Biomass charcoal-based composite saline-alkali soil modifier and application thereof

Abstract

The invention discloses a biomass charcoal-based composite saline-alkali soil modifier which is obtained by mixing biomass charcoal and a glomalin extracting solution, oscillating, drying in the shade, and fully and uniformly mixing with monopotassium phosphate, potassium nitrate, potassium humate, algal polysaccharides and starch modified bentonite according to a formula. According to the modifier disclosed by the invention, after the glomalin is loaded on the biomass charcoal, under the supporting action of a carbon skeleton, the glomalin is used as an organic cementing substance for expanding a space, so that the soil agglomeration process is accelerated, the proportion of large aggregates is remarkably increased, and meanwhile, a positive promoting effect on the growth of a soil root system is achieved; the soil structure of a plough layer is improved, saline-alkali obstacles are reduced, and particularly the corn yield increasing effect is remarkable. In addition, the glomalin is loaded on the biomass charcoal, so that the degradation or loss of the glomalin is reduced, the glomalin can be slowly released and synergized under the action of microorganisms, and the application efficiency of the glomalin is improved.

Description

Technical Field

[0001] The present application relates to the technical field of soil remediation, and in particular to a biomass carbon-based composite saline-alkali land conditioner and its application. Background Art

[0002] Driven by economic benefits and in the context of cost saving and efficiency improvement, farmers are accustomed to applying excessive amounts of diammonium phosphate at one time. Especially in semi-arid areas, people are accustomed to using a "one-shot" fertilization management method of corn compound fertilizer. Long-term heavy use and light maintenance have caused serious damage to the soil aggregate structure, reduced soil porosity and permeability, and poor development of crop roots. The evaporation of surface water in the soil causes deep water to continuously move upward through the capillary action of the soil, which in turn causes deep soil salt to accumulate in the surface layer, causing associated secondary salinization. While the soil's water and fertilizer retention performance continues to decline, plant root development is restricted, and water and fertilizer utilization efficiency is reduced, causing unstable or even significantly reduced yields. Therefore, taking effective soil improvement measures is of great practical significance for ecological restoration and reconstruction as well as local economic stability.

[0003] Soil conditioners are important products for improving soil structure, increasing fertility and regulating pH, and are vital to agricultural production. With the popularization of the concept of sustainable agriculture, the demand for environmentally friendly soil conditioners is growing, among which natural source conditioners such as biochar, humic acid and beneficial microbial agents are favored. In the current soil conditioner market, traditional soil conditioners usually promote the cementation properties of soil aggregates by adding humus and organic materials. These substances can provide the energy and nutrients required by soil microorganisms, thereby enhancing microbial activity, promoting the formation of soil organic carbon and improving soil structure. However, these conditioners often lack specificity and cannot directly enhance specific components in the soil that are strongly related to aggregate cement. They have poor durability after application and large amounts can easily lead to reduced economic benefits.

[0004] Glomalin is a special glycoprotein with good thermal stability produced by arbuscular mycorrhizal fungi (AMF). It plays an important role in soil aggregate formation, stability maintenance, soil organic carbon pool increase, plant stress resistance improvement and heavy metal toxicity reduction. Glomalin and its related soil protein (GRSP) play an important role in soil ecosystem, especially in the process of black soil degradation. GRSP has a strong cementing effect on soil particles, and its cementing capacity is 3 to 10 times that of other cementing substances. Its contribution to soil organic carbon is 6.98% to 31.3%, and its turnover time in soil is 6 to 42 years. In addition, GRSP can chelate different heavy metals, reduce their toxic effects in soil and reduce potential toxicity. Straw biochar particles are carbon-rich products obtained by pyrolysis of crop straw (biomass) under conditions of anoxic or limited oxygen supply at relatively low temperatures (<700℃). They have a microporous structure with well-developed pores and a high degree of aromatization. Their elemental composition mainly includes C, H, O, as well as mineral elements such as N, S, P, and K. They have the functions of improving soil, increasing resource utilization efficiency, and alleviating environmental pollution.

[0005] Although glomalin or biochar is also added to the current improvers, these improvers only improve the soil structure, and there is a lack of research on composite conditioners. For example, patent application CN 106167706 A discloses a preparation method and use method of an exogenous easily extractable glomalin soil improver, which uses the extracted glomalin solution to be directly injected into the soil from the rhizosphere of citrus trees. However, the application conditions of this method are limited and require special liquid fertilizer machinery, and the uniformity and depth of fertilization are difficult to control in actual operation, resulting in poor results and poor benefits. Patent application CN116924854 A discloses a cadmium-reducing and selenium-enriched soil conditioner and its preparation method and use method. The raw materials of the soil conditioner include 5-20 parts of glomalin-related soil protein, 35-55 parts of limestone powder or dolomite powder, 30-50 parts of selenium-rich organic fertilizer, 10-25 parts of polyphosphate, and 10-30 parts of nano-hydrated manganese oxide modified biochar; the soil conditioner is prepared by mixing and granulating all raw materials except the glomalin-related soil protein, and spraying the glomalin-related protein solution after the granules are basically formed. This patent application only targets the absorption of cadmium in the soil. The glomalin-related soil protein is directly sprayed on the raw material and is not attached to a carrier with a large surface area and porosity, which easily causes the degradation or loss of the glomalin-related soil protein, which is not conducive to the formation of soil structure and aggregates. Therefore, it is urgent to study a composite functional soil structure conditioner and improvement method that can provide loaded glomalin, accelerate the formation of soil aggregates in a scientifically reasonable carbon-soil particle mixing space, and at the same time improve the stability of soil organic carbon and the production capacity of the soil-crop system. Summary of the invention

[0006] The present invention provides a biomass carbon-based composite saline-alkali land improver, which comprises, by weight: 60-65 parts of biomass carbon loaded with glomalin;

[0007] 2-5 parts of potassium dihydrogen phosphate;

[0008] 2-5 parts potassium nitrate;

[0009] Potassium humate 5-10 parts;

[0010] 1-5 parts of seaweed polysaccharide;

[0011] 5-15 parts of starch modified bentonite;

[0012] Wherein, the biomass charcoal loaded with glomalin is composed of biomass charcoal and glomalin extract in a weight ratio of 8-15:1;

[0013] The content of glomalin in the glomalin extract is 8-23 mg / g;

[0014] Preferably, the improver comprises, by weight:

[0015] 62 parts of biochar loaded with glomalin;

[0016] 2 parts of potassium dihydrogen phosphate;

[0017] 2 parts potassium nitrate;

[0018] Potassium humate 5 parts;

[0019] 1 part of seaweed polysaccharide;

[0020] 5 parts of starch modified bentonite;

[0021] The biomass charcoal loaded with glomalin is composed of biomass charcoal and glomalin extract in a weight ratio of 15:1;

[0022] The content of glomalin in the glomalin extract is 15 mg / g.

[0023] Includes one or more of the following (1)-(9):

[0024] (1) The biochar is corn straw biochar;

[0025] (2) The particle size of the biochar is less than 2 mm;

[0026] (3) The biochar is used after being soaked and cleaned in water;

[0027] (4) The glomalin extract is obtained by colonizing Glomerella mosseae in a substrate for alfalfa cultivation and then extracting the alfalfa rhizosphere soil with sodium citrate;

[0028] (5) The starch-modified bentonite is obtained by dissolving, stirring, drying and grinding dried calcium-based bentonite, hexadecyltrimethylammonium bromide and soluble starch;

[0029] (6) The particle size of the starch-modified bentonite is less than 0.15 mm;

[0030] (7) The seaweed polysaccharide is fucoidan extracted from kelp;

[0031] (8) mixing the biochar with the glomalin extract, shaking for 12 hours, and then drying in the shade to obtain the glomalin-loaded biochar;

[0032] (9) The biomass charcoal loaded with glomalin is fully mixed with potassium dihydrogen phosphate, potassium nitrate, potassium humate, seaweed polysaccharide, and starch-modified bentonite according to the formula to obtain the improver. The mixed material is fully stirred at room temperature to ensure that the fine biomass charcoal particles loaded with glomalin are evenly dispersed with other materials.

[0033] Specifically, the biomass carbon-based composite saline-alkali land improver further comprises one or more of the following (1)-(3):

[0034] (1) The preparation method of the glomalin extract is as follows: the glomalin species and the substrate are inoculated at a mass ratio of 1:200, and the alfalfa planting density is 450-600 plants / m 2 , after 45-60 days of greenhouse planting, remove the above-ground and underground parts of the alfalfa plants, take the alfalfa rhizosphere soil and mix it with 50mM sodium citrate solution at a solid-liquid ratio (g / ml) of 1:5-10, extract at pH 8.0 and 121°C for 60 minutes, extract several times until the extract loses its reddish brown color, mix the extracts and filter to collect the supernatant;

[0035] (2) The preparation method of the starch-modified bentonite is as follows: 10 g of dried calcium-based bentonite, 3.7770 g of hexadecyltrimethylammonium bromide and 1 g of soluble starch are dissolved in 400 ml of distilled water, stirred at a constant temperature of 25° C. for 24 h, filtered, dried, ground, and passed through a 120-mesh sieve to obtain the starch-modified bentonite;

[0036] (3) The biomass charcoal particles are obtained by removing impurities from corn stalks, drying them, and crushing them into raw material particles, which are then carbonized in a carbonization furnace at 400-500°C under oxygen-free or low-oxygen conditions for 1-2 hours, and then crushed and passed through a sieve with a pore size of 2-5 mm after cooling.

[0037] The present invention also provides an application of the aforementioned biomass charcoal-based composite saline-alkali land conditioner in saline-alkali land soil improvement, wherein the conditioner is evenly spread at an amount of 100-500 kg / mu, and then the saline-alkali land soil is plowed 20-30 cm to evenly mix the conditioner with the plowed soil.

[0038] Preferably, for severe saline-alkali land, the dosage of the improver is 200-250 kg / mu in the first year; and 200-250 kg / mu in the second year. For moderate saline-alkali land, the dosage of the improver is 250 kg / mu, and the saline-alkali land soil is plowed 20-25 cm. The improved saline-alkali land soil is used in a rotation cropping system with corn as the main crop.

[0039] The beneficial effects of the present invention include:

[0040] After the modifier of the present invention is applied to the soil, the carbon-based structure provides a porous scene for the activity of soil microorganisms. As a stabilizing component of the organic cement of soil aggregates, glomalin, under the condition of large specific surface area of ​​biochar, binds more soil particles of various particle sizes around the carbon particles through cementation, and forms microaggregates and then quickly forms a large number of water-stable macroaggregates through physical entanglement and chemical bond compounding in the porous carbon-rich environment of the carbon structure. Glomalin is attached to the biochar with large surface area and porosity, which reduces the degradation or loss of glomalin, and can be sustained-released and enhanced under the action of microorganisms, thereby improving the application efficiency of glomalin.

[0041] At the same time, seaweed polysaccharides promote root growth, nutrient absorption and stress resistance, and improve the secondary salinization that previously occurred. Under the action of good porosity, infiltration water flow and glomalin, the soluble salts are leached into the deep soil, and the salinization barrier is gradually reduced, thereby increasing the storage capacity of the soil plow layer for water and fertilizer storage, and having a significant effect on improving farmland soil structure and increasing crop yields, especially corn yields.

[0042] The improver of the present invention has a simple preparation process, is economical and environmentally friendly, and is conducive to large-scale promotion and application in fields and facility cultivated land. DETAILED DESCRIPTION

[0043] The present invention is further illustrated and described below in conjunction with embodiments, but the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the present invention and embodiments, all other inventions and embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0045] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0046] Example 1: A biomass carbon-based composite saline-alkali land improver

[0047] The improver of this embodiment includes, by weight:

[0048] 62 parts of biomass charcoal loaded with glomalin, 2 parts of potassium dihydrogen phosphate, 2 parts of potassium nitrate, 5 parts of potassium humate, 1 part of seaweed polysaccharide, and 5 parts of starch-modified bentonite. The biomass charcoal loaded with glomalin is composed of biomass charcoal and glomalin extract in a weight ratio of 15:1.

[0049] The biochar is corn stalk biochar. The corn stalk is free of impurities, dried, and then crushed into 2 mm raw material particles, placed in a carbonization furnace at 400°C and low-temperature carbonized for 1 hour under oxygen-free or low-oxygen conditions, and then crushed to <2 mm after cooling, and passed through a 2 mm aperture sieve. The biochar is fully soaked in clean water, washed 3 times, and then dried in the shade to obtain the biochar. Biochar can reduce soil pH and total salt content, and increase water and fertilizer retention properties.

[0050] Preparation of glomalin extract: The glomalin fungus was inoculated with the substrate at a weight ratio of 1:200, and the alfalfa planting density was 600 plants / m 2 After 45 days of greenhouse planting, the above-ground and underground parts of the alfalfa plants were removed, and the alfalfa rhizosphere soil was mixed with 50 mM sodium citrate solution at a solid-liquid ratio (g / ml) of 1:10, and extracted at pH = 8.0 and temperature 121°C for 60 minutes, and the extraction was repeated 3 times. The extracts were mixed and filtered, and the supernatant was collected. It was determined that the content of glomalin in the glomalin extract of this example was about 15 mg / g.

[0051] Seaweed polysaccharide: The seaweed polysaccharide is fucoidan extracted from kelp;

[0052] The starch-modified bentonite is prepared by dissolving 10g of calcium-based bentonite, 3.7770g of hexadecyltrimethylammonium bromide and 1g of soluble starch in 400ml of distilled water, stirring at a constant temperature of 25°C for 24h, then filtering, drying at 60°C, grinding, and passing through a 120-mesh sieve to obtain the starch-modified bentonite.

[0053] The preparation method of the improver comprises:

[0054] (1) The biochar was mixed with the glomalin extract and shaken for 12 hours to simultaneously complete the modification of the corn straw biochar and the loading of glomalin, and the glomalin-loaded biochar was obtained and dried in the shade for later use.

[0055] (2) mixing the biomass charcoal loaded with glomalin with potassium dihydrogen phosphate, potassium nitrate, potassium humate, seaweed polysaccharide, and starch-modified bentonite according to a formula to obtain a mixture;

[0056] (3) Stir the mixture thoroughly at room temperature to ensure that the fine biochar particles are evenly dispersed with other materials.

[0057] Example 2: A biomass carbon-based composite saline-alkali land improver

[0058] In parts by weight, it includes:

[0059] 60 parts of biomass charcoal loaded with glomalin, 2 parts of potassium dihydrogen phosphate, 2 parts of potassium nitrate, 5 parts of potassium humate, 2 parts of seaweed polysaccharide, and 5 parts of starch-modified bentonite. The biomass charcoal loaded with glomalin is composed of biomass charcoal and glomalin extract in a weight ratio of 15:1.

[0060] The preparation method of the improver in this example is the same as that in Example 1.

[0061] Example 3: A biomass carbon-based composite saline-alkali land improver

[0062] In parts by weight, it includes:

[0063] 64 parts of biomass charcoal loaded with glomalin, 2 parts of potassium dihydrogen phosphate, 2 parts of potassium nitrate, 5 parts of potassium humate, 2 parts of seaweed polysaccharide, and 5 parts of starch-modified bentonite. The biomass charcoal loaded with glomalin is composed of biomass charcoal and glomalin extract in a weight ratio of 15:1.

[0064] The preparation method of the improver in this example is the same as that in Example 1.

[0065] Comparative Example 1: A modifier

[0066] The components, proportions and preparation methods of the improver of this example are the same as those of Example 1, but the preparation method of the improver is different from that of Example 1. Specifically, the preparation method of the improver includes:

[0067] (1) mixing biochar with potassium dihydrogen phosphate, potassium nitrate, potassium humate, seaweed polysaccharide, and starch-modified bentonite according to a formula to obtain a mixture;

[0068] (2) Mix the mixture with the glomalin extract and stir thoroughly at room temperature to ensure that the fine biochar particles are evenly dispersed with other materials.

[0069] Application Example 1: Application of the saline-alkali land improver of the present invention in improving saline-alkali land for growing corn

[0070] Starting from 2022, severely saline soil and moderately saline soil were selected and improved using the modifiers provided in Examples 1-3 and Comparative Example 1 of the present invention (corresponding to Treatments 1-4, respectively).

[0071] Application amount and method for severely saline soil:

[0072] The first year: Improvement + crops, evenly spread saline-alkali land improver at a rate of 250kg / mu, and till the soil 20-30cm; the crop planted is corn, which is planted according to conventional planting methods.

[0073] The second year: Improvement + crops, evenly spread saline-alkali land improver at a rate of 200kg / mu, and till the soil 20-30cm. Plant corn according to conventional planting methods.

[0074] Application amount and method for moderately saline soil:

[0075] Improvement + crops, 200kg / mu of saline-alkali land improver was evenly spread, and the soil was tilled 20-25cm. The crop was corn, which was planted according to the conventional planting method.

[0076] The control group was directly planted with corn without applying any amendments.

[0077] Table 1 Changes in physical and chemical indicators of heavily saline soil after application of modifiers in the first year

[0078]

[0079] As shown in Table 1, in 2022, the changes in the physical and chemical properties of the severely salinized soil in the treatment groups using the three modifiers of Examples 1-3 of the present invention (Treatment 1, Treatment 2, Treatment 3) and the modifier of Comparative Example 1 (Treatment 4) showed that the total salt content was reduced by 327.5%, 285.1%, 75.8%, and 72.6% respectively compared with the control (without improvement treatment); the pH was reduced by 11.6%, 3.8%, 2.0%, and 1.7% respectively compared with the control; the alkalinity was reduced by 56.5%, 34.9%, 53.0%, and 46.4% respectively compared with the control; the total porosity was increased by 3.10%, 0.89%, 0.51%, and 0.31% respectively compared with the control; and the content of water-stable macroaggregates in the soil was increased by 25.44%, 5.33%, 4.45%, and 2.10% respectively compared with the control.

[0080] Table 2 Changes in corn growth indicators after applying amendments in severely saline soil in the first year

[0081]

[0082]

[0083] As shown in Table 2, in 2022, the number of seedlings in each treatment (treatment 1-4) with application of modifiers increased by 63.13%, 59.47%, 29.78%, and 28.82% respectively compared with the control; the corn yield increased by 83.87%, 22.42%, 14.68%, and 14.24% respectively compared with the control; the plant height increased by 37.97%, 13.92%, 15.19%, and 12.66% respectively compared with the control; the number of leaves increased by 26.32%, 22.47%, 16.37%, and 15.41% respectively compared with the control; and the dry weight of corn roots increased by 20.27%, 6.12%, 5.42%, and 3.54% respectively compared with the control.

[0084] Table 3 Changes in indicators of heavily saline soil after application of modifiers in the second year

[0085]

[0086] As shown in Table 3, in 2023, the changes in the physical and chemical properties of severely salinized soil in the four amendment treatment groups (treatment 1, treatment 2, treatment 3 and treatment 4) showed that the total salt content was reduced by 73.87%, 70.40%, 42.67% and 38.67% respectively compared with the control; the pH was reduced by 10.65%, 3.55%, 1.89% and 1.54% respectively compared with the control; the alkalinity was reduced by 40.55%, 26.27%, 34.89% and 34.21% respectively compared with the control; the total porosity was increased by 3.43%, 1.22%, 0.88% and 0.68% respectively compared with the control; the content of soil water-stable macroaggregates was increased by 24.95%, 7.61%, 3.15% and 2.45% respectively compared with the control

[0087] Table 4 Changes in corn growth indicators after application of amendments in heavily saline soil in the second year

[0088]

[0089] As shown in Table 4, the number of seedlings in each treatment with application of modifiers in 2023 increased by 43.14%, 42.17%, 33.17% and 24.46% respectively compared with the control; the corn yield increased by 98.18%, 22.80%, 35.88% and 20.38% respectively compared with the control; the plant height increased by 44.74%, 10.53%, 18.42% and 15.79% respectively compared with the control; the number of leaves increased by 15.43%, 4.80%, 14.70% and 13.10% respectively compared with the control; the dry weight of corn roots increased by 17.98%, 3.85%, 5.68% and 1.54% respectively compared with the control.

[0090] Table 5 Changes of physical and chemical indexes of moderately saline soil after application of modifiers in the first year

[0091]

[0092] As shown in Table 5, in 2022, the changes in the physical and chemical properties of moderately salinized soil in the four amendment treatment groups (Treatment 1, Treatment 2, Treatment 3 and Treatment 4) showed that the total salt content was reduced by 71.88%, 63.93%, 24.40% and 21.49% respectively compared with the control; the pH was reduced by 8.82%, 3.34%, 1.31% and 0.12% respectively compared with the control; the alkalinity was reduced by 60.18%, 51.07%, 39.71% and 38.79% respectively compared with the control; the total porosity was increased by 10.87%, 7.90%, 5.32% and 4.47% respectively compared with the control; and the content of soil water-stable macroaggregates was increased by 24.94%, 5.59%, 3.29% and 2.23% respectively compared with the control.

[0093] Table 6 Changes of corn growth indicators after applying amendments in moderately saline soil in the first year

[0094]

[0095] As shown in Table 6, in 2022, the number of seedlings in each treatment with amendments applied to moderately saline soil increased by 47.55%, 36.06%, 28.11%, and 28.62% respectively compared with the control; the corn yield increased by 95.34%, 22.63%, 21.92%, and 20.32% respectively compared with the control; the plant height increased by 37.66%, 23.38%, 27.27%, and 25.97% respectively compared with the control; the number of leaves increased by 12.64%, 4.89%, 12.93%, and 11.93% respectively compared with the control; and the dry weight of corn roots increased by 20.01%, 3.84%, 16.67%, and 1.38% respectively compared with the control.

[0096] Compared with the control and comparative example 1, treatment 1, treatment 2 and treatment 3 all improved soil physical and chemical properties and promoted corn growth to varying degrees. Treatments 1-3 loaded glomalin on the surface of biochar directly provided the cementing material required for the agglomeration effect, and accelerated the agglomeration of soil particles around the carbon particles under the action of microorganisms to form more and more stable water-stable large aggregates, making the organic carbon pool of the cultivated layer more stable, thereby significantly desalting the infiltration water flow under the cultivated layer and promoting the growth of crop roots. In terms of the improvement of heavily saline soil and moderately saline soil, treatment 1 performed better. In the first year of application of heavily saline soil, the total salt content was reduced to about 1.0g / kg. In the second year, the amount of the modifier was reduced by 50 kg / hectare to reduce the effect of mild alkalinization, and the pH dropped to between 7 and 8. The content of aggregates formed in treatment 1 increased by 22.9% compared with treatment 4 without loading, and the total porosity increased by 2.78%. In terms of crop growth, the increase in the number of seedlings in treatment 1 ensured the increase in harvest yield, and at the same time, the above-ground plant height and underground root dry weight increased accordingly (seaweed polysaccharides and starch-modified calcium bentonite mainly promoted root growth). From the perspective of soil improvement and crop growth indicators, the comprehensive effect of each component in treatment 1 performed best.

Claims

1. A biomass carbon-based composite saline-alkali land improver, characterized in that: The modifier comprises, by weight: 60-65 parts of biochar loaded with glomalin; 2-5 parts of potassium dihydrogen phosphate; 2-5 parts potassium nitrate; Potassium humate 5-10 parts; 1-5 parts of seaweed polysaccharide; 5-15 parts of starch modified bentonite; Wherein, the biomass charcoal loaded with glomalin is composed of biomass charcoal and glomalin extract in a weight ratio of 8-15:1; The content of glomalin in the glomalin extract is 8-23 mg / g.

2. The biomass carbon-based composite saline-alkali land modifier according to claim 1, characterized in that: The improver comprises, by weight: 62 parts of biochar loaded with glomalin; 2 parts of potassium dihydrogen phosphate; 2 parts potassium nitrate; Potassium humate 5 parts; 1 part of seaweed polysaccharide; 5 parts of starch modified bentonite; The biomass charcoal loaded with glomalin is composed of biomass charcoal and glomalin extract in a weight ratio of 15:1; The content of glomalin in the glomalin extract is 15 mg / g.

3. The biomass carbon-based composite saline-alkali land modifier according to claim 1, characterized in that: Includes one or more of the following (1)-(9): (1) The biochar is corn straw biochar; (2) The particle size of the biochar is less than 2 mm; (3) The biochar is used after being soaked and cleaned in water; (4) The glomalin extract is obtained by colonizing Glomerella mosseae in a substrate for alfalfa cultivation and then extracting the alfalfa rhizosphere soil with sodium citrate; (5) The starch-modified bentonite is obtained by dissolving, stirring, drying and grinding dried calcium-based bentonite, hexadecyltrimethylammonium bromide and soluble starch; (6) The particle size of the starch-modified bentonite is less than 0.15 mm; (7) The seaweed polysaccharide is fucoidan extracted from kelp; (8) mixing the biochar with the glomalin extract, shaking for 12 hours, and then drying in the shade to obtain the glomalin-loaded biochar; (9) The biomass charcoal loaded with glomalin is thoroughly mixed with potassium dihydrogen phosphate, potassium nitrate, potassium humate, seaweed polysaccharide, and starch-modified bentonite according to a formula to obtain the improver.

4. The biomass carbon-based composite saline-alkali land modifier according to claim 3, characterized in that: Includes one or more of the following (1)-(3): (1) The preparation method of the glomalin extract is as follows: the glomalin species and the substrate are inoculated at a mass ratio of 1:200, and the alfalfa planting density is 450-600 plants / m 2 , after 45-60 days of greenhouse planting, remove the above-ground and underground parts of the alfalfa plants, take the alfalfa rhizosphere soil and mix it with 50mM sodium citrate solution at a solid-liquid ratio (g / ml) of 1:5-10, extract at pH 8.0 and 121°C for 60 minutes, extract several times until the extract loses its reddish brown color, mix the extracts and filter to collect the supernatant; (2) The preparation method of the starch-modified bentonite is as follows: 10 g of dried calcium-based bentonite, 3.7770 g of hexadecyltrimethylammonium bromide and 1 g of soluble starch are dissolved in 400 ml of distilled water, stirred at a constant temperature of 25° C. for 24 h, filtered, dried, ground, and passed through a 120-mesh sieve to obtain the starch-modified bentonite; (3) The biomass charcoal particles are obtained by removing impurities from corn stalks, drying them, and crushing them into raw material particles, which are then carbonized in a carbonization furnace at 400°C-500°C under oxygen-free or low-oxygen conditions for 1-2 hours, and then crushed and sieved through a sieve with a pore size of 2-5 mm after cooling.

5. The use of the biomass carbon-based composite saline-alkali land improver according to any one of claims 1 to 4 in improving saline-alkali land soil, characterized in that: The improver is evenly spread at a rate of 100-500 kg / mu, and then the saline-alkali soil is plowed 20-30 cm to evenly mix the improver with the plowed soil.

6. The use according to claim 5, characterized in that: For severely saline-alkali land, the dosage of the improver is 200-250 kg / mu in the first year; and the dosage of the improver is 200-250 kg / mu in the second year.

7. The use according to claim 5, characterized in that: For moderate saline-alkali land, the dosage of the improver is 250kg / mu, and the saline-alkali land soil is plowed to 20-25cm.

8. The use according to claim 5, characterized in that: Improved saline-alkali soils are used in a maize-based rotation cropping system.

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