CN118638556B - A biochar-based multi-effect soil conditioner and its preparation method - Google Patents

Abstract

The invention discloses a biochar-based multifunctional soil conditioner and a preparation method thereof, and belongs to the technical field of soil remediation. The microbial agent is prepared from the following raw materials, by weight, 100-120 parts of modified biochar, 10-20 parts of microbial agent, 20-30 parts of modified red mud, 20-30 parts of diatomite, 80-100 parts of livestock manure and 10-20 parts of activating agent, wherein the microbial agent is composed of Brevibacillus laterosporus, trichoderma koningii and streptomyces cellulosicus according to a mass ratio of 1:1:1. The biochar-based multi-effect soil conditioner prepared by the invention can effectively improve the physical and chemical properties of soil through the synergistic effect of various components, such as increasing the pH value of acid soil, increasing the organic matter content of soil, improving the soil structure, improving the enzymatic activity of soil and the like, thereby obviously improving the fertility and the health level of soil, being beneficial to promoting the growth and development of plants and improving the yield and quality of crops. Meanwhile, the modified biochar and the modified red mud are adopted to act synergistically, so that the air permeability and the water permeability of the soil can be improved after the modified biochar and the modified red mud are applied to the soil, the compactness of the soil is reduced, the physical property of the soil is improved, meanwhile, the modified biochar and the modified red mud can be combined with heavy metal ions in the soil, the bioavailability of heavy metal is reduced, the pollution of the heavy metal to the soil and crops is reduced, the modified red mud has an excellent multiple soil improvement effect, and the market application prospect is wide.

Description

Biochar-based multifunctional soil conditioner and preparation method thereof

Technical Field

The invention belongs to the technical field of soil remediation, and particularly relates to a biochar-based multifunctional soil conditioner and a preparation method thereof.

Background

In recent years, the agricultural production level of China is continuously improved, but a series of problems such as resource waste, ecological degradation, environmental pollution, soil hardening and the like caused by a high-consumption low-efficiency rough production mode become bottlenecks for restricting sustainable development of agriculture in China, so that the vital interests of peasants are damaged, and the deterioration of the ecological environment of soil is aggravated. At present, the soil environment conditions of China are generally optimistic, and the soil pollution overstandard rate of China reaches 16.1 percent. The soil environment quality of the cultivated land is cause anxiety, the farmland polluted by the organic pollutants in the whole country reaches 3600 ten thousand hectares, the soil polluted by the heavy metals reaches 2000 ten thousand hectares, and the severely polluted soil exceeds 70 ten thousand hectares. Soil pollution has been a threat to sustainable land resource utilization and ecological safety of agricultural products. The problems of soil pollution, acidification, hardening, salinization, soil-borne disease frequency and the like are increasingly prominent because of the increasing pollution of heavy metals and organic matters in soil caused by excessive application of chemical fertilizers and lack of organic fertilizers. In the aspect of cultivated soil, the cultivation layer is thinned, nutrient is unbalanced, heavy metal, pesticide and poor-quality chemical fertilizer are polluted seriously, acidification, salinization, drought and desertification are serious, organic matters and medium trace elements are generally lacking, crops are planted in succession, soil-borne diseases are aggravated, soil fertility is reduced, microbial activity is poor, and productivity is reduced. In the aspect of fertilizer utilization, nitrogen loss, fixed phosphorus and potassium loss occur. This has severely affected the sustainable development of Chinese agriculture.

Soil conditioners are also called soil improvement and restoration agents, and have the functions of improving physical and chemical properties of soil, promoting nutrient absorption of crops and reducing heavy metal accumulation in the crops. The physical and chemical indexes and the nutrient promotion requirements which need to be improved are different for different soils and crops. Biochar generally refers to carbonaceous solid materials that are converted by pyrolysis of biomass or solid waste (agricultural waste, sludge, animal waste) under anoxic or anaerobic conditions. Biochar is considered a renewable "carbon-neutralizing" material because the amount of CO ₂ emitted by biomass during thermal conversion to biochar is equivalent to the amount of biomass immobilized from the environment for photosynthesis. Compared with non-renewable curing agents such as cement, the biochar can effectively stabilize heavy metals in polluted soil, can improve the physicochemical properties of the soil, is beneficial to plant growth and has wide application in soil restoration. However, the adsorption-fixation effect of biochar used as a soil conditioner is limited by the structure and the component composition of raw materials, and the expected restoration effect of the biochar used as the soil conditioner is often difficult to achieve in the face of the complex pollution condition of the actual soil environment. Although the existing biochar-based soil conditioner has a certain soil conditioning effect, the function is single, necessary nutrients cannot be provided for the growth and development of plants, and the yield is not high, so that the comprehensive performance is poor.

Disclosure of Invention

The invention aims to provide a biochar-based multifunctional soil conditioner and a preparation method thereof. The biochar-based multi-effect soil conditioner prepared by the invention can effectively improve the physical and chemical properties of soil through the synergistic effect of various components, such as increasing the pH value of acid soil, increasing the organic matter content of soil, improving the soil structure, improving the enzymatic activity of soil and the like, thereby obviously improving the fertility and the health level of soil, being beneficial to promoting the growth and development of plants and improving the yield and quality of crops. Meanwhile, the modified biochar and the modified red mud are adopted to act synergistically, so that the air permeability and the water permeability of the soil can be improved after the modified biochar and the modified red mud are applied to the soil, the compactness of the soil is reduced, the physical property of the soil is improved, meanwhile, the modified biochar and the modified red mud can be combined with heavy metal ions in the soil, the bioavailability of heavy metal is reduced, the pollution of the heavy metal to the soil and crops is reduced, the modified red mud has an excellent multiple soil improvement effect, and the market application prospect is wide.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

The biochar-based multifunctional soil conditioner is prepared from the following raw materials, by weight, 100-120 parts of modified biochar, 10-20 parts of a microbial agent, 20-30 parts of modified red mud, 20-30 parts of diatomite, 80-100 parts of livestock manure and 10-20 parts of an activating agent, wherein the microbial agent comprises Brevibacillus laterosporus, trichoderma koningii and streptomyces cellulosum according to a mass ratio of 1:1:1.

Preferably, the preparation method of the modified biochar comprises the following steps of mixing the cleaned plant straws with 0.1mol/L nickel chloride solution according to a solid-to-liquid ratio, magnetically stirring at room temperature for reaction for 24 hours, centrifuging, drying and grinding into fine powder, calcining the straw powder in a high-temperature furnace, calcining at a high temperature of 500 ℃ for 1 hour, calcining at a temperature of 700 ℃ for 30 minutes, preserving heat for 4 hours, and naturally cooling to room temperature to obtain the modified biochar.

Preferably, the solid-to-liquid ratio of the plant straw to the nickel chloride solution of 0.1mol/L is 1g:50ml.

Preferably, the preparation method of the modified red mud comprises the following steps:

(1) Mixing hydrochloric acid solution and red mud according to a liquid-solid ratio, reacting in an 80 ℃ water bath for 1.5 hours, washing with deionized water to be neutral, drying for 24 hours at 100 ℃, and calcining in a muffle furnace for 6 hours at 550 ℃ to obtain acid-treated red mud, wherein the concentration of the hydrochloric acid solution is 1mol/L;

(2) Mixing 1mol/L Cu (NO ₃)₂·3H₂ O solution and the acid-treated red mud obtained in the step (1) according to the ratio of 50ml to 1g, magnetically stirring at room temperature for reaction for 24 hours, centrifuging and drying to obtain a solid product, and finally placing the solid product in a muffle furnace for calcining at 550 ℃ for 5 hours, taking out and grinding into 80-mesh powder to obtain the modified red mud.

Preferably, the liquid-solid ratio in the step (1) is 10 ml/1 g.

Preferably, the activator is obtained by mixing 2mol/L zinc chloride solution and 1mol/L phosphoric acid solution according to a volume ratio of 1:1.

Preferably, the collection number of the bacillus laterosporus is CGMCC No.1.15087, the collection date is 15 days of 2 months of 2015 of China general microbiological collection center, the collection number of the trichoderma koningii is CGMCC No.3.17875, the collection date is 15 days of 12 months of 2015 of China general microbiological collection center, the collection number of the streptomyces cellulosicus is CGMCC No.4.6365, the collection date is 3 days of 9 months of 2008 of China general microbiological collection center. The Brevibacillus laterosporus, the trichoderma koningii and the streptomyces cellulosicus used in the invention can be purchased through a collection center strain catalog, and additional collection is not needed.

Preferably, the preparation method of the microbial agent comprises the steps of respectively inoculating Brevibacillus laterosporus, trichoderma koningii and Streptomyces cellulosicus into a sterilized beef extract peptone culture medium 500 mL shake flask, carrying out shake culture at 37 ℃ and 250 r/min for 24 h to obtain bacterial suspensions respectively, and mixing the bacterial suspensions according to a mass ratio of 1:1:1 to obtain the microbial agent. Beef extract peptone media were purchased from Qingdao high tech industrial park Haibo biotechnology Co.

The preparation method of the biochar-based multifunctional soil conditioner comprises the following steps:

(1) Preparing a microbial agent;

(2) Preparing modified biochar;

(3) Preparing modified red mud;

(4) Uniformly mixing the modified biochar obtained in the step (2) with deionized water with the volume of 2 times, adding an activating agent into the mixture, stirring the mixture at room temperature for reaction for 24 hours, filtering to obtain filter residues, washing the filter residues with deionized water to be neutral, and drying the filter residues in an oven at 80 ℃ to obtain the activated biochar;

(5) Uniformly mixing livestock manure, diatomite and modified red mud according to parts by weight, adding water to enable the water content to be 50%, adding the prepared microbial agent into the mixture, uniformly stirring, composting and fermenting, controlling the temperature of a piled body to be not higher than 55 ℃ through turning over the fertilizer, continuously fermenting for 10 days, adding the activated biochar obtained in the step (4), uniformly stirring, continuously fermenting for 12 hours, drying and crushing a fermentation product after the fermentation is finished, and granulating into 4-5mm particles by using a granulator to obtain the biochar-based multifunctional soil conditioner.

The raw materials used in the invention are all obtained by commercial purchase unless otherwise specified.

The microbial agent is prepared by culturing three strains of the Brevibacterium laterosporus, the trichoderma koningii and the streptomyces cellulosus, wherein the streptomyces cellulosus and the trichoderma koningii have remarkable antibacterial capability, can prevent and treat various plant soil-borne diseases or inhibit pathogens, can secrete various enzyme active substances, promote formation of new roots, strengthen fibrous roots and old roots, and quickly construct a healthy and strong root system, and the Brevibacterium laterosporus not only has remarkable nematicide function, but also can decompose toxic and harmful residual pesticide and other organic pollutants in soil, and adsorb and prevent heavy metals from entering plants. The three strains are used in a compounding way in equal proportion, and the three strains act together with other components to act synergistically, so that the soil conditioner has good conditioning effect.

Red mud, also known as bauxite residue, is an industrial byproduct produced in the extraction of alumina from bauxite. By 2020, global red mud inventory has exceeded 50 million tons, with our country red mud inventory exceeding 8 hundred million tons. Because the safe disposal cost of the red mud is higher, the disposal mode of the red mud at present mainly adopts dry accumulation, so that serious land resource waste is caused, and a great amount of pollution is caused. Therefore, comprehensive resource utilization of the red mud is very necessary. The red mud has unique oxide-rich structure (especially iron and aluminum oxides), surface hydroxyl and porosity, has certain heavy metal adsorption potential, and can be used as an environment restoration material. The invention adopts the red mud modified by the copper nitrate, improves the adsorption activity of the red mud on heavy metal ions, and effectively reduces the heavy metal pollution in soil.

The modified biochar prepared by the method is characterized in that metal nickel ions are attached to the surface of the porous biochar, so that the pore structure of the biochar is changed, the types of surface chemical functional groups are changed, the modified biochar has larger specific surface area, adjustable pore structure and rich active functional sites, so that pollutants in the soil environment can be effectively removed, and meanwhile, the activator can further improve the activity of a plurality of functional groups of the modified biochar, improve the physical property of the soil, combine with heavy metal ions in the soil, reduce the bioavailability of heavy metal and reduce the pollution of heavy metal to the soil and crops.

The biochar-based multi-effect soil conditioner can be mixed with chemical fertilizers, and the dosage is 80-100 kg/mu. Through adsorption and slow release, the loss and volatilization of the chemical fertilizer are reduced, and the utilization efficiency of the chemical fertilizer is improved. The method can reduce the dosage of chemical fertilizers, reduce the agricultural production cost and reduce the pollution and damage to the environment.

The modified biological carbon and the modified red mud are mixed according to a specific proportion, the modified red mud serving as mineral particles can be spread in a porous carbon structure of the biological carbon, and the pH of acid soil can be obviously improved and the content of heavy metal ions in the soil can be reduced under the combined action of the modified biological carbon and the modified red mud. Meanwhile, after the modified biochar porous structure and the modified red mud particle structure are used in a combined mode, places suitable for survival and propagation of a large number of microorganisms are provided, the colonization success rate of the microorganisms is greatly improved, the number of microorganisms in the plant soil environment is effectively increased, and the physical and chemical properties of the soil, the disease and pest resistance of plants and the soil fertility can be remarkably improved due to the fact that a large number of microorganisms act on the soil. The soil conditioner disclosed by the invention is also rich in various trace elements and vitamins, provides comprehensive nutrition support for plants, and can increase the organic matter content of soil and improve the structure and air permeability of the soil by organic matters, microorganisms and other components.

Detailed Description

The technical scheme of the present invention is further described below with reference to specific examples, but is not limited thereto. The red mud used in the invention is solid waste residue discharged from the sintering method of alumina in certain Shandong aluminum factory, and the specific chemical compositions are shown in table 1.

Table 1 chemical composition of red mud

Example 1

The biochar-based multifunctional soil conditioner is prepared from the following raw materials, by weight, 100 parts of modified biochar, 10 parts of microbial agents, 20 parts of modified red mud, 20 parts of diatomite, 80 parts of livestock manure and 10 parts of activators, wherein the microbial agents comprise Brevibacillus laterosporus, trichoderma koningii and Streptomyces cellulosicus according to a mass ratio of 1:1:1.

The preparation method of the modified biochar comprises the following steps of mixing the cleaned plant straws with 0.1mol/L nickel chloride solution according to a solid-to-liquid ratio, magnetically stirring at room temperature for reaction for 24 hours, centrifuging, drying and grinding into fine powder, calcining the straw powder in a high-temperature furnace, calcining at a high temperature of 500 ℃ for 1 hour, calcining at a temperature of 700 ℃ for 30 minutes, preserving heat for 4 hours, and naturally cooling to room temperature to obtain the modified biochar.

The solid-liquid ratio of the plant straw to the nickel chloride solution of 0.1mol/L is 1g:50ml.

The preparation method of the modified red mud comprises the following steps:

(1) Mixing hydrochloric acid solution and red mud according to a liquid-solid ratio, reacting in an 80 ℃ water bath for 1.5 hours, washing to be neutral by deionized water, drying for 24 hours at 100 ℃, and calcining in a muffle furnace at 550 ℃ for 6 hours to obtain acid-treated red mud, wherein the concentration of the hydrochloric acid solution is 1mol/L, and the liquid-solid ratio is 10 ml/1 g;

(2) Mixing 1mol/L Cu (NO ₃)₂·3H₂ O solution and the acid-treated red mud obtained in the step (1) according to the ratio of 50ml to 1g, magnetically stirring at room temperature for reaction for 24 hours, centrifuging and drying to obtain a solid product, and finally placing the solid product in a muffle furnace for calcining at 550 ℃ for 5 hours, taking out and grinding into 80-mesh powder to obtain the modified red mud.

The activator is obtained by mixing 2mol/L zinc chloride solution and 1mol/L phosphoric acid solution according to a volume ratio of 1:1.

The collection number of the bacillus laterosporus is CGMCC No.1.15087, the collection date is 15 days of 2015 of China general microbiological collection center, the collection number of the trichoderma koningii is CGMCC No.3.17875, the collection date is 15 days of 2015 of China general microbiological collection center, the collection date is 4.6365 of CGMCC No.4.6365, the collection date is 2008 of 9 months and 3 days of China general microbiological collection center. The Brevibacillus laterosporus, the trichoderma koningii and the streptomyces cellulosicus used in the invention can be purchased through a collection center strain catalog, and additional collection is not needed.

The preparation method of the microbial agent comprises the steps of respectively inoculating Brevibacillus laterosporus, trichoderma koningii and Streptomyces cellulosicus into sterilized beef extract peptone culture medium 500 mL shake flask, performing shake culture at 37 ℃ and 250 r/min for 24 h to obtain bacterial suspensions, and mixing the bacterial suspensions according to a mass ratio of 1:1:1 to obtain the microbial agent. Beef extract peptone media were purchased from Qingdao high tech industrial park Haibo biotechnology Co.

The preparation method of the biochar-based multifunctional soil conditioner comprises the following steps:

(1) Preparing a microbial agent;

(2) Preparing modified biochar;

(3) Preparing modified red mud;

(4) Uniformly mixing the modified biochar obtained in the step (2) with deionized water with the volume of 2 times, adding an activating agent into the mixture, stirring the mixture at room temperature for reaction for 24 hours, filtering to obtain filter residues, washing the filter residues with deionized water to be neutral, and drying the filter residues in an oven at 80 ℃ to obtain the activated biochar;

(5) Uniformly mixing livestock manure, diatomite and modified red mud according to parts by weight, adding water to enable the water content to be 50%, adding the prepared microbial agent into the mixture, uniformly stirring, composting and fermenting, controlling the temperature of a piled body to be not higher than 55 ℃ through turning over the fertilizer, continuously fermenting for 10 days, adding the activated biochar obtained in the step (4), uniformly stirring, continuously fermenting for 12 hours, drying and crushing a fermentation product after the fermentation is finished, and granulating into 4-5mm particles by using a granulator to obtain the biochar-based multifunctional soil conditioner.

Example 2

The biochar-based multifunctional soil conditioner is prepared from the following raw materials, by weight, 120 parts of modified biochar, 20 parts of microbial agents, 30 parts of modified red mud, 30 parts of diatomite, 100 parts of livestock manure and 20 parts of activators, wherein the microbial agents comprise Brevibacillus laterosporus, trichoderma koningii and Streptomyces cellulosicus according to a mass ratio of 1:1:1.

The preparation method of the modified biochar comprises the following steps of mixing the cleaned plant straws with 0.1mol/L nickel chloride solution according to a solid-to-liquid ratio, magnetically stirring at room temperature for reaction for 24 hours, centrifuging, drying and grinding into fine powder, calcining the straw powder in a high-temperature furnace, calcining at a high temperature of 500 ℃ for 1 hour, calcining at a temperature of 700 ℃ for 30 minutes, preserving heat for 4 hours, and naturally cooling to room temperature to obtain the modified biochar.

The solid-liquid ratio of the plant straw to the nickel chloride solution of 0.1mol/L is 1g:50ml.

The preparation method of the modified red mud comprises the following steps:

(1) Mixing hydrochloric acid solution and red mud according to a liquid-solid ratio, reacting in an 80 ℃ water bath for 1.5 hours, washing to be neutral by deionized water, drying for 24 hours at 100 ℃, and calcining in a muffle furnace at 550 ℃ for 6 hours to obtain acid-treated red mud, wherein the concentration of the hydrochloric acid solution is 1mol/L, and the liquid-solid ratio is 10 ml/1 g;

(2) Mixing 1mol/L Cu (NO ₃)₂·3H₂ O solution and the acid-treated red mud obtained in the step (1) according to the ratio of 50ml to 1g, magnetically stirring at room temperature for reaction for 24 hours, centrifuging and drying to obtain a solid product, and finally placing the solid product in a muffle furnace for calcining at 550 ℃ for 5 hours, taking out and grinding into 80-mesh powder to obtain the modified red mud.

The activator is obtained by mixing 2mol/L zinc chloride solution and 1mol/L phosphoric acid solution according to a volume ratio of 1:1.

The collection number of the bacillus laterosporus is CGMCC No.1.15087, the collection date is 15 days of 2 months of 2015 of China general microbiological collection center, the collection number of the trichoderma koningii is CGMCC No.3.17875, the collection date is 15 days of 12 months of 2015 of China general microbiological collection center, the collection number of the streptomyces cellulosicus is CGMCC No.4.6365, the collection date is 3 days of 9 months of 2008 of China general microbiological collection center. The Brevibacillus laterosporus, the trichoderma koningii and the streptomyces cellulosicus used in the invention can be purchased through a collection center strain catalog, and additional collection is not needed.

The preparation method of the microbial agent comprises the steps of respectively inoculating Brevibacillus laterosporus, trichoderma koningii and Streptomyces cellulosicus into sterilized beef extract peptone culture medium 500 mL shake flask, performing shake culture at 37 ℃ and 250 r/min for 24 h to obtain bacterial suspensions, and mixing the bacterial suspensions according to a mass ratio of 1:1:1 to obtain the microbial agent. Beef extract peptone media were purchased from Qingdao high tech industrial park Haibo biotechnology Co.

The preparation method of the biochar-based multifunctional soil conditioner comprises the following steps:

(1) Preparing a microbial agent;

(2) Preparing modified biochar;

(3) Preparing modified red mud;

(4) Uniformly mixing the modified biochar obtained in the step (2) with deionized water with the volume of 2 times, adding an activating agent into the mixture, stirring the mixture at room temperature for reaction for 24 hours, filtering to obtain filter residues, washing the filter residues with deionized water to be neutral, and drying the filter residues in an oven at 80 ℃ to obtain the activated biochar;

(5) Uniformly mixing livestock manure, diatomite and modified red mud according to parts by weight, adding water to enable the water content to be 50%, adding the prepared microbial agent into the mixture, uniformly stirring, composting and fermenting, controlling the temperature of a piled body to be not higher than 55 ℃ through turning over the fertilizer, continuously fermenting for 10 days, adding the activated biochar obtained in the step (4), uniformly stirring, continuously fermenting for 12 hours, drying and crushing a fermentation product after the fermentation is finished, and granulating into 4-5mm particles by using a granulator to obtain the biochar-based multifunctional soil conditioner.

Example 3

The biochar-based multifunctional soil conditioner is prepared from the following raw materials, by weight, 110 parts of modified biochar, 15 parts of microbial agents, 25 parts of modified red mud, 20-30 parts of kieselguhr, 90 parts of livestock manure and 15 parts of activators, wherein the microbial agents comprise Brevibacillus laterosporus, trichoderma koningii and Streptomyces cellulosae according to a mass ratio of 1:1:1.

The preparation method of the modified biochar comprises the following steps of mixing the cleaned plant straws with 0.1mol/L nickel chloride solution according to a solid-to-liquid ratio, magnetically stirring at room temperature for reaction for 24 hours, centrifuging, drying and grinding into fine powder, calcining the straw powder in a high-temperature furnace, calcining at a high temperature of 500 ℃ for 1 hour, calcining at a temperature of 700 ℃ for 30 minutes, preserving heat for 4 hours, and naturally cooling to room temperature to obtain the modified biochar.

The solid-liquid ratio of the plant straw to the nickel chloride solution of 0.1mol/L is 1g:50ml.

The preparation method of the modified red mud comprises the following steps:

(1) Mixing hydrochloric acid solution and red mud according to a liquid-solid ratio, reacting in an 80 ℃ water bath for 1.5 hours, washing to be neutral by deionized water, drying for 24 hours at 100 ℃, and calcining in a muffle furnace at 550 ℃ for 6 hours to obtain acid-treated red mud, wherein the concentration of the hydrochloric acid solution is 1mol/L, and the liquid-solid ratio is 10 ml/1 g;

(2) Mixing 1mol/L Cu (NO ₃)₂·3H₂ O solution and the acid-treated red mud obtained in the step (1) according to the ratio of 50ml to 1g, magnetically stirring at room temperature for reaction for 24 hours, centrifuging and drying to obtain a solid product, and finally placing the solid product in a muffle furnace for calcining at 550 ℃ for 5 hours, taking out and grinding into 80-mesh powder to obtain the modified red mud.

The activator is obtained by mixing 2mol/L zinc chloride solution and 1mol/L phosphoric acid solution according to a volume ratio of 1:1.

The collection number of the bacillus laterosporus is CGMCC No.1.15087, the collection date is 15 days of 2 months of 2015 of China general microbiological collection center, the collection number of the trichoderma koningii is CGMCC No.3.17875, the collection date is 15 days of 12 months of 2015 of China general microbiological collection center, the collection number of the streptomyces cellulosicus is CGMCC No.4.6365, the collection date is 3 days of 9 months of 2008 of China general microbiological collection center. The Brevibacillus laterosporus, the trichoderma koningii and the streptomyces cellulosicus used in the invention can be purchased through a collection center strain catalog, and additional collection is not needed.

The preparation method of the microbial agent comprises the steps of respectively inoculating Brevibacillus laterosporus, trichoderma koningii and Streptomyces cellulosicus into sterilized beef extract peptone culture medium 500 mL shake flask, performing shake culture at 37 ℃ and 250 r/min for 24 h to obtain bacterial suspensions, and mixing the bacterial suspensions according to a mass ratio of 1:1:1 to obtain the microbial agent. Beef extract peptone media were purchased from Qingdao high tech industrial park Haibo biotechnology Co.

The preparation method of the biochar-based multifunctional soil conditioner comprises the following steps:

(1) Preparing a microbial agent;

(2) Preparing modified biochar;

(3) Preparing modified red mud;

(4) Uniformly mixing the modified biochar obtained in the step (2) with deionized water with the volume of 2 times, adding an activating agent into the mixture, stirring the mixture at room temperature for reaction for 24 hours, filtering to obtain filter residues, washing the filter residues with deionized water to be neutral, and drying the filter residues in an oven at 80 ℃ to obtain the activated biochar;

(5) Uniformly mixing livestock manure, diatomite and modified red mud according to parts by weight, adding water to enable the water content to be 50%, adding the prepared microbial agent into the mixture, uniformly stirring, composting and fermenting, controlling the temperature of a piled body to be not higher than 55 ℃ through turning over the fertilizer, continuously fermenting for 10 days, adding the activated biochar obtained in the step (4), uniformly stirring, continuously fermenting for 12 hours, drying and crushing a fermentation product after the fermentation is finished, and granulating into 4-5mm particles by using a granulator to obtain the biochar-based multifunctional soil conditioner.

Comparative example 1

The preparation method of the biochar-based multifunctional soil conditioner is basically the same as that of the embodiment 3, and the only difference is that the used biochar is unmodified biochar, and the preparation method comprises the steps of drying and grinding the cleaned plant straws into fine powder, calcining the straw powder in a high-temperature furnace, calcining at a high temperature of 500 ℃ for 1h, calcining at a temperature of 700 ℃ for 30min, preserving heat for 4h, and naturally cooling to room temperature to obtain the unmodified biochar.

Comparative example 2

The biochar-based multifunctional soil conditioner is basically the same as that in example 3 in raw material composition and preparation method, and the only difference is that the red mud is unmodified red mud, and the red mud discharged from the sintering method of certain aluminum factory in Shandong is directly used as raw material.

Comparative example 3

The biochar-based multifunctional soil conditioner is basically the same as that of example 3 in raw material composition and preparation method, except that modified biochar and steps of the corresponding preparation method are not contained in the raw material. The preparation method of the biochar-based soil conditioner comprises the following steps:

(1) Preparing a microbial agent;

(2) Preparing modified red mud;

(3) Uniformly mixing livestock manure, diatomite, modified red mud and an activating agent according to parts by weight, adding water to enable the water content to be 50%, adding the prepared microbial agent into the mixture, uniformly stirring, composting and fermenting, controlling the temperature of a composting body to be not higher than 55 ℃ through turning over the fertilizer, continuously fermenting for 10 days, drying and crushing a fermentation product, and granulating the fermentation product into 4-5mm particles by using a granulator to obtain the biochar-based multi-effect soil conditioner.

Comparative example 4

The biochar-based multifunctional soil conditioner is basically the same as that of example 3 in raw material composition and preparation method, and the only difference is that the raw material does not contain modified red mud and the steps of the corresponding preparation method, and the preparation method of the specific biochar-based soil conditioner is as follows:

(1) Preparing a microbial agent;

(2) Preparing modified biochar;

(3) Uniformly mixing the modified biochar obtained in the step (2) with deionized water with the volume of 2 times, adding an activating agent into the mixture, stirring the mixture at room temperature for reaction for 24 hours, filtering to obtain filter residues, washing the filter residues with deionized water to be neutral, and drying the filter residues in an oven at 80 ℃ to obtain the activated biochar;

(4) Uniformly mixing livestock manure and diatomite according to parts by weight, adding water to enable the water content to be 50%, adding the prepared microbial agent into the mixture, uniformly stirring, composting and fermenting, controlling the temperature of a piled body to be not higher than 55 ℃ through turning over, continuously fermenting for 10 days, adding the activated biochar obtained in the step (3), uniformly stirring, continuously fermenting for 12 hours, drying and crushing a fermentation product after fermentation, and granulating into 4-5mm particles by using a granulator to obtain the biochar-based multifunctional soil conditioner.

Comparative example 5

The biochar-based multifunctional soil conditioner is basically the same as that of example 3 in raw material composition and preparation method, and the only difference is that the preparation method does not contain an activating agent and comprises the steps of preparing active biochar, and the preparation method of the corresponding biochar-based soil conditioner is as follows:

(1) Preparing a microbial agent;

(2) Preparing modified biochar;

(3) Preparing modified red mud;

(4) Uniformly mixing livestock manure, diatomite and modified red mud according to parts by weight, adding water to enable the water content to be 50%, adding the prepared microbial agent into the mixture, uniformly stirring, composting and fermenting, controlling the temperature of a piled body to be not higher than 55 ℃ through turning over the fertilizer, continuously fermenting for 10 days, adding the modified biochar obtained in the step (2), uniformly stirring, continuously fermenting for 12 hours, drying and crushing a fermentation product after the fermentation is finished, and granulating into 4-5mm particles by using a granulator to obtain the biochar-based multifunctional soil conditioner.

Comparative example 6

A biochar-based multifunctional soil conditioner is basically the same as that of example 3 in raw material composition and preparation method, except that the activating agent is a 2mol/L zinc chloride solution.

Comparative example 7

A biochar-based multifunctional soil conditioner is basically the same as that of example 3 in raw material composition and preparation method, and the only difference is that an activator is 1mol/L phosphoric acid solution.

Comparative example 8

The biochar-based multifunctional soil conditioner is basically the same as that in the embodiment 3, and the only difference is that the microbial agent is composed of Brevibacillus laterosporus and Trichoderma koningii according to the mass ratio of 1:1. The preparation method of the microbial agent comprises the steps of respectively inoculating Brevibacillus laterosporus and Trichoderma koningii into sterilized beef extract peptone culture medium 500 mL shake flasks, performing shake culture at 37 ℃ and 250 r/min for 24h to obtain bacterial suspensions, and mixing the bacterial suspensions according to a mass ratio of 1:1 to obtain the microbial agent. Beef extract peptone media were purchased from Qingdao high tech industrial park Haibo biotechnology Co.

Comparative example 9

The biochar-based multifunctional soil conditioner is basically the same as that in the embodiment 3, and the only difference is that the microbial agent is composed of Brevibacillus laterosporus and Streptomyces cellulosicus according to the mass ratio of 1:1. The preparation method of the microbial agent comprises the steps of respectively inoculating Brevibacillus laterosporus and streptomyces celluloses into a sterilized beef extract peptone culture medium 500 mL shake flask, carrying out shake culture at 37 ℃ and 250 r/min for 24 h to respectively obtain bacterial suspensions, and mixing the bacterial suspensions according to a mass ratio of 1:1 to obtain the microbial agent. Beef extract peptone media were purchased from Qingdao high tech industrial park Haibo biotechnology Co.

Comparative example 10

The biochar-based multifunctional soil conditioner is basically the same as that in the embodiment 3, and the only difference is that the microbial agent is composed of trichoderma koningii and streptomyces cellulosicus according to the mass ratio of 1:1. The preparation method of the microbial agent comprises the steps of respectively inoculating trichoderma koningii and streptomyces celluloses into a sterilized beef extract peptone culture medium 500 mL shake flask, carrying out shake culture at 37 ℃ and 250 r/min for 24 h to obtain bacterial suspensions, and mixing the bacterial suspensions according to a mass ratio of 1:1 to obtain the microbial agent. Beef extract peptone media were purchased from Qingdao high tech industrial park Haibo biotechnology Co.

Planting test

In order to further describe the technical effect of the invention, the biochar-based multifunctional soil conditioner prepared by the invention is applied to rice planting.

The test site is a moderately polluted land of a certain administrative village of Junan county of Shandong province, cross road town is selected as a test land block, the physical and chemical properties of the test soil are shown in table 2, and the heavy metal content of the test soil is shown in table 3.

TABLE 2 basic physicochemical Properties of soil tested

TABLE 3 heavy metal content of test soil

The test method is that the rice variety to be tested is fragrant japonica 9407. The experiments were divided into 14 treatment groups and designated 1-14 respectively, wherein 1-3 were the treatment groups of examples 1-3, 4-13 were the treatment groups of comparative examples 1-10, and 14 was the blank control group. The specific treatment method of each treatment group comprises the steps of applying the soil conditioner prepared by each treatment group as a base fertilizer and conventional fertilizers (N: P ₂O₅:K₂ O=17-6-20, total nutrients are more than or equal to 45%) into soil in a ploughing mode, wherein the dosage of the soil conditioner is 100 kg/mu, and the dosage of the fertilizer is 40 kg/mu, and the blank control group uses the conventional fertilizers as the base fertilizer to plough and apply the conventional fertilizers into the soil. The treatment groups are consistent with other field management measures except that different soil conditioners are applied to the soil after turning and ploughing before planting. Continuous 30 rice ears with consistent growth vigor are collected in each treatment group in the rice harvesting period, and the biomass of overground parts, the rice yield and the yield constitution factors are measured, and the results are shown in Table 4.

Table 4 rice planting test results

From the above data, it can be seen that the rice yield is significantly improved after the soil conditioner of the present invention is used, compared with the blank group, and the plant height, the spike number and the thousand seed weight index are superior to those of the comparative examples 1 to 10 and the blank group. The biochar-based multifunctional soil conditioner prepared by the invention can effectively improve the physical and chemical properties of soil through the synergistic effect of multiple components, so that the fertility and the health level of the soil are obviously improved, and the biochar-based multifunctional soil conditioner is beneficial to promoting the growth and development of plants and improving the yield and quality of crops.

Samples of surface soil (0-20 cm) were collected after harvesting of rice, and soil samples were collected per treatment group according to the S-shaped sampling method. When the soil is taken, the soil drill is drilled to the depth of 20cm once, 3 repetitions are collected for each treatment group, 3 repeated samples of the same treatment group are mixed into one sample, visible impurities such as gravel, plant roots and the like are removed, and the sample is brought back to a laboratory to measure soil microorganisms, enzyme activity, basic physicochemical properties of the soil and effective heavy metal content in the soil, and test results are shown in tables 5, 6 and 7.

The test method comprises the steps of adopting a ring cutter method for soil volume weight, adopting a potential method for pH value (water: soil=2.5:1), adopting a K ₂Cr₂O₇ oxidation-external heating method for organic matter content, adopting a mixed catalyst-flow analyzer method for total nitrogen content, adopting a HClO ₄+H₂SO₄ digestion-molybdenum-antimony colorimetric method for total phosphorus content, adopting a NaOH fusion-flame photometry method for total potassium content, adopting a KCl digestion-continuous flow analyzer method for alkaline hydrolysis nitrogen content, adopting a NaHCO ₃ digestion-molybdenum-antimony colorimetric method for quick-acting phosphorus content, and adopting a CH ₃COONH₄ digestion-flame photometry method for quick-acting potassium content. The Pb content of the soil heavy metal effective state is determined by adopting a DTPA leaching-atomic absorption spectrophotometry, the Hg content of the soil heavy metal effective state is determined by adopting a sodium dihydrogen phosphate extraction-atomic fluorescence method, the Cd content of the soil heavy metal effective state is determined by adopting an HCl-HNO ₃-HF-HClO₄ micro-thermal digestion-graphite furnace atomic absorption spectrophotometry, the As content of the soil heavy metal effective state is determined by adopting an HNO ₃ -HCl heating digestion-KBH ₄ reduction-atomic fluorescence method, and the Cr content of the soil heavy metal effective state is determined by adopting an HCl-HNO ₃-HF-HClO₄ micro-thermal digestion-flame atomic absorption spectrophotometry.

TABLE 5 basic physicochemical Properties of soil after harvesting Rice

From the above data, it can be seen that the soil conditioner of the present invention has improved pH, reduced volume weight and significantly improved organic matter content, compared with the blank, compared with the comparative examples 1 to 10 and the blank. The biochar-based multifunctional soil conditioner prepared by the invention can effectively improve the physical and chemical properties of soil through the synergistic effect of multiple components, improve the pH value of acid soil, increase the organic matter content of soil and improve the soil structure, and has remarkable comprehensive soil improvement effect.

TABLE 6 heavy metal content of post-harvest soil of rice

Soil microbiology determination the number of three microbial groups of soil bacteria, fungi and actinomycetes is determined by a dilution plate separation counting method, and the number is expressed as colony count (cfu) contained in each gram of dry soil. The bacterial beef extract peptone culture medium is used for culturing for 2-3d at 37 ℃, the fungal culture medium is used for culturing for 3d at 27-28 ℃ by Ma Dingshi-Bengal culture medium, the actinomycetes are used for culturing for 6d at 27-28 ℃ by using Gao's first culture medium, the colony count of each type of strain is recorded, and the colony count (cfu) of each gram of dry soil is calculated according to the soil moisture content.

The soil enzyme activity is determined by adopting a sodium phenolate colorimetric method, the catalase activity is determined by adopting a potassium permanganate titration method, the acid phosphatase activity is determined by adopting a kit method, and the sucrase activity is determined by adopting a nitrosalicylic acid method.

TABLE 7 results of soil microbial and enzymatic Activity tests

As can be seen from the data in Table 7, the soil conditioner prepared in examples 1-3 of the present invention was significantly higher in both soil microbial index and soil enzyme activity index than those of comparative examples 1-10 and the blank. And the formula composition of the biochar, the red mud, the activating agent and the microbial agent is changed, and the soil microbial index and the soil enzyme activity index are reduced. Soil microorganisms participate in numerous biochemical processes of the soil, including degradation of organic residues, conversion of organic matter, mineralization and fixation of nutrients, and formation and stabilization of soil aggregates, while also storing soil nutrients, providing available nutrients for plant growth. Bacteria play an important role in the process of converting soil organic matters and inorganic matters, and fungi play a great role in the process of circulating soil carbon and energy sources. After the porous structure of the medium modified biochar and the particle structure of the modified red mud are used in a composite mode, the porous structure is loose, the specific surface area and the pore distribution are large, soluble organic matters, gas, soil nutrients and moisture can be adsorbed, and a good environment is provided for aggregation, growth and propagation of various microorganisms. On the other hand, the soil conditioner is rich in carbon, energy and mineral nutrients, and provides raw materials for the growth of microorganisms after being degraded, so that the growth of specific microorganisms is promoted and the microbial community structure is changed. The soil conditioner disclosed by the invention has the advantages that after being applied to soil, the multiple components are synergistic, the ventilation condition of the soil can be obviously improved, the formation of soil aggregates is promoted, and the gas and moisture conditions of the soil are further improved. The comprehensive performance is that the enzymatic activity of soil is improved, and the number of three groups of microorganisms in the soil is increased. Any component in the biochar-based multifunctional soil conditioner is reduced, and the corresponding effect is disappeared or weakened. Therefore, the biochar-based multifunctional soil conditioner components supplement each other, and are indispensable.

It should be noted that the above-mentioned embodiments are merely some, but not all embodiments of the preferred mode of carrying out the invention. It is evident that all other embodiments obtained by a person skilled in the art without making any inventive effort, based on the above-described embodiments of the invention, shall fall within the scope of protection of the invention.

Claims (4)

1. A biochar-based multi-effect soil conditioner is characterized by being prepared from the following raw materials, by weight, 100-120 parts of modified biochar, 10-20 parts of microbial agents, 20-30 parts of modified red mud, 20-30 parts of diatomite, 80-100 parts of livestock manure and 10-20 parts of activators, wherein the microbial agents comprise Brevibacillus laterosporus, trichoderma koningii and Streptomyces cellulosicus according to a mass ratio of 1:1:1;

Mixing the cleaned plant straw with 0.1mol/L nickel chloride solution according to a solid-liquid ratio of 1g to 50ml, magnetically stirring at room temperature for reaction for 24 hours, centrifuging, drying and grinding into fine powder, calcining the straw powder in a high-temperature furnace, calcining at a high temperature of 500 ℃ for 1 hour, calcining at a temperature of 700 ℃ for 30 minutes, preserving heat for 4 hours, and naturally cooling to room temperature to obtain the modified biochar;

The preparation method of the modified red mud comprises the following steps:

(1) Mixing hydrochloric acid solution and red mud according to a liquid-solid ratio of 10ml to 1g, reacting in an 80 ℃ water bath for 1.5h, washing with deionized water to be neutral, drying at 100 ℃ for 24h, and transferring into a muffle furnace to calcine at 550 ℃ for 6h to obtain acid-treated red mud, wherein the concentration of the hydrochloric acid solution is 1mol/L;

(2) Mixing 1mol/L Cu (NO ₃)₂·3H₂ O solution and acid-treated red mud obtained in the step (1) according to the ratio of 50ml to 1g, magnetically stirring at room temperature for reaction for 24 hours, centrifuging and drying to obtain a solid product, and finally placing the solid product in a muffle furnace for calcining at 550 ℃ for 5 hours, taking out and grinding into 80-mesh powder to obtain modified red mud;

the activator is obtained by mixing 2mol/L zinc chloride solution and 1mol/L phosphoric acid solution according to a volume ratio of 1:1.

2. The biochar-based multifunctional soil conditioner according to claim 1, wherein the bacillus laterosporus has a preservation number of CGMCC No.1.15087 and is selected from China general microbiological preservation center, a preservation date of 2015, 2 months and 15 days, the trichoderma koningii has a preservation number of CGMCC No.3.17875 and is selected from China general microbiological preservation center, a preservation date of 2015, 12 months and 15 days, and the streptomyces cellulosus has a preservation number of CGMCC No.4.6365 and is selected from China general microbiological preservation center, and a preservation date of 2008, 9 months and 3 days.

3. The charcoal-based multifunctional soil conditioner according to claim 1, wherein the microbial agent is prepared by respectively inoculating Brevibacillus laterosporus, trichoderma koningii and Streptomyces cellulosae into sterilized beef extract peptone culture medium 500mL shake flask, performing shake culture at 37 ℃ and 250 r/min for 24 and h to obtain bacterial suspensions respectively, and mixing the bacterial suspensions according to a mass ratio of 1:1:1 to obtain the microbial agent.

4. A method of preparing a biochar-based multi-effect soil conditioner according to any one of claims 1 to 3, comprising the steps of:

(1) Preparing a microbial agent;

(2) Preparing modified biochar;

(3) Preparing modified red mud;

(4) Uniformly mixing the modified biochar obtained in the step (2) with deionized water with the volume of 2 times, adding an activating agent into the mixture, stirring the mixture at room temperature for reaction for 24 hours, filtering to obtain filter residues, washing the filter residues with deionized water to be neutral, and drying the filter residues in an oven at 80 ℃ to obtain the activated biochar;

(5) Uniformly mixing livestock manure, diatomite and modified red mud according to parts by weight, adding water to enable the water content to be 50%, adding the prepared microbial agent into the mixture, uniformly stirring, composting and fermenting, controlling the temperature of a piled body to be not higher than 55 ℃ through turning over the fertilizer, continuously fermenting for 10 days, adding the activated biochar obtained in the step (4), uniformly stirring, continuously fermenting for 12 hours, drying and crushing a fermentation product after the fermentation is finished, and granulating into 4-5mm particles by using a granulator to obtain the biochar-based multifunctional soil conditioner.