Nitrogen and phosphorus loss prevention and control method for sandy and dry cultivated land based on EICP root reinforcement combined with sandy and dry cultivated land

Abstract

The invention provides a method for preventing and controlling nitrogen and phosphorus loss of sandy and dry cultivated land based on EICP root reinforcement and relates to the field of soil ecological protection and agricultural pollution prevention and control. According to the method, a three-dimensional prevention and control system is formed from the two dimensions of surface layer film covering protection and deep root system soil fixation through the synergistic effect of EICP film covering and local plant root system three-dimensional reinforcement, wind erosion and water erosion are effectively resisted, the soil nitrogen and phosphorus loss rate of the large-gradient sandy and dry cultivated land is remarkably reduced, and meanwhile the soil desertification process is slowed down; the EICP film covering layer has good water permeability and moisture retention, nitrogen and phosphorus loss can be prevented, rainfall infiltration and soil moisture conservation can be guaranteed, and the germination rate and the growth speed of crops are increased; according to the method, local crop root system reinforcement is selected, the original planting structure is not disturbed, the economic benefit of cultivated land yield per mu is guaranteed, a harmless means of combining microorganisms, geotechnical engineering and agricultural planting is adopted, external pollution sources are not introduced, original basic characteristics of soil are not damaged, and the requirement for ecological protection of the Yellow River basin is met.

Description

Technical Field

[0001] This invention relates to the field of soil ecological protection and agricultural pollution control technology, specifically to a method for controlling nitrogen and phosphorus loss in sandy and dry farmland based on EICP-based root reinforcement. Background Technology

[0002] Ecological protection and restoration of the Yellow River Basin is a crucial ecological strategic task for my country, with the prevention and control of soil nitrogen and phosphorus loss pollution being a key focus. In some areas along the Yellow River Basin, there are large sloping, sandy, and arid farmlands. These farmlands suffer from severely declining soil organic fertility, prominent desertification, and exacerbated soil erosion, leading to significant losses of nitrogen and phosphorus nutrients. This nitrogen and phosphorus loss not only reduces the economic benefits of farmland per acre but also contributes to eutrophication of the Yellow River, disrupting the ecological balance of the basin.

[0003] Existing soil nitrogen and phosphorus loss control technologies mostly approach the issue from a single perspective, such as ecology, botany, chemistry, or physical methods. These technologies have drawbacks, including limited effectiveness, poor adaptability, and the potential to damage the original soil properties or introduce external pollution sources. For example, while traditional physical mulching techniques can reduce soil erosion to some extent, their poor permeability affects crop growth. Single-plant protection techniques are insufficient for soil stabilization on steep, sandy, and dry farmland, and are unable to effectively curb nitrogen and phosphorus loss through runoff or wind.

[0004] EICP (urease-induced calcium carbonate precipitation) technology, as a microbial solidification technology, has been applied in desert sand fixation, roadbed treatment, cultural relic restoration, concrete repair, and soil improvement. Its core advantage is the formation of a solidified layer with good mechanical properties and permeability. However, there is still no research on applying this technology to the agricultural field to achieve the coordinated development of nitrogen and phosphorus loss control in arable land and crop growth. Meanwhile, although the three-dimensional reinforcement technology of native plant roots has been initially explored in the field of geotechnical engineering, research on combining it with microbial technology for the control of nitrogen and phosphorus loss in sandy and arid arable land to form a standardized and green solution remains lacking.

[0005] Therefore, to address the severe nitrogen and phosphorus loss in sloping sandy and dry farmland and the ineffectiveness of existing control technologies, it is necessary to develop a combined control technology that considers control effectiveness, crop growth needs, and ecological safety to support ecological protection and high-quality development in the Yellow River Basin. Therefore, a combined nitrogen and phosphorus loss control method based on EICP root reinforcement and combined with other technologies is proposed for sandy and dry farmland. Summary of the Invention

[0006] The purpose of this invention is to address the problems raised in the existing background technology. To achieve the above-mentioned objective, this invention provides the following technical solution: a method for controlling nitrogen and phosphorus loss in sandy and dryland farmland based on EICP root reinforcement, comprising the following steps: Step 1: Preliminary investigation and parameter adaptation, investigating the soil characteristics, farming methods, crop types, fertilization status and meteorological conditions of the target area's steep sandy and dryland farmland, and determining the basic adaptation parameters of EICP mulching technology and native plant root three-dimensional reinforcement technology; Step 2: Modification and optimization of the EICP reaction system. Based on the survey data from Step 1, a local mineral-based modifier is added to the EICP reaction system to regulate the reaction rate and the mineralization of the coating layer. Step 3: EICP mulching construction. Based on the parameters determined in Step 1 and the modified EICP reaction system in Step 2, a segmented and layered spraying process is used to form a calcified hard crust mulching layer on the surface of the cultivated land. Step 4: Pretreatment of native plant seeds. After screening native crop seeds, seeds are soaked in EICP reaction byproducts to improve seed stress resistance and root growth rate after germination. Step 5: Construction of three-dimensional reinforcement of native plant root system. Based on the parameters determined in Step 1 and the pretreated seeds in Step 4, the plants are planted in an intercropping mode to form a three-dimensional reinforcement network of root system in the cultivated soil. Step 6: Coordinated regulation and maintenance, matching the implementation sequence of steps 3 and 5, and carrying out targeted maintenance and management of the mulch layer and crop root system; Step 7: Enhanced dynamic interception of nitrogen and phosphorus loss. Root-mulch synergistic interception strips are deployed in key runoff areas on farmland slopes to dynamically intercept lost nitrogen and phosphorus nutrients. Step 8: Standardize monitoring and optimization, formulate full-process monitoring specifications, continuously monitor the control effect and iteratively optimize technical parameters based on monitoring data; the nitrogen and phosphorus loss rate control target of the method satisfies the formula: ; in, The percentage of nitrogen and phosphorus loss after the application of combined technologies. The original nitrogen and phosphorus loss rate (%) without the use of any control technologies. The coefficient of influence of coating thickness (%·cm) -2 The value ranges from 0.008 to 0.012, where d is the thickness (cm) of the calcified hard shell coating layer. The influence coefficient of root reinforcement density (%·(g·cm)) -3 ) -1.5 The value ranges from 0.015 to 0.025. The root trunk density (g·cm³) of the three-dimensional reinforced root network -3 ), The influence coefficient of the amount of modifier added (%·(g·kg)) -1 ) -0.8 The value ranges from 0.005 to 0.015. The amount of local mineral-based modifier added (g·kg) -1 ), This is the slope correction factor, with a value ranging from 0.8 to 1.2. The slope of the cultivated land is in degrees (°). The value is the influence coefficient of relative soil moisture content, ranging from 0.08 to 0.12. Soil relative moisture content (%) =Actual soil moisture content / Saturated soil moisture content × 100%) Meanwhile, the modification effect evaluation of the EICP reaction system satisfies the formula: ; in, This is an evaluation index for the modification effect (unitless, value range 0-1). The compressive strength (kPa) of the unmodified EICP coating layer. The compressive strength (kPa) of the modified EICP coating layer. The moisture retention rate (%) of the unmodified EICP coating layer. The percentage of moisture retention of the modified EICP coating is %.

[0007] As a preferred technical solution of the present invention, the preliminary research and parameter adaptation in step 1 specifically includes the following steps: Step 1.1: Soil and environmental parameter survey, test the soil texture, fertility, pH value, desertification degree and slope of the target area, collect the average annual rainfall and wind speed meteorological data of the area, and record the conventional farming methods, fertilizer types and amounts, and main crop varieties. Step 1.2: Determine basic parameters. Based on the survey results, determine the initial concentration range of the EICP reaction system, the target thickness of the mulch layer, the screening criteria for native crops, the core parameters of the intercropping pattern, and the types of native mineral-based modifiers.

[0008] As a preferred technical solution of the present invention, the modification and optimization of the EICP reaction system in step 2 specifically includes the following steps: Step 2.1: Modifier pretreatment. The screened local mineral-based modifier is crushed to a particle size ≤200 mesh and dried at 105℃ for 2-3 hours before use. Step 2.2: Preparation of the modified system. According to the parameters determined in Step 1, first prepare the basic EICP reaction system with urease concentration of 0.5-1.0 U / mL, urea concentration of 0.5-1.0 mol / L, and calcium chloride concentration of 0.5-1.0 mol / L. Then add the pretreated local mineral-based modifier to the basic system, stir evenly, and let it stand for 30-60 minutes to activate. The amount of modifier added, m, needs to be dynamically adjusted according to the degree of soil desertification. Step 3: The specific steps for EICP membrane application are as follows: Step 3.1: Spray in sections and layers. The total spraying amount V0 per acre needs to be calculated and determined based on the film thickness, soil bulk density and porosity. Step 3.2: Curing and shaping. After the final spraying, allow the plant to cure naturally for 7 days to form a calcified hard shell coating layer with a thickness of 1-2 cm.

[0009] As a preferred technical solution of the present invention, the pretreatment of native plant seeds in step 4 includes the following steps: Step 4.1: Seed screening and disinfection. Select plump, undamaged local crop seeds, disinfect them by soaking them in a 5% sodium hypochlorite solution for 10-15 minutes, rinse them with clean water and drain. Step 4.2: Preparation of EICP byproduct soaking solution. Collect the clear liquid after the EICP reaction is completed. It contains trace amounts of ammonia nitrogen and calcium ions. Dilute it at a volume ratio of 1:5 to obtain the soaking solution. Step 4.3: Seed soaking treatment. Place the disinfected seeds into the soaking solution and soak them at a constant temperature of 25-30℃ for 6-8 hours. After soaking, remove them and air dry them for later use. Step 5, the three-dimensional reinforcement of native plant root systems, specifically includes the following steps: Step 5.1: Crop combination determination. Select native crops in the target area that have both deep vertical roots and horizontal extension characteristics, and determine the combination type of deep-rooted crops and shallow-rooted crops. Step 5.2: Intercropping pattern design. Based on the slope of the cultivated land and the degree of soil desertification, determine the crop intercropping density and row spacing parameters. The intercropping density D must satisfy the formula: ; in, Total intercropping density (plants / acre). The basic intercropping density (plants / acre) is set at 14,000–18,000 plants / acre. The slope of the cultivated land is in degrees (°). The degree of soil desertification (%) The thickness of the mulch layer is (cm); and the intercropping density can be broken down into deep-rooted crop density and shallow-rooted crop density, satisfying the formula: ; in, Planting density (plants / acre) for deep-rooted crops. Planting density for shallow-rooted crops (plants / acre); Step 5.3: Sowing and initial management. Sow the pretreated seeds according to the designed intercropping pattern, apply organic fertilizer and carry out initial field management to promote crop root growth, ensuring that the longitudinal root depth h1 of deep-rooted crops is ≥30cm and the lateral root extension width h2 of shallow-rooted crops is ≥20cm, forming a uniformly distributed three-dimensional reinforced network.

[0010] As a preferred technical solution of the present invention, the crop combination in step 5.1 is as follows: millet is selected as the deep-rooted crop, and soybean is selected as the shallow-rooted intercropping crop; the row spacing parameters in step 5.2 are as follows: the row spacing of millet is 50cm, and soybeans are intercropped between the millet rows with a row spacing of 25cm; the sowing time is selected after the EICP film covering construction is completed and cured in step 3 to ensure that the film layer structure is not damaged during the sowing process; and the germination rate of seeds after soaking treatment is ≥90%.

[0011] As a preferred technical solution of the present invention, step 6, the coordinated regulation and maintenance, specifically includes the following steps: Step 6.1: Time-series coordinated management to ensure that crop sowing is carried out only after the EICP film covering construction is completed and cured for 7 days, with a curing time t≥7 days; Step 6.2: Repair of the mulch layer. During the later stages of crop growth, regularly inspect the integrity of the mulch layer. If damage occurs, use the modified EICP reaction system for re-spraying and repair. The amount of re-spraying Vᵣ needs to be determined comprehensively based on the degree of damage, soil characteristics and meteorological conditions. Step 6.3: Root care. Adjust the amount of fertilizer and irrigation method according to the crop growth cycle, apply organic fertilizer that is compatible with the EICP system to promote continuous root growth, enhance the interlocking effect between the root system and the soil, and at the same time avoid the impact of chemical fertilizers on the performance of the mulch layer. Step 7, the dynamic interception and enhancement of nitrogen and phosphorus loss, specifically includes the following steps: Step 7.1: Deployment of interception strips. Layout a root-mulch synergistic interception strip every 10-15m on the farmland slope. The width of the interception strip is 50-80cm. Adopt a composite structure of mulch and densely planted shallow-root crops. The spacing L of the interception strips needs to be optimized according to the slope and rainfall intensity. Step 7.2: Dynamic control. Based on seasonal changes in rainfall, strengthen the spraying of the mulch layer and crop maintenance in the interception zone before the flood season to improve the interception effect.

[0012] As a preferred technical solution of the present invention, the standardization monitoring and optimization in step 8 specifically includes the following steps: Step 8.1: Development of monitoring standards. Based on topographic features, soil properties, meteorological conditions and crop types, develop standardized technical standards covering the entire process of technology selection, construction operation, maintenance management and effect monitoring. Add monitoring indicators for the effect of modifiers, the effect of seed pretreatment and the interception efficiency of interception strips. Step 8.2: Periodic monitoring. The monitoring period T needs to be dynamically adjusted according to the season and meteorological conditions. The monitoring indicators include soil nitrogen and phosphorus content, integrity and performance of the mulch layer, root growth status, soil and water loss, nitrogen and phosphorus interception in the interception zone, and crop yield. Step 8.3: Optimize the scheme. Based on the monitoring data, adjust the modification parameters of the EICP reaction system, seed pretreatment conditions, crop intercropping patterns, spacing of interception strips, and maintenance methods. Iterate and improve the standardized technical scheme to ensure that the nitrogen and phosphorus loss control effect is stable and meets the standards.

[0013] As a preferred technical solution of the present invention, the calcified hard shell coating layer formed in step 3 needs to meet the following performance requirements: water permeability coefficient k ≥ 1 × 10⁻⁶ -4 cm / s, moisture retention rate ω≥60%, wind erosion resistance ≥15m / s, and bonding strength with soil ≥25kPa; the film layer can reduce soil moisture evaporation, ensure rainfall infiltration, and prevent nitrogen and phosphorus nutrients carried by the surface soil from being lost by wind or runoff. After being modified with local minerals, the crack resistance of the film layer is improved by more than 20% compared with the unmodified layer.

[0014] As a preferred technical solution of the present invention, the three-dimensional root reinforcement network formed in step 5 needs to meet the following performance requirements: wind erosion resistance improvement Δv ≥ 30%, water erosion resistance improvement Δq ≥ 40%; Crop roots that have undergone seed soaking pretreatment with EICP byproducts show a biomass increase of more than 25% compared to untreated roots. This network can significantly slow down the rate of soil desertification, promote the absorption of nitrogen and phosphorus by crops, and reduce nitrogen and phosphorus loss at the source.

[0015] As a preferred technical solution of the present invention, the method is applicable to sandy and dry farmland with steep slopes in the Yellow River Basin. The applicable conditions are: farmland slope α≥15°, soil desertification degree s≥20%, where desertification degree s is the percentage of sand content in the total mass of soil; the implementation of the technology does not introduce external pollution sources, does not damage the original basic characteristics of the soil, and does not disrupt the local crop planting structure. It adopts harmless means that combine microbial technology, geotechnical engineering technology and agricultural planting technology; and the economic benefits per mu of farmland after the application of the technology increase ΔY≥15%.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Significant control effect: Through the synergistic effect of EICP mulching technology and local plant root three-dimensional reinforcement technology, a three-dimensional control system is formed from two dimensions: surface mulching protection and deep root soil fixation. This effectively resists wind erosion and water erosion, significantly reduces the soil nitrogen and phosphorus loss rate of sandy dry farmland with large slopes, and slows down the process of soil desertification. (2) Adapting to agricultural production needs: The EICP film layer has good water permeability and moisture retention, which can prevent nitrogen and phosphorus loss, ensure rainwater infiltration and soil moisture retention, and improve the germination rate and growth rate of crops; the use of local crop root reinforcement technology does not disrupt the original planting structure and ensures the economic benefits of arable land per mu. (3) Green ecological safety: The entire technical solution adopts harmless means that combine microbial technology, geotechnical engineering technology and agricultural planting technology, without introducing external pollution sources, without damaging the original basic characteristics of the soil, and meets the requirements of ecological protection in the Yellow River Basin. (4) Standardization and promotion: Standardized application solutions adapted to the characteristics of cultivated land in specific regions can be formed. Through verification and promotion in demonstration bases, these solutions can not only serve as a model for the treatment of nitrogen and phosphorus loss in soil, but also provide technical guidance for the restoration of soil degradation in other sandy and arid cultivated land in the Yellow River Basin. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the method flow provided by the present invention; Figure 2 A schematic diagram illustrating the specific steps of parameter adaptation provided by this invention; Figure 3 This is a schematic diagram of the modification and optimization steps of the EICP reaction system provided by the present invention; Figure 4 This is a schematic diagram of the EICP coating construction steps provided by the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention.

[0019] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely illustrates some embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments and features and technical solutions in the embodiments of the present invention can be combined with each other. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0020] Example 1: A method for controlling nitrogen and phosphorus loss in sandy and dry farmland based on EICP root reinforcement, including the following steps: Step 1: Preliminary investigation and parameter adaptation, investigate the soil characteristics, farming methods, crop types, fertilization and meteorological conditions of the target area's steep sandy and dry farmland, and determine the basic adaptation parameters of EICP mulching technology and native plant root three-dimensional reinforcement technology. Step 2: Modification and optimization of the EICP reaction system. Based on the survey data from Step 1, a local mineral-based modifier is added to the EICP reaction system to regulate the reaction rate and the mineralization of the coating layer. Step 3: EICP mulching construction. Based on the parameters determined in Step 1 and the modified EICP reaction system in Step 2, a segmented and layered spraying process is used to form a calcified hard crust mulching layer on the surface of the cultivated land. Step 4: Pretreatment of native plant seeds. After screening native crop seeds, seeds are soaked in EICP reaction byproducts to improve seed stress resistance and root growth rate after germination. Step 5: Construction of three-dimensional reinforcement of native plant root system. Based on the parameters determined in Step 1 and the pretreated seeds in Step 4, the plants are planted in an intercropping mode to form a three-dimensional reinforcement network of root system in the cultivated soil. Step 6: Coordinated regulation and maintenance, matching the implementation sequence of steps 3 and 5, and carrying out targeted maintenance and management of the mulch layer and crop root system; Step 7: Enhanced dynamic interception of nitrogen and phosphorus loss. Root-mulch synergistic interception strips are deployed in key runoff areas on farmland slopes to dynamically intercept lost nitrogen and phosphorus nutrients. Step 8: Standardize monitoring and optimization, formulate full-process monitoring specifications, continuously monitor the control effect and iteratively optimize technical parameters based on monitoring data; the nitrogen and phosphorus loss rate control target of the method satisfies the formula: ; in, The percentage of nitrogen and phosphorus loss after the application of combined technologies. The original nitrogen and phosphorus loss rate (%) without the use of any control technologies. The coefficient of influence of coating thickness (%·cm) -2 The value ranges from 0.008 to 0.012, where d is the thickness (cm) of the calcified hard shell coating layer. The influence coefficient of root reinforcement density (%·(g·cm)) -3 ) -1.5 The value ranges from 0.015 to 0.025. The root trunk density (g·cm³) of the three-dimensional reinforced root network -3 ), The influence coefficient of the amount of modifier added (%·(g·kg)) -1 ) -0.8 The value ranges from 0.005 to 0.015. The amount of local mineral-based modifier added (g·kg) -1 ), This is the slope correction factor, with a value ranging from 0.8 to 1.2. The slope of the cultivated land is in degrees (°). The value is the influence coefficient of relative soil moisture content, ranging from 0.08 to 0.12. Soil relative moisture content (%) =Actual soil moisture content / Saturated soil moisture content × 100%) Meanwhile, the modification effect evaluation of the EICP reaction system satisfies the formula: ; in, This is an evaluation index for the modification effect (unitless, value range 0-1). The compressive strength (kPa) of the unmodified EICP coating layer. The compressive strength (kPa) of the modified EICP coating layer. The moisture retention rate (%) of the unmodified EICP coating layer. The percentage of moisture retention of the modified EICP coating is %.

[0021] Step 1, the preliminary research and parameter adaptation, specifically includes the following steps: Step 1.1: Soil and environmental parameter survey, test the soil texture, fertility, pH value, desertification degree and slope of the target area, collect the average annual rainfall and wind speed meteorological data of the area, and record the conventional farming methods, fertilizer types and amounts, and main crop varieties. Step 1.2: Determine basic parameters. Based on the survey results, determine the initial concentration range of the EICP reaction system, the target thickness of the mulch layer, the screening criteria for native crops, the core parameters of the intercropping pattern, and the types of native mineral-based modifiers.

[0022] Step 2, the modification and optimization of the EICP reaction system, specifically includes the following steps: Step 2.1: Modifier pretreatment. The screened local mineral-based modifier is crushed to a particle size ≤200 mesh and dried at 105℃ for 2-3 hours before use. Step 2.2: Preparation of the modified system. According to the parameters determined in Step 1, first prepare the basic EICP reaction system with urease concentration of 0.5-1.0 U / mL, urea concentration of 0.5-1.0 mol / L, and calcium chloride concentration of 0.5-1.0 mol / L. Then add the pretreated local mineral-based modifier to the basic system, stir evenly, and let it stand for 30-60 minutes to activate. The amount of modifier added, m, needs to be dynamically adjusted according to the degree of soil desertification. Step 3: The specific steps for EICP membrane application are as follows: Step 3.1: Spray in sections and layers. The total spraying amount V0 per acre needs to be calculated and determined based on the film thickness, soil bulk density and porosity. Step 3.2: Curing and shaping. After the final spraying, allow the plant to cure naturally for 7 days to form a calcified hard shell coating layer with a thickness of 1-2 cm.

[0023] Step 4, the pretreatment of native plant seeds, includes the following steps: Step 4.1: Seed screening and disinfection. Select plump, undamaged local crop seeds, disinfect them by soaking them in a 5% sodium hypochlorite solution for 10-15 minutes, rinse them with clean water and drain. Step 4.2: Preparation of EICP byproduct soaking solution. Collect the clear liquid after the EICP reaction is completed. It contains trace amounts of ammonia nitrogen and calcium ions. Dilute it at a volume ratio of 1:5 to obtain the soaking solution. Step 4.3: Seed soaking treatment. Place the disinfected seeds into the soaking solution and soak them at a constant temperature of 25-30℃ for 6-8 hours. After soaking, remove them and air dry them for later use. Step 5, the three-dimensional reinforcement of native plant root systems, specifically includes the following steps: Step 5.1: Crop combination determination. Select native crops in the target area that have both deep vertical roots and horizontal extension characteristics, and determine the combination type of deep-rooted crops and shallow-rooted crops. Step 5.2: Intercropping pattern design. Based on the slope of the cultivated land and the degree of soil desertification, determine the crop intercropping density and row spacing parameters. The intercropping density D must satisfy the formula: ; in, Total intercropping density (plants / acre). The basic intercropping density (plants / acre) is set at 14,000–18,000 plants / acre. The slope of the cultivated land is in degrees (°). The degree of soil desertification (%) The thickness of the mulch layer is (cm); and the intercropping density can be broken down into deep-rooted crop density and shallow-rooted crop density, satisfying the formula: ; in, Planting density (plants / acre) for deep-rooted crops. Planting density for shallow-rooted crops (plants / acre); Step 5.3: Sowing and initial management. Sow the pretreated seeds according to the designed intercropping pattern, apply organic fertilizer and carry out initial field management to promote crop root growth, ensuring that the longitudinal root depth h1 of deep-rooted crops is ≥30cm and the lateral root extension width h2 of shallow-rooted crops is ≥20cm, forming a uniformly distributed three-dimensional reinforced network.

[0024] The crop combination in step 5.1 is as follows: millet is selected as the deep-rooted crop, and soybean is selected as the shallow-rooted intercropping crop; the row spacing parameters in step 5.2 are as follows: millet row spacing is 50cm, and soybean is intercropped between millet rows with a row spacing of 25cm; the sowing time is selected after the EICP film covering construction in step 3 is completed and cured to ensure that the film covering layer structure is not damaged during the sowing process; and the germination rate of seeds after soaking treatment is ≥90%.

[0025] Step 6, coordinated regulation and maintenance, specifically includes the following steps: Step 6.1: Time-series coordinated management to ensure that crop sowing is carried out only after the EICP film covering construction is completed and cured for 7 days, with a curing time t≥7 days; Step 6.2: Repair of the mulch layer. During the later stages of crop growth, regularly inspect the integrity of the mulch layer. If damage occurs, use the modified EICP reaction system for re-spraying and repair. The amount of re-spraying Vᵣ needs to be determined comprehensively based on the degree of damage, soil characteristics and meteorological conditions. Step 6.3: Root care. Adjust the amount of fertilizer and irrigation method according to the crop growth cycle, apply organic fertilizer that is compatible with the EICP system to promote continuous root growth, enhance the interlocking effect between the root system and the soil, and at the same time avoid the impact of chemical fertilizers on the performance of the mulch layer. Step 7, the dynamic interception and enhancement of nitrogen and phosphorus loss, specifically includes the following steps: Step 7.1: Deployment of interception strips. Layout a root-mulch synergistic interception strip every 10-15m on the farmland slope. The width of the interception strip is 50-80cm. Adopt a composite structure of mulch and densely planted shallow-root crops. The spacing L of the interception strips needs to be optimized according to the slope and rainfall intensity. Step 7.2: Dynamic control. Based on seasonal changes in rainfall, strengthen the spraying of the mulch layer and crop maintenance in the interception zone before the flood season to improve the interception effect.

[0026] Step 8, standardization monitoring and optimization, specifically includes the following steps: Step 8.1: Development of monitoring standards. Based on topographic features, soil properties, meteorological conditions and crop types, develop standardized technical standards covering the entire process of technology selection, construction operation, maintenance management and effect monitoring. Add monitoring indicators for the effect of modifiers, the effect of seed pretreatment and the interception efficiency of interception strips. Step 8.2: Periodic monitoring. The monitoring period T needs to be dynamically adjusted according to the season and meteorological conditions. The monitoring indicators include soil nitrogen and phosphorus content, integrity and performance of the mulch layer, root growth status, soil and water loss, nitrogen and phosphorus interception in the interception zone, and crop yield. Step 8.3: Optimize the scheme. Based on the monitoring data, adjust the modification parameters of the EICP reaction system, seed pretreatment conditions, crop intercropping patterns, spacing of interception strips, and maintenance methods. Iterate and improve the standardized technical scheme to ensure that the nitrogen and phosphorus loss control effect is stable and meets the standards.

[0027] The calcified hard shell coating layer formed in step 3 must meet the following performance requirements: water permeability coefficient k ≥ 1 × 10⁻⁶ - 4 cm / s, moisture retention rate ω≥60%, wind erosion resistance ≥15m / s, and bonding strength with soil ≥25kPa; the film layer can reduce soil moisture evaporation, ensure rainfall infiltration, and prevent nitrogen and phosphorus nutrients carried by the surface soil from being lost by wind or runoff. After being modified with local minerals, the crack resistance of the film layer is improved by more than 20% compared with the unmodified layer.

[0028] The three-dimensional root reinforcement network formed in step 5 must meet the following performance requirements: wind erosion resistance improvement Δv ≥ 30%, water erosion resistance improvement Δq ≥ 40%; Crop roots that have undergone seed soaking pretreatment with EICP byproducts show a biomass increase of more than 25% compared to untreated roots. This network can significantly slow down the rate of soil desertification, promote the absorption of nitrogen and phosphorus by crops, and reduce nitrogen and phosphorus loss at the source.

[0029] The method is applicable to sandy and dry farmland with steep slopes in the Yellow River Basin. The applicable conditions are: farmland slope α≥15°, soil desertification degree s≥20%, where s is the percentage of sand content in the total mass of soil; the implementation of the technology does not introduce external pollution sources, does not damage the original basic characteristics of the soil, and does not disrupt the local crop planting structure. It adopts harmless means that combine microbial technology, geotechnical engineering technology and agricultural planting technology; and the economic benefits per mu of farmland after the application of the technology increase ΔY≥15%.

[0030] Example 2: A method for controlling nitrogen and phosphorus loss in sandy and dry farmland based on EICP root reinforcement. Implementation preparation: (1) Preliminary investigation: Conduct a comprehensive investigation of the soil characteristics (soil texture, fertility, pH value), farming methods, fertilization, meteorological data (rainfall, wind speed) and farmland slope of the target area to determine the core prevention and control needs of the large-slope sandy dry farmland in the area; (2) Site selection and construction of demonstration base: Select a representative plot of land in the target area to build a demonstration base with an area of ​​50 mu and a slope of 25°~30°, and install soil moisture sensors, nitrogen and phosphorus content detectors and soil erosion monitoring devices. (3) Material and crop preparation: Prepare EICP reaction system materials (urease, urea, calcium chloride) and spraying equipment; screen local deep-rooted crops (millet) and shallow-rooted intercropping crops (soybean) as crop varieties for three-dimensional root reinforcement.

[0031] Implementation of EICP soil mulching technology: (1) Parameter determination: Based on the preliminary survey data, the concentration of the EICP reaction system was determined to be urease 0.5~1.0U / mL, urea 0.5~1.0mol / L, calcium chloride 0.5~1.0mol / L, and the coating thickness was controlled to be 1.5cm; (2) Construction timing: EICP spraying should be carried out 10 to 15 days before spring sowing, when the soil moisture is suitable, to avoid damage to the mulch layer during subsequent sowing; (3) Construction process: adopt the segmented spraying method, with a spraying amount of 200~300L per mu, sprayed in 3 times, with an interval of 24 hours between each spraying, and naturally cured for 7 days after spraying to form a calcified hard shell coating layer.

[0032] Implementation of three-dimensional soil stabilization technology for native crop roots: (1) Planting pattern: The millet and soybean intercropping pattern is adopted. The millet row spacing is 50cm, and the soybean is intercropped between the millet rows with a row spacing of 25cm, forming a three-dimensional root network with deep vertical penetration (millet root system) and horizontal extension (soybean root system). (2) Planting management: Sowing, fertilization (using organic fertilizer to avoid the impact of chemical fertilizers on EICP response) and field management are carried out in accordance with local conventional farming methods to promote crop root growth; (3) Growth monitoring: Regularly monitor the growth status of crop roots, including root depth, distribution density and degree of contact with soil.

[0033] Joint technology and coordinated regulation: (1) Timing coordination: Ensure that the EICP mulching construction is completed and cured before sowing crops to avoid damaging the mulch layer during the sowing process; if the mulch layer is partially damaged in the later stage of crop growth, repair spraying should be carried out in conjunction with field management. (2) Parameter optimization: Adjust the frequency and amount of EICP mulching, as well as the amount of fertilizer and irrigation method of crops, based on monitoring data to ensure that the performance of the mulch layer is compatible with root growth. (3) Benefit monitoring: Continuously monitor the soil nitrogen and phosphorus loss rate, soil moisture content and crop yield indicators of the demonstration base, and compare them with the control plots that did not use the technology of this invention to verify the control effect and economic benefits of the combined technology.

[0034] Based on the implementation data from the demonstration base, the technical standards were revised and improved to form a standardized application manual covering the entire process, including preliminary research, parameter design, construction operation, maintenance management, and monitoring and evaluation. The manual clarifies the key technical points of EICP mulching parameters, crop selection, and intercropping patterns under different slopes and soil types, so as to promote its application in similar sandy and dry farmland in the Yellow River Basin.

[0035] The implementation period for this embodiment was three years. The first year involved preliminary research, demonstration base construction, and optimization of key technical parameters. The second year saw the full implementation of the joint technical solution and monitoring. The third year saw the development of a standardized plan and its demonstration and promotion. Results showed that nitrogen and phosphorus loss from cultivated land in the target area decreased by more than 60%, soil desertification slowed by more than 50%, and yields of corn and millet increased by more than 15%, achieving a win-win situation for both ecological and economic benefits.

[0036] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the specific embodiments described above. Therefore, any modifications or substitutions to the present invention, as well as all technical solutions and improvements that do not depart from the spirit and scope of the invention, are covered within the scope of the claims of the present invention.

Claims

1. A method for controlling nitrogen and phosphorus loss in sandy and dry farmland based on EICP root reinforcement, characterized in that: Includes the following steps: Step 1: Preliminary investigation and parameter adaptation. Investigate the soil characteristics, farming methods, crop types, fertilization status and meteorological conditions of the target area's steep sandy dryland farmland to determine the basic adaptation parameters between EICP mulching technology and the three-dimensional reinforcement technology for native plant roots. Step 2: Modification and optimization of the EICP reaction system. Based on the survey data from Step 1, a local mineral-based modifier is added to the EICP reaction system to regulate the reaction rate and the mineralization of the coating layer. Step 3: EICP mulching construction. Based on the parameters determined in Step 1 and the modified EICP reaction system in Step 2, a segmented and layered spraying process is used to form a calcified hard crust mulching layer on the surface of the cultivated land. Step 4: Pretreatment of native plant seeds. After screening native crop seeds, seeds are soaked in EICP reaction byproducts to improve seed stress resistance and root growth rate after germination. Step 5: Construction of three-dimensional reinforcement of native plant root system. Based on the parameters determined in Step 1 and the pretreated seeds in Step 4, the plants are planted in an intercropping mode to form a three-dimensional reinforcement network of root system in the cultivated soil. Step 6: Coordinated regulation and maintenance, matching the implementation sequence of steps 3 and 5, and carrying out targeted maintenance and management of the mulch layer and crop root system; Step 7: Enhanced dynamic interception of nitrogen and phosphorus loss. Root-mulch synergistic interception strips are deployed in key runoff areas on farmland slopes to dynamically intercept lost nitrogen and phosphorus nutrients. Step 8: Standardize monitoring and optimization, formulate full-process monitoring specifications, continuously monitor the control effect and iteratively optimize technical parameters based on monitoring data; the nitrogen and phosphorus loss rate control target of the method satisfies the formula: ； in, The percentage of nitrogen and phosphorus loss after the application of combined technologies. The original nitrogen and phosphorus loss rate (%) without the use of any control technologies. The coefficient of influence of coating thickness (%·cm) -2 The value ranges from 0.008 to 0.012, where d is the thickness (cm) of the calcified hard shell coating layer. The influence coefficient of root reinforcement density (%·(g·cm)) -3 ) -1.5 The value ranges from 0.015 to 0.

025. The root trunk density (g·cm³) of the three-dimensional reinforced root network -3 ), The influence coefficient of the amount of modifier added (%·(g·kg)) -1 ) -0.8 The value ranges from 0.005 to 0.

015. The amount of local mineral-based modifier added (g·kg) -1 ), This is the slope correction factor, with a value ranging from 0.8 to 1.

2. The slope of the cultivated land is in degrees (°). The value is the influence coefficient of relative soil moisture content, ranging from 0.08 to 0.

12. Soil relative moisture content (%) =Actual soil moisture content / Saturated soil moisture content × 100%) Meanwhile, the modification effect evaluation of the EICP reaction system satisfies the formula: ； in, This is an evaluation index for the modification effect (unitless, value range 0-1). The compressive strength (kPa) of the unmodified EICP coating layer. The compressive strength (kPa) of the modified EICP coating layer. The moisture retention rate (%) of the unmodified EICP coating layer. The percentage of moisture retention of the modified EICP coating is %.

2. The method for controlling nitrogen and phosphorus loss in sandy and dryland farmland based on EICP root reinforcement combined with the method described in claim 1, characterized in that, The preliminary research and parameter adaptation in step 1 specifically includes the following steps: Step 1.1: Soil and environmental parameter survey, test the soil texture, fertility, pH value, desertification degree and slope of the target area farmland, collect the average annual rainfall and wind speed meteorological data of the area, and record the conventional farming methods, fertilizer types and amounts, and main crop varieties. Step 1.2: Determine basic parameters. Based on the survey results, determine the initial concentration range of the EICP reaction system, the target thickness of the mulch layer, the screening criteria for native crops, the core parameters of the intercropping pattern, and the types of native mineral-based modifiers.

3. The method for controlling nitrogen and phosphorus loss in sandy and dryland farmland based on EICP root reinforcement combined with the method described in claim 1, characterized in that, The EICP reaction system modification and optimization in step 2 specifically includes the following steps: Step 2.1: Modifier pretreatment. The screened local mineral-based modifier is crushed to a particle size ≤200 mesh and dried at 105℃ for 2-3 hours before use. Step 2.2: Preparation of the modified system. According to the parameters determined in Step 1, first prepare the basic EICP reaction system with urease concentration of 0.5-1.0 U / mL, urea concentration of 0.5-1.0 mol / L, and calcium chloride concentration of 0.5-1.0 mol / L. Then add the pretreated local mineral-based modifier to the basic system, stir evenly, and let it stand for 30-60 minutes to activate. The amount of modifier added, m, needs to be dynamically adjusted according to the degree of soil desertification. Step 3: The specific steps for EICP membrane application are as follows: Step 3.1: Spray in sections and layers. The total spraying amount V0 per acre needs to be calculated and determined based on the film thickness, soil bulk density and porosity. Step 3.2: Curing and shaping. After the final spraying, allow the plant to cure naturally for 7 days to form a calcified hard shell coating layer with a thickness of 1-2 cm.

4. The method for controlling nitrogen and phosphorus loss in sandy and dryland farmland based on EICP root reinforcement and according to claim 1, characterized in that, Step 4, the pretreatment of native plant seeds, includes the following steps: Step 4.1: Seed screening and disinfection. Select plump, undamaged local crop seeds, disinfect them by soaking them in a 5% sodium hypochlorite solution for 10-15 minutes, rinse them with clean water and drain. Step 4.2: Preparation of EICP byproduct soaking solution. Collect the clear liquid after the EICP reaction is completed. It contains trace amounts of ammonia nitrogen and calcium ions. Dilute it at a volume ratio of 1:5 to obtain the soaking solution. Step 4.3: Seed soaking treatment. Place the disinfected seeds into the soaking solution and soak them at a constant temperature of 25-30℃ for 6-8 hours. After soaking, remove them and air dry them for later use. Step 5, the three-dimensional reinforcement of native plant root systems, specifically includes the following steps: Step 5.1: Crop combination determination. Select native crops in the target area that have both deep vertical roots and horizontal extension characteristics, and determine the combination type of deep-rooted crops and shallow-rooted crops. Step 5.2: Intercropping pattern design. Based on the slope of the cultivated land and the degree of soil desertification, determine the crop intercropping density and row spacing parameters. The intercropping density D must satisfy the formula: ； in, Total intercropping density (plants / acre). The basic intercropping density (plants / acre) is set at 14,000–18,000 plants / acre. The slope of the cultivated land is in degrees (°). The degree of soil desertification (%) The thickness of the mulch layer is (cm); and the intercropping density can be broken down into deep-rooted crop density and shallow-rooted crop density, satisfying the formula: ； in, Planting density (plants / acre) for deep-rooted crops. Planting density for shallow-rooted crops (plants / acre); Step 5.3: Sowing and initial management. Sow the pretreated seeds according to the designed intercropping pattern, apply organic fertilizer and carry out initial field management to promote crop root growth, ensuring that the longitudinal root depth h1 of deep-rooted crops is ≥30cm and the lateral root extension width h2 of shallow-rooted crops is ≥20cm, forming a uniformly distributed three-dimensional reinforced network.

5. The method for controlling nitrogen and phosphorus loss in sandy and dryland farmland based on EICP root reinforcement and according to claim 4, characterized in that, The crop combination in step 5.1 is as follows: millet is selected as the deep-rooted crop, and soybean is selected as the shallow-rooted intercropping crop; the row spacing parameters in step 5.2 are as follows: the row spacing of millet is 50cm, and soybeans are intercropped between the millet rows with a row spacing of 25cm; the sowing time is selected after the EICP film covering construction in step 3 is completed and cured to ensure that the film layer structure is not damaged during the sowing process; and the germination rate of seeds after soaking treatment is ≥90%.

6. The method for controlling nitrogen and phosphorus loss in sandy and dryland farmland based on EICP root reinforcement according to claim 1, characterized in that, The coordinated regulation and maintenance in step 6 specifically includes the following steps: Step 6.1: Time-series coordinated management to ensure that crop sowing is carried out only after the EICP film covering construction is completed and cured for 7 days, with a curing time t≥7 days; Step 6.2: Repair of the mulch layer. During the later stages of crop growth, regularly inspect the integrity of the mulch layer. If damage occurs, use the modified EICP reaction system for re-spraying and repair. The amount of re-spraying Vᵣ needs to be determined comprehensively based on the degree of damage, soil characteristics and meteorological conditions. Step 6.3: Root care. Adjust the amount of fertilizer and irrigation method according to the crop growth cycle. Apply organic fertilizer that is compatible with the EICP system to promote continuous root growth and enhance the interlocking effect between the root system and the soil. At the same time, avoid the impact of chemical fertilizers on the performance of the mulch layer. Step 7, the dynamic interception and enhancement of nitrogen and phosphorus loss, specifically includes the following steps: Step 7.1: Deployment of interception strips. Layout a root-mulch synergistic interception strip every 10-15m on the farmland slope. The width of the interception strip is 50-80cm. Adopt a composite structure of mulch and densely planted shallow-root crops. The spacing L of the interception strips needs to be optimized according to the slope and rainfall intensity. Step 7.2: Dynamic control. Based on seasonal changes in rainfall, strengthen the spraying of the mulch layer and crop maintenance in the interception zone before the flood season to improve the interception effect.

7. The method for controlling nitrogen and phosphorus loss in sandy and dryland farmland based on EICP root reinforcement according to claim 1, characterized in that, The standardized monitoring and optimization in step 8 specifically includes the following steps: Step 8.1: Development of monitoring standards. Based on topographic features, soil properties, meteorological conditions and crop types, develop standardized technical standards covering the entire process of technology selection, construction operation, maintenance management and effect monitoring. Add monitoring indicators for the effect of modifiers, the effect of seed pretreatment and the interception efficiency of interception strips. Step 8.2: Periodic monitoring. The monitoring period T needs to be dynamically adjusted according to the season and meteorological conditions. The monitoring indicators include soil nitrogen and phosphorus content, integrity and performance of the mulch layer, root growth status, soil and water loss, nitrogen and phosphorus interception in the interception zone, and crop yield. Step 8.3: Optimize the scheme. Based on the monitoring data, adjust the modification parameters of the EICP reaction system, seed pretreatment conditions, crop intercropping patterns, spacing of interception strips, and maintenance methods. Iterate and improve the standardized technical scheme to ensure that the nitrogen and phosphorus loss control effect is stable and meets the standards.

8. The method for controlling nitrogen and phosphorus loss in sandy and dryland farmland based on EICP root reinforcement and according to claim 1, characterized in that, The calcified hard shell coating layer formed in step 3 must meet the following performance requirements: water permeability coefficient k ≥ 1 × 10⁻⁶ - 4 cm / s, moisture retention rate ω≥60%, wind erosion resistance strength≥15m / s, and bonding strength with soil≥25kPa; the film layer can reduce soil moisture evaporation, ensure rainfall infiltration, and prevent nitrogen and phosphorus nutrients carried by the surface soil from being lost by wind or runoff. After being modified with local minerals, the crack resistance of the film layer is improved by more than 20% compared with the unmodified layer.

9. The method for controlling nitrogen and phosphorus loss in sandy and dryland farmland based on EICP root reinforcement according to claim 1, characterized in that, The three-dimensional root reinforcement network formed in step 5 must meet the following performance requirements: wind erosion resistance improvement Δv ≥ 30%, water erosion resistance improvement Δq ≥ 40%; Crop roots that have undergone seed soaking pretreatment with EICP byproducts show a biomass increase of more than 25% compared to untreated roots. This network can significantly slow down the rate of soil desertification, promote the absorption of nitrogen and phosphorus by crops, and reduce nitrogen and phosphorus loss at the source.

10. The method for controlling nitrogen and phosphorus loss in sandy and dryland farmland based on EICP root reinforcement and according to claim 1, characterized in that, The method is applicable to sandy and dry farmland with steep slopes in the Yellow River Basin. The applicable conditions are: farmland slope α ≥ 15°, soil desertification degree s ≥ 20%, and desertification degree s is the percentage of sand content to total soil mass. The technology implementation process does not introduce external pollution sources, does not damage the original basic characteristics of the soil, and does not disrupt the local crop planting structure. It adopts harmless methods that combine microbial technology, geotechnical engineering technology and agricultural planting technology; and the economic benefits per mu of cultivated land after the application of the technology increase by ΔY≥15%.

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