阅读说明：本技术 一种含生物质炭的复混肥及其制备方法 (Compound fertilizer containing biomass charcoal and preparation method thereof ) 是由 田慎重 董亮 张玉凤 边文范 郭洪海 高燕 于 2019-03-05 设计创作，主要内容包括：本发明提供一种含生物质炭的复混肥及其制备方法,涉及生物炭复混肥技术领域,本发明所述含生物质炭的复混肥包括以下重量份的原料：生物质炭60～100份、氮磷钾复合肥40～60份、解磷菌菌液30～50份、高岭土12～20份和禽畜粪便20～60份；所述生物质炭以玉米秸秆和果枝为原料制备而成；所述氮磷钾复合肥中氮磷钾的质量比为18-15-10；所述解磷菌菌液的活菌数在1×10<Sup>8</Sup>cfu/g以上。本发明所述复混肥可改善土壤结构、增加土壤养分有效性、提高作物抗性功能,综合提高作物产量,并减少作物种植过程中肥料和农药施用量,减缓土壤板结和农业面源污染。本发明提供的制备方法可以延长复混肥的持效时间和保质期。(The invention provides a compound fertilizer containing biomass charcoal and a preparation method thereof, and relates to the technical field of a compound fertilizer containing biomass charcoal, wherein the compound fertilizer containing biomass charcoal comprises the following raw materials in parts by weight: 60-100 parts of biomass charcoal, 40-60 parts of nitrogen-phosphorus-potassium compound fertilizer, 30-50 parts of phosphate solubilizing bacteria liquid, 12-20 parts of kaolin and 20-60 parts of livestock manure; the biomass charcoal is prepared by taking corn straws and fruit branches as raw materials; the mass ratio of nitrogen, phosphorus and potassium in the nitrogen, phosphorus and potassium compound fertilizer is 18-15-10The viable count of the phosphate-solubilizing bacterium liquid is 1 × 10 8 cfu/g or more. The compound fertilizer can improve the soil structure, increase the effectiveness of soil nutrients, improve the resistance function of crops, comprehensively improve the crop yield, reduce the application amount of fertilizers and pesticides in the crop planting process and slow soil hardening and agricultural non-point source pollution. The preparation method provided by the invention can prolong the lasting time and the quality guarantee period of the compound fertilizer.)

1. A compound fertilizer containing biomass charcoal comprises the following raw materials in parts by weight: 60-100 parts of biomass charcoal, 40-60 parts of nitrogen-phosphorus-potassium compound fertilizer, 30-50 parts of phosphate solubilizing bacteria liquid, 12-20 parts of kaolin and 20-60 parts of livestock manure;

the biomass charcoal is prepared by taking corn straws and fruit branches as raw materials;

the mass ratio of nitrogen, phosphorus and potassium in the nitrogen, phosphorus and potassium compound fertilizer is 18-15-10;

the viable count of the phosphate-solubilizing bacterium liquid is 1 × 10⁸cfu/g or more.

2. The compound fertilizer as claimed in claim 1, which comprises 70-80 parts of biomass charcoal, 45-50 parts of nitrogen-phosphorus-potassium compound fertilizer, 40-45 parts of phosphate-solubilizing bacteria liquid, 15-18 parts of kaolin and 30-40 parts of livestock manure.

3. Compound fertilizer according to claim 1 or 2, characterized in that the organic matter content of the livestock manure is not less than 75%.

4. The compound fertilizer as claimed in claim 1 or 2, wherein the preparation method of biomass charcoal comprises the following steps:

(1) mixing corn straws and fruit branches according to the mass ratio of 1-4: 1-2 to obtain a mixture of the straws and the fruit branches;

(2) mixing the straw mixture with a potassium carbonate aqueous solution, soaking and drying to obtain an activated mixture;

the mass ratio of the mixture to the potassium carbonate in the potassium carbonate aqueous solution is 1: 2-4;

(3) heating the activated straw mixture to 380-420 ℃ and keeping for 45-60 min; then heating to 580-620 ℃, and keeping for 60-100 min to obtain a carbonized material;

(4) and cooling the carbonized material, soaking the cooled carbonized material in a hydrochloric acid solution, taking out the carbonized material, washing the carbonized material to be neutral, and drying the washed material to obtain the biomass charcoal.

5. The compound fertilizer as claimed in claim 4, wherein in the step (3), the temperature rise rate is 5-8 ℃/min when the temperature rises to 380-420 ℃, and the temperature rise rate is 10-12 ℃/min when the temperature rises to 580-620 ℃.

6. The compound fertilizer as claimed in claim 4, wherein in the step (4), the concentration of the hydrochloric acid solution is 0.05-0.2 mol/L, and the soaking time is 20-60 min.

7. The preparation method of the compound fertilizer as claimed in any one of claims 1 to 6, which comprises the following steps:

s1, mixing and dipping the biomass charcoal and the phosphate-removing bacterium liquid to obtain a first mixture;

s2, mixing the nitrogen-phosphorus-potassium compound fertilizer, the livestock manure and water to obtain a second mixture;

s3, mixing the first mixture with the second mixture, and impregnating to obtain a third mixture;

and S4, mixing the third mixture with kaolin, granulating and drying to obtain the compound fertilizer containing the biomass charcoal.

8. The method according to claim 7, wherein in step S1, the immersion time is 2-6 h.

9. The method according to claim 7, wherein in step S4, the granulation temperature is not more than 80 ℃ and the drying temperature is not more than 75 ℃.

Technical Field

The invention relates to the technical field of biochar compound fertilizers, in particular to a compound fertilizer containing biochar and a preparation method thereof.

Background

Biochar is a black material with a high carbon content obtained by low-temperature pyrolysis of biomass (crop straw, livestock manure, organic waste, etc.), which does not include fossil fuel products and carbon of other geological causes (warneck DDet et al, 2007, pangen et al, 2010).

Biochar is generally considered to be one of the category of black charcoal (black char). Biochar can be classified into charcoal, bamboo charcoal, straw charcoal, rice hull charcoal, animal manure charcoal, etc., depending on the source of the biomass material (zhangongsheng et al 2006; Cao X D et al 2010; Golldberg E D et al 1985). The constituent elements of biochar are mainly carbon, hydrogen, oxygen, etc., and highly carbon-rich (70% -80%) is used as a main mark (Lehmann J et al, 2006; Lin's army, etc., 2007).

From a microscopic point of view, biochar is composed of tightly packed, highly distorted aromatic ring sheets, which X-rays show to have a turbostratic structure (leersin et al, 2009). The surface of the biochar has obvious porosity characteristics, so that the biochar has a large specific surface area and a high surface energy. The biochar has strong water absorption and air suction capability, has more negative charges, can form an electromagnetic field, and has high aromatizing, physical thermal stability and biochemical decomposition resistance.

The composition properties of the biochar are related to the properties of raw materials for producing the biochar on one hand and the combustion temperature in the production process on the other hand. The properties of the raw material itself greatly affect the material composition, nutrient content, etc. of the biochar, which may be related to the material composition and nutrient content of the raw material itself and the existence state. The charcoal produced by using poultry manure as a raw material has the carbon content of only 40 percent and the residual proportion of nitrogen is less than one third of 27 percent, while the carbon content of the charcoal produced by using pine scraps as the raw material is almost twice as high as 78 percent of that of the charcoal produced by using poultry manure, and the residual proportion of nitrogen is more than 3 times as high as that of the charcoal produced by using poultry manure and reaches 89.6 percent (Gaskin J W et al, 2008). The reason for the high carbon and nitrogen residue of the pine scrap biochar is probably related to the existence of carbon and nitrogen in the more stable lignin and fiber, while the carbon and nitrogen exist in the poultry manure mostly in a simple organic state or an inorganic state. In addition to the type of raw material, the combustion temperature also has a large influence on the composition and properties of the biochar. Biochar produced at higher temperatures has higher available nutrient content, higher specific surface and more number of micro-pores, and thus has better physical adsorption properties (Gaskin J W et al, 2008; Yu X Y et al, 2010; Zhang H H et al, 2010). However, biochar produced at low temperature has more negative charges and thus has higher cation exchange capacity, and thus has stronger physicochemical adsorption capacity for ions (zhangwenling et al, 2009).

The effect of the biomass charcoal in soil is determined by the physicochemical properties of the biomass charcoal, and research results show that the biomass charcoal contains a certain amount of mineral nutrient elements required by crops, and the content of mineral sheep manure in soil can be obviously increased after the biomass charcoal is applied to the soil, such as increasing the content of phosphorus, potassium, calcium, magnesium, nitrogen elements and the like in the soil. Especially, the biomass charcoal prepared by taking the livestock and poultry manure as the raw material has higher mineral substance nutrient content. Can play a role in soil fertility improvement. Meanwhile, the biomass carbon can also adsorb organic molecules in soil, improve the holding and slow-release capacity of the soil to nitrogen and other elements, and play a role in slow release and prolonging the fertilizer efficiency.

The biomass charcoal has small density and larger porosity, can obviously reduce the volume weight of soil, increase the total porosity of the soil and improve the soil aggregation after being applied into the soil, and the complex pore structure of the biomass charcoal can also influence the water storage capacity of the soil. Namely, the rich pore structure of the biochar can effectively improve the physical properties of the soil, improve the soil structure, adjust the pH value of the soil and promote the retention capacity of the soil on moisture and fertilizer.

The biomass charcoal can be used as a soil conditioner and can also play a role of a fertilizer, so that the content of nutrients such as nitrogen, phosphorus and potassium in soil is increased, and the yield of crops is improved. The biomass charcoal is mainly used for promoting the yield increase of crops by changing the physical, chemical and microbial properties of soil. The mineral nutrients with a large content in the biomass charcoal can obviously increase the soil fertility, and on the other hand, the change of the biomass charcoal to the physical properties of the soil can also improve the living environment of crop roots.

Besides being influenced by soil structure and fertility in the growth process of crops, diseases and pests are also one of important influencing factors influencing crop yield. The existing fertilizer containing biomass charcoal mainly focuses on improving crop yield and improving soil, has single function, can obtain ideal yield only by controlling crop diseases and insect pests by adding pesticides and the like after the fertilizer containing biomass charcoal is applied, and is not healthy and environment-friendly.

Disclosure of Invention

The invention provides a compound fertilizer containing biomass charcoal and a preparation method thereof, aiming at overcoming the defect of single effect of the existing fertilizer containing biomass charcoal.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a compound fertilizer containing biomass charcoal, which comprises the following raw materials in parts by weight: 60-100 parts of biomass charcoal, 40-60 parts of nitrogen-phosphorus-potassium compound fertilizer, 30-50 parts of phosphate solubilizing bacteria liquid, 12-20 parts of kaolin and 20-60 parts of livestock manure;

the biomass charcoal is prepared by taking corn straws and fruit branches as raw materials;

the mass ratio of nitrogen, phosphorus and potassium in the nitrogen, phosphorus and potassium compound fertilizer is 18-15-10;

the viable count of the phosphate-solubilizing bacterium liquid is 1 × 10⁸cfu/g or more.

Preferably, the composite fertilizer comprises 70-80 parts of biomass charcoal, 45-50 parts of nitrogen-phosphorus-potassium compound fertilizer, 40-45 parts of phosphate solubilizing bacteria liquid, 15-18 parts of kaolin and 30-40 parts of livestock manure.

Preferably, the organic matter content of the livestock manure is more than or equal to 75 percent.

Preferably, the preparation method of the biomass charcoal comprises the following steps:

(1) mixing corn straws and fruit branches according to the mass ratio of 1-4: 1-2 to obtain a straw and fruit branch mixture;

(2) mixing the straw and fruit branch mixture with a potassium carbonate aqueous solution, soaking and drying to obtain an activated straw and fruit branch mixture;

the mass ratio of the straw and fruit branch mixture to the potassium carbonate contained in the potassium carbonate aqueous solution is 1: 2-4;

(3) heating the activated straw and fruit branch mixture to 380-420 ℃ and keeping for 45-60 min; then heating to 580-620 ℃, and keeping for 60-100 min to obtain a carbonized material;

(4) and cooling the carbonized material, soaking the cooled carbonized material in a hydrochloric acid solution, taking out the carbonized material, washing the carbonized material to be neutral, and drying the washed material to obtain the biomass charcoal.

Preferably, in the step (3), the temperature rise rate is 5-8 ℃/min when the temperature rises to 380-420 ℃, and the temperature rise rate is 10-12 ℃/min when the temperature rises to 580-620 ℃.

Preferably, in the step (4), the concentration of the hydrochloric acid solution is 0.05-0.2 mol/L, and the soaking time is 20-60 min.

The invention also provides a preparation method of the compound fertilizer in the technical scheme, which comprises the following steps:

s1, mixing and dipping the biomass charcoal and the phosphate-removing bacterium liquid to obtain a first mixture;

s2, mixing the nitrogen-phosphorus-potassium compound fertilizer, the livestock manure and water to obtain a second mixture;

s3, mixing the first mixture with the second mixture, and impregnating to obtain a third mixture;

and S4, mixing the third mixture with kaolin, granulating and drying to obtain the compound fertilizer containing the biomass charcoal.

Preferably, the time for soaking in the step S1 is 2-6 h.

Preferably, in step S4, the granulation temperature is not higher than 80 ℃ and the drying temperature is not higher than 75 ℃.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides a compound fertilizer containing biomass charcoal, which comprises the following raw materials in parts by weight: biomass charcoal 60-100 part of phosphate-solubilizing bacteria liquid, 40-60 parts of nitrogen-phosphorus-potassium compound fertilizer, 30-50 parts of phosphate-solubilizing bacteria liquid, 12-20 parts of kaolin and 20-60 parts of livestock manure, wherein the biomass charcoal is prepared from corn straw and fruit branches, the mass ratio of nitrogen to phosphorus and potassium in the phosphate-potassium compound fertilizer is 18-15-10, and the viable count of the phosphate-solubilizing bacteria liquid is 1 × 10⁸cfu/g or more. The compound fertilizer disclosed by the invention has the functions of improving the soil structure, improving the nutrient effectiveness and improving the crop resistance, comprehensively improves the crop yield, reduces the application amount of fertilizers and pesticides in the crop planting process, slows down the soil hardening and agricultural non-point source pollution, and is safer and more environment-friendly.

The invention provides the biochar prepared from the composite raw materials of the corn straws and the fruit branches, the biochar has the characteristics of large specific surface area and high aromatic degree, and is easier to adsorb nutrient substances such as nitrogen, phosphorus and potassium, and the action time of the compound fertilizer is prolonged. The compound fertilizer containing the biomass charcoal provided by the invention has high fertilizer efficiency and long action time, and can induce crops to generate stronger pest resistance and reduce the incidence of soil-borne diseases, thereby reducing the application of pesticides in the crop planting process.

The compound fertilizer adopts the compound fertilizer with the proportion of nitrogen, phosphorus and potassium of 18-15-10, reduces the supply of phosphorus element in fertilizer raw materials, delays the initial concentration of the phosphorus element by combining the action of phosphate solubilizing bacteria, is more suitable for the requirement of the phosphorus element in the growth of crops, and is beneficial to the growth of the crops.

The compound fertilizer adopts livestock and poultry manure as a raw material, increases organic matters in the compound fertilizer, and can improve the microbial activity of soil and increase the organic matter content of the soil by matching the slow release effect of the biomass charcoal.

The invention also provides a preparation method of the compound fertilizer containing the biomass charcoal, which comprises the following steps of mixing and impregnating the biomass charcoal and the phosphate solubilizing bacteria liquid to ensure that the phosphate solubilizing bacteria fully enter the biomass charcoal; mixing and adsorbing the dissolved nitrogen phosphorus potassium compound fertilizer and the livestock manure with the first mixture, so that nutrient components in the nitrogen phosphorus potassium compound fertilizer and the livestock manure partially enter the biomass charcoal, thereby providing a culture medium for growth and development of phosphate solubilizing bacteria, maintaining the activity of the phosphate solubilizing bacteria and enhancing the slow release effect of the compound fertilizer; kaolin is used as a bonding agent for bonding and granulation, and the compound fertilizer can be obtained. The compound fertilizer prepared by the method has long lasting time, is more in crop growth condition, and can effectively improve crop yield.

Detailed Description

The invention provides a compound fertilizer containing biomass charcoal, which comprises the following raw materials in parts by weight: 60-100 parts of biomass charcoal, 40-60 parts of nitrogen-phosphorus-potassium compound fertilizer, 30-50 parts of phosphate solubilizing bacteria liquid, 12-20 parts of kaolin and 20-60 parts of livestock manure;

the biomass charcoal is prepared by taking corn straws and fruit branches as raw materials;

the mass ratio of nitrogen, phosphorus and potassium in the nitrogen, phosphorus and potassium compound fertilizer is 18-15-10;

the viable count of the phosphate-solubilizing bacterium liquid is 1 × 10⁸cfu/g or more.

The pH value of the compound fertilizer containing the biomass charcoal provided by the invention is 8.3-8.6, the compound fertilizer is granular, and the effective viable count is more than or equal to 5 × 10⁶cfu/g, can be placed at normal temperature for more than 6 months.

In the preferable compound fertilizer containing biomass charcoal, the raw materials preferably include: 70-80 parts of biomass charcoal, 45-50 parts of nitrogen-phosphorus-potassium compound fertilizer, 40-45 parts of phosphate solubilizing bacteria liquid, 15-18 parts of kaolin and 30-40 parts of livestock manure; more preferably, it comprises: 75 parts of biomass charcoal, 42 parts of nitrogen-phosphorus-potassium compound fertilizer, 42 parts of phosphate-solubilizing bacterium liquid, 16 parts of kaolin and 35 parts of livestock manure.

In the present invention, the source of the livestock manure includes, but is not limited to, one or more of pig manure, chicken manure, cow manure, and sheep manure. In the invention, the organic matter mass content of the livestock manure is preferably more than or equal to 75%, and more preferably 80-95%. The livestock manure plays a role in providing organic matters and moderating fertilizer efficiency in the compound fertilizer.

In the invention, compared with the conventional nitrogen-phosphorus-potassium ratio of 15-15-15, the nitrogen-phosphorus-potassium compound fertilizer with the mass ratio of nitrogen, phosphorus and potassium of 18-15-10 is more beneficial to the growth of crops. Although the phosphate fertilizer can increase the dry matter mass of crops, promote the accumulation of nitrogen nutrients and improve the yield of the crops, the phosphorus has weak mobility in soil and is easy to fix, so that the immediate utilization rate of the quick-acting phosphate fertilizer is low.

The nitrogen-phosphorus-potassium compound fertilizer plays a role in providing quick-acting nutrients, one part of the nitrogen-phosphorus-potassium compound fertilizer enters the inner aperture of the biomass charcoal during preparation of the compound fertilizer, and the other part of the nitrogen-phosphorus-potassium compound fertilizer is used for providing a large amount of nutrients required by crops in the growth period. The invention has no special limitation on the source of the nitrogen-phosphorus-potassium compound fertilizer, and can be prepared by self or purchased from commercial products.

In the present invention, the viable cell count of the phosphate solubilizing bacterium liquid is preferably 1 × 10⁸～1×10⁹cfu/g. The phosphate solubilizing bacteria of the present invention are any microorganisms known in the art that have the ability to convert soil-anchored phosphorus elements into a form of available phosphorus that can be assimilated by plants, and may be commercially available or self-isolated.

In the invention, the preparation method of the biomass charcoal comprises the following steps:

(1) mixing corn straws and fruit branches according to the mass ratio of 1-4: 1-2 to obtain a straw and fruit branch mixture;

(2) mixing the straw and fruit branch mixture with a potassium carbonate aqueous solution, soaking and drying to obtain an activated straw mixture;

the mass ratio of the straw and fruit branch mixture to the potassium carbonate contained in the potassium carbonate aqueous solution is 1: 2-4;

(3) heating the activated straw and fruit branch mixture to 380-420 ℃ and keeping for 45-60 min; then heating to 580-620 ℃, and keeping for 60-100 min to obtain a carbonized material;

(4) and cooling the carbonized material, soaking the cooled carbonized material in a hydrochloric acid solution, taking out the carbonized material, washing the carbonized material to be neutral, and drying the washed material to obtain the biomass charcoal.

In the present invention, the fruit branch refers to the waste branch of fruit trees, including but not limited to apple branch, peach branch, etc.

According to the invention, corn straws and fruit branches are mixed according to the mass ratio of 1-4: 1-2 to obtain a straw and fruit branch mixture. According to the invention, the corn straw and the fruit branches are mixed as the raw materials of the biomass charcoal, so that the biomass charcoal has a better crop resistance induction effect, and the nutrient components contained in the corn straw and the fruit branches can be combined, so that the proportion of the nutrient components is more balanced, and the biomass charcoal is more suitable for the growth and development of crops.

In the invention, the mass ratio of the corn straws to the fruit branches is preferably 2-3: 1. Under the mass ratio limited by the invention, the prepared biomass charcoal has higher nitrogen content and more balanced proportion of other nutrient components. The invention can also provide a new utilization way for the corn straws and the fruit branches, and reduces waste.

In the invention, the corn straw and the fruit branch are preferably respectively crushed and then mixed; the independent crushing particle size is preferably 20-100 meshes, and more preferably 40-60 meshes. The invention is more beneficial to the subsequent steps of activation and carbonization after crushing the corn straws and the fruit branches.

After the straw and fruit branch mixture is obtained, the straw and fruit branch mixture is mixed with a potassium carbonate aqueous solution, and the mixture is soaked and dried to obtain an activated straw and fruit branch mixture. According to the invention, the straw and fruit branch mixture is activated by adopting potassium carbonate, the carbonization specific surface area of the straw and fruit branch mixture treated by the potassium carbonate is larger, and the aroma degree of the prepared biomass charcoal can be improved.

In the invention, the mass ratio of the straw and fruit branch mixture to the potassium carbonate contained in the potassium carbonate aqueous solution is 1: 2-4, and more preferably 1: 3. Under the condition of the limited dosage proportion of the potassium carbonate, the prepared biomass charcoal has enhanced hydrophilic capability and stronger adsorption capability on nonpolar substances, can adsorb nitrogen, phosphorus, potassium and mineral elements, and can also adsorb nonpolar substances such as organic matters and the like, thereby prolonging the lasting time of the compound fertilizer.

In the invention, the concentration of the potassium carbonate aqueous solution is preferably 0.5-5 mol/L, and more preferably 1.5-3 mol/L. The invention adopts the potassium carbonate aqueous solution to better impregnate the straw and fruit branch mixture, and the main influencing factor on the activation of the straw and fruit branch mixture is the mass ratio of the straw and fruit branch mixture to the potassium carbonate. The addition of potassium carbonate can improve the pore size distribution of the prepared biochar and increase the number of micropores.

In the invention, the dipping time is preferably 5-8 h, and more preferably 6 h. In the invention, the dipping temperature is preferably 30-35 ℃, and more preferably 32 ℃.

In the invention, the drying temperature is preferably 50-60 ℃, and more preferably 55 ℃; in the present invention, the drying is preferably performed until the moisture content of the material is less than 10%.

After the activated straw and fruit branch mixture is obtained, the activated straw and fruit branch mixture is heated to 380-420 ℃ and kept for 45-60 min; and then heating to 580-620 ℃, and keeping for 60-100 min to obtain the carbonized material. In order to obtain the functional biomass charcoal with large specific surface area, strong adsorption capacity and crop resistance induction, the invention adopts a temperature programming mode for carbonization.

In the invention, the heating rate when the temperature is raised to 380-420 ℃ is preferably 5-8 ℃/min, and more preferably 6 ℃/min. In the invention, the holding time at 380-420 ℃ is preferably 50-55 min.

In the invention, the heating rate when the temperature is raised to 580-620 ℃ is preferably 10-12 ℃/min, and more preferably 11 ℃/min. In the invention, the retention time at 580-620 ℃ is preferably 75-80 min.

After the carbonized material is obtained, the carbonized material is cooled and then soaked in a hydrochloric acid solution, taken out and washed to be neutral, and dried to obtain the biomass charcoal. In the invention, the concentration of the hydrochloric acid solution is preferably 0.05-0.2 mol/L, and more preferably 0.1-0.15 mol/L; the soaking time is preferably 20-60 min, and more preferably 40-50 min.

The biomass charcoal prepared by the method of the invention has the total specific surface area (S)_BET)≥592m²G, mesoporous specific surface area(s)_meso)≥84.64m²G, micropore surface area (S)_micro)≥442m²G, mesopore volume (V)_meso) Not less than 0.17ml/g, micropore volume (V)_micro)≥0.27ml/g, Total pore volume (V)_T) Not less than 0.621ml/g, microporous porosity not less than 63.48%, mesoporous porosity not less than 37.66%, and average pore diameter not less than 11.28 nm.

The invention also provides a preparation method of the compound fertilizer in the technical scheme, which comprises the following steps:

s1, mixing and dipping the biomass charcoal and the phosphate-removing bacterium liquid to obtain a first mixture;

s2, mixing the nitrogen-phosphorus-potassium compound fertilizer, the livestock manure and water to obtain a second mixture;

s3, mixing the first mixture with the second mixture, and impregnating to obtain a third mixture;

and S4, mixing the third mixture with kaolin, granulating and drying to obtain the compound fertilizer containing the biomass charcoal.

According to the invention, biomass charcoal and phosphate-removing bacterium liquid are mixed and dipped to obtain a first mixture. The aim of mixing and soaking the biomass carbon and the phosphate solubilizing bacteria liquid is to enable the biomass carbon to adsorb the phosphate solubilizing bacteria, and part of the phosphate solubilizing bacteria enter the biomass carbon, so that the action time of the phosphate solubilizing bacteria and the quality guarantee period of the compound fertilizer can be prolonged.

In the invention, the soaking time is preferably 2-6 h, and more preferably 3-4 h. In the invention, the dipping temperature is preferably 27-32 ℃, and more preferably 28-30 ℃. In the present invention, the impregnation is preferably accompanied by stirring, and the stirring rate is preferably 200 to 400rpm, more preferably 300 rpm.

The invention mixes nitrogen-phosphorus-potassium compound fertilizer, livestock manure and water to obtain a second mixture. The nitrogen-phosphorus-potassium compound fertilizer, the livestock manure and the water are mixed to facilitate the subsequent adsorption of the biomass charcoal. The second mixture obtained in the present invention is a suspension containing a solid component which is partially insoluble.

In the invention, the volume of the water for mixing is preferably 2-4 times of the total volume of the nitrogen-phosphorus-potassium compound fertilizer and the livestock manure. In the present invention, stirring is preferably performed during the mixing process, and the stirring rate is preferably 400 to 600rpm, so that the effective ingredient is sufficiently dissolved in water.

In the present invention, the preparation processes of the first mixture and the second mixture are not limited in sequence.

After the first mixture and the second mixture are obtained, the first mixture and the second mixture are mixed and impregnated to obtain a third mixture. In the impregnation process, nutrient substances dissolved in water in the second mixture are partially adsorbed by the biomass charcoal, so that the nutrient substances are provided for the phosphate solubilizing bacteria in the second mixture, and the lasting time of the compound fertilizer can be delayed.

In the invention, the soaking time is preferably 1-5 h, and more preferably 2-3 h. In the invention, the dipping temperature is preferably 25-30 ℃, and more preferably 28 ℃. In the present invention, the dipping is preferably accompanied by stirring, and the stirring rate is preferably 150 to 400rpm, more preferably 200 to 300 rpm.

After the third mixture is obtained, the third mixture is mixed with the kaolin, and then the compound fertilizer containing the biomass charcoal is obtained after granulation and drying. The invention uses kaolin as a bonding agent to carry out granulation, thereby preparing the granular compound fertilizer containing the biomass charcoal.

In the present invention, the granulation is preferably performed by using a granulator, and the specific granulation process is not particularly limited in the present invention. In the invention, the granulation temperature is preferably not more than 80 ℃, and more preferably 60-75 ℃.

In the present invention, the specific manner of drying is not particularly limited, and the temperature of drying is preferably not more than 75 ℃, and more preferably 55 to 65 ℃.

The compound fertilizer containing the biomass charcoal prepared by the method has long lasting time and can meet the basic nutrient substance requirement of the whole growth cycle of crops. Meanwhile, the compound fertilizer containing the biomass charcoal can also induce the improvement of crop resistance and reduce the incidence rate of soil-borne diseases, thereby comprehensively promoting the crop growth and reducing the application amount of pesticides.

The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.