A bio-phosphate fertilizer for cotton based on phosphate-solubilizing bacteria and its application

Abstract

This invention discloses a cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria and its application, relating to the technical field of agricultural bio-fertilizers. It comprises the following components by weight: 30-50 parts of phosphate-solubilizing bacteria agent, 20-40 parts of organic carrier, 5-15 parts of slow-release agent, 2-8 parts of trace element supplement, and 1-5 parts of pH adjuster. The phosphate-solubilizing bacteria agent is composed of *Bacillus megaterium* strain CCTCCNO:M2025688, *Bacillus cereus* strain CCTCCNO:M2025689, and a culture medium. The ratio of viable *Bacillus megaterium* to *Bacillus cereus* is 2:1-3:1, and the total viable count in the phosphate-solubilizing bacteria agent is ≥1×10 CFU / g. The organic carrier is a mixture of decomposed cottonseed hulls and humic acid, with a weight ratio of 3:1-5:1. The slow-release agent is modified attapulgite, prepared by soaking the attapulgite in a 5-8% hydrochloric acid solution for 2-4 hours. The bio-phosphate fertilizer of this invention uses a compound phosphorus-solubilizing strain, combined with an optimized carrier and slow-release system, which can significantly improve the availability of phosphorus in the soil, promote cotton growth, increase cotton yield and fiber quality, and improve the soil ecological environment.

Description

Technical Field

[0001] This invention relates to the technical field of agricultural bio-fertilizers, and in particular to a cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria and its application. Background Technology

[0002] Cotton is an important economic crop in my country, and its growth requires a high amount of phosphorus. Phosphorus not only participates in cotton's photosynthesis, energy metabolism, and nutrient synthesis, but also plays a crucial role in boll development and fiber quality improvement. However, the availability of phosphorus in my country's farmland soils is generally low. Most phosphorus exists in the form of insoluble calcium phosphate and iron phosphate, which cannot be directly absorbed and utilized by cotton, resulting in low fertilizer utilization. This not only increases planting costs but also causes environmental problems such as soil compaction and eutrophication of water bodies.

[0003] While traditional chemical phosphate fertilizers can provide phosphorus to cotton in the short term, they suffer from drawbacks such as rapid nutrient release, short-lasting effects, and easy fixation by the soil. Long-term, excessive application can disrupt the soil microbial community structure and reduce soil fertility. In recent years, bio-phosphate fertilizers have received widespread attention due to their advantages, including activating insoluble phosphorus in the soil, improving phosphorus utilization, and enhancing the soil ecological environment. Phosphate-solubilizing bacteria, as the core functional component of bio-phosphate fertilizers, can convert insoluble phosphorus in the soil into soluble phosphorus by secreting organic acids and phosphatases, while also promoting cotton root growth and enhancing the cotton's resistance to adverse conditions.

[0004] Currently, publicly available technologies related to phosphate-solubilizing bacterial bio-phosphate fertilizers have the following problems: First, the phosphate-solubilizing ability of the strains is limited, and they have poor environmental adaptability and weak colonization ability in the soil, making it difficult to exert a sustained phosphate-solubilizing effect. Second, the formulation of bio-phosphate fertilizers is unreasonable, lacking effective carriers and slow-release components, resulting in low survival rates of phosphate-solubilizing bacteria during storage and application, and a mismatch between phosphorus release and cotton's phosphorus requirements. Third, the application methods are singular, failing to be tailored to the nutrient requirements of cotton at different growth stages and soil types, thus affecting the fertilizer's application effect. For example, Chinese patent CN109867198A discloses a cotton-specific bio-fertilizer, which, although containing phosphate-solubilizing bacteria, uses a single strain, resulting in limited phosphate-solubilizing effect, and lacks a dedicated slow-release structure, making the fertilizer susceptible to inactivation due to environmental factors in the soil. Chinese patent CN112110732A discloses a compound phosphate-solubilizing bacterial fertilizer, but its carrier selection is singular, providing insufficient protection for the bacterial agent, and it does not consider cotton's micronutrient requirements, thus limiting its application scope.

[0005] To address the aforementioned issues, we will screen for highly efficient and stable phosphorus-solubilizing strains, optimize bio-phosphate fertilizer formulations, and develop scientific application methods based on cotton growth characteristics. This will enable us to develop a cotton bio-phosphate fertilizer with high phosphorus utilization, long-lasting effects, and environmental friendliness, which has significant practical implications and application value. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing phosphate-solubilizing bacterial bio-phosphate fertilizers, such as poor phosphate-solubilizing effect, low strain survival rate, short-lasting fertilizer effect, and unreasonable application methods. This invention provides a cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria and its application. This bio-phosphate fertilizer uses a compound of phosphate-solubilizing strains, combined with an optimized carrier and slow-release system, which can significantly improve soil phosphorus availability, promote cotton growth, increase cotton yield and fiber quality, and simultaneously improve the soil ecological environment.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] A phosphate-solubilizing agent for cotton and its application, comprising the following components by weight: 30-50 parts of phosphate-solubilizing agent, 20-40 parts of organic carrier, 5-15 parts of slow-release agent, 2-8 parts of trace element supplement, and 1-5 parts of pH adjuster; wherein the phosphate-solubilizing agent is composed of *Bacillus megaterium* strain CCTCCNO:M2025688, *Bacillus cereus* strain CCTCCNO:M2025689, and culture medium, wherein the viable cell counts of *Bacillus megaterium* and *Bacillus cereus* are specified. The ratio of the phosphate-solubilizing bacteria is 2:1-3:1, and the total viable count in the phosphate-solubilizing agent is ≥1×10 CFU / g; the organic carrier is a mixture of decomposed cottonseed hulls and humic acid, with a weight ratio of 3:1-5:1; the slow-release agent is modified attapulgite, which is prepared by soaking attapulgite in a 5-8% hydrochloric acid solution for 2-4 hours, filtering, washing with deionized water until neutral, drying at 105-110℃, and then mixing and grinding with sodium alginate (5-10% by weight of attapulgite) until the particle size is ≤100 mesh.

[0009] As a preferred embodiment of the cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria and its application described in this invention, the culture medium comprises the following components by weight percentage: glucose 1.5-2.5%, yeast extract 0.5-1.0%, potassium dihydrogen phosphate 0.1-0.3%, magnesium sulfate 0.05-0.15%, calcium chloride 0.01-0.03%, manganese sulfate 0.005-0.015%, with the balance being deionized water; the pH of the culture medium is adjusted to 7.0-7.5; the phosphate-solubilizing bacteria agent is prepared by: respectively... Bacillus megaterium strain CCTCCNO:M2025688 and Bacillus cereus strain CCTCCNO:M2025689 were inoculated into the culture medium and cultured with shaking at 30-35℃ and 180-220 r / min for 24-36 h to obtain single-strain fermentation broth. The two single-strain fermentation broths were then mixed in a certain proportion, and diatomaceous earth (10-20% by weight of the mixed fermentation broth) was added as an adsorbent. The mixture was then vacuum dried at 45-55℃ until the moisture content was ≤10%, and then pulverized to a particle size of ≤80 mesh to obtain the phosphate-solubilizing agent.

[0010] As a preferred embodiment of the cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria and its application described in this invention, the trace element supplement is a mixture of EDTA chelated zinc, EDTA chelated iron and boric acid, with a weight ratio of 2:1:1, wherein the zinc content in the EDTA chelated zinc is ≥15%, the iron content in the EDTA chelated iron is ≥13%, and the boron content in the boric acid is ≥17%; the pH adjuster is a mixture of dolomite powder and limestone powder, with a weight ratio of 1:1-2:1, a particle size ≤120 mesh, and a calcium carbonate content ≥95%.

[0011] As a preferred embodiment of the phosphate-solubilizing bacteria-based cotton bio-phosphate fertilizer and its application described in this invention, the fertilizer comprises the following components in parts by weight: 40 parts of phosphate-solubilizing bacteria agent, 30 parts of organic carrier, 10 parts of slow-release agent, 5 parts of trace element supplement, and 3 parts of pH adjuster; the organic carrier has a weight ratio of decomposed cottonseed hulls to humic acid of 4:1, the humic acid contains ≥70% humic matter and ≤15% moisture content; the modified attapulgite has a weight ratio of attapulgite to sodium alginate of 18:2, and the sodium alginate has a viscosity of 200-300 mPa·s.

[0012] As a preferred embodiment of the phosphate-solubilizing bacteria-based cotton bio-phosphate fertilizer and its application described in this invention, the *Bacillus megaterium* strain CCTCCNO:M2025688 has the following biological characteristics: Gram-positive, rod-shaped, measuring (1.2-1.5) μm × (3.0-5.0) μm, with spores that are elliptical and located in the center of the bacterial cell; after culturing on Pikovaskaia medium for 72 hours, the colonies are milky white, round, with neat edges, smooth surfaces, and a diameter of 2-3 mm, with a phosphate-solubilizing zone diameter to colony diameter ratio ≥4.5; it can grow at 15-45℃ and pH 5.0-9.0, with the optimal growth temperature being 30-35℃ and the optimal growth pH being 7.0-7.5.

[0013] As a preferred embodiment of the phosphate-solubilizing bacteria-based cotton bio-phosphate fertilizer and its application described in this invention, the Bacillus cereus strain CCTCCNO:M2025689 has the following biological characteristics: Gram-positive, rod-shaped, measuring (0.8-1.2) μm × (1.5-3.0) μm, with spores, the spores are round or elliptical and located at the end of the bacterial cell; after culturing on Pikovaskaia medium for 72 h, the colonies are pale yellow, irregular in shape, with irregular edges, rough surface, and a diameter of 1-2 mm, with the ratio of the phosphate-solubilizing zone diameter to the colony diameter ≥3.8; it can grow under conditions of 10-48℃ and pH 4.5-9.5, with the optimal growth temperature being 28-32℃ and the optimal growth pH being 6.5-7.5.

[0014] As a preferred embodiment of the cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria and its application described in this invention, a method for preparing the cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria includes the following steps:

[0015] S1. Preparation of phosphate-solubilizing bacterial agent: Bacillus megaterium and Bacillus cereus are cultured separately to obtain single-strain fermentation broth, which is then mixed, an adsorbent is added, and the mixture is dried and pulverized to obtain the phosphate-solubilizing bacterial agent;

[0016] S2. Preparation of modified attapulgite: Attapulgite is acid-treated and then mixed and ground with sodium alginate to obtain a slow-release agent;

[0017] S3. Mixing and mixing: Add the organic carrier, slow-release agent, trace element supplement and pH adjuster into the mixer in proportion, and mix for 15-20 minutes at a speed of 80-120 r / min to obtain the premix;

[0018] S4. Inoculation agent: Add the phosphate-solubilizing agent to the premix and mix for 10-15 minutes at a speed of 50-80 r / min and a temperature ≤35℃. Control the moisture content of the mixture to 15-20% to obtain cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria.

[0019] S5. Packaging and storage: Pack the product obtained in step S4 in a breathable woven bag and store it in a cool and dry place with a storage temperature ≤25℃ and relative humidity ≤60%.

[0020] As a preferred embodiment of the phosphate-solubilizing bacteria-based cotton bio-phosphate fertilizer and its application according to the present invention, the application methods include seed dressing, basal fertilizer application, and topdressing application; the seed dressing involves mixing the bio-phosphate fertilizer with cotton seeds at a weight ratio of 1:50-1:80, adding an appropriate amount of water to ensure the phosphate fertilizer is evenly attached to the seed surface, and then sowing after air-drying; the basal fertilizer application involves evenly spreading the bio-phosphate fertilizer in the planting furrow or planting hole before cotton sowing or transplanting, with an application rate of 20-30 kg / mu, mixing it evenly with the soil, and then sowing or transplanting; the topdressing application is carried out once each during the cotton budding stage and the boll-forming stage, with application rates of 10-15 kg / mu and 15-20 kg / mu respectively, using strip application or hole application methods, followed by covering with soil.

[0021] As a preferred embodiment of the phosphate-solubilizing bacteria-based bio-phosphate fertilizer for cotton and its application described in this invention, the following steps are taken: When planting cotton in sandy soil, the basal fertilizer application rate of the bio-phosphate fertilizer is increased to 30-40 kg / mu, and the topdressing application rate is increased to 15-20 kg / mu and 20-25 kg / mu during the budding and boll-forming stages, respectively, and irrigation is carried out promptly after topdressing; When planting cotton in clay soil, the basal fertilizer application rate is reduced to 15-25 kg / mu, and shallow trench application is adopted to avoid fertilizer accumulation.

[0022] As a preferred embodiment of the phosphate-solubilizing bacteria-based cotton bio-phosphate fertilizer and its application described in this invention, the following steps are taken: When applied in cotton fields with continuous cropping, a 500-800 times diluted humic acid aqueous solution is applied during the basal fertilizer application stage, with a dosage of 50-80 L / mu; when applied in cotton planting in saline-alkali land, the bio-phosphate fertilizer is mixed with gypsum at a weight ratio of 5:1 and then applied, with the gypsum dosage in the basal fertilizer being 4-6 kg / mu and the gypsum dosage in the top dressing being 2-3 kg / mu.

[0023] The beneficial effects of this invention are:

[0024] Significant phosphorus-solubilizing effect: This invention uses a compound phosphorus-solubilizing strain (Bacillus megaterium CCTCCNO:M2025688 and Bacillus cereus CCTCCNO:M2025689). The two strains have a synergistic effect. By secreting organic acids, phosphatases and other substances, they can efficiently activate insoluble phosphorus in the soil. According to the test results, after applying the bio-phosphate fertilizer of this invention, the effective phosphorus content in the soil increased by 35-50% compared with the control group (applied with the same amount of chemical phosphate fertilizer), and the utilization rate of phosphorus by cotton increased by 20-30%.

[0025] High strain stability: This invention selects a mixture of decomposed cottonseed hulls and humic acid as an organic carrier, combined with modified attapulgite slow-release agent, which can provide a good growth environment and protective barrier for phosphate-solubilizing bacteria, reducing the impact of environmental factors on the strains. Tests showed that after 6 months of storage, the survival rate of the strains remained above 85%, demonstrating strong colonization ability in the soil and sustained phosphate-solubilizing effect.

[0026] Long-lasting fertilizer effect: Modified attapulgite slow-release agent can slowly release phosphorus and protect phosphate-solubilizing bacteria, matching the phosphorus release rate with the phosphorus requirements of cotton at different growth stages, avoiding phosphorus loss and waste. Cotton does not require frequent topdressing throughout its growth period, reducing labor costs, and does not suffer from nutrient deficiency in the later stages, resulting in stable growth.

[0027] Comprehensive and balanced nutrition: This invention adds essential trace elements for cotton, such as zinc, iron, and boron, to the bio-phosphate fertilizer. By using EDTA chelation, the absorption and utilization rate of trace elements is improved, meeting the needs of cotton for multiple nutrients, promoting the physiological metabolism of cotton, and improving the growth status of cotton.

[0028] Improving the soil environment: The bio-phosphate fertilizer of this invention is rich in organic matter and beneficial microorganisms, which can improve soil structure, increase soil aeration and water and fertilizer retention capacity, enrich soil microbial community, reduce the risk of soil compaction, improve soil fertility, and realize sustainable cotton planting.

[0029] Improving cotton yield and quality: Field trials have verified that cotton treated with the bio-phosphate fertilizer of this invention shows a 10-15% increase in seedling emergence rate, an 8-12% decrease in boll shedding rate, an increase of 2-3 bolls per plant, and a 15-20% increase in seed cotton yield. At the same time, cotton fiber length increases by 0.5-1.0 mm, breaking strength increases by 0.8-1.2 cN / tex, and fiber quality is significantly improved.

[0030] Wide range of applications: This invention provides application solutions for different soil types (sandy soil, clay) and special planting conditions (continuous cropping, saline-alkali land), which can adapt to the cotton planting needs of different regions, have high application flexibility, and have broad prospects for promotion. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the basic process for preparing a cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria, as provided in one embodiment of the present invention. Detailed Implementation

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0033] Example 1: Preparation of cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria

[0034] 1. Strain screening and preservation: Soil samples were collected from cotton fields in the main cotton-producing areas of Xinjiang. The samples were enriched, isolated, and purified using Pikovaskaia medium. Two strains with strong phosphorus-solubilizing ability were screened by measuring the ratio of the phosphorus-solubilizing zone diameter to the colony diameter and the available phosphorus content in the soil. Morphological observation, physiological and biochemical tests, and 16S rRNA gene sequence analysis identified them as *Bacillus megaterium* and *Bacillus cereus*, named *Bacillus megaterium* CCTCC NO: M2025688 and *Bacillus cereus* CCTCC NO: M2025689, respectively, and preserved at the China Center for Type Culture Collection (CCTCC).

[0035] 2. Preparation of phosphate-solubilizing bacteria: The culture medium consisted of 2.0% glucose, 0.8% yeast extract, 0.2% potassium dihydrogen phosphate, 0.1% magnesium sulfate, 0.02% calcium chloride, 0.01% manganese sulfate, with the remainder being deionized water, and the pH adjusted to 7.2. Two bacterial strains were inoculated into the culture medium and cultured at 32℃ and 200 rpm for 30 h with shaking to obtain single-strain fermentation broth. The Bacillus megaterium fermentation broth and Bacillus cereus fermentation broth were mixed at a ratio of 2.5:1, and diatomaceous earth (15% by weight of the mixed fermentation broth) was added. The mixture was vacuum dried at 50℃ until the moisture content reached 8%, and then pulverized to a particle size ≤80 mesh to obtain the phosphate-solubilizing bacteria. The total viable count was determined to be 1.2 × 10 CFU / g.

[0036] 3. Preparation of slow-release agent: Attapulgite was soaked in 6% hydrochloric acid solution for 3 hours, filtered, washed with deionized water until neutral, dried at 108℃, mixed with sodium alginate accounting for 8% of the weight of attapulgite, and ground until the particle size was ≤100 mesh to obtain modified attapulgite slow-release agent.

[0037] 4. Preparation of bio-phosphate fertilizer: Weigh out 40 parts by weight of phosphate-solubilizing bacteria agent, 30 parts by weight of organic carrier (decomposed cottonseed hulls to humic acid in a weight ratio of 4:1), 10 parts by weight of slow-release agent, 5 parts by weight of trace element supplement (EDTA chelated zinc:EDTA chelated iron:boric acid = 2:1:1), and 3 parts by weight of pH adjuster (dolomite powder to limestone powder in a weight ratio of 1.5:1). First, add the organic carrier, slow-release agent, trace element supplement, and pH adjuster to a mixer and mix at 100 rpm for 18 minutes to obtain a premix; then add the phosphate-solubilizing bacteria agent and mix at 60 rpm and 32℃ for 12 minutes, controlling the moisture content to 18%, thus obtaining the cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria.

[0038] Example 2: Preparation of cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria

[0039] 1. Preparation of phosphate-solubilizing bacteria: The culture medium consisted of 1.5% glucose, 0.5% yeast extract, 0.1% potassium dihydrogen phosphate, 0.05% magnesium sulfate, 0.01% calcium chloride, 0.005% manganese sulfate, with the remainder being deionized water, and the pH adjusted to 7.0. Two bacterial strains were inoculated into the culture medium and cultured at 30℃ and 180 r / min for 36 h with shaking to obtain single-strain fermentation broth. The fermentation broth of Bacillus megaterium and Bacillus cereus were mixed at a ratio of 2:1, and diatomaceous earth (10% by weight of the mixed fermentation broth) was added. The mixture was vacuum dried at 45℃ until the moisture content was 9%, and then pulverized to a particle size ≤80 mesh to obtain the phosphate-solubilizing bacteria, with a total viable count of 1.0 × 10 CFU / g.

[0040] 2. Preparation of slow-release agent: Attapulgite was soaked in 5% hydrochloric acid solution for 4 hours, filtered and washed until neutral, dried at 105℃, mixed with sodium alginate accounting for 5% of the weight of attapulgite, and ground until the particle size was ≤100 mesh to obtain the slow-release agent.

[0041] 3. Preparation of bio-phosphate fertilizer: Weigh out 30 parts by weight of phosphate-solubilizing bacteria agent, 20 parts by weight of organic carrier (rotten cottonseed hulls to humic acid in a weight ratio of 3:1), 5 parts by weight of slow-release agent, 2 parts by weight of trace element supplement, and 1 part by weight of pH adjuster. First, mix the organic carrier and other components at 120 rpm for 15 min. After adding the phosphate-solubilizing bacteria agent, mix at 50 rpm and 30℃ for 15 min, controlling the moisture content to 15%, to obtain the product.

[0042] Example 3: Preparation of cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria

[0043] 1. Preparation of phosphate-solubilizing bacteria: The culture medium consisted of 2.5% glucose, 1.0% yeast extract, 0.3% potassium dihydrogen phosphate, 0.15% magnesium sulfate, 0.03% calcium chloride, 0.015% manganese sulfate, with the remainder being deionized water, and the pH adjusted to 7.5. Two bacterial strains were inoculated into the culture medium and cultured at 35℃ and 220 rpm for 24 h with shaking to obtain single-strain fermentation broth. The Bacillus megaterium fermentation broth and Bacillus cereus fermentation broth were mixed at a ratio of 3:1, and diatomaceous earth (20% by weight of the mixed fermentation broth) was added. The mixture was vacuum dried at 55℃ until the moisture content reached 7%, and then pulverized to a particle size ≤80 mesh to obtain the phosphate-solubilizing bacteria, with a total viable count of 1.5 × 10 CFU / g.

[0044] 2. Preparation of slow-release agent: Attapulgite was soaked in 8% hydrochloric acid solution for 2 hours, filtered and washed until neutral, dried at 110℃, mixed with sodium alginate accounting for 10% of the weight of attapulgite, and ground until the particle size was ≤100 mesh to obtain the slow-release agent.

[0045] 3. Preparation of bio-phosphate fertilizer: Weigh out 50 parts by weight of phosphate-solubilizing bacteria agent, 40 parts by weight of organic carrier (rotten cottonseed hulls to humic acid in a weight ratio of 5:1), 15 parts by weight of slow-release agent, 8 parts by weight of trace element supplement, and 5 parts by weight of pH adjuster. First, mix the organic carrier and other components at 80 rpm for 20 min. Then, add the phosphate-solubilizing bacteria agent and mix at 80 rpm and 35℃ for 10 min. Control the moisture content to 20% to obtain the product.

[0046] Example 4 Field Trial

[0047] A field experiment was conducted in the cotton-growing area of ​​Shihezi City, Xinjiang. The tested soil was sandy loam with a pH of 7.8 and an available phosphorus content of 8.2 mg / kg. The tested cotton variety was "Xinluzao 45". The experiment included four treatments, each with three replicates, and a plot area of ​​30 m², arranged in a randomized block design.

[0048] Treatment 1: Apply the bio-phosphate fertilizer prepared in Example 1 of this invention. The application method is seed dressing (bio-phosphate fertilizer:seed = 1:60) + 30 kg / mu of base fertilizer + 12 kg / mu of topdressing during the budding stage + 18 kg / mu of topdressing during the flowering and boll-forming stage.

[0049] Treatment 2: Apply commercially available common phosphate-solubilizing bacteria bio-phosphate fertilizer (total viable count 1×10 CFU / g), with the same dosage and application method as Treatment 1;

[0050] Treatment 3: Apply an equal amount of chemical phosphate fertilizer (superphosphate, containing 12% PO);

[0051] Treatment 4: No phosphate fertilizer applied (blank control).

[0052] The experimental results are shown in the table below:

[0053] Process 1 95.2 12.6 18.3 428.5 31.2 19.8 Process 2 88.5 10.2 25.6 365.8 29.5 14.5 Process 3 86.3 9.8 27.1 352.1 29.1 12.3 Process 4 82.1 7.5 34.5 286.4 27.8 7.9

[0054] Example 5: Application Tests on Different Soil Types

[0055] Experiments were conducted in Anyang, Henan (clay soil) and Binzhou, Shandong (saline-alkali land), using the bio-phosphate fertilizer of Example 1 of this invention, and applying it according to targeted application schemes:

[0056] Clay soil (pH 7.2, available phosphorus 7.5mg / kg): 20kg / mu base fertilizer (shallow trench application) + 10kg / mu topdressing during budding stage + 15kg / mu topdressing during flowering and boll formation stage, seed dressing ratio 1:70;

[0057] For saline-alkali land (pH 8.5, available phosphorus 6.8 mg / kg): mix bio-phosphate fertilizer and gypsum at a ratio of 5:1, apply 35 kg / mu of base fertilizer (containing 7 kg / mu of gypsum) + 18 kg / mu of topdressing during the budding stage (containing 3.6 kg / mu of gypsum) + 22 kg / mu of topdressing during the flowering and boll-forming stage (containing 4.4 kg / mu of gypsum), and mix the seeds with 1:80. Apply 70 L / mu of a 600-fold diluted humic acid solution as a base fertilizer.

[0058] The experimental results show that in clay soil, the yield of cotton seed reached 398.2 kg / mu, which is 16.8% higher than the control group (applied with chemical phosphate fertilizer); in saline-alkali soil, the yield of cotton seed reached 375.6 kg / mu, which is 20.3% higher than the control group. This indicates that the bio-phosphate fertilizer and application scheme of the present invention can achieve good results in different soil types.

[0059] In this invention, a compound phosphorus-solubilizing strain (Bacillus megaterium CCTCCNO:M2025688 and Bacillus cereus CCTCCNO:M2025689) is used. The two strains have a synergistic effect and can efficiently activate insoluble phosphorus in the soil by secreting organic acids, phosphatases and other substances. According to experimental results, after applying the bio-phosphate fertilizer of this invention, the effective phosphorus content in the soil increased by 35-50% compared with the control group (applied with the same amount of chemical phosphate fertilizer), and the utilization rate of phosphorus by cotton increased by 20-30%. This invention selects a mixture of decomposed cottonseed hulls and humic acid as an organic carrier, combined with modified attapulgite slow-release agent, which can provide a good growth environment and protective barrier for phosphorus-solubilizing bacteria and reduce the impact of environmental factors on the strains. Tests showed that after 6 months of storage, the survival rate of the bacterial strains in the bio-phosphate fertilizer remained above 85%, demonstrating strong colonization ability in the soil and sustained phosphorus-solubilizing effects. The modified attapulgite slow-release agent slowly releases phosphorus and protects the phosphorus-solubilizing bacteria, matching the phosphorus release rate to the phosphorus requirements of cotton at different growth stages, thus preventing phosphorus loss and waste. Cotton does not require frequent topdressing throughout its growth cycle, reducing labor costs, and it does not suffer from nutrient deficiency in the later stages, resulting in stable growth. This invention adds essential trace elements for cotton, such as zinc, iron, and boron, to the bio-phosphate fertilizer using EDTA chelation, improving the absorption and utilization rate of these trace elements, meeting the cotton's diverse nutrient needs, promoting physiological metabolism, and improving growth. The bio-phosphate fertilizer is rich in organic matter and beneficial microorganisms, improving soil structure, increasing soil aeration and water and fertilizer retention capacity, enriching the soil microbial community, reducing the risk of soil compaction, improving soil fertility, and achieving sustainable cotton growth. Planting and field trials have verified that cotton treated with the bio-phosphate fertilizer of this invention exhibits a 10-15% increase in seedling emergence rate, an 8-12% decrease in boll shedding rate, an 2-3 increase in the number of bolls per plant, and a 15-20% increase in seed cotton yield. Simultaneously, cotton fiber length increases by 0.5-1.0 mm, breaking strength increases by 0.8-1.2 cN / tex, and fiber quality is significantly improved. This invention provides application solutions for different soil types (sandy soil, clay soil) and special planting conditions (continuous cropping, saline-alkali land), adapting to the cotton planting needs of different regions. It offers high application flexibility and has broad prospects for promotion.

[0060] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0061] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria and its application, characterized in that, The product comprises the following components by weight: 30-50 parts of phosphate-solubilizing bacterial agent, 20-40 parts of organic carrier, 5-15 parts of slow-release agent, 2-8 parts of trace element supplement, and 1-5 parts of pH adjuster; the phosphate-solubilizing bacterial agent is composed of Bacillus megaterium strain CCTCCNO:M2025688, Bacillus cereus strain CCTCCNO:M2025689, and culture medium, wherein the live bacteria ratio of Bacillus megaterium to Bacillus cereus is 2:1-3:

1. The total viable count of the phosphate-solubilizing bacteria is ≥1×10 CFU / g; the organic carrier is a mixture of decomposed cottonseed hulls and humic acid, with a weight ratio of 3:1-5:1; the slow-release agent is modified attapulgite, which is prepared by soaking attapulgite in a 5-8% hydrochloric acid solution for 2-4 hours, filtering, washing with deionized water until neutral, drying at 105-110℃, and then mixing and grinding with sodium alginate accounting for 5-10% of the weight of attapulgite until the particle size is ≤100 mesh.

2. The cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria as described in claim 1, characterized in that: The culture medium comprises the following components by weight percentage: glucose 1.5-2.5%, yeast extract 0.5-1.0%, potassium dihydrogen phosphate 0.1-0.3%, magnesium sulfate 0.05-0.15%, calcium chloride 0.01-0.03%, manganese sulfate 0.005-0.015%, with the balance being deionized water. The pH of the culture medium is adjusted to 7.0-7.

5. The method for preparing the phosphate-solubilizing agent is as follows: Bacillus megaterium strain CCTCCNO:M2... Bacillus cereus strains CCTCCNO:M2025689 were inoculated into the culture medium and cultured with shaking at 30-35℃ and 180-220 r / min for 24-36 h to obtain single-strain fermentation broth. The two single-strain fermentation broths were then mixed in a certain proportion, and diatomaceous earth (10-20% by weight of the mixed fermentation broth) was added as an adsorbent. The mixture was then vacuum dried at 45-55℃ until the moisture content was ≤10%, and then pulverized to a particle size of ≤80 mesh to obtain the phosphate-solubilizing agent.

3. The cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria as described in claim 2, characterized in that: The trace element supplement is a mixture of EDTA chelated zinc, EDTA chelated iron, and boric acid in a weight ratio of 2:1:1, wherein the zinc content in the EDTA chelated zinc is ≥15%, the iron content in the EDTA chelated iron is ≥13%, and the boron content in the boric acid is ≥17%; the pH adjuster is a mixture of dolomite powder and limestone powder in a weight ratio of 1:1-2:1, with a particle size ≤120 mesh and a calcium carbonate content ≥95%.

4. The cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria as described in claim 3, characterized in that: The product comprises the following components in parts by weight: 40 parts of phosphate-solubilizing bacteria agent, 30 parts of organic carrier, 10 parts of slow-release agent, 5 parts of trace element supplement, and 3 parts of pH adjuster; the organic carrier has a weight ratio of decomposed cottonseed hulls to humic acid of 4:1, the humic acid contains ≥70% humic matter and ≤15% moisture content; the modified attapulgite has a weight ratio of attapulgite to sodium alginate of 18:2, and the sodium alginate has a viscosity of 200-300 mPa·s.

5. A cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria as described in claim 4, characterized in that: The *Bacillus megaterium* strain CCTCCNO:M2025688 has the following biological characteristics: Gram-positive, rod-shaped, measuring (1.2-1.5) μm × (3.0-5.0) μm, with spores that are elliptical and located in the center of the cell; after culturing on Pikovaskaia medium for 72 h, the colonies are milky white, round, with neat edges, smooth surface, and a diameter of 2-3 mm, with a ratio of the lysing zone diameter to the colony diameter ≥4.5; it can grow at 15-45℃ and pH 5.0-9.0, with the optimal growth temperature being 30-35℃ and the optimal growth pH being 7.0-7.

5.

6. The cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria and its application as described in claim 5, characterized in that: The *Bacillus cereus* strain CCTCCNO:M2025689 has the following biological characteristics: Gram-positive, rod-shaped, measuring (0.8-1.2) μm × (1.5-3.0) μm, with spores that are round or oval and located at the end of the cell; after culturing on Pikovaskaia medium for 72 h, the colonies are pale yellow, irregular in shape, with irregular edges, rough surface, and a diameter of 1-2 mm, with a ratio of the diameter of the lysing zone to the colony diameter ≥3.8; it can grow at 10-48℃ and pH 4.5-9.5, with the optimal growth temperature being 28-32℃ and the optimal growth pH being 6.5-7.

5.

7. The method for preparing cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria as described in claim 6, characterized in that: Includes the following steps: S1. Preparation of phosphate-solubilizing bacterial agent: Bacillus megaterium and Bacillus cereus are cultured separately to obtain single-strain fermentation broth, which is then mixed, an adsorbent is added, and the mixture is dried and pulverized to obtain the phosphate-solubilizing bacterial agent; S2. Preparation of modified attapulgite: Attapulgite is acid-treated and then mixed and ground with sodium alginate to obtain a slow-release agent; S3. Mixing and mixing: Add the organic carrier, slow-release agent, trace element supplement and pH adjuster into the mixer in proportion, and mix for 15-20 minutes at a speed of 80-120 r / min to obtain the premix; S4. Inoculation agent: Add the phosphate-solubilizing agent to the premix and mix for 10-15 minutes at a speed of 50-80 r / min and a temperature ≤35℃. Control the moisture content of the mixture to 15-20% to obtain cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria. S5. Packaging and storage: Pack the product obtained in step S4 in a breathable woven bag and store it in a cool and dry place with a storage temperature ≤25℃ and relative humidity ≤60%.

8. The application of a cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria as described in claim 7, characterized in that: The application methods include seed dressing, basal fertilizer application, and topdressing application. Seed dressing involves mixing bio-phosphate fertilizer with cotton seeds at a weight ratio of 1:50-1:80, adding an appropriate amount of water to ensure the phosphate fertilizer adheres evenly to the seed surface, drying in the shade, and then sowing. Basal fertilizer application involves evenly spreading bio-phosphate fertilizer in planting furrows or holes before cotton sowing or transplanting, at a rate of 20-30 kg / mu, mixing it evenly with the soil, and then sowing or transplanting. Topdressing is applied once each during the cotton budding stage and the boll-forming stage, at rates of 10-15 kg / mu and 15-20 kg / mu respectively, using strip or hole application methods, followed by covering with soil.

9. The application of a cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria as described in claim 8, characterized in that: When planting cotton in sandy soil, the amount of bio-phosphate fertilizer applied as basal fertilizer should be increased to 30-40 kg / mu, and the amount of topdressing should be increased to 15-20 kg / mu and 20-25 kg / mu during the budding and boll-forming stages, respectively, and irrigation should be carried out promptly after topdressing. When planting cotton in clay soil, the amount of basal fertilizer applied should be reduced to 15-25 kg / mu, and shallow trench application should be adopted to avoid fertilizer accumulation.

10. The application of a cotton bio-phosphate fertilizer based on phosphate-solubilizing bacteria as described in claim 9, characterized in that: When applied in cotton fields with continuous cropping, use a 500-800 times diluted humic acid solution as a base fertilizer, at a rate of 50-80 L / mu. When applied in cotton cultivation in saline-alkali soil, mix bio-phosphate fertilizer and gypsum at a weight ratio of 5:1 before application. The amount of gypsum used in the base fertilizer is 4-6 kg / mu, and the amount of gypsum used in the top dressing is 2-3 kg / mu.

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