Acid modified carbon-based fertilizer synergist for improving saline-alkali soil and preparation method of acid modified carbon-based fertilizer synergist

Abstract

The invention discloses an acid-modified carbon-based fertilizer synergist for improving saline-alkali soil and a preparation method thereof, and the acid-modified carbon-based fertilizer synergist for improving saline-alkali soil comprises the following raw materials in parts by weight: 65-80 parts of acid-modified biomass charcoal, 10-15 parts of a microbial agent, 5-10 parts of organic acid, 3-6 parts of an inhibitor and 2-4 parts of a binder. Wherein the pH (Potential of Hydrogen) of the acid modified biomass charcoal is 4.5 to 6.5. According to the acid-modified carbon-based fertilizer synergist for improving the saline-alkali soil, the fertilizer efficiency of nitrogen, phosphorus, potassium and other fertilizers can be enhanced, the physicochemical properties of saline-alkali soil are improved, and absorption of plants to nutrients in the soil is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of soil improvement, and in particular to an acid-modified carbon-based fertilizer synergist for improving saline-alkali land and a preparation method thereof. Background Art

[0002] my country's saline-alkali land is widely distributed and has great potential for development and utilization. It is an important reserve land resource. The comprehensive utilization of saline-alkali land has become a strategic issue to ensure national food security. At present, under the huge pressure of food demand, there are widespread phenomena such as large fertilizer input and unbalanced nutrient ratios, which not only lead to low fertilizer utilization and serious fertilizer losses, but also lead to bottleneck problems such as soil compaction, surface salt accumulation, microbial flora disorder, and continuous decline in fertility of the cultivated layer of soil in saline-alkali land, which seriously restrict the improvement of food production capacity. Therefore, scientific regulation of saline-alkali land improvement and increase in production and efficiency is imminent, which is of great significance for increasing reserve arable land resources, ecological and environmental safety, ensuring arable land safety, and stabilizing food production.

[0003] In order to comply with the country's requirements for improving fertilizer utilization and developing modern agriculture, the development of fertilizer enhancers has received more and more attention from agricultural researchers around the world. Fertilizer enhancers are a type of active substance that aims to increase nutrient effectiveness. They can activate nitrogen, phosphorus, and potassium in the soil, promote the absorption of nutrients in the soil by crop roots, and meet the nutrient needs of crops. At present, different types of fertilizer enhancers have emerged in the market. Most of them are aimed at improving fertilizer utilization and crop yields. However, due to the main constraints such as low nutrient utilization rate of saline-alkali soil, repeated secondary salinization, poor water permeability and air permeability, there is still a lack of effective, low-cost and environmentally friendly multifunctional fertilizer enhancers for saline-alkali land. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the present invention is to provide an acid-modified carbon-based fertilizer synergist for improving saline-alkali land, which can enhance the fertilizer efficiency of fertilizers such as nitrogen, phosphorus and potassium, improve the physical and chemical properties of saline-alkali soil, and promote plants to absorb nutrients in the soil.

[0005] Another object of the present invention is to provide a method for preparing an acid-modified carbon-based fertilizer synergist for improving saline-alkali land.

[0006] According to the first embodiment of the present invention, the acid-modified carbon-based fertilizer synergist for improving saline-alkali land includes raw materials and their weight portions as follows: 65-80 parts of acid-modified biochar, 10-15 parts of microbial agents, 5-10 parts of organic acids, 3-6 parts of inhibitors and 2-4 parts of binders, wherein the pH of the acid-modified biochar is 4.5-6.5.

[0007] According to the acid-modified carbon-based fertilizer synergist for improving saline-alkali land according to the specific embodiment of the present invention, acidified modified biochar is used as a synergistic carrier, and is combined with raw materials such as microbial agents, biostimulants and inhibitors to obtain a multifunctional acid-modified carbon-based fertilizer synergist for improving saline-alkali land. Among them, the acid-modified biochar has a large specific surface area and strong adsorption performance and is acidic. Thereby, the specific surface area of ​​the biochar can be significantly improved and the negative charge density can be increased, which can play a strong fertilizer synergistic role. The addition of microbial agents can gradually release microorganisms into saline-alkali soil, improve microbial activity and repair ability, improve soil nutrient effectiveness, and improve the structure of sudden microbial community outbreaks. In this way, the synergist of the present invention can further regulate the physical and chemical properties of the soil.

[0008] According to some embodiments of the present invention, the raw material of the acid-modified biochar includes at least one of rice straw, corn straw, wheat straw, rice husk, corn cob, peanut shell, tree stump and sawdust.

[0009] According to some embodiments of the present invention, the microbial agent includes at least one of Bacillus subtilis ACCC 11025, Bacillus gelatinosarum ACCC10013, Bacillus megaterium FBs03ACCC10011 and Rhizobium oryzae ACCC60121.

[0010] According to some embodiments of the present invention, the organic acid includes at least one of alginic acid, fulvic acid and gamma-aminobutyric acid.

[0011] According to some embodiments of the present invention, the inhibitor includes a urease inhibitor and a nitrification inhibitor; further, a weight ratio of the urease inhibitor to the nitrification inhibitor is 1:0.5-3.

[0012] According to some embodiments of the present invention, the binder is acidic bentonite; and / or the pH value of the binder is 5-6.

[0013] According to an embodiment of the second aspect of the present invention, there is provided a method for preparing the acid-modified carbon-based fertilizer synergist for improving saline-alkali land according to an embodiment of the first aspect of the present invention, comprising the following steps:

[0014] Step 1, preparing acid-modified biochar, drying and crushing the raw materials of the acid-modified biochar, and then adding the powder into a mixed solution A obtained by mixing concentrated sulfuric acid and concentrated nitric acid for immersion treatment, pyrolysis, and carbonization, and then obtaining the acid-modified biochar;

[0015] Step 2: Divide the acid-modified biochar obtained in step 1 into two parts, and evenly mix one part of the acid-modified biochar with the microbial agent and the binder in a weight ratio of 1-1.5:8:0.5-1 to obtain a mixture B; and mix the other part of the acid-modified biochar with the organic acid, the inhibitor and the leavening agent in a weight ratio of 80-100:10-15:3-7:3-7 to obtain a mixture C;

[0016] Step 3: Evenly mix the mixture B and the mixture C obtained in step 2, add the remaining amount of binder, dry, and sieve to obtain the acid-modified carbon-based fertilizer synergist for improving saline-alkali land.

[0017] According to some embodiments of the present invention, the moisture content of the raw material of the acid-modified biochar after drying in step 1 is less than 10%.

[0018] According to some embodiments of the present invention, in step 1, the mixed solution A is a mixture of 65% concentrated nitric acid and 98% concentrated sulfuric acid in a volume ratio of 1:1 to 3, and diluted to obtain a concentration of 20% to 40% of the initial mixed solution concentration after dilution; and / or the solid-liquid ratio of the powder and the mixed solution A is: 0.5g to 1.5g: 20ml; and / or the immersion treatment time is 24 to 48 hours.

[0019] According to some embodiments of the present invention, the pyrolysis in step 1 is to place the impregnated liquid into a pyrolysis material bin, heat the material bin to 100-150° C., and keep it warm for 30-40 minutes; and / or

[0020] The carbonization is to feed the pyrolyzed mixture into a carbonization furnace, raise the temperature to 250-300°C, maintain the temperature for 10-15 minutes, then raise the temperature to 500°C at 8-12°C / min, and maintain the temperature for 2-4 hours, then rapidly cool to 100-150°C within 5-8 minutes, maintain the temperature for 0.5-1.5 hours, so that the material is fully carbonized and then naturally cooled to obtain the acid-modified biochar.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 is the scanning electron microscope image of the unmodified biochar;

[0024] Figure 2 This is a scanning electron microscope image of biochar modified with 30% H2SO4;

[0025] Figure 3 This is a scanning electron microscope image of biochar modified with 30% HNO3;

[0026] Figure 4 Scanning electron microscope image and energy spectrum of biochar modified by 30% HNO3+H2SO4 mixed solution (65% concentrated nitric acid and 98% concentrated sulfuric acid are mixed in a volume ratio of 1:2 and the concentration is diluted to 30% of the initial mixed concentration);

[0027] Figure 5 is the energy spectrum of unmodified biochar;

[0028] Figure 6 The energy spectrum of biochar modified by 30% H2SO4;

[0029] Figure 7 The energy spectrum of biochar modified with 30% HNO3;

[0030] Figure 8 Energy spectrum of biochar modified by 30% HNO3+H2SO4 mixed solution (65% concentrated nitric acid and 98% concentrated sulfuric acid are mixed in a volume ratio of 1:2 and then the concentration is diluted to 30% of the initial mixed concentration). DETAILED DESCRIPTION

[0031] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The acid-modified carbon-based fertilizer synergist for improving saline-alkali land according to the first aspect of the present invention is specifically described below. The raw materials and their weight parts are as follows: 65-80 parts of acid-modified biochar, 10-15 parts of microbial agents, 5-10 parts of organic acids, 3-6 parts of inhibitors and 2-4 parts of binders. First of all, biochar has the properties of improving soil physical and chemical properties, increasing soil aeration, improving soil water holding capacity, and fixing mineral nutrients, while also promoting the absorption and utilization of soil nutrients by plants. Applying biochar in the soil can effectively reduce soil nutrient leaching and improve soil fertility through adsorption. Furthermore, the acid-modified biochar has a large specific surface area and strong adsorption performance and is acidic, so that the specific surface area of ​​the biochar can be significantly increased and the negative charge density can be increased, thereby playing a strong fertilizer synergistic role. Specifically, acid-modified biochar is obtained by acidifying biochar. Acid-modified biochar is acidic, has a large number of oxygen-containing functional groups on the surface, a large specific surface area, more adsorption sites and stronger adsorption performance. In this way, it has a regulating effect on the physical and chemical properties of saline-alkali soil. For example, it can enhance the absorption of saline-alkali soil to Na + The adsorption performance of Figure 1-Figure 8The functional groups and atomic energies of the surface of biomass carbon before and after modification have significant changes. Figure 1-Figure 4 ,like Figure 1 , the surface of unmodified biochar has a uniform pore structure and a flaky porous structure; Figure 2 , the surface pores of biochar modified with 30% H2SO4 are larger and more uniform; Figure 3 , the surface pores of 30% HNO3 biochar are small; the surface pores of biochar modified by 30% HNO3 and H2SO4 mixture (65% concentrated nitric acid and 98% concentrated sulfuric acid are mixed in a volume ratio of 1:2 and then diluted to 30% of the initial mixed concentration) are irregular in shape and have sharp edges. However, the carbon frame morphology of biochar has basically not changed after acid modification and before modification. Combined with Figure 5-Figure 8 , EDS analysis of biochar surface showed that all biochars were mainly composed of C and O elements, and contained other small amounts of mineral elements (combined with Figure 5-Figure 8 and Table 1). Compared with the unmodified biochar, the proportion of O in the acid-modified biochar increased, while the proportion of C decreased. The proportions of sulfur (S) and oxygen (O) in the modified biochar modified by 30% H2SO4 and 30% HNO3+H2SO4 mixed solution (65% concentrated nitric acid and 98% concentrated sulfuric acid were mixed in a volume ratio of 1:2 and diluted to 30% of the initial mixed concentration) were higher than those in other biochars.

[0032] At the same time, biomass charcoal can come from straw, rice husk, etc., achieving the effect of recycling plant straw waste. In addition, the addition of microbial agents can gradually release microorganisms into saline-alkali soil, improve the activity and repair ability of microorganisms in the soil, improve the effectiveness of soil nutrients, and improve the structure of soil microbial communities. This plays a role in further regulating the physical and chemical properties of the soil.

[0033] Table 1 Surface energy spectrum analysis of different biochars

[0034]

[0035]

[0036] Among them, the pH of the acid-modified biochar is 4.5-6.5. In this way, if the pH is less than 4.5, the acidity of the acid-modified biochar is too strong, and the acidification effect on the soil is too strong, which is not conducive to improving the physical and chemical properties of the soil, and the active groups on the surface of the acid-modified biochar are not conducive to the loading of other components on the acid-modified biochar, thereby affecting the effect of the synergist. If the pH is greater than 6.5, the acidity of the acid-modified biochar is weak, and it may not play a role in acidifying the soil, which is not conducive to improving the physical and chemical properties of the soil. The specific surface area of ​​the acid-modified biochar is small, and the surface oxygen-containing functional groups are less, which is not conducive to the loading of other components on the acid-modified biochar, thereby affecting the effect of the synergist. By setting the pH of the acid-modified biochar to 4.5-6.5, the acidity of the acid-modified biochar is appropriate, which can improve the physical and chemical properties of the soil and has a strong synergistic effect on fertilizers.

[0037] According to the specific embodiment of the present invention, the acid-modified carbon-based fertilizer synergist for improving saline-alkali land uses acidified modified biochar as a synergist carrier, combined with raw materials such as microbial agents, biostimulants and inhibitors, to obtain a multifunctional acid-modified carbon-based fertilizer synergist for improving saline-alkali land. Among them, the acid-modified biochar has a large specific surface area and strong adsorption performance and is acidic. This can significantly increase the specific surface area of ​​the biochar and increase the negative charge density, enhancing the absorption of Na + The addition of microbial agents can improve the activity and repair ability of saline-alkali soil microorganisms, improve the effectiveness of soil nutrients, and improve the structure of sudden microbial communities. In this way, the synergist of the present invention can further regulate the physical and chemical properties of the soil.

[0038] According to some embodiments of the present invention, the raw material of the acid-modified biochar includes at least one of rice straw, corn straw, wheat straw, rice husk, corn cob, peanut shell, tree stump and sawdust. With such an arrangement, the source of biochar is wide. Using straw as a synergist can not only realize the return of straw to the field, but also adjust the physical and chemical properties of the soil.

[0039] According to some embodiments of the present invention, the microbial agent includes at least one of Bacillus subtilis ACCC 11025, Bacillus jelly ACCC10013, Bacillus megaterium FBs03ACCC10011 and Rhizobium oryzihabitans M15 ACCC60121. Preferably, the microbial agent includes Bacillus subtilis ACCC11025, Bacillus jelly ACCC10013, Bacillus megaterium FBs03ACCC10011 and Rhizobium oryzihabitans M15 ACCC60121 in equal weight ratios. In this way, the microbial agent has diversity, can improve the diversity of microorganisms in the soil, and improve the stability of the repair effect. Microbial agents can effectively supplement beneficial bacteria in the soil. The reproduction of beneficial bacteria can effectively regulate the structure of soil flora, inhibit the reproduction and growth of harmful bacteria, and reduce soil-borne diseases. Through the biological action of microorganisms, phosphorus and potassium elements solidified in the soil can be effectively released to improve the utilization rate of phosphorus and potassium fertilizers. Microorganisms are conducive to the formation of granular structure, alleviate soil compaction, and repair soil. Among them, the effective viable count (cfu) of each microbial agent is not less than 200 million / g, and a single group is not less than 10,000.

[0040] According to other embodiments of the present invention, the organic acid includes at least one of alginic acid, fulvic acid and γ-aminobutyric acid. In this way, the synergist can increase the accumulation of dry matter of plant species and the growth rate of plants under saline-alkali conditions, and can also take into account the reduction of saline-alkali stress in saline-alkali soil and the regulation of soil physical and chemical properties. The source of the organic acid can be plant-extracted or natural.

[0041] According to some embodiments of the present invention, the inhibitor includes a urease inhibitor and a nitrification inhibitor. In this way, the urease inhibitor and the nitrification inhibitor can be used together to effectively inhibit urea hydrolysis, reduce nitrogen loss caused by rapid urea hydrolysis, play a good slow release and controlled release role, and effectively improve the utilization rate of nitrogen fertilizer.

[0042] According to other embodiments of the present invention, the weight ratio of the urease inhibitor to the nitrification inhibitor is 1:0.5 to 3. Preferably, it is 1:2. In this way, the ratio of the urease inhibitor to the nitrification inhibitor is moderate, which can better synergize and enhance the utilization rate of nitrogen fertilizer.

[0043] According to some embodiments of the present invention, the binder is acidic bentonite. Using acidic bentonite as a binder can promote the molding of the synergist on the one hand, and is conducive to adjusting the pH value of the synergist on the other hand.

[0044] According to other embodiments of the present invention, the pH value of the binder is 5 to 6. In this way, the pH value of the binder is equivalent to the pH value of the acid-modified biochar, which is conducive to promoting the loading effect of the acid-modified biochar on other components.

[0045] According to an embodiment of the second aspect of the present invention, the present invention provides a method for preparing an acid-modified carbon-based fertilizer synergist for improving saline-alkali land according to an embodiment of the first aspect of the present invention, comprising the following steps:

[0046] Step 1, prepare acid-modified biochar, dry and crush the raw materials of acid-modified biochar, then add the powder to the mixed solution A obtained by mixing concentrated sulfuric acid and concentrated nitric acid, immerse, pyrolyze, and carbonize, and then obtain acid-modified biochar. In this way, the mixed solution A obtained by mixing concentrated sulfuric acid and concentrated nitric acid is used to immerse the raw materials of biochar, and then the acid-modified biochar is obtained by pyrolysis and carbonization. On the one hand, the pH value of biochar is reduced, so that the modified biochar is acidic, which has a certain regulating effect on the physical and chemical properties of saline-alkali soil. For example, the adsorption performance of Na+ in saline-alkali soil is enhanced, the soil conductivity and pH value are reduced, the salt content is reduced, and the effect of recycling plant straw waste is achieved at the same time. On the other hand, the specific surface area of ​​biochar can be increased and a large number of oxygen-containing groups can be introduced on the surface of biochar. In this way, the acid-modified biochar can have a large specific surface area and strong adsorption performance, as other components of the reaction site loading synergist, so as to play a synergistic role.

[0047] Step 2: The acid-modified biochar obtained in step 1 is divided into two parts, one part of the acid-modified biochar is mixed with the microbial agent and the binder at a weight ratio of 1-1.5:8:0.5-1 to obtain a mixture B; the other part of the acid-modified biochar is mixed with the organic acid, the inhibitor and the leavening agent at a weight ratio of 80-100:10-15:3-7:3-7 to obtain a mixture C. In this way, the microbial agent is loaded on part of the acid-modified biochar, and the organic acid and the inhibitor are loaded on the other part of the acid-modified biochar, so that the microbial agent, the organic acid and the inhibitor are fully loaded respectively, thereby ensuring the effect of the synergist.

[0048] Step 3: Evenly mix the mixture B and the mixture C obtained in step 2, add the remaining amount of binder, dry, and sieve to obtain an acid-modified carbon-based fertilizer synergist for improving saline-alkali land. Such an arrangement promotes the granulation and molding of the synergist, and facilitates the storage, transportation and application of the synergist. Optionally, the drying temperature is 60°C to 70°C. Optionally, the sieving is to pass through a 10-30 mesh sieve, and take the material under the sieve.

[0049] According to the preparation method of a specific embodiment of the present invention, the raw material of biochar is impregnated with a mixed solution A obtained by mixing concentrated sulfuric acid and concentrated nitric acid, and then the acid-modified biochar is obtained by pyrolysis and carbonization. On the one hand, the pH value of the biochar is reduced, making the modified biochar acidic, which has a certain regulating effect on the physical and chemical properties of saline-alkali soil. And the adsorption performance of the acid-modified biochar is improved, which is conducive to improving the synergistic effect of the synergist. On the other hand, the organic acid and the inhibitor are loaded with another part of the acid-modified biochar, so that the microbial agent, the organic acid and the inhibitor are fully loaded respectively, thereby ensuring the effect of the synergist.

[0050] According to some embodiments of the present invention, the moisture content of the raw material of the acid-modified biochar after drying in step 1 is less than 10%. In this way, the raw material of the acid-modified biochar has a low moisture content, which can ensure the effect of acidification modification.

[0051] According to some embodiments of the present invention, the mixed solution of concentrated sulfuric acid and concentrated nitric acid in step 1 is mixed solution A, which is 65% concentrated nitric acid and 98% concentrated sulfuric acid mixed and diluted in a volume ratio of 1:1 to 3, and the concentration after dilution is 20% to 40% of the initial mixed solution concentration. In this way, 65% concentrated nitric acid and 98% concentrated sulfuric acid are mixed to ensure that the acid solution has sufficient acidity and certain oxidation properties, so that the acid-modified biochar is acidic, and the specific surface area of ​​the acid-modified biochar is increased, and the active sites on the surface of the acid-modified biochar are increased, so that the acid-modified biochar has a suitable pH value and has strong adsorption properties. Further, 65% concentrated nitric acid and 98% concentrated sulfuric acid are mixed in a volume ratio of 1:1 to 3. If the volume ratio of 65% concentrated nitric acid and 98% concentrated sulfuric acid is less than 1:3, the proportion of 98% concentrated sulfuric acid in the mixed solution A is relatively large, the oxidation property of the mixed solution A is relatively strong, and the biochar raw material is easily carbonized and burned, resulting in the deterioration of the biochar raw material. If the volume ratio of 65% concentrated nitric acid and 98% concentrated sulfuric acid is greater than 1:1, the proportion of 65% concentrated nitric acid in the mixed solution A is large, the oxidation performance of the mixed solution A is weak, the number of oxygen-containing functional groups on the surface of biochar is small, and the negative charge density is small, which may lead to poor adsorption performance of the acidified modified biochar. By setting the volume ratio of 65% concentrated nitric acid and 98% concentrated sulfuric acid to be mixed and diluted at 1:1-3, the concentration obtained after dilution is 20%-40% of the initial mixed solution concentration, the proportion of A concentration of 65% concentrated nitric acid and 98% concentrated sulfuric acid in the mixed solution is appropriate, the pH value of the obtained acidified modified biochar is appropriate, and the adsorption performance is strong.

[0052] According to some embodiments of the present invention, the solid-liquid ratio of the powder to the mixed liquid A is 0.5 g to 1.5 g: 20 ml. In this way, the solid-liquid ratio of the powder to the mixed liquid A is appropriate, which is convenient for sufficient impregnation of the powder.

[0053] According to some embodiments of the present invention, the impregnation treatment time is 24 to 48 hours. In this way, the impregnation time is appropriate, which is convenient for fully acidifying and modifying the biochar raw material to obtain acid-modified biochar with a suitable pH and more oxygen-containing functional groups. Optionally, the acidification and impregnation process is carried out at room temperature (20 to 30°C).

[0054] According to some embodiments of the present invention, the first step of pyrolysis is to place the impregnated liquid into a pyrolysis material bin, heat the bin to 100-150°C, and keep it warm for 30-40 minutes. This arrangement ensures that the raw materials of biochar can fully undergo pyrolysis reaction in the pyrolysis material bin. In order to improve the utilization rate of the pyrolysis material bin, the filling rate of the liquid in the pyrolysis material bin is generally greater than 80%. Furthermore, during the pyrolysis process, the water vapor generated by the pyrolysis can be used to fully discharge the residual air in the bin to avoid the generation of odor caused by the fermentation of the gas in the pyrolysis material bin.

[0055] According to some embodiments of the present invention, carbonization is to feed the pyrolyzed mixture into a carbonization furnace, raise the temperature to 250-300°C, maintain the temperature for 10-15 minutes, then raise the temperature to 500°C at 8-12°C / min, and maintain the temperature for 2-4 hours, then rapidly cool to 100-150°C within 5-8 minutes, maintain the temperature for 0.5-1.5 hours, and allow the material to fully complete carbonization and then cool naturally to obtain acid-modified biochar. In this way, by strictly controlling the temperature and duration of the carbonization process, it is ensured that the pyrolyzed biochar raw material can be fully carbonized.

[0056] Specific exemplary embodiments

[0057] The technical solution of the present invention is further described below in conjunction with specific exemplary embodiments, but is not limited thereto. All raw materials are commercially available products unless otherwise indicated by special sources.

[0058] Example 1

[0059] An acid-modified carbon-based fertilizer synergist for improving saline-alkali land comprises raw materials and their weight parts are as follows: 65 parts of acid-modified biochar, 10 parts of microbial agents, 5 parts of organic acids, 3 parts of inhibitors and 2 parts of binders, wherein the pH of the acid-modified biochar is 4.5.

[0060] The raw materials of the acid-modified biochar include rice straw, corn straw, wheat straw and rice husk, which are mixed in equal weight ratios;

[0061] The microbial agent includes Bacillus subtilis, Bacillus jelly, Bacillus megaterium FBs03 and Rhizobium oryzihabitans M15 mixed in equal weight ratios. The effective viable count (cfu) of each microbial agent is not less than 200 million / g, and a single group is not less than white ten thousand grade;

[0062] The organic acid is alginic acid extracted from plants; the inhibitors include urease inhibitors and nitrification inhibitors; and the weight ratio of the urease inhibitor to the nitrification inhibitor is 1:2.

[0063] The binder is acidic bentonite, and the pH value of the binder is 5.

[0064] The preparation method thereof comprises the following steps:

[0065] Step 1, preparing acid-modified biochar, drying the raw material of the acid-modified biochar at 80°C for 2h, wherein the moisture content of the raw material of the acid-modified biochar after drying is less than 10%; crushing the raw material to a size of 2mm, and then adding the powder to a mixed solution A obtained by mixing concentrated sulfuric acid and concentrated nitric acid for immersion treatment, pyrolysis, and carbonization, and then obtaining acid-modified biochar;

[0066] Step 2: The acid-modified biochar obtained in step 1 is divided into two parts, one part of the acid-modified biochar is mixed with a microbial agent and a binder at a weight ratio of 1:8:0.5 to obtain a mixture B; the other part of the acid-modified biochar is mixed with an organic acid, an inhibitor and a leavening agent at a weight ratio of 80:10:3:3 to obtain a mixture C;

[0067] Step 3: Evenly mix the mixture B and the mixture C obtained in step 2, add the remaining amount of the binder, dry at 60° C., and pass through a 10-mesh sieve to obtain an acid-modified carbon-based fertilizer synergist for improving saline-alkali land.

[0068] In step 1, the mixed solution of concentrated sulfuric acid and concentrated nitric acid in step 1 is a mixture of 65% concentrated nitric acid and 98% concentrated sulfuric acid in a volume ratio of 1:1, and the concentration is diluted to 30% of the initial concentration; the solid-liquid ratio of the powder and the mixed solution A is: 0.5g:20ml; the immersion treatment time is 24 hours;

[0069] In step 1, pyrolysis is to put the impregnated liquid into a pyrolysis material bin, heat the bin to 100°C, and keep it warm for 30 minutes; in step 1, carbonization is to put the pyrolyzed mixture into a carbonization furnace, heat it to 250°C, keep the temperature for 10 minutes, then heat it to 500°C at a rate of 10°C / min, keep the temperature for 2 hours, then rapidly cool it to 100°C within 5 minutes, keep the temperature for 1 hour, so that the material is fully carbonized and then naturally cooled to obtain acid-modified biochar.

[0070] Example 2

[0071] An acid-modified carbon-based fertilizer synergist for improving saline-alkali land comprises raw materials and their weight proportions are as follows: 70 parts of acid-modified biochar, 12 parts of microbial agents, 8 parts of organic acid, 4.5 parts of inhibitors and 3 parts of binders, wherein the pH of the acid-modified biochar is 5.5.

[0072] Among them, the raw materials of acid-modified biochar include a mixture of rice straw, corn straw and wheat straw, and the three are mixed in equal weight ratios; the microbial agents include Bacillus subtilis, Bacillus gelatinous, Bacillus megaterium FBs03 and Rhizobium oryzihabitans M15, which are mixed in equal weight ratios, wherein the effective viable count (cfu) of each agent is not less than 200 million / g, and a single group is not less than 10,000 level; the organic acid is natural γ-aminobutyric acid; the inhibitors include urease inhibitors and nitrification inhibitors; the weight ratio of urease inhibitors to nitrification inhibitors is 1:2; the binder is acidic bentonite, and the pH value of the binder is 5.5.

[0073] The preparation method thereof comprises the following steps:

[0074] Step 1: prepare acid-modified biochar, dry the raw material of acid-modified biochar at 100°C for 1h, and the moisture content of the raw material of acid-modified biochar after drying is less than 10%; crush to 0.8mm, and then add the powder to a mixed solution A obtained by mixing concentrated sulfuric acid and concentrated nitric acid, immerse, pyrolyze, and carbonize, and then obtain acid-modified biochar (such as Figure 4 and Figure 8 shown);

[0075] Step 2: The acid-modified biochar obtained in step 1 is divided into two parts, one part of the acid-modified biochar is mixed with a microbial agent and a binder at a weight ratio of 1.2:8:0.7 to obtain a mixture B; the other part of the acid-modified biochar is mixed with an organic acid, an inhibitor and a leavening agent at a weight ratio of 90:12:5:5 to obtain a mixture C;

[0076] Step 3: Evenly mix the mixture B and the mixture C obtained in step 2, add the remaining amount of binder, dry at 65° C., and pass through a 20-mesh sieve to obtain an acid-modified carbon-based fertilizer synergist (such as) for improving saline-alkali land.

[0077] In step 1, the mixed solution of concentrated sulfuric acid and concentrated nitric acid in step 1 is 65% concentrated nitric acid and 98% concentrated sulfuric acid mixed in a volume ratio of 1:2, and the concentration is diluted to 30% of the initial mixed solution concentration; the solid-liquid ratio of the powder and the mixed solution A is 1g:20ml; the immersion treatment time is 36 hours;

[0078] In step 1, pyrolysis is to put the impregnated liquid into a pyrolysis material bin, heat the material bin to 120°C, and keep it warm for 35 minutes; in step 1, carbonization is to put the pyrolyzed mixture into a carbonization furnace, heat it to 270°C, keep the temperature for 12 minutes, then heat it to 500°C at a rate of 10°C / min, keep the temperature for 3 hours, then rapidly cool it to 120°C within 7 minutes, keep the temperature for 1 hour, allow the material to fully complete carbonization and then cool it naturally to obtain acid-modified biochar.

[0079] Example 3

[0080] An acid-modified carbon-based fertilizer synergist for improving saline-alkali land, comprising raw materials and their weight parts as follows: 80 parts of acid-modified biochar, 15 parts of microbial agent, 10 parts of organic acid, 6 parts of inhibitor and 4 parts of binder,

[0081] Among them, the pH of the acid-modified biochar is 6.5.

[0082] The raw materials of acid-modified biochar include rice husk, corn cob and peanut shell, which are mixed in equal weight ratio;

[0083] The microbial agent includes Bacillus subtilis, Bacillus gelatinus, Bacillus megaterium FBs03 and Rhizobium oryzihabitans M15 in a weight ratio. The effective viable bacteria count (cfu) of each agent is not less than 200 million / g, and the single group is not less than the white ten thousand level; the organic acid is natural fulvic acid; the inhibitor includes urease inhibitor and nitrification inhibitor; the weight ratio of urease inhibitor to nitrification inhibitor is 1:2; the binder is acidic bentonite, and the pH value of the binder is 6.

[0084] The preparation method thereof comprises the following steps:

[0085] Step 1, preparing acid-modified biochar, drying the raw material of the acid-modified biochar at 90° C. for 1.5 hours, wherein the moisture content of the raw material of the acid-modified biochar after drying is less than 10%; crushing, and then adding the powder to a mixed solution A obtained by mixing concentrated sulfuric acid and concentrated nitric acid for immersion treatment, pyrolysis, and carbonization, and then obtaining acid-modified biochar;

[0086] Step 2: The acid-modified biochar obtained in step 1 is divided into two parts, one part of the acid-modified biochar is mixed with a microbial agent and a binder at a weight ratio of 1.5:8:1 to obtain a mixture B; the other part of the acid-modified biochar is mixed with an organic acid, an inhibitor and a leavening agent at a weight ratio of 100:15:7:7 to obtain a mixture C;

[0087] Step 3: Evenly mix the mixture B and the mixture C obtained in step 2, add the remaining amount of binder, dry at 70° C., and pass through a 30-mesh sieve to obtain an acid-modified carbon-based fertilizer synergist for improving saline-alkali land.

[0088] In step 1, the mixed solution of concentrated sulfuric acid and concentrated nitric acid is a mixture of 65% concentrated nitric acid and 98% concentrated sulfuric acid in a volume ratio of 1:3, and the concentration is diluted to 30% of the initial mixed solution concentration; the solid-liquid ratio of the powder and the mixed solution A is 1.5g:20ml; the immersion treatment time is 48 hours;

[0089] In step 1, pyrolysis is to put the impregnated liquid into a pyrolysis material bin, heat the bin to 150°C, and keep it warm for 40 minutes; in step 1, carbonization is to put the pyrolyzed mixture into a carbonization furnace, heat it to 300°C, keep the temperature for 15 minutes, then heat it to 500°C at a rate of 10°C / min, keep the temperature for 4 hours, then rapidly cool it to 150°C within 8 minutes, keep the temperature for 1 hour, allow the material to fully complete carbonization and then cool it naturally to obtain acid-modified biochar.

[0090] Example 4

[0091] Example 4 is substantially the same as Example 2, except that the weight ratio of the urease inhibitor to the nitrification inhibitor is 1:3.

[0092] Example 5

[0093] Example 5 is substantially the same as Example 2, except that the weight ratio of the urease inhibitor to the nitrification inhibitor is 5:1.

[0094] Example 6

[0095] Example 6 is basically the same as Example 2, except that the mixed solution A is replaced by 30% concentrated nitric acid. Figure 3 and Figure 7 shown.

[0096] Example 7

[0097] Example 7 is basically the same as Example 2, except that the mixed solution A is replaced by 30% concentrated sulfuric acid. Figure 2 and Figure 6 shown.

[0098] Comparative Example 1

[0099] Comparative Example 1 is substantially the same as Example 2, except that an equal volume of acetic acid is used in the mixed solution A to replace 65% of the concentrated nitric acid.

[0100] Comparative Example 2

[0101] Comparative Example 2 is substantially the same as Example 2, except that an equal amount of unmodified biochar is used to replace the acidified modified biochar.

[0102] Comparative Example 3

[0103] Comparative Example 3 is substantially the same as Example 2, except that the microbial agent does not include Bacillus subtilis.

[0104] Comparative Example 4

[0105] Comparative Example 4 is substantially the same as Example 2, except that no inhibitor is included.

[0106] Field test

[0107] The experiment was carried out in a field plot experiment at the Shandong Dongying Agricultural High-tech Zone Experimental Base (118°34′E, 37°26′N) from May to October 2022 to explore the effects of modified biochar on soil properties and corn yield in mild saline-alkali land. The experiment set up 11 treatments, namely the embodiment group, the comparative group and the control group, arranged in random blocks. The plot area is 60m 2 2m wide protective rows were set between the cells. The corn variety was Zhengdan 958. 40kg / mu of (26-10-12) compound fertilizer (Luxi Chemical) was applied. 10kg / hm of acid-modified carbon-based fertilizer synergist for improving saline-alkali land in each embodiment of the present invention and the comparative example was applied. 2 .

[0108] Yield: Harvest and measure yield, record aboveground biomass and grain yield

[0109] 1. Determination of soil chemical properties:

[0110] 1.1. Soil pH value determination method: water-soil ratio 2.5:1;

[0111] The EC of soil is measured by the water-soil ratio of 5:1;

[0112] The cation exchange capacity (CEC) of soil was determined by sodium acetate-flame photometry;

[0113] Soil organic carbon (SOC) was determined by K2Cr2O7 oxidation-external heating method;

[0114] The total nitrogen in the soil was determined by the semi-micro Kjeldahl method; the available phosphorus was determined by the 0.05 mol / L NaHCO3 solution extraction-UV spectrophotometer colorimetry method; and the available potassium was determined by the ammonium acetate solution extraction-flame photometer method.

[0115] Table 2. Performance test results of soils in field experiments of the embodiments, comparative examples and control group

[0116]

[0117]

[0118] Conclusion: The cation exchange capacity, total carbon and available phosphorus content of the soil in Example 2 increased the most compared with the original soil sample, while the soil pH and conductivity tended to decrease.

[0119] 2. Fertilizer efficiency experiment

[0120] The corn yield and aboveground biomass of each group of embodiments were observed and recorded, and it was found that the corn yield and aboveground biomass corresponding to the embodiment 2 group were the largest. It can be seen that embodiment 2 is more conducive to improving the soil fertility level of saline-alkali land and increasing corn yield.

[0121] Table 3. Yield experiment

[0122]

[0123] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0124] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An acid-modified carbon-based fertilizer synergist for improving saline-alkali land, characterized in that: The raw materials and their weight parts are as follows: 65-80 parts of acid-modified biochar, 10-15 parts of microbial agent, 5-10 parts of organic acid, 3-6 parts of inhibitor and 2-4 parts of binder. Wherein, the pH of the acid-modified biochar is 4.5-6.

5.

2. The acid-modified carbon-based fertilizer synergist for improving saline-alkali land according to claim 1, characterized in that: The raw material of the acid-modified biochar includes at least one of rice straw, corn straw, wheat straw, rice husk, corn cob, peanut shell, tree stump and wood chips.

3. The acid-modified carbon-based fertilizer synergist for improving saline-alkali land according to claim 1, characterized in that: The microbial agent includes at least one of Bacillus subtilis ACCC 11025, Bacillus gelatinus ACCC10013, Bacillus megaterium FBs03ACCC10011 and Rhizobium oryzae ACCC60121.

4. The acid-modified carbon-based fertilizer synergist for improving saline-alkali land according to claim 1, characterized in that: The organic acid includes at least one of alginic acid, fulvic acid and gamma-aminobutyric acid.

5. The acid-modified carbon-based fertilizer synergist for improving saline-alkali land according to claim 1, characterized in that: The inhibitor comprises a urease inhibitor and a nitrification inhibitor; further, the weight ratio of the urease inhibitor to the nitrification inhibitor is 1:0.5-3.

6. The acid-modified carbon-based fertilizer synergist for improving saline-alkali land according to claim 1, characterized in that: The binder is acidic bentonite; and / or The pH value of the binder is 5-6.

7. A method for preparing an acid-modified carbon-based fertilizer synergist for improving saline-alkali land according to any one of claims 1 to 6, characterized in that: The steps include: Step 1, preparing acid-modified biochar, drying and crushing the raw materials of the acid-modified biochar, and then adding the powder into a mixed solution A obtained by mixing concentrated sulfuric acid and concentrated nitric acid for immersion treatment, pyrolysis, and carbonization, and then obtaining the acid-modified biochar; Step 2: Divide the acid-modified biochar obtained in step 1 into two parts, and evenly mix one part of the acid-modified biochar with the microbial agent and the binder in a weight ratio of 1-1.5:8:0.5-1 to obtain a mixture B; and mix the other part of the acid-modified biochar with the organic acid, the inhibitor and the leavening agent in a weight ratio of 80-100:10-15:3-7:3-7 to obtain a mixture C; Step 3: Evenly mix the mixture B and the mixture C obtained in step 2, add the remaining amount of binder, dry, and sieve to obtain the acid-modified carbon-based fertilizer synergist for improving saline-alkali land.

8. The preparation method according to claim 7, characterized in that: The moisture content of the raw material of the acid-modified biochar after drying in step 1 is less than 10%.

9. The preparation method according to claim 7, characterized in that: The mixed solution A in step 1 is a mixture of 65% concentrated nitric acid and 98% concentrated sulfuric acid in a volume ratio of 1:1 to 3, and diluted to a concentration of 20% to 40% of the initial mixed solution concentration after dilution; and / or The solid-liquid ratio of the powder and the mixed liquid A is: 0.5g-1.5g:20ml; and / or The immersion treatment time is 24 to 48 hours.

10. The preparation method according to claim 7, characterized in that: The pyrolysis in step 1 is to place the impregnated liquid into a pyrolysis material bin, heat the bin to 100-150° C., and keep it warm for 30-40 minutes; and / or The carbonization is to feed the pyrolyzed mixture into a carbonization furnace, raise the temperature to 250-300°C, maintain the temperature for 10-15 minutes, then raise the temperature to 500°C at 8-12°C / min, and maintain the temperature for 2-4 hours, then rapidly cool to 100-150°C within 5-8 minutes, maintain the temperature for 0.5-1.5 hours, so that the material is fully carbonized and then naturally cooled to obtain the acid-modified biochar.

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