Production method of compound ecological phosphate fertilizer

Abstract

The invention discloses a production method of a composite ecological phosphate fertilizer, and belongs to the technical field of fertilizer preparation. Comprising the following steps: mixing activated phosphorite mud and alkali lignin, reacting, and drying to obtain a mixture; mixing and granulating the mixture and dry eichhornia crassipes, and co-pyrolyzing to obtain a charcoal phosphate fertilizer; the brevibacillus laterosporus KN-705 and the charcoal phosphate fertilizer are mixed, gamma-polyglutamic acid is added, and the compound ecological phosphate fertilizer is obtained through granulation. The low-quality low-grade phosphorite, alkali lignin, eichhornia crassipes and other substances are subjected to activation, complexation, co-pyrolysis and other reactions to produce the composite ecological phosphate fertilizer with a good effect, the resource utilization rate is increased, and the accumulation of ineffective phosphorus in soil is reduced.

Description

Technical Field

[0001] This invention belongs to the field of compound phosphate fertilizer preparation technology, specifically relating to a method for producing compound ecological phosphate fertilizer. Background Technology

[0002] Phosphorus is an essential element for vegetable growth and development. Total phosphorus in soil refers to the sum of all forms of phosphorus present in the soil, including organic phosphorus and inorganic insoluble phosphorus that are difficult for plants to absorb directly. Available phosphorus, on the other hand, refers to soluble phosphorus forms that can be directly absorbed and utilized by plants. Vegetables mainly absorb phosphorus from the soil, but soluble phosphorus that can be directly absorbed and utilized by plants is unstable and easily combines with metal ions in the soil to form insoluble phosphates. Water hyacinth (Eichhornia crassipes) is a highly adaptable and rapidly reproducing aquatic floating plant, especially prone to explosive growth in eutrophic water bodies (such as nitrogen- and phosphorus-rich rivers and lakes). Its stolons can spread rapidly and form dense carpets, multiplying asexually through division. A single plant can cover a large area of ​​water surface in a short period. In many southern waterways, its strong reproductive capacity has led to overpopulation, blocking waterways and damaging aquatic ecosystems. Relevant departments are currently managing the plant through mechanical dredging and exploring resource utilization methods such as converting it into nutrients or biogas feedstock. my country's pulp and paper industry is highly developed, generating approximately 10 million tons of alkali lignin, a byproduct of pulp and paper production, annually. However, the current utilization rate of alkali lignin in my country is low, with the vast majority being discharged directly into rivers as "black liquor" or concentrated and burned, resulting in resource waste and environmental pollution. my country also has relatively high reserves of low-grade phosphate rock, but due to its low phosphorus content, its overall utilization rate is currently low.

[0003] Patent CN114890842A discloses a method for preparing environmentally friendly modified porous biochar using crop straw, wood ash, eggshells, and chicken feathers as raw materials. This method involves microwave-assisted pyrolysis, activation and pore expansion, and surface functional modification. Finally, the modified porous biochar is enriched with phosphorus-rich waste liquid to achieve the preparation of environmentally friendly slow-release phosphate fertilizer.

[0004] Turning waste into treasure and treating waste with waste are important ways to improve resource utilization. Therefore, researching a production method for preparing compound ecological phosphate fertilizer using water hyacinth, alkali lignin, and low-grade phosphate rock has broad application prospects. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention activates low-grade phosphate rock, converting insoluble phosphorus into soluble phosphorus. The complexation reaction of alkali lignin binds the metal ions generated during the activation process, improving the stability of the soluble phosphorus. Furthermore, co-pyrolysis with phosphorus-rich dried water hyacinth further increases the soluble phosphorus content. Simultaneously, the porous structure generated by co-pyrolysis effectively adsorbs insoluble phosphates in the soil. The added *Bacillus laterosporus* KN-705 converts these insoluble phosphates into soluble phosphorus. γ-polyglutamic acid, as an excellent water-retaining agent, effectively maintains the activity of *Bacillus laterosporus* KN-705 and adsorbs and binds the metal ions generated during the conversion of insoluble phosphates into soluble phosphorus, reducing the probability of unstable soluble phosphorus being re-fixed. This solves the technical problems mentioned in the background art. Specifically, the technical solution of this invention includes the following: A method for producing a compound eco-friendly phosphate fertilizer, characterized in that the production method includes the following steps: After the activated phosphate rock mud and alkali lignin were stirred and mixed, the mixture was reacted and dried at 40°C for 12 hours to obtain a mixture. After mixing the mixture with dried water hyacinth and forming it into 4mm diameter granules, it was pyrolyzed at 520℃~550℃ for 60 minutes under nitrogen atmosphere and then cooled to room temperature to obtain biochar phosphate fertilizer. Compound phosphate fertilizer is obtained by mixing Bacillus retroflexus KN-705 and biochar phosphate fertilizer. Compound phosphate fertilizer and γ-polyglutamic acid are mixed and made into granules with a diameter of 2 mm to obtain compound ecological phosphate fertilizer.

[0006] Furthermore, the method for preparing the activated phosphate rock mud includes the following steps: Low-grade phosphate rock is crushed to a size that can pass through a 100-mesh sieve to obtain phosphate rock powder; Activated phosphate rock mud is obtained by mixing phosphate rock powder and 10wt% phosphoric acid aqueous solution and reacting them in a closed environment at 70℃~80℃ for 24 hours.

[0007] Furthermore, the 10wt% phosphoric acid aqueous solution is obtained by mixing 1 part by weight of phosphoric acid and 9 parts by weight of deionized water.

[0008] Furthermore, the mass ratio of the phosphate rock powder to the 10wt% phosphoric acid aqueous solution is 5:1.

[0009] Furthermore, the mass ratio of activated phosphate rock mud to alkali lignin is 2:1.

[0010] Furthermore, the method for preparing the dried water hyacinth material includes the following steps: Dehydrated water hyacinth was obtained by drying the whole fresh water hyacinth plant in an air-dried environment at 80℃ for 24 hours. Dehydrated water hyacinth is crushed until it can pass through a 5-mesh sieve to obtain dried water hyacinth.

[0011] Furthermore, the mass ratio of the mixture to dried water hyacinth is 1:4.

[0012] Furthermore, the effective viable count of the *Bacillus lateralis* KN-705 is greater than or equal to 1 billion / mL.

[0013] Furthermore, the mass ratio of the *Bacillus lateralis* KN-705 to biochar phosphate fertilizer is 1:10.

[0014] Furthermore, the mass ratio of the compound phosphate fertilizer to γ-polyglutamic acid is 5:2.

[0015] A method for producing compound ecological phosphate fertilizer.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention converts insoluble phosphorus into soluble phosphorus through the reaction of phosphoric acid with minerals such as apatite in low-grade phosphate rock. The activated phosphate sludge after the reaction becomes loose and porous, which can increase the contact area with alkali lignin and the degree of encapsulation of soluble phosphorus by co-pyrolysis.

[0017] (2) This invention adds alkali lignin to activated phosphate rock mud and uses a complexation reaction to combine the metal ions generated when insoluble phosphorus in low-grade phosphate rock is converted into soluble phosphorus. This avoids the reversal of a large amount of unstable soluble phosphorus into insoluble phosphorus due to excessively high local temperature during subsequent co-pyrolysis. Furthermore, alkali lignin, as an alkaline substance, can neutralize part of the acidity of activated phosphate rock mud, which is more conducive to subsequent mixing with Bacillus lateralis KN-705. At the same time, alkali lignin can be carbonized during co-pyrolysis and become part of biochar.

[0018] (3) The present invention uses water hyacinth dried material rich in phosphorus as the main body for preparing biochar, thereby increasing the overall phosphorus content. At the same time, water hyacinth dried material will generate reducing gas and organic acid during co-pyrolysis, which can convert the remaining insoluble phosphorus into soluble phosphorus.

[0019] (4) This invention forms biochar with a porous structure by co-pyrolyzing activated phosphate rock mud, alkali lignin and dried water hyacinth, which effectively encapsulates soluble phosphorus elements, thereby achieving the effect of slow release and improving the stability of soluble phosphorus elements. At the same time, its porous structure can adsorb insoluble phosphates in the soil, thereby increasing the contact rate between Bacillus lateralis KN-705 and insoluble phosphates.

[0020] (5) By adding Bacillus lateralis KN-705, this invention utilizes its phosphorus solubilization function to continuously convert the insoluble phosphate accumulated in the soil into soluble phosphorus that can be absorbed by plants, thereby further improving the fertilizer efficiency of phosphate fertilizer.

[0021] (6) By adding γ-polyglutamic acid, the present invention improves the environmental resistance of Bacillus lateralis KN-705 by utilizing its good water retention and biocompatibility, and can effectively adsorb and bind the metal ions generated when insoluble phosphate is converted into soluble phosphorus, thereby reducing the probability of unstable soluble phosphorus being fixed back into insoluble phosphate. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below through embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Unless otherwise stated, all raw materials and reagents used in this invention are commercially available or can be prepared by known methods.

[0024] The Bacillus lateralis KN-705 was purchased from Wuhan Kenuo Biotechnology Co., Ltd.

[0025] Alkali lignin was purchased from Shandong Gaotang Liya Technology Co., Ltd.

[0026] Preparation Example 1: The preparation of activated phosphate rock slime includes the following processes: Low-grade phosphate rock is crushed in a pulverizer and passed through a 100-mesh sieve to obtain phosphate rock powder. 9 parts by weight of deionized water and 1 part by weight of phosphoric acid are added to a beaker and stirred at 50 rpm for 1 min. Then 50 parts by weight of phosphate rock powder are added and stirred at 50 rpm for 5 min. The mixture is then placed in a reaction vessel and the temperature is controlled at 80℃ for 24 h to obtain activated phosphate rock mud.

[0027] Preparation Example 2: The preparation of activated phosphate rock slime includes the following processes: Low-grade phosphate rock was crushed in a pulverizer and passed through a 100-mesh sieve to obtain phosphate rock powder. Nine parts by weight of deionized water and one part by weight of phosphoric acid were placed in a beaker and stirred at 50 rpm for 5 minutes. Then, 50 parts by weight of phosphate rock powder were added, and the mixture was stirred at 50 rpm for another 5 minutes. The mixture was then placed in a reactor and reacted at 70°C for 24 hours to obtain activated phosphate rock mud.

[0028] Preparation Example 3: The preparation of dried water hyacinth includes the following processes: Fresh water hyacinth plants were placed in a forced-air drying oven at 80℃ and dried for 24 hours. After drying, they were taken out and crushed in a pulverizer and then passed through a 5-mesh sieve to obtain dried water hyacinth material. Example 1:

[0029] A method for producing a compound eco-friendly phosphate fertilizer specifically includes the following processes: Two parts by weight of activated phosphate rock mud from Preparation Example 1 and one part by weight of alkali lignin were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then placed in a dry oven at 40°C and reacted for 12 h. After drying, a mixture was obtained. One part by weight of the mixture and four parts by weight of dried water hyacinth from Preparation Example 3 were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form 4 mm diameter granules, which were then placed in a high-temperature reactor. Nitrogen gas was introduced to purge air, and the temperature was set to 520°C for pyrolysis for 60 min. The mixture was then cooled to room temperature to obtain biochar phosphate fertilizer. One part by weight of Bacillus laterosporus KN-705 and ten parts by weight of biochar phosphate fertilizer were added to a beaker and stirred at 50 rpm for 5 min to obtain compound phosphate fertilizer. Five parts by weight of compound phosphate fertilizer and two parts by weight of γ-polyglutamic acid were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form 2 mm diameter granules to obtain compound ecological phosphate fertilizer. Example 2:

[0030] A method for producing a compound eco-friendly phosphate fertilizer specifically includes the following processes: Two parts by weight of activated phosphate rock mud from Preparation Example 2 and one part by weight of alkali lignin were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then placed in a dry oven at 40°C and dried for 12 h to obtain a mixture. One part by weight of the mixture and four parts by weight of dried water hyacinth from Preparation Example 3 were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form granules with a diameter of 4 mm. The granules were then placed in a high-temperature reactor, nitrogen was introduced to purge the air, and the temperature was set at 520°C for pyrolysis for 60 min. The mixture was then cooled to room temperature to obtain biochar phosphate fertilizer. One part by weight of Bacillus laterosporus KN-705 and ten parts by weight of biochar phosphate fertilizer were added to a beaker and stirred at 50 rpm for 5 min to obtain a compound phosphate fertilizer. Five parts by weight of the compound phosphate fertilizer and two parts by weight of γ-polyglutamic acid were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form granules with a diameter of 2 mm to obtain a compound ecological phosphate fertilizer. Example 3:

[0031] A method for producing a compound eco-friendly phosphate fertilizer specifically includes the following processes: Two parts by weight of activated phosphate rock mud from Preparation Example 1 and one part by weight of alkali lignin were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then placed in a dry oven at 40°C and dried for 12 h to obtain a mixture. One part by weight of the mixture and four parts by weight of dried water hyacinth from Preparation Example 3 were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form granules with a diameter of 4 mm. The granules were then placed in a high-temperature reactor, nitrogen was introduced to purge the air, and the temperature was set at 550°C for pyrolysis for 60 min. The mixture was then cooled to room temperature to obtain biochar phosphate fertilizer. One part by weight of Bacillus laterosporus KN-705 and ten parts by weight of biochar phosphate fertilizer were added to a beaker and stirred at 50 rpm for 5 min to obtain a compound phosphate fertilizer. Five parts by weight of the compound phosphate fertilizer and two parts by weight of γ-polyglutamic acid were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form granules with a diameter of 2 mm to obtain a compound ecological phosphate fertilizer. Example 4:

[0032] A method for producing a compound eco-friendly phosphate fertilizer specifically includes the following processes: Two parts by weight of activated phosphate rock mud from Preparation Example 2 and one part by weight of alkali lignin were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then placed in a dry oven at 40°C and dried for 12 h to obtain a final product. One part by weight of the final product and four parts by weight of dried water hyacinth from Preparation Example 3 were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form 4 mm diameter granules, which were then placed in a high-temperature reactor. Nitrogen gas was introduced to purge the air, and the temperature was set to 550°C for pyrolysis for 60 min. The mixture was then cooled to room temperature to obtain biochar phosphate fertilizer. One part by weight of Bacillus laterosporus KN-705 and ten parts by weight of biochar phosphate fertilizer were added to a beaker and stirred at 50 rpm for 5 min to obtain a compound phosphate fertilizer. Five parts by weight of the compound phosphate fertilizer and two parts by weight of γ-polyglutamic acid were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form 2 mm diameter granules to obtain a compound ecological phosphate fertilizer.

[0033] Comparative Example 1: A method for producing a compound eco-friendly phosphate fertilizer specifically includes the following processes: Low-grade phosphate rock was crushed in a pulverizer and passed through a 100-mesh sieve to obtain phosphate rock powder. Two parts by weight of phosphate rock powder and one part by weight of alkali lignin were added to a beaker and stirred at 50 rpm for 5 minutes. The mixture was then placed in a dry oven at 40°C and dried for 12 hours to obtain a mixture. One part by weight of the mixture and four parts by weight of dried water hyacinth from Preparation Example 3 were added to a beaker and stirred at 50 rpm for 5 minutes. The mixture was then poured into a granulator to form granules with a diameter of 4 mm. These granules were then placed in a high-temperature reactor, nitrogen was introduced to purge air, and the temperature was set to 550°C for pyrolysis for 60 minutes. After cooling to room temperature, biochar phosphate fertilizer was obtained. One part by weight of Bacillus retroflexus KN-705 and ten parts by weight of biochar phosphate fertilizer were added to a beaker and stirred at 50 rpm for 5 minutes to obtain a compound phosphate fertilizer. Five parts by weight of the compound phosphate fertilizer and two parts by weight of γ-polyglutamic acid were added to a beaker and stirred at 50 rpm for 5 minutes. The mixture was then poured into a granulator to form granules with a diameter of 2 mm to obtain a compound ecological phosphate fertilizer.

[0034] Comparative Example 2: A method for producing a compound eco-friendly phosphate fertilizer specifically includes the following processes: One part by weight of activated phosphate rock mud from Preparation Example 1 and four parts by weight of dried water hyacinth from Preparation Example 3 were added to a beaker and stirred at 50 rpm for 5 minutes. The mixture was then poured into a granulator to form granules with a diameter of 4 mm. The granules were then placed in a high-temperature reactor, nitrogen was introduced to purge air, and the temperature was set to 550°C. After pyrolysis for 60 minutes, the mixture was allowed to cool to room temperature to obtain biochar phosphate fertilizer. One part by weight of Bacillus retroflexus KN-705 and ten parts by weight of biochar phosphate fertilizer were added to a beaker and stirred at 50 rpm for 5 minutes to obtain compound phosphate fertilizer. Five parts by weight of compound phosphate fertilizer and two parts by weight of γ-polyglutamic acid were added to a beaker and stirred at 50 rpm for 5 minutes. The mixture was then poured into a granulator to form granules with a diameter of 2 mm to obtain compound ecological phosphate fertilizer.

[0035] Comparative Example 3: A method for producing a compound eco-friendly phosphate fertilizer specifically includes the following processes: Two parts by weight of activated phosphate rock mud from Preparation Example 1 and one part by weight of alkali lignin were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then placed in a dry oven at 40°C and dried for 12 h to obtain a mixture. One part by weight of the mixture and four parts by weight of straw were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form granules with a diameter of 4 mm. The granules were then placed in a high-temperature reactor, nitrogen was introduced to purge the air, and the temperature was set at 550°C for pyrolysis for 60 min. The mixture was then cooled to room temperature to obtain biochar phosphate fertilizer. One part by weight of Bacillus laterosporus KN-705 and ten parts by weight of biochar phosphate fertilizer were added to a beaker and stirred at 50 rpm for 5 min to obtain a compound phosphate fertilizer. Five parts by weight of the compound phosphate fertilizer and two parts by weight of γ-polyglutamic acid were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form granules with a diameter of 2 mm to obtain a compound ecological phosphate fertilizer.

[0036] Comparative Example 4: Two parts by weight of activated phosphate rock mud from Preparation Example 1 and one part by weight of alkali lignin were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then placed in a dry oven at 40°C and dried for 12 h to obtain a mixture. Four parts by weight of dried water hyacinth from Preparation Example 3 were placed in a high-temperature reactor, nitrogen was introduced to purge air, and the temperature was set to 550°C. After pyrolysis for 60 min, the mixture was cooled to room temperature to obtain biochar. This biochar was then placed in a beaker, and one part by weight of the mixture was added. The mixture was stirred at 50 rpm for 5 min and then poured into a granulator to form granules with a diameter of 4 mm to obtain biochar phosphate fertilizer. One part by weight of Bacillus laterosporus KN-705 and ten parts by weight of biochar phosphate fertilizer were added to a beaker and stirred at 50 rpm for 5 min to obtain compound phosphate fertilizer. Five parts by weight of compound phosphate fertilizer and two parts by weight of γ-polyglutamic acid were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form granules with a diameter of 2 mm to obtain compound ecological phosphate fertilizer.

[0037] Comparative Example 5: A method for producing a compound eco-friendly phosphate fertilizer specifically includes the following processes: Two parts by weight of activated phosphate rock mud from Preparation Example 1 and one part by weight of alkali lignin were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then placed in a dry oven at 40°C and dried for 12 h to obtain a mixture. One part by weight of the mixture and four parts by weight of dried water hyacinth from Preparation Example 3 were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form granules with a diameter of 4 mm. The granules were then placed in a high-temperature reactor, nitrogen was introduced to purge the air, and the temperature was set to 600°C for pyrolysis for 60 min. The mixture was then cooled to room temperature to obtain biochar phosphate fertilizer. One part by weight of Bacillus laterosporus KN-705 and ten parts by weight of biochar phosphate fertilizer were added to a beaker and stirred at 50 rpm for 5 min to obtain a compound phosphate fertilizer. Five parts by weight of the compound phosphate fertilizer and two parts by weight of γ-polyglutamic acid were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form granules with a diameter of 2 mm to obtain a compound ecological phosphate fertilizer.

[0038] Comparative Example 6: A method for producing a compound eco-friendly phosphate fertilizer specifically includes the following processes: Two parts by weight of activated phosphate rock mud from Preparation Example 1 and one part by weight of alkali lignin were added to a beaker and stirred at 50 rpm for 5 minutes. The mixture was then placed in a dry oven at 40°C and dried for 12 hours to obtain a mixture. One part by weight of the mixture and four parts by weight of dried water hyacinth from Preparation Example 3 were added to a beaker and stirred at 50 rpm for 5 minutes. The mixture was then poured into a granulator to form granules with a diameter of 4 mm. These granules were then placed in a high-temperature reactor, and nitrogen gas was introduced to purge the air. The temperature was set at 550°C, and the mixture was pyrolyzed for 60 minutes. After cooling to room temperature, biochar phosphate fertilizer was obtained. Five parts by weight of biochar phosphate fertilizer and two parts by weight of γ-polyglutamic acid were added to a beaker and stirred at 50 rpm for 5 minutes. The mixture was then poured into a granulator to form granules with a diameter of 2 mm to obtain a compound ecological phosphate fertilizer.

[0039] Comparative Example 7: A method for producing a compound eco-friendly phosphate fertilizer specifically includes the following processes: Two parts by weight of activated phosphate rock mud from Preparation Example 1 and one part by weight of alkali lignin were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then placed in a dry oven at 40°C and dried for 12 h to obtain a mixture. One part by weight of the mixture and four parts by weight of dried water hyacinth from Preparation Example 3 were added to a beaker and stirred at 50 rpm for 5 min. The mixture was then poured into a granulator to form granules with a diameter of 4 mm. The granules were then placed in a high-temperature reactor, nitrogen was introduced to purge the air, and the temperature was set at 550°C for pyrolysis for 60 min. The mixture was then cooled to room temperature to obtain biochar phosphate fertilizer. One part by weight of Bacillus laterosporus brevis 5N-705 and ten parts by weight of biochar phosphate fertilizer were added to a beaker and stirred at 50 rpm for 5 min to obtain a compound phosphate fertilizer. The compound phosphate fertilizer was then poured into a granulator to form granules with a diameter of 2 mm to obtain a compound ecological phosphate fertilizer.

[0040] Farmland soil was selected, and after sifting out stones and other impurities, it was thoroughly mixed. The total phosphorus content was determined using the acid-molybdenum-antimony colorimetric method, and the soluble phosphorus content was determined using the molybdenum-antimony-scandium colorimetric method. The results are shown in Table 1 below:

[0041] The soil samples were divided into 11 equal portions, each weighing 2000g. Each portion was mixed with 5g of the samples from Examples 1-4 and Comparative Examples 1-7, and then placed into 11 5L beakers. These beakers were placed in an artificial climate chamber at a temperature of (25±1)℃, maintaining soil moisture at 45%-50% for a total of 120 days. The total phosphorus content in the soil was determined using the acid-molybdenum antimony colorimetric method at 1, 10, 30, 60, 90, and 120 days. The soluble phosphorus content in the soil was determined using the molybdenum antimony scandium colorimetric method. The results are shown in Table 2 below.

[0042] The data above shows that: (1) As can be seen from the results of fertilization of Examples 1-4 and single phosphate fertilizer, the compound ecological phosphate fertilizer of the present invention has excellent fertility, long-lasting effect and high utilization rate. In actual use, it can effectively reduce the amount of phosphate fertilizer used and the frequency of fertilization, and reduce the content of insoluble phosphorus in farmland.

[0043] (2) As can be seen from Comparative Example 1, phosphorus in low-grade phosphate rock is mostly in the form of insoluble phosphorus, especially when it is wrapped in biochar, it is difficult to release soluble phosphorus. However, by pretreatment with phosphoric acid, the insoluble phosphorus in low-grade phosphate rock can be effectively activated into soluble phosphorus.

[0044] (3) As can be seen from Comparative Example 2, alkali lignin has a strong complexing ability, which can adsorb the metal ions released during the process of activating insoluble phosphorus into soluble phosphorus in advance, and reduce the reversal of soluble phosphorus into insoluble phosphorus during high-temperature co-pyrolysis. At the same time, alkali lignin can effectively neutralize the acidity of activated phosphate rock mud, providing a good environment for the subsequent addition of Bacillus lateralis KN-705.

[0045] (4) Comparative Example 3 shows that using straw as the main material for biochar is not as effective as using dried water hyacinth. This may be because dried water hyacinth contains more phosphorus, and the organic acid produced during the pyrolysis of dried water hyacinth can further convert insoluble phosphorus into soluble phosphorus, thereby improving the fertility of the compound ecological phosphate fertilizer.

[0046] (5) As can be seen from Comparative Example 4, if activated phosphate mud is simply mixed with biochar, the soluble phosphorus element cannot be effectively encapsulated and will be released quickly. Due to its instability, it will soon be converted into insoluble phosphate by metal ions in the soil, which will drastically reduce the fertility of the compound ecological phosphate fertilizer.

[0047] (6) As can be seen from Comparative Example 5, soluble phosphorus is more easily converted into insoluble phosphorus under high temperature conditions. Therefore, it is necessary to improve the stability of soluble phosphorus by adding alkali lignin and controlling the temperature.

[0048] (7) As can be seen from Comparative Example 6, Bacillus lateralis KN-705 has excellent phosphorus solubilization effect, which can continuously and slowly convert insoluble phosphate in the soil into soluble phosphorus, thus prolonging the effect of compound ecological phosphate fertilizer.

[0049] (8) As can be seen from Comparative Example 7, γ-polyglutamic acid can effectively protect Bacillus retroflexus KN-705 and improve its environmental resistance. At the same time, it can also further improve its phosphorus solubilization efficiency by adsorbing and binding the metal ions produced by Bacillus retroflexus KN-705 during phosphorus solubilization.

[0050] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method for producing a compound ecological phosphate fertilizer, characterized in that, The production method includes the following steps: After the activated phosphate rock mud and alkali lignin were stirred and mixed, they were reacted at 40°C for 12 hours and then dried to obtain a mixture. After mixing the mixture with dried water hyacinth and forming it into 4mm diameter granules, it was pyrolyzed at 520℃~550℃ for 60 minutes under nitrogen atmosphere and then cooled to room temperature to obtain biochar phosphate fertilizer. Compound phosphate fertilizer is obtained by mixing Bacillus retroflexus KN-705 and biochar phosphate fertilizer. Compound phosphate fertilizer and γ-polyglutamic acid are mixed and made into granules with a diameter of 2 mm to obtain compound ecological phosphate fertilizer.

2. The method for producing a compound ecological phosphate fertilizer according to claim 1, characterized in that, The method for preparing the activated phosphate rock mud includes the following steps: Low-grade phosphate rock is crushed to a size that can pass through a 100-mesh sieve to obtain phosphate rock powder; Activated phosphate rock mud is obtained by mixing phosphate rock powder and 10wt% phosphoric acid aqueous solution and reacting them in a closed environment at 70℃~80℃ for 24 hours.

3. The method for producing a compound ecological phosphate fertilizer according to claim 2, characterized in that, The mass ratio of the phosphate rock powder to the 10wt% phosphoric acid aqueous solution is 5:

1.

4. The method for producing a compound ecological phosphate fertilizer according to claim 1, characterized in that, The mass ratio of activated phosphate rock mud to alkali lignin is 2:

1.

5. The method for producing a compound ecological phosphate fertilizer according to claim 1, characterized in that, The preparation method of the dried water hyacinth material includes the following steps: Dehydrated water hyacinth was obtained by drying the whole fresh water hyacinth plant in an air-dried environment at 80℃ for 24 hours. Dehydrated water hyacinth is crushed and sieved to obtain dried water hyacinth.

6. The method for producing a compound ecological phosphate fertilizer according to claim 1, characterized in that, The mass ratio of the mixture to dried water hyacinth is 1:

4.

7. The method for producing a compound ecological phosphate fertilizer according to claim 1, characterized in that, The effective viable count of the *Bacillus lateralis* KN-705 is greater than or equal to 1 billion / mL.

8. The method for producing a compound ecological phosphate fertilizer according to claim 1, characterized in that, The mass ratio of Bacillus lateralis KN-705 to biochar phosphate fertilizer is 1:

10.

9. The method for producing a compound ecological phosphate fertilizer according to claim 1, characterized in that, The mass ratio of the compound phosphate fertilizer to γ-polyglutamic acid is 5:2.

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