Saline-alkali soil composite modifier as well as preparation method and application thereof

Abstract

The invention belongs to the field of organic contaminated soil remediation, and particularly relates to a saline-alkali soil composite modifier as well as a preparation method and application thereof. The saline-alkali soil composite modifier is composed of an alkali-removing shaping slow-release carburant, a powerful carburant fertilizing agent and a salt-controlling carbon-sequestration bacteria-retaining agent. Wherein the alkali-removing shaping slow-release carburant is obtained by mixing beet filter mud, gulonic acid waste liquid stock solution and peat; the powerful recarburizing and fertilizing agent is obtained by mixing partially decomposed sugar beet pulp and a diluent of gulonic acid waste liquid; the salt-controlling carbon-sequestration bacteria-retaining agent is obtained by mixing beet pulp medium-temperature biochar, beet pulp high-temperature modified biochar and water plant bottom mud and then fermenting the mixture through a functional bacteria agent. The saline-alkali soil composite modifier is composed of industrial and agricultural wastes such as sugar beet pulp and sugar beet filter mud which are sugar beet processing byproducts, water plant bottom mud rich in iron and manganese, peat and gulonic acid waste liquid produced through fermentation of vitamin C, so that the circular economy of resource utilization is realized, and wastes are treated by wastes.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of remediation of organically contaminated soil, and particularly relates to a saline-alkali soil composite improver and a preparation method and application thereof. BACKGROUND

[0002] Saline-alkali soil is regarded as "barren land", which is a major obstacle to the sustainable development of global agriculture. The governance and utilization of saline-alkali soil are directly related to national food security and ecological security, and have extremely important practical significance and far-reaching historical significance. The saline-alkali soil in China is mainly distributed in the Songnen Plain in the northeast, the arid region in the northwest, the coastal area of Bohai Bay in North China, the Yellow River Delta and the Hetao Plain in Inner Mongolia, etc. The historical stock of saline-alkali soil distribution in China is huge. Unreasonable irrigation methods, climate change and seawater intrusion in coastal areas and other factors continue to exist the risk of secondary salinization, and even the improved land may be repeated. The task of protecting the existing farmland achievements is still arduous.

[0003] The saline-alkali soil is harmful to agricultural land, and the saline-alkali soil directly poisons and stresses crops. High-concentration salt ions directly poison the roots of crops, interfere with their normal ability to absorb water and nutrients, cause "physiological drought", and lead to stunted plants, scorched leaves, growth stagnation and even death. This not only causes a substantial reduction in crop yield or even complete loss, but also severely limits the types of crops that can be planted, making it difficult for many high-value conventional crops to survive. In addition, saline-alkali substances destroy soil structure and ecosystems, leading to the collapse of soil aggregate structure, resulting in soil hardening, compaction and poor permeability. This further hinders the root system from penetrating, water infiltration and gas exchange, forming a vicious cycle. At the same time, high-salt environments severely inhibit the activity of rich and beneficial microbial colonies in the soil, causing soil ecological imbalance, poor land, and extremely low natural fertility. Further, a hard crust layer often forms on the surface of saline-alkali soil, causing great difficulties in farming, sowing, harvesting and other agricultural operations, increasing the cost of agricultural production. Therefore, saline-alkali soil improvement is an inevitable choice to ensure national food security, an important engine to promote agricultural modernization and rural revitalization, a major measure to implement ecological civilization construction, and a manifestation of the country's responsibility and technological self-confidence.

[0004] Current saline-alkali soil improvement methods mainly involve physical improvement methods such as deep ploughing, platform leaching, and underground pipe drainage, chemical improvement methods such as applying gypsum and humic acid, biological improvement methods such as applying microbial inoculants and planting salt-tolerant plants, and water conservancy methods such as establishing drainage systems to pressurize salt and wash salt with water. Among them, the chemical improvement method relying on the application of improvement agents is one of the classic and core methods of saline-alkali soil improvement. The application of improvement agents has the advantages of rapid effect, direct effect, strong root-removing effect, improvement of soil microbial survival environment, improvement of soil nutrient availability, and relatively simple operation, and is easy to popularize, and is an important research and development, application and commercial development object of the saline-alkali soil improvement industry. However, the existing improvement agents have single functions, mainly single salt-reducing or alkali-removing processes, and the cost is generally high, and the long-acting property is not high.

[0005] Therefore, it is urgent to develop a technology for preparing an improvement agent from waste to realize multifunctional salt reduction and alkali removal. SUMMARY

[0006] The purpose of the present application is to provide a saline-alkali soil composite improvement agent and its preparation method and application.

[0007] To achieve the above purpose, the technical solution adopted by the present application is: A saline-alkali soil composite improvement agent is composed of an alkali-removing plastic slow-release carbon-increasing agent, a high-efficiency carbon-increasing fertilizer, and a salt-controlling carbon-fixing bacteria-preserving agent. The alkali-removing plastic slow-release carbon-increasing agent is obtained by mixing sugar beet filter mud and gulonic acid waste liquid stock solution with peat. The high-efficiency carbon-increasing fertilizer is obtained by mixing partially decomposed sugar beet residues and dilute gulonic acid waste liquid. The salt-controlling carbon-fixing bacteria-preserving agent is obtained by mixing sugar beet residue medium-temperature biochar, sugar beet residue high-temperature modified biochar, and water plant sludge, and then fermenting the mixture with functional microbial inoculants.

[0008] The amount ratio of the alkali-removing plastic slow-release carbon-increasing agent, the high-efficiency carbon-increasing fertilizer, and the salt-controlling carbon-fixing bacteria-preserving agent is 2-3:5-7:4-6.

[0009] The partially decomposed sugar beet residues are prepared by biological composting of sugar beet residues. The composting conditions are as follows: after dehydration, the sugar beet residues are mixed with crushed sugar beet stem and leaf waste, gulonic acid waste liquid diluent, and functional microbial inoculants, and then the mixture is fermented and cultured. When the C / N ratio of the mixture reaches 22:1-24:1, and the germination rate GI of Chinese cabbage seeds in the material extract is greater than 60%, the partially decomposed sugar beet residues are obtained.

[0010] Specific composting conditions are: the dehydrated sugar beet residue dry matter and sugar beet stem and leaf waste are crushed into 0.5-1.0 cm fragments, 60-70 parts (mass fraction) of sugar beet residue fragments and 30-40 parts of sugar beet stem and leaf waste fragments are mixed, 20 times diluted solution of gulonic acid waste liquid is added at a ratio of 5.0%-10.0% (V / W), and 1.0%-3.0% (V / W) of functional microbial agent fermentation liquid is added, the moisture content of the material is adjusted to 50%-60% for fermentation culture of sugar beet residue material, and the preparation of partially decomposed sugar beet residue material is completed after the decomposition degree reaches a certain level; The judgment standard for the decomposition degree reaching a certain level is that the C / N ratio of the mixed material reaches 22:1-24:1, and the cabbage seed germination rate GI in the material extract is greater than 60%; The strain for preparing the functional microbial agent is Klebsiella michiganensis HDJT1 Klebsiella michiganensis Klebsiella michiganensis HDJT1 was preserved in the General Microbiological Center of China on December 24, 2024, with a preservation number of CGMCC NO.33184, and was classified and named as Klebsiella michiganensis Klebsiella michiganensis The address is No. 3, Beichen West Road, Chaoyang District, Beijing.

[0011] The sugar beet residue medium-temperature biochar is dehydrated and dried at 120°C, and crushed into 1.0-5.0 mm granular material; the granular material is pyrolyzed at 250-350°C for 2-3h to produce sugar beet residue medium-temperature biochar.

[0012] Specifically, the sugar beet residue material is dehydrated and dried at 120°C, and crushed into 1.0-5.0 mm granular material; the granular material is pyrolyzed at 250-350°C for 2-3h to produce sugar beet residue medium-temperature biochar.

[0013] The sugar beet residue high-temperature modified biochar is dehydrated and dried at 120°C, and crushed into 1.0-5.0 mm granular material; the granular material is pyrolyzed at 500-600°C for 1-2h, and after the material is cooled, it is immersed in 1-2 mol·L -1 Phosphoric acid solution for acidolysis modification treatment, the material is washed with water to pH 6.0-7.0, and then dehydrated and dried to produce sugar beet residue high-temperature modified biochar; Specifically, the sugar beet residue material is dehydrated and dried at 120°C, and crushed into 1.0-5.0 mm granular material; the granular material is pyrolyzed at 500-600°C for 1-2h, and after the material is cooled, it is immersed in 1-2 mol·L -1The modified treatment of acidolysis in phosphoric acid solution, water cleaning material to pH 6.0-7.0 range, after dehydration and drying to make beet pulp high temperature modified biochar.

[0014] The beet filter mud, peat, and water plant sludge are respectively dried and crushed for pretreatment, wherein the crushing particle size of the beet filter mud and the water plant sludge is 0.5-1.0 mm, and the crushing particle size of the peat is 3.0-5.0 mm. The water plant sludge is a water supply treatment sludge with a total iron (calculated as Fe2O3) and total manganese (calculated as MnO2) content ratio higher than 30%.

[0015] A preparation method of the saline-alkali soil composite improver, 1) Preparation of alkali-removing plasticizing slow-release carbon-increasing agent: the beet filter mud is mixed with the gulonic acid waste liquid stock solution, the gulonic acid waste liquid stock solution is sprayed into the beet filter mud by atomization spraying until no air bubbles are generated, then 20-40 parts of peat is slowly mixed in batches, and the pH of the mixture is controlled to be 4.5-5.5, and the adjusted mixture is dried for standby; 2) Preparation of high-efficiency carbon-increasing and soil-fertilizing agent: part of the rotten beet pulp is mixed with 20 times diluted gulonic acid waste liquid, the 20 times diluted gulonic acid waste liquid is sprayed into the part of the rotten beet pulp by atomization spraying, and the mixture is stirred and mixed uniformly, then the mixed material is stacked into a pile and covered with tarpaulin for maturation for 1-3 days, and the obtained product is used as standby; 3) Preparation of salt-controlling, carbon-fixing and fungus-protecting agent: the beet pulp medium-temperature biochar, beet pulp high-temperature modified biochar, and water plant sludge are mixed, and then the functional bacteria agent fermentation liquor is sprayed into the solid material by atomization spraying, so that the microbial abundance in the solid material reaches 10 9 -10 10 CFU·g -1 , and the water content of the mixture after air drying and dehydration is 20%-30%, and the obtained product is used as standby.

[0016] Specifically, 1) Preparation of alkali-removing plasticizing slow-release carbon-increasing agent: 100 parts of beet filter mud is mixed with 80-120 parts of gulonic acid waste liquid stock solution, the gulonic acid waste liquid stock solution is sprayed into the beet filter mud by atomization spraying until no air bubbles are generated, then 20-40 parts of peat is slowly mixed in batches, and the pH of the mixture is controlled to be 4.5-5.5, and the adjusted mixture is dried for standby; 2) Preparation of high-efficiency carbon-increasing and soil-fertilizing agent: 100 parts of part of rotten beet pulp is mixed with 100-150 parts of 20 times diluted gulonic acid waste liquid, the 20 times diluted gulonic acid waste liquid is sprayed into the part of rotten beet pulp by atomization spraying, and the mixture is continuously stirred and mixed to ensure uniformity, then the mixed material is stacked into a pile and covered with tarpaulin for maturation for 1-3 days, and the obtained product is used as standby; 3) Preparation of the salt control and carbon fixation microbial agent: 100 parts of beet residue medium-temperature biochar, 50-80 parts of beet residue high-temperature modified biochar and 50-100 parts of water plant sludge material are mixed thoroughly, and then the functional microbial agent fermentation liquor is sprayed into the solid material by atomization, so that the microbial abundance in the solid material reaches 10 9 -10 10 CFU·g -1 The water content of the mixture after drying is maintained at a level of 20%-30%.

[0017] The application of the salt-alkali soil composite improver is for improving the salt-alkali soil, and the application dose of the composite improver is 1%-5% of the mass of the soil to be treated.

[0018] The alkali-removing, plasticizing, slow-releasing and carbon-increasing agent is applied to the soil to be treated, is mixed thoroughly by deep ploughing, the soil humidity is maintained at 10%-15%, and the soil is incubated for 2-4 weeks; then, the soil is irrigated and leached to remove sodium ions, the effective carbon-increasing and fertilizing agent is applied after drainage, is mixed by rotary ploughing, and the soil is incubated for 2-4 weeks under the condition of 10%-15% soil humidity; finally, the salt control and carbon fixation microbial agent is applied, and the soil is incubated for a long time after rotary ploughing and can be planted with plants.

[0019] Specifically, the alkali-removing, plasticizing, slow-releasing and carbon-increasing agent is applied to the soil to be treated, is mixed thoroughly by deep ploughing, the soil humidity is maintained at 10%-15%, and the soil is incubated for 2-4 weeks; then, the soil is irrigated and leached to remove sodium ions, the effective carbon-increasing and fertilizing agent is applied after drainage, is mixed by rotary ploughing, and the soil is incubated for 2-4 weeks under the condition of 10%-15% soil humidity; finally, the salt control and carbon fixation microbial agent is applied, and the soil is incubated for a long time after rotary ploughing and can be planted with plants.

[0020] The salt-tolerant crops include but are not limited to sugar beets and cotton, and plants can be planted to further perform ecological restoration when the soil salt-alkali conditions meet the requirements of plant planting after improvement.

[0021] The salt-alkali soil includes but is not limited to soda-type saline soil, sulfate-type saline soil and chloride-type saline soil. The salt-alkali soil includes but is not limited to soda-type saline soil, sulfate-type saline soil and chloride-type saline soil.

[0022] The application has the following advantages and beneficial effects: 1. The salt-alkali soil composite improver of the application is composed of beet residue, a byproduct of beet processing, beet filter mud, water plant sludge rich in iron and manganese, peat and vitamin C fermentation production of gulonic acid waste liquid and other industrial and agricultural wastes, realizes recycling economy of resource utilization, and treats waste with waste.

[0023] 2. The salt and alkali soil composite improver adopts gulonic acid waste liquid, peat, partially decomposed sugar beet residue material, and sugar beet residue medium-temperature biochar, all of which have the function of increasing carbon, especially providing easily available carbon for microorganisms. However, due to the differences in carbon source supply materials and preparation process, the multi-component combination application will maximize the diversity of organic carbon structure, thereby improving soil fertility, microbial biomass, community diversity, and metabolic activity in the soil.

[0024] 3. The partially decomposed sugar beet residue material in the salt and alkali soil composite improver, to some extent, kills parasites and pathogenic bacteria through microbial fermentation and decomposition, while retaining long-acting and partially available organic matter and fibrous nutrients, which play a role in nutrient release in the soil, benefiting the long-term activity of soil microorganisms and plants.

[0025] 4. The partially decomposed sugar beet residue material in the salt and alkali soil composite improver has a decomposition degree judgment standard set as a mixture material C / N ratio of 22:1-24:1, and a cabbage seed germination rate GI>60% in the material extract. This level is obtained from practical experience, and within this parameter range, the sugar beet residue material is in a state of partial biological degradation and partial retention of complex structures such as cellulose, providing both readily available nutrients and nutrient release capacity. The cabbage seed germination rate GI>60% ensures the degree of harmlessness of the material to plant seeds, and cabbage is a commonly used material in the field of biological toxicity evaluation species, thus having wide representativeness.

[0026] 5. The sugar beet residue biochar in the salt and alkali soil composite improver includes medium-temperature biochar and high-temperature acid-modified biochar. The medium-temperature biochar retains part of the active cellulose structure of the sugar beet residue, while providing acidic conditions, more functional groups, and active slow-release organic matter. The high-temperature acid-modified biochar provides a large specific surface area, cation exchange capacity, and strong adsorption capacity, while further providing carboxyl and hydroxyl groups, and also functions as a carrier for functional microorganisms and a salt ion adsorption function.

[0027] 6. The alkali removal shaping slow-release carbon enhancer in the salt and alkali soil composite improver is composed of sugar beet filter mud, peat, and gulonic acid waste liquid. During preparation, the sugar beet filter mud and gulonic acid waste liquid are mixed first, which helps to release calcium ions from calcium carbonate in the sugar beet filter mud, and also helps to release sodium ions adsorbed on the surface of soil particles by exchanging with sodium ions. Further, mixing with peat fragments helps to supplement organic carbon in saline-alkali soil and reshape the soil physical structure, enhancing soil water retention and air permeability.

[0028] 7. The peat used in the alkali-removing plasticizing, slow-releasing and carbon-increasing agent of the salt-alkali soil composite improver has been used as a single improver in the existing salt-alkali soil improvement, however, the peat is relatively expensive, and the cost of large-scale application is too high, and the market application prospect is not good; in the present application, the peat is only used as a pioneer carbon source for providing organic carbon in the salt-alkali soil and a pioneer material for improving the soil physical structure, to a certain extent, the extreme environment of salt-alkali stress is rapidly improved, and a possible environment is provided for the growth of microorganisms in the soil and even the planting of plants, and then the application of the subsequent improvement precast material further strengthens the salt-alkali soil improvement effect, not only greatly reduces the improvement cost, but also plays a valuable improvement effect.

[0029] 8. The high-efficiency carbon-increasing and fertilizer-preparing agent in the salt-alkali soil composite improver is mixed by partially decomposed sugar beet residue material and 20 times diluted solution of gulonic acid waste liquid, the partially decomposed sugar beet residue mainly has the ability to adsorb small molecule acids in the gulonic acid waste liquid, and can provide the slow-release function of carbon, nitrogen, phosphorus, potassium and other substance elements after being applied to the salt-alkali soil; in addition, the small molecule acids have the function of activating soil microorganisms, and can quickly improve the metabolic activity of functional microorganisms.

[0030] 9. The salt-controlling, carbon-fixing and microorganism-protecting agent in the salt-alkali soil composite improver is composed of sugar beet residue medium-temperature biochar, sugar beet residue high-temperature modified biochar, water plant sediment material and functional microorganism fermentation liquid, the sugar beet residue medium-temperature biochar can not only provide slow-release organic matter supply capacity, but also can provide more oxygen-containing functional groups, which is helpful to the adsorption and stabilization of sodium ions and other cations, and the adsorption and fixation of functional microorganisms, so as to provide a persistent and stable micro-ecological environment and prolong the active maintenance period of microorganisms in the soil; the sugar beet residue high-temperature acid modified biochar has better pore structure, specific surface area and adsorption capacity, and plays an outstanding role in reducing soil bulk density, adsorbing salt-based ions and optimizing soil structure; the water plant sediment material contains rich iron and manganese metal oxides, which can be combined with organic carbon in the soil to have a significant carbon fixation capacity and enhance the nutrient improvement of the salt-alkali soil; in addition, the functional microorganisms can continuously metabolize the partially decomposed sugar beet residue material in the soil to provide slow-release supply capacity for subsequent land cultivation and planting utilization.

[0031] 10. The application method of the salt-alkali soil composite improver, firstly, the alkali-removing plasticizing, slow-releasing and carbon-increasing agent is applied, which is beneficial to quickly removing alkali by chemical neutralization method and improving soil structure, increasing soil water retention and air permeability, and providing an excellent condition basis for subsequent application of microbial agents and organic carbon fixation; then the high-efficiency carbon-increasing and fertilizer-preparing agent is applied, which can realize the supply of various carbon sources and easily available nutrients, and further provide small molecule carbon sources for subsequent functional microorganism activation and further stabilize the soil suitable pH environment; finally, the salt-controlling, carbon-fixing and microorganism-protecting agent is applied, to realize the ecological improvement and fertilization process of the salt-alkali soil, prevent repeated salt-alkali damage, and continuously create an excellent ecological environment after the salt-alkali soil improvement.

[0032] 11. The improved process of the present application and the planting of salt-tolerant plants in the improved later stage have the ecological advantage of further stabilizing the improvement effect of saline-alkali soil, and form a two-way income model of solid waste utilization and economic benefit circulation in the process of planting economic crops such as sugar beets. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The preparation flowchart of the composite improver material provided for the embodiments of the present application is provided.

[0034] Figure 2 The application flowchart of each type of prefabricated material in the composite improver provided for the embodiments of the present application is provided.

[0035] Figure 3 The comparison chart of soil pore structure before and after the improvement of soda saline-alkali soil provided for the embodiments of the present application is provided.

[0036] Figure 4 The chart of changes in total salt content and sodium ion, carbonate ion and bicarbonate ion content of soil before and after the improvement of soda saline-alkali soil provided for the embodiments of the present application is provided.

[0037] Figure 5 The chart of changes in soil alkalization degree and pH before and after the improvement of soda saline-alkali soil provided for the embodiments of the present application is provided.

[0038] Figure 6 The chart of changes in soil organic carbon content before and after the improvement of soda saline-alkali soil provided for the embodiments of the present application is provided.

[0039] Figure 7 The chart of changes in soil microbial necromass carbon (MNC) content before and after the improvement of soda saline-alkali soil provided for the embodiments of the present application is provided.

[0040] Figure 8 The chart of changes in mineral-associated organic carbon (MAOC) content in the remediation of organically contaminated soil by the electrically enhanced ecological pile provided for the embodiments of the present application is provided.

[0041] Figure 9 The chart of changes in sugar beet biomass planted after the incubation of the improved soda saline-alkali soil provided for the embodiments of the present application is provided.

[0042] Figure 10 The chart of changes in photosynthetic pigment content of sugar beet leaves planted after the incubation of the improved soda saline-alkali soil provided for the embodiments of the present application is provided.

[0043] Figure 11 The chart of changes in malondialdehyde and proline content in the leaves and roots of sugar beets planted after the incubation of the improved soda saline-alkali soil provided for the embodiments of the present application is provided.

[0044] Figure 12 The chart of changes in total salt content of soil after the improvement of soda saline-alkali soil under different application conditions provided for the embodiments of the present application is provided.

[0045] Figure 13 The diagram shows the changes in soil pH after amending soda saline-alkali soil under different application conditions, as provided in the embodiments of the present invention.

[0046] Figure 14 The graph shows the change in soil organic carbon content after soda-based saline-alkali soil improvement under different application conditions, as provided in the embodiments of the present invention. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] This invention, which utilizes solid waste to prepare a soil conditioner for saline-alkali soil, has significant environmental and economic implications, enabling "waste treatment of waste" and significantly reducing costs. It leverages industrial and agricultural waste, including beet pulp and beet filter mud (byproducts of beet processing), iron- and manganese-rich water plant sediment, peat, and gulonic acid fermentation wastewater, to reduce environmental pollution and land occupation caused by accumulation. Furthermore, the combined application of functional microbial materials results in low costs, significantly reducing the production cost of the conditioner and representing a potentially efficient and economically feasible solution for large-scale saline-alkali land remediation.

[0049] Example 1: Preparation of a composite soil conditioner for saline-alkali soil Beet pulp and beet filter mud were obtained from sugar production waste of a sugar factory that uses beet tubers as raw material. The water treatment plant sludge came from a sedimentation tank of a waterworks in Northeast China. The sludge was water treatment sludge with a total iron (Fe2O3) and total manganese (MnO2) content of 38.9%. The peat came from the Sanjiang Plain. Gluconic acid waste liquid came from the downstream of a vitamin C production line in a pharmaceutical factory in Northeast China that uses a two-step fermentation method. A cellulose-degrading strain, Klebsiella Michigani HDJT1, was isolated from the semi-rotten beet pulp. Klebsiella michiganensis Klebsiella micranthae HDJT1 (CGMCC NO. 33184) was deposited on December 24, 2024, at the China General Microbiological Culture Collection Center (CGMCC), and is classified as Klebsiella micranthae. Klebsiella michiganensis The depositary address is No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. The functional microbial inoculum fermentation broth was prepared by inoculating *Klebsiella Michiganlis* HDJT1 onto beef extract peptone medium (3.0 g / L beef extract). -1 10.0 g / L of peptone -1 Sodium chloride 5.0 g·L -1Seed liquid was activated by culturing in the medium, and then inoculated into the rich medium (sodium carboxymethyl cellulose 3.0 g / L -1 , yeast extract 0.2 g / L -1 , ammonium sulfate 2.0 g / L -1 , potassium dihydrogen phosphate 4.0 g / L -1 , magnesium sulfate heptahydrate 0.3 g / L -1 ) to produce fermentation liquid under the conditions of 32°C and 180 rpm.

[0050] (1) The above raw materials were pretreated respectively The fresh sugar beet residue was dewatered by plate and frame filter press, and then spread out and dried to further prepare partially decomposed sugar beet residue and sugar beet residue biochar: 1) Preparation of partially decomposed sugar beet residue: 60 parts of dewatered sugar beet residue and 40 parts of sugar beet stem and leaf waste were mixed and crushed into 0.5 cm fragments. 2% (V / W) of functional microbial inoculum and 7% (V / W) of 20-fold diluted gulonic acid waste liquid were added to the fragments by atomizing spraying. The mixture was stacked into a stack with a height of 0.8 m. Ventilation pipes were arranged at the bottom of the stack. The moisture content of the material was adjusted to 56% (V / W). The surface of the stack was covered with tarpaulin for fermentation culture of the sugar beet residue. The stack was turned over every 6 days. Oxygen was supplied through the pipes every 2 days. The material was sampled every 3 days for monitoring. The total C and total N content ratio (TC / TN) of the mixed material sample was determined by a TC / TN analyzer. Meanwhile, a mixed material extract was prepared under the condition of a solid-liquid ratio of 1:10. The extract was added to a culture dish containing filter paper and kept moist. 100 cabbage seeds were inoculated on the moist filter paper and cultured in a 28°C incubator in the dark for 7 days. The number of germinated seeds was counted and the germination rate (GI = number of germinated seeds / total number of seeds planted) was calculated. When the material was stacked for 12 days, the TC / TN of the mixed material reached 23.2:1 and the GI value reached 67%, meeting the requirements of partially decomposed sugar beet residue material.

[0051] 2) Preparation of medium-temperature biochar from sugar beet residue: The sugar beet residue material was dewatered and dried at 120°C and crushed into 1.0-5.0 mm granular material. The dried and crushed material was pyrolyzed at 350°C under anaerobic conditions for 2h. After cooling, medium-temperature biochar was prepared from the sugar beet residue. 3) Preparation of high-temperature modified biochar from sugar beet residue: The material was pyrolyzed at 550°C under anaerobic conditions for 2h. After pyrolysis, the material was immersed in 1.0 mol / L -1 phosphoric acid solution and shaken at 120 rpm for 30 min to achieve acid modification. The acid-modified material was repeatedly washed with water until the pH of the washing solution reached 6.0-7.0. After dewatering and drying, high-temperature modified biochar was prepared from the sugar beet residue.

[0052] 4) The beet filter mud, peat, and water plant sludge were dried naturally and crushed, respectively. The crushed particle size of the beet filter mud was 1.0 mm, the crushed particle size of the peat was 5.0 mm, and the crushed particle size of the water plant sludge was 1.0 mm.

[0053] (2) The pretreated materials were respectively compounded to prepare the improver preformulation, see Figure 1 : 1) Preparation of alkali-removing plasticizing slow-release carbon-increasing agent, 100 parts of beet filter mud was mixed with 80 parts of gulonic acid waste liquid stock solution, the gulonic acid waste liquid stock solution was sprayed into the beet filter mud by atomization spraying until no air bubbles were generated, and the mixture was continuously stirred during the mixing process. Then, 20 parts of peat was slowly mixed in batches, the pH of the mixture was monitored and adjusted to 5.2, and the adjusted mixture was dried for standby; 2) Preparation of high-efficiency carbon-increasing and fertilizing agent, 100 parts of partially decomposed beet pulp material was mixed with 100 parts of 20-fold diluted gulonic acid waste liquid, the 20-fold diluted gulonic acid waste liquid was sprayed into the partially decomposed beet pulp material by atomization spraying, and the mixture was continuously stirred to ensure uniformity. Then, the mixed material was stacked into a heap shape and covered with tarpaulin for maturation for 3 days before standby; 3) Preparation of salt-controlling, carbon-fixing, and bacteria-preserving agent, 100 parts of beet pulp medium-temperature biochar, 50 parts of beet pulp high-temperature modified biochar, and 50 parts of water plant sludge material were mixed, and then the functional bacteria agent fermentation liquor was applied to the solid material by atomization spraying. It was determined that the microbial abundance in the solid material was 3.1 x 10 9 CFU·g -1 dry material, the mixture was continuously dried in a cool environment, and the water content of the mixture was 17%.

[0054] Application of composite improver in the improvement of soda saline soil in Example 2 The saline soil was collected from the administrative area of Duer Bort Mongol Autonomous County in Daqing City (N 46.11542783, E 124.20692781), which was a typical soda saline soil. In order to facilitate the disposal and control of the test, the saline soil was pretreated by artificial impurity removal, air drying, grinding, and sieving (2 mm) before standby. The total salt content of the homogenized saline soil was 1.6 ± 0.1% (W / W), and the main ions included Na + (3.26 g·Kg -1 ), K + (0.057 g·Kg -1 ), Ca 2+ (0.433 g·Kg -1 ), Mg 2+ (0.077 g·Kg -1 ), CO3 2-(2.01 g·Kg -1 - (0.187 g·Kg -1 - (0.76 g·Kg -1 2- (7.2 g·Kg -1 ), the content of organic matter was 0.41% (W / W), and the pH reached 10.26.

[0055] The collected soda saline soil was impurity-removed, dried, and crushed to form a simulated soil layer with a length of 1.5 m, a width of 1.5 m, and a height of 30 cm. The composite modifier was applied at a dose of 2%. The specific operation was as follows: 100 parts of the alkali-removing plasticizing slow-release carbon-increasing agent prepared in Example 1 was added to the soil, and after thorough mixing, the soil moisture was maintained at 12%. If the moisture was insufficient, water was added to maintain the moisture; a mulch film was covered on the saline soil layer, and the soil was incubated for 4 weeks while maintaining the soil moisture. Further, the soil was irrigated, and after the water was drained, the soil was dried and maintained at a moisture level of about 20%. Then, 250 parts of the strong carbon-increasing fertilizer prepared in Example 1 was applied, and the soil was mixed by rotary plowing to ensure that the soil and the agent were thoroughly mixed. The soil was naturally incubated for 4 weeks while maintaining the soil moisture at 15%. Finally, 200 parts of the salt-controlling carbon-fixing fungus-protecting agent prepared in Example 1 was applied, and the soil was mixed by rotary plowing. A mulch film was covered on the surface of the soil, and after incubation for 4 weeks, the mulch film was removed and the soil was naturally incubated for another 50 days. The results are shown in Table 1. Figure 2 .

[0056] The sugar beet seeds were planted in the incubated soda saline soil. The seeds were soaked in water for 12 hours, and after the water was discarded and the surface water of the seeds was absorbed, the seeds were ready for planting. The seeds were planted in the saline soil before and after the improvement (control) by hole planting, with a distance of 10 cm between two holes, and two seeds were planted in each hole. After planting, the soil was covered, and the seeds were pressed to make close contact with the soil. The soil surface was covered with a mulch film, and after two true leaves grew, the seedlings were manually removed from the film and continued to grow.

[0057] Effect evaluation of the soda saline soil improved by the composite modifier of Example 3 After the test seedlings provided in Example 2 grew for 12 days, the complete plants of the sugar beet seedlings were collected, and the saline soil samples were collected. The soil property indexes and the physiological index characteristics of the sugar beet were analyzed.

[0058] The BET analysis of the pore structure of the soil before and after the improvement showed that Figure 3 ​​​The adsorption-desorption isotherms of the unmodified saline-alkali soil exhibited a Type I characteristic, indicating that micropores composed of dispersed particles were dominant. The adsorption-desorption isotherms of the modified soil exhibited a Type IV characteristic, with a decreased proportion of micropores, but the pore structure was predominantly mesopores, with a significantly increased proportion, reflecting a well-structured pore structure in the modified soil. The specific surface area of ​​the original saline-alkali soil sample reached 8.0193 m². 2 / g, total pore volume reaches 0.0220cm³ 3 / g, with an average pore size of 6.9581nm, and a modified specific surface area of ​​11.4529m². 2 / g, total pore volume is 0.0288cm³ 3 The average pore size is 10.0542 nm, which are significantly improved compared to the previous version.

[0059] Regarding desalination effectiveness, the Na+ in the improved soil... + K + Ca 2+ Mg 2+ CO3 2- HCO3 - Cl - and SO4 2- The ion content decreased, and the total salt content dropped from 1.6% to 0.46%. Figure 4 Soil alkalinity decreased from 39.15% to 28.03%, and pH decreased from a strongly alkaline state of 10.26 to a slightly alkaline state of 7.95. Figure 5 This method achieved good desalination and alkali removal effects. Further analysis of the total organic carbon (SOC) content in the soil showed that the SOC decreased from 4.1 g·kg⁻¹. -1 Increased to 20.51g·Kg -1 ( Figure 6 The microbial residue carbon content (MNC) also increased from 1.435 g·kg. -1 Increased to 5.611 g·kg -1 ( Figure 7 The mineral-bound organic carbon (MAOC) content ranges from 2.665 g·kg⁻¹. -1 Increased to 3.837g·Kg -1 ( Figure 8 This reflects a significant improvement in the fertility of saline-alkali soil, represented by organic carbon content, after the application of compound soil conditioner. Furthermore, the organic carbon fixation effect is more pronounced, which is beneficial for the long-term stability of soil fertility. Twelve days after planting sugar beets, the average fresh weight of the underground parts of the sugar beet plants in the improved area and the initial saline-alkali soil were 0.0628 g and 0.0336 g, respectively. Figure 9 The fresh weights of the above-ground parts reached 1.701g and 0.604g respectively. Figure 9), indicating that the improved soil is more suitable for the growth of sugar beet, and the biomass is significantly improved; in addition, the photosynthetic pigment content (chlorophyll a + chlorophyll b + carotenoids) of sugar beet in the improved soil is also increased from 2.144 mg·g -1 (planting before improvement) to 4.250 mg·g -1 ( Figure 10 ), indicating that the physiological activity of the sugar beet plant growing in the improved saline soil is improved; the malondialdehyde content of the sugar beet plant in the improved soil is lower ( Figure 11 ), reflecting the reduction of inorganic ion and organic solute exudates in the sugar beet cell, the reduction of the damage degree of the plasma membrane, and the higher proline content ( Figure 11 ), revealing that the sugar beet planted in the improved soil has stronger osmotic regulation ability under saline stress.

[0060] Example 4 Effect comparison of saline soil composite improver under different application conditions According to the steps of Example 2, the treatments of only single application of alkali removal shaping slow-release carbon increasing agent (T1), strong carbon increasing and fertilizing agent (T2) and salt control carbon fixation and bacteria preservation agent (T3), as well as the application procedures of "alkali removal shaping slow-release carbon increasing agent + salt control carbon fixation and bacteria preservation agent + strong carbon increasing and fertilizing agent" (T1-3-2), "strong carbon increasing and fertilizing agent + alkali removal shaping slow-release carbon increasing agent + salt control carbon fixation and bacteria preservation agent" (T2-1-3), "strong carbon increasing and fertilizing agent + salt control carbon fixation and bacteria preservation agent + alkali removal shaping slow-release carbon increasing agent" (T2-3-1), "salt control carbon fixation and bacteria preservation agent + alkali removal shaping slow-release carbon increasing agent + strong carbon increasing and fertilizing agent" (T3-1-2) and "salt control carbon fixation and bacteria preservation agent + strong carbon increasing and fertilizing agent + alkali removal shaping slow-release carbon increasing agent" (T3-2-1) were used for saline soil treatment test, and the test effects were compared with the complete application effect (T1-2-3) of the composite improver of Example 2, and the soil sample before improvement (T0) was set. The total amount of the improver in each treatment was 2%, and the composite improver was applied according to the proportion shown in Table 1.

[0061] The test results show that the saline soil treatment according to the application procedure of "alkali removal shaping slow-release carbon increasing agent + strong carbon increasing and fertilizing agent + salt control carbon fixation and bacteria preservation agent" (T1-2-3) of Example 2 has the lowest Na + content and total salt ion content ( Figure 12 ), the best alkali removal effect ( Figure 13 ), and the highest organic carbon content ( Figure 14 ). Therefore, the optimal effect of soda saline soil improvement can be obtained only by using the composite improver provided by the application and the use procedure thereof.

[0062] Table 1 Single improver application dose in each treatment procedure (unit: part)

[0063] In summary, the present application prepares a multifunctional pre-made composite material by effectively pretreating and compounding various industrial and agricultural wastes, the prepared saline-alkali soil composite improver has good desalination, alkali removal and carbon increase effects, and through the application process design, the application method of the improver is constructed, which can be perfectly combined with salt-tolerant and salt-aggregating plant planting, such as sugar beet, to achieve multiple beneficial effects such as "salt reduction, alkali removal, carbon increase and soil fertilization", and good saline-alkali soil improvement effect and economic benefit are obtained, which has great popularization and application value and prospect.

Claims

1. A saline soil composite improver characterized in that: The saline-alkali soil composite improver is composed of alkali-removing plasticizing slow-release carbon-increasing agent, strong carbon-increasing and fertilizing agent and salt-controlling carbon-fixing and bacteria-preserving agent; wherein the alkali-removing plasticizing slow-release carbon-increasing agent is obtained by mixing beet filter mud and original solution of gulonic acid waste liquid with peat; the strong carbon-increasing and fertilizing agent is obtained by mixing partially rotted beet residue and 20 times diluted solution of gulonic acid waste liquid; and the salt-controlling carbon-fixing and bacteria-preserving agent is obtained by mixing beet residue medium-temperature biochar, beet residue high-temperature modified biochar and water plant bottom mud and then fermenting the mixture with functional bacteria agent.

2. The saline soil composite improver according to claim 1, characterized by: The use amount ratio of the alkali-removing plasticizing slow-release carbon-increasing agent, the strong carbon-increasing and fertilizing agent and the salt-controlling carbon-fixing and bacteria-preserving agent is 2-3:5-7:4-6.

3. The saline soil composite improver according to claim 1, characterized by: The partially rotted beet residue is prepared by beet residue bio-pile rotting; the pile rotting conditions are as follows: after dehydration, the beet residue dry matter is mixed with beet stem and leaf waste, and then gulonic acid waste liquid diluent and functional microorganism agent are added to carry out beet residue fermentation culture; when the C / N ratio of the mixture reaches 22:1-24:1 and the white cabbage seed germination rate GI in the material extract is greater than 60%, the partially rotted beet residue is obtained.

4. The saline soil composite improver according to claim 1, characterized by: The beet residue medium-temperature biochar is obtained by dehydrating and drying the beet residue and crushing it into 1.0-5.0 mm granular material; the granular material is pyrolyzed at 250-350℃ in an anaerobic environment for 2-3 hours to obtain the beet residue medium-temperature biochar.

5. The saline soil composite improver according to claim 1, characterized by: The beet residue high-temperature modified biochar is prepared by drying and crushing the beet residue into 1.0-5.0 mm granular materials; the granular materials are pyrolyzed at 500-600 DEG C without oxygen for 1-2 h, and then the materials are immersed in 1-2 mol / L -1 phosphoric acid solution after cooling; the beet residue high-temperature modified biochar is prepared after the materials are washed with water to pH 6.0-7.0 and dried.

6. The saline soil composite improver according to claim 1, characterized by: The water plant bottom mud is a water supply treatment sludge with a total iron (calculated as Fe2O3) and total manganese (calculated as MnO2) content ratio higher than 30%.

7. A preparation method of the saline-alkali soil composite improver according to claim 1, characterized in that: 1) Preparation of the alkali-removing plasticizing slow-release carbon-increasing agent: the beet filter mud is mixed with the original solution of gulonic acid waste liquid, the original solution of gulonic acid waste liquid is sprayed into the beet filter mud by atomization spraying until no air bubbles are generated, and then the peat is slowly mixed batch by batch, and the pH of the mixture is controlled to reach 4.5-5.5 for standby; 2) Preparation of the strong carbon-increasing and fertilizing agent: the partially rotted beet residue is mixed with 20 times diluted solution of gulonic acid waste liquid, the 20 times diluted solution of gulonic acid waste liquid is sprayed into the partially rotted beet residue by atomization spraying, and the mixture is stirred and mixed uniformly, and then the mixture is piled up into a pile and covered with tarpaulin for maturation before standby; 3) Salt control and carbon fixation bacteria preparation: Mix the medium-temperature biochar from sugar beet residue, high-temperature modified biochar from sugar beet residue, and water plant sediment thoroughly, then spray the functional bacteria fermentation broth into the solid material through atomization, so that the microbial abundance in the solid material reaches 10 9 -10 10 CFU·g -1 After air-drying and dehydration, the moisture content of the mixture is 20%-30%, ready for use.

8. Use of the saline soil composite improver according to claim 1, characterized in that: The composite improver is used for improving saline-alkali soil, and the application dose of the composite improver is 1%-5% of the mass of the soil to be treated.

9. Use of the saline soil composite improver according to claim 8, characterized in that: The alkali-removing plasticizing slow-release carbon-increasing agent is applied to the soil to be treated, and then mixed by deep ploughing, the soil humidity is maintained at 10%-15%, and incubation is carried out for 2-4 weeks, then the soil is irrigated and leached to remove sodium ions, after drainage, the strong carbon-increasing and fertilizing agent is applied, and then mixed by rotary ploughing, and incubation is continued for 2-4 weeks, finally the salt-controlling carbon-fixing and bacteria-preserving agent is applied, thereby realizing the improvement of saline-alkali soil.

10. The use of the saline soil composite improver according to claim 9, characterized in that: During the application of the saline-alkali soil composite improver or after the application of the saline-alkali soil composite improver, salt-tolerant crops are planted for further ecological restoration.

Images