbial agent with sodium bentonite (particle size ≤100 mesh), add trehalose and gelatinized lotus root powder and continue mixing evenly, dry at room temperature to achieve inoculum loading, and obtain loaded inoculum.

[0042] Step 3: Mix soybean meal, bagasse, rice husk ash, brewer's grains, tea residue, turmeric powder and nano hydroxyapatite, then pulverize and sieve through a 100-mesh sieve. Mix the sieved material with the loaded microbial agent evenly and dry thoroughly to obtain an agricultural soil conditioner.

[0043] Example 2

[0044] The only difference from Example 1 is that the mass fraction of rice husk ash is adjusted to 18 parts and the mass fraction of compound microbial agent is adjusted to 9 parts.

[0045] Prepare the raw materials according to the following mass ratio: 35 parts soybean meal, 22 parts bagasse, 18 parts rice husk ash, 12 parts brewer's grains, 12 parts tea residue, 5 parts lotus root powder, 9 parts compound microbial agent, 5 parts trehalose, 25 parts sodium bentonite, 8 parts turmeric powder, and 10 parts nano hydroxyapatite.

[0046] Preparation of agricultural soil conditioners:

[0047] Step 1: Inoculate Bacillus subtilis, Bacillus pumilus, Alcaligenes xylose oxidizing subsp. denitrifying, and Alcaligenes feces into LB medium and culture until ≥1 CFU / g is mixed at a live colony count ratio of 1:1:1.5:0.8 to form a compound microbial agent;

[0048] Step 2: Dissolve lotus root starch in water at a concentration of 8 wt%, and heat to 70°C. Gelatinize the mixture, cool it to room temperature, mix the compound microbial agent with sodium bentonite (particle size ≤100 mesh), add trehalose and gelatinized lotus root powder and continue mixing evenly, dry at room temperature to achieve inoculum loading, and obtain loaded inoculum.

[0049] Step 3: Mix soybean meal, bagasse, rice husk ash, brewer's grains, tea residue, turmeric powder and nano hydroxyapatite, then pulverize and sieve through a 100-mesh sieve. Mix the sieved material with the loaded microbial agent evenly and dry thoroughly to obtain an agricultural soil conditioner.

[0050] Example 3

[0051] The only difference from Example 1 is that the mass fraction of rice husk ash is adjusted to 15 parts and the mass fraction of compound microbial agent is adjusted to 8 parts.

[0052] Prepare the raw materials according to the following mass ratio: 35 parts soybean meal, 22 parts bagasse, 15 parts rice husk ash, 12 parts brewer's grains, 12 parts tea residue, 5 parts lotus root powder, 8 parts compound microbial agent, 5 parts trehalose, 25 parts sodium bentonite, 8 parts turmeric powder, and 10 parts nano hydroxyapatite.

[0053] Preparation of agricultural soil conditioners:

[0054] Step 1: Inoculate Bacillus subtilis, Bacillus pumilus, Alcaligenes xylose oxidizing subsp. denitrifying, and Alcaligenes feces into LB medium and culture until ≥1 CFU / g is mixed at a live colony count ratio of 1:1:1.5:0.8 to form a compound microbial agent;

[0055] Step 2: Dissolve lotus root starch in water at a concentration of 8 wt%, and heat to 70°C. Gelatinize the mixture, cool it to room temperature, mix the compound microbial agent with sodium bentonite (particle size ≤100 mesh), add trehalose and gelatinized lotus root powder and continue mixing evenly, dry at room temperature to achieve inoculum loading, and obtain loaded inoculum.

[0056] Step 3: Mix soybean meal, bagasse, rice husk ash, brewer's grains, tea residue, turmeric powder and nano hydroxyapatite, then pulverize and sieve through a 100-mesh sieve. Mix the sieved material with the loaded microbial agent evenly and dry thoroughly to obtain an agricultural soil conditioner.

[0057] Example 4

[0058] The only difference from Example 2 is that the ratio of viable colony counts of Bacillus subtilis, Bacillus pumilus, Alcaligenes xylose oxidizing subsp. denitrification and Alcaligenes faecalis is adjusted to 1:1:1.4:0.9.

[0059] Prepare the raw materials according to the following mass ratio: 35 parts soybean meal, 22 parts bagasse, 18 parts rice husk ash, 12 parts brewer's grains, 12 parts tea residue, 5 parts lotus root powder, 9 parts compound microbial agent, 5 parts trehalose, 25 parts sodium bentonite, 8 parts turmeric powder, and 10 parts nano hydroxyapatite.

[0060] Preparation of agricultural soil conditioners:

[0061] Step 1: Inoculate Bacillus subtilis, Bacillus pumilus, Alcaligenes xylose oxidizing subsp. denitrifying, and Alcaligenes feces into LB medium and culture until ≥1 CFU / g is mixed at a live colony count ratio of 1:1:1.4:0.9 to form a compound microbial agent;

[0062] Step 2: Dissolve lotus root starch in water at a concentration of 8 wt%, and heat to 70°C. Gelatinize the mixture, cool it to room temperature, mix the compound microbial agent with sodium bentonite (particle size ≤100 mesh), add trehalose and gelatinized lotus root powder and continue mixing evenly, dry at room temperature to achieve inoculum loading, and obtain loaded inoculum.

[0063] Step 3: Mix soybean meal, bagasse, rice husk ash, brewer's grains, tea residue, turmeric powder and nano hydroxyapatite, then pulverize and sieve through a 100-mesh sieve. Mix the sieved material with the loaded microbial agent evenly and dry thoroughly to obtain an agricultural soil conditioner.

[0064] Example 5

[0065] The only difference from Example 2 is that the ratio of viable colony counts of Bacillus subtilis, Bacillus pumilus, Alcaligenes xylose oxidizing subsp. denitrification and Alcaligenes faecalis is adjusted to 1:1:1.2:1.

[0066] Prepare the raw materials according to the following mass ratio: 35 parts soybean meal, 22 parts bagasse, 18 parts rice husk ash, 12 parts brewer's grains, 12 parts tea residue, 5 parts lotus root powder, 9 parts compound microbial agent, 5 parts trehalose, 25 parts sodium bentonite, 8 parts turmeric powder, and 10 parts nano hydroxyapatite.

[0067] Preparation of agricultural soil conditioners:

[0068] Step 1: Inoculate Bacillus subtilis, Bacillus pumilus, Alcaligenes xylose oxidizing subsp. denitrifying, and Alcaligenes feces into LB medium and culture until ≥1 CFU / g is mixed at a live colony count ratio of 1:1:1.2:1 to form a compound microbial agent;

[0069] Step 2: Dissolve lotus root starch in water at a concentration of 8 wt%, and heat to 70°C. Gelatinize the mixture, cool it to room temperature, mix the compound microbial agent with sodium bentonite (particle size ≤100 mesh), add trehalose and gelatinized lotus root powder and continue mixing evenly, dry at room temperature to achieve inoculum loading, and obtain loaded inoculum.

[0070] Step 3: Mix soybean meal, bagasse, rice husk ash, brewer's grains, tea residue, turmeric powder and nano hydroxyapatite, then pulverize and sieve through a 100-mesh sieve. Mix the sieved material with the loaded microbial agent evenly and dry thoroughly to obtain an agricultural soil conditioner.

[0071] Example 6

[0072] The only difference from Example 4 is that the mass fraction of turmeric powder is adjusted to 7 parts.

[0073] Example 7

[0074] The only difference from Example 4 is that the mass fraction of turmeric powder is adjusted to 6 parts, while the other conditions and steps are the same as in Example 4.

[0075] Example 8

[0076] The only difference from Example 1 is that the mass fraction of lotus root powder is adjusted to 10 parts and the mass fraction of trehalose is adjusted to 3 parts, while the other conditions and steps are the same as in Example 1.

[0077] Example 9

[0078] The only difference from Example 1 is that the mass fraction of lotus root powder is adjusted to 15 parts and the mass fraction of trehalose is adjusted to 2 parts, while the other conditions and steps are the same as in Example 1.

[0079] Example 10

[0080] The only difference from Example 1 is that the number of nano-hydroxyapatite parts is adjusted to 8 parts, while the other conditions and steps are the same as in Example 1.

[0081] Example 11

[0082] The only difference from Example 1 is that the number of nano-hydroxyapatite parts is adjusted to 5 parts, while the other conditions and steps are the same as in Example 1.

[0083] Example 12

[0084] The only difference from Example 1 is that the bacterial strain in the compound microbial agent is Bacillus subtilis instead of Bacillus thuringiensis, while the other conditions and steps are the same as in Example 1.

[0085] Example 13

[0086] The only difference from Example 1 is that the bacterial strain in the compound microbial agent is replaced with Bacillus pumilus instead of Bacillus simulans, while the other conditions and steps are the same as in Example 1.

[0087] Comparative Example 1

[0088] The only difference from Example 1 is that the compound microbial agent does not contain *Alcaligenes xylose oxidizing subsp. *denitrifying*.

[0089] Prepare the raw materials according to the following mass ratio: 35 parts soybean meal, 22 parts bagasse, 20 parts rice husk ash, 12 parts brewer's grains, 12 parts tea residue, 5 parts lotus root powder, 10 parts compound microbial agent, 5 parts trehalose, 25 parts sodium bentonite, 8 parts turmeric powder, and 10 parts nano hydroxyapatite.

[0090] Preparation of agricultural soil conditioners:

[0091] Step 1: Inoculate Bacillus subtilis, Bacillus pumilus, and Alcaligenes faecalis into LB medium and culture until ≥1 CFU / g is mixed at a live colony count ratio of 1:1:0.8 to form a compound microbial agent;

[0092] Step 2: Dissolve lotus root starch in water at a concentration of 8 wt%, and heat to 70°C. Gelatinize the mixture, cool it to room temperature, mix the compound microbial agent with sodium bentonite (particle size ≤100 mesh), add trehalose and gelatinized lotus root powder and continue mixing evenly, dry at room temperature to achieve inoculum loading, and obtain loaded inoculum.

[0093] Step 3: Mix soybean meal, bagasse, rice husk ash, brewer's grains, tea residue, turmeric powder and nano hydroxyapatite, then pulverize and sieve through a 100-mesh sieve. Mix the sieved material with the loaded microbial agent evenly and dry thoroughly to obtain an agricultural soil conditioner.

[0094] Comparative Example 2

[0095] The only difference from Example 1 is that no Bacillus is added to the compound microbial agent.

[0096] Prepare the raw materials according to the following mass ratio: 35 parts soybean meal, 22 parts bagasse, 20 parts rice husk ash, 12 parts brewer's grains, 12 parts tea residue, 5 parts lotus root powder, 10 parts compound microbial agent, 5 parts trehalose, 25 parts sodium bentonite, 8 parts turmeric powder, and 10 parts nano hydroxyapatite.

[0097] Preparation of agricultural soil conditioners:

[0098] Step 1: Inoculate *Alcaligenes xylose-oxidizing* subsp. *denitrifying* and *Alcaligenes fecalis* separately into LB medium and culture until ≥1... CFU / g is mixed at a live colony count ratio of 1.5:0.8 to form a compound microbial agent;

[0099] Step 2: Dissolve lotus root starch in water at a concentration of 8 wt%, and heat to 70°C. Gelatinize the mixture, cool it to room temperature, mix the compound microbial agent with sodium bentonite (particle size ≤100 mesh), add trehalose and gelatinized lotus root powder and continue mixing evenly, dry at room temperature to achieve inoculum loading, and obtain loaded inoculum.

[0100] Step 3: Mix soybean meal, bagasse, rice husk ash, brewer's grains, tea residue, turmeric powder and nano hydroxyapatite, then pulverize and sieve through a 100-mesh sieve. Mix the sieved material with the loaded microbial agent evenly and dry thoroughly to obtain an agricultural soil conditioner.

[0101] Comparative Example 3

[0102] The only difference from Example 1 is that trehalose is used instead of lotus root starch in the raw materials.

[0103] Prepare the raw materials according to the following mass ratio: 35 parts soybean meal, 22 parts bagasse, 20 parts rice husk ash, 12 parts brewer's grains, 12 parts tea residue, 10 parts compound microbial agent, 10 parts trehalose, 25 parts sodium bentonite, 8 parts turmeric powder, and 10 parts nano hydroxyapatite.

[0104] Preparation of agricultural soil conditioners:

[0105] Step 1: Inoculate Bacillus subtilis, Bacillus pumilus, Alcaligenes xylose oxidizing subsp. denitrifying, and Alcaligenes feces into LB medium and culture until ≥1 CFU / g is mixed at a live colony count ratio of 1:1:1.5:0.8 to form a compound microbial agent;

[0106] Step 2: Mix the compound microbial inoculant with sodium bentonite (particle size ≤100 mesh), add trehalose and continue mixing until homogeneous, then dry at room temperature to achieve inoculum loading and obtain the loaded inoculant.

[0107] Step 3: Mix soybean meal, bagasse, rice husk ash, brewer's grains, tea residue, turmeric powder and nano hydroxyapatite, then pulverize and sieve through a 100-mesh sieve. Mix the sieved material with the loaded microbial agent evenly and dry thoroughly to obtain an agricultural soil conditioner.

[0108] Comparative Example 4

[0109] This comparative example uses lime as an acidic soil conditioner.

[0110] The soil conditioners prepared in Examples 1-13 and Comparative Examples 1-4 were subjected to field tests. Experimental fields were selected, and the soil pH value of the experimental fields was tested. The pH value was 4.3. Soil conditioners were applied to the soil at a rate of 130 kg / mu. Rice was planted in the fields, and a blank control group was set up. The soil pH value changes and crop yields at different stages were measured. The results are shown in Table 1.

[0111] Table 1

[0112]

[0113] As shown in Table 1, the rice yield after applying the soil conditioner prepared in the examples was significantly higher than that in the comparative example. Among Examples 1-3, the optimal ratio of rice husk ash and compound microbial agent in Example 2 was the best. Although excessive application of rice husk ash reduced the soil pH... The changes are significant, but the organic matter in rice husk ash has been converted into carbon black, which reduces the nutrients for microorganisms in the soil conditioner. The low proportion of rice husk ash also reduces the rapid increase in soil pH. Optimizing the proportions of various microbial species in the compound microbial agent, under the conditions of Example 4, *Alcaligenes xylose-oxidizing* subsp. *denitrifying* and *Alcaligenes foetida* can work synergistically to maximize the long-term effect of regulating soil pH. Examples 6 and 7 reduced the content of turmeric powder compared to Example 4. While the turmeric powder content does not significantly affect the overall soil pH, it can affect crop health. In the soil conditioner prepared in Example 6, the turmeric powder and the antibacterial substances produced by microorganisms work together to increase yield. In Examples 8 and 9, the ratio of lotus root powder to trehalose affects the survival rate of the microbial species in the compound microbial agent, indirectly affecting the pH regulation effect and yield. Examples 12 and 13 adjusted the combination of microbial species. In Example 12, the combined use of *Bacillus mucilaginosus* and *Bacillus pumilus* significantly increased crop yield.

[0114] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0115] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An agricultural soil conditioner, characterized in that, By weight, it includes the following raw materials: 30-40 parts soybean meal, 20-25 parts bagasse, 15-20 parts rice husk ash, 5-15 parts brewer's grains, 6-12 parts tea residue, 5-15 parts lotus root powder, 8-10 parts compound microbial agent, 2-5 parts trehalose, 15-25 parts bentonite, 6-8 parts turmeric powder, and 5-10 parts inorganic chelating agent. The compound microbial agent includes Bacillus, xylose-oxidizing alkalinobacterium denitrification subspecies, and fecal alkalinobacterium. The preparation method of the agricultural soil conditioner includes the following steps: Step 1: Inoculate Bacillus, *Alcaligenes xylose-oxidizing* subsp. *denitrifying*, and *Alcaligenes faecalis* separately into LB medium and culture until ≥10⁻⁶. 8 CFU / g is mixed according to the colony count ratio to form a compound microbial agent; Step 2: Mix the compound microbial inoculant with bentonite, add trehalose and gelatinized lotus root powder and continue mixing evenly. Dry at room temperature to achieve inoculum loading and obtain the loaded inoculant. Step 3: Mix soybean meal, bagasse, rice husk ash, brewer's grains, tea residue, turmeric powder and inorganic chelating agent, then pulverize and sieve through a 100-mesh sieve. Mix the sieved material with the loaded microbial agent evenly and dry thoroughly to obtain an agricultural soil conditioner.

2. The agricultural soil conditioner according to claim 1, characterized in that, The ratio of viable colony counts of Bacillus, Alcaligenes xylose oxidizing subsp. denitrifyingus, and Alcaligenes fecalis in the compound microbial agent is 2:1.2-1.5:0.8-1.

3. The agricultural soil conditioner according to claim 1, characterized in that, The Bacillus species is at least one of Bacillus subtilis, Bacillus pumilus, and Bacillus jellyoidus.

4. The agricultural soil conditioner according to claim 1, characterized in that, The Bacillus species are Bacillus subtilis and Bacillus pumilus with a live colony count ratio of 1:

1.

5. An agricultural soil conditioner according to claim 1, characterized in that, The mass ratio of lotus root powder to trehalose is 2-3:

1.

6. An agricultural soil conditioner according to claim 1, characterized in that, The bentonite is sodium-based bentonite with a particle size ≤100 mesh.

7. An agricultural soil conditioner according to claim 1, characterized in that, The inorganic chelating agent is nano-hydroxyapatite.

8. An agricultural soil conditioner according to claim 7, characterized in that, The nano-hydroxyapatite was prepared using seashells as raw material.

9. An agricultural soil conditioner according to claim 1, characterized in that, The gelatinized lotus root powder is made by dissolving lotus root powder in water, heating to gelatinize, and then cooling to room temperature. The concentration of lotus root powder in water is 5-10 wt%, and the heating temperature is 60-80℃.

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