A method for soil fertility recovery after soil electrokinetic remediation and application thereof
By adjusting soil pH in different zones and precisely replenishing nutrients, the problems of soil acid-base imbalance and nutrient loss after electro-remediation were solved, achieving rapid restoration of soil fertility and structural improvement, meeting the needs of farmland reclamation, and reducing environmental risks.
Patent Information
- Application Number
- CN202610924623.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-25
- Publication Date
- 2026-08-25
AI Technical Summary
After electro-remediation, soil pH becomes disordered and nutrients are lost, leading to a sharp drop in soil fertility. Existing technologies are unable to achieve rapid and stable fertility recovery, hindering the engineering application of electro-remediation technology and the safe utilization of remediated farmland.
By adopting a zoned differentiated method of acid-base adjustment, combined with precise supplementation of nitrogen, phosphorus, and potassium fertilizers, using natural organic acids and biochar to regulate soil pH, and improving soil structure through tillage and mulching, soil fertility can be rapidly restored.
It has achieved stable soil pH within the suitable growth range for crops, nutrient content that meets the standards for replanting, shortened the recovery period, reduced fertilizer use, avoided secondary pollution, and improved soil structure and crop growth performance.
Smart Images
Figure CN122623484A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of soil remediation and improvement technology, and in particular to a method for restoring soil fertility after soil electroremediation and its application. Background Technology
[0002] Paddy fields are the core area of my country's grain production, but cadmium pollution in them has become a major hidden danger restricting sustainable agricultural development and food security. Electrokinetic remediation technology, with its advantages of high remediation efficiency, controllable secondary pollution, and rapid reduction of heavy metals, has become one of the core technologies for cadmium pollution control in paddy fields. However, engineering practice shows that the electrokinetic remediation process can cause drastic changes in the soil's physicochemical properties:
[0003] On the one hand, the electrode hydrolysis reaction leads to the generation of a large amount of H⁺ in the anode area, resulting in severe soil acidification; on the other hand, the cathode area is enriched with OH⁻, resulting in strong soil alkalinization. The extreme pH environment will destroy the soil aggregate structure, inhibit microbial activity, and directly hinder crop growth.
[0004] On the other hand, the electric field-driven effect causes charged nutrient molecules such as nitrogen, phosphorus, and potassium in the soil to migrate and be lost in a specific direction, resulting in a sharp drop in soil fertility after restoration, weak crop plants, reduced biomass, and inability to directly meet the requirements for recultivation.
[0005] Currently, soil improvement after electroremediation often relies on single measures: while applying chemical fertilizers can replenish nutrients in the short term, it cannot fundamentally solve the pH imbalance problem, and excessive fertilization can easily lead to soil compaction, nitrate leaching, and eutrophication of water bodies; while single acid-base adjustment can improve soil pH, it cannot compensate for nutrient deficiencies, and the adjustment effect is prone to rebound. Existing technologies lack a systematic solution targeting the "pH zonal imbalance and synergistic nutrient loss" characteristics after electroremediation, making it difficult to achieve rapid and stable restoration of soil fertility, which seriously restricts the engineering application of electroremediation technology and the safe utilization of remediated farmland. Based on this, a method for restoring soil fertility after electroremediation has been developed. This method involves differentiated acid-base adjustment in different zones while simultaneously replenishing basic nutrients, precisely applying nitrogen, phosphorus, and potassium, and applying structural modifiers to synergistically improve soil pH, nutrients, and soil structure, rapidly restoring fertility and enabling safe recultivation of remediated farmland. Summary of the Invention
[0006] This invention discloses a method for restoring soil fertility after electro-remediation and its application, which effectively solves the problems of traditional technology being unable to differentiate the pH of electro-remediated soil by region, and the inability to synchronize pH adjustment, nutrient replenishment, and structural improvement, resulting in slow fertility recovery and delayed farmland reclamation.
[0007] The technical implementation scheme of the present invention is as follows:
[0008] A method for restoring soil fertility after electroremediation includes the following steps:
[0009] S1. Soil basic parameter testing: The soil after electro-remediation was divided into zones, and the pH value, available nitrogen, available phosphorus, available potassium content and moisture content of the soil in each zone were tested.
[0010] S2, Precise pH Adjustment: Based on the soil pH value of each region, differentiated reagents are used to adjust the pH to achieve the suitable growth range for crops;
[0011] S3. Precise Nutrient Supplementation: Based on the detection and analysis of nutrient deficit, combined with the nutrient amount brought in during pH adjustment, calculate and supplement nitrogen, phosphorus, and potassium fertilizers;
[0012] S4. Soil structure improvement and maintenance: Add soil conditioner to the soil, till and mix evenly, adjust soil moisture content, cover with film for maintenance, and complete soil fertility restoration.
[0013] As a further description of the above technical solution, in step S1, the soil is divided into three zones: an anode zone, a transition zone, and a cathode zone.
[0014] As a further description of the above technical solution, in step S2, the soil pH value is adjusted to the suitable growth range of crops, which is 6.0-7.5; when adjusting the pH of the anode zone: when the soil pH is <5.5, a compound solution of ammonium carbonate and potassium phosphate is used for adjustment, with a mass ratio of (2-3):1; the adjustment method is: spraying and stirring at the same time during the adjustment process until the pH reaches 6.0-7.0.
[0015] As a further description of the above technical solution, in step S2, when adjusting the pH of the cathode area: when the soil pH > 8.0, a compound solution of lactic acid and citric acid is used for adjustment, with a compound mass ratio of (1-2):1; the adjustment method is: spraying and stirring at the same time during the adjustment process until the pH reaches 6.5-7.5.
[0016] As a further description of the above technical solution, in step S2, if the pH of the transition zone soil is between 5.5 and 8.0, no additional adjustment is required, as it will be naturally buffered through the subsequent nutrient replenishment process.
[0017] As a further description of the above technical solution, in step S3, the adjusted soil alkaline available nitrogen is ≥90mg / kg, available phosphorus is ≥10mg / kg, and available potassium is ≥100mg / kg.
[0018] As a further description of the above technical solution, in step S3, the nitrogen source is selected from at least one of urea and ammonium carbonate; the phosphorus source is selected from at least one of superphosphate and potassium dihydrogen phosphate; the potassium source is selected from at least one of potassium chloride and potassium phosphate; in step S3, the nitrogen brought in by ammonium carbonate and the phosphorus and potassium brought in by potassium phosphate during the pH adjustment process need to be deducted from the total amount of fertilizer applied.
[0019] As a further description of the above technical solution, in S4, the soil conditioner is a biochar made from fruit shells or straw, with a particle size of 300-400 mesh and an addition amount of 10-30 g / kg soil.
[0020] As a further description of the above technical solution, the soil moisture content is adjusted to 40%-60%, and the soil is covered with film for 7-14 days for curing.
[0021] The above-described methods for soil fertility restoration after electroremediation are applied in the restoration of soil fertility and farmland reclamation in heavy metal contaminated farmland after electroremediation.
[0022] The present invention has the following advantages:
[0023] 1. Precise and efficient pH regulation: By adopting a zoned differentiated regulation strategy, the problem of polarization of soil pH after electrokinetic remediation is solved. The regulated soil pH is stable within the suitable growth range for crops, with no rebound phenomenon.
[0024] 2. Synergistic nutrient supplementation: The pH adjusting reagent itself carries nutrients, achieving synergistic "pH correction + nutrient supplementation", reducing the amount of chemical fertilizer applied and lowering costs;
[0025] 3. Rapid fertility recovery: After 7-14 days of maintenance, the soil pH and nitrogen, phosphorus and potassium content can reach the standards for paddy field recultivation, shortening the recovery period by more than 50% compared with traditional single measures;
[0026] 4. Environmentally friendly and free of secondary pollution: It uses natural organic acids and nutrient-based conditioning agents. The biochar is derived from agricultural waste and has no toxic or harmful residues, thus avoiding the risk of secondary pollution from traditional chemical amendments.
[0027] 5. Simultaneous improvement of soil structure: The addition of biochar can improve soil aggregate structure, enhance soil water and fertilizer retention capacity, and provide a good microenvironment for crop growth. After restoration, the rice plant height, root length and biomass are significantly better than those of traditional fertilization treatment. Attached Figure Description
[0028] Figure 1 This is a comparison chart of soil pH changes after electroremediation in different treatment groups according to the present invention.
[0029] Figure 2This is a comparison chart of soil nitrogen, phosphorus, and potassium nutrient content in different treatment groups according to the present invention.
[0030] Figure 3 This is a comparison chart of the growth status of rice seedlings in different treatment groups after 14 days. Detailed Implementation
[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below. It is hereby declared that all reagents used are commercially available analytical grade or agricultural grade products, and experimental methods without specified conditions are conventional techniques in the field.
[0032] Example 1:
[0033] Regarding the restoration of soil fertility in paddy fields in the anode zone after electro-remediation:
[0034] The first step involved taking soil samples from the anode area of a cadmium-contaminated paddy field in southern China after electrokinetic remediation. Tests showed that the soil had a pH of 4.8, available nitrogen content of 32 mg / kg, available phosphorus content of 4.5 mg / kg, available potassium content of 58 mg / kg, and a moisture content of 45%.
[0035] The second step is pH adjustment: Prepare a compound aqueous solution of ammonium carbonate and potassium phosphate in a mass ratio of 2.5:1, and spray it while tilling the soil until the soil pH reaches 6.5; it is calculated that this adjustment introduces 18 mg / kg of nitrogen, 12 mg / kg of phosphorus, and 15 mg / kg of potassium.
[0036] The third step is nutrient supplementation: based on the amount of nutrient deficiency, apply 120 kg / hm² of urea, 80 kg / hm² of superphosphate, and 60 kg / hm² of potassium chloride, and mix them evenly after tilling.
[0037] Step 4, Soil Improvement and Maintenance: Add 20g / kg of 325-mesh straw biochar to the soil, plow to a depth of 15cm, adjust the soil moisture content to 50%, and cover with film for maintenance for 10 days.
[0038] It should be noted that, in view of the different characteristics of anodic acidification and cathodic alkalization, nutrient-based acid-base regulating agents are used: ammonium carbonate applied to the anodic area can neutralize H⁺ and supplement nitrogen at the same time; potassium phosphate can provide phosphorus and potassium nutrients, and phosphate ions have a pH buffering effect.
[0039] It should be further explained that by detecting the background nutrient content of the soil and deducting the nutrients introduced by pH adjustment, nitrogen, phosphorus and potassium can be supplemented as needed, avoiding resource waste and environmental pollution caused by excessive fertilization, while ensuring soil nutrient balance and meeting the needs of crop growth.
[0040] Example 2:
[0041] Regarding the restoration of soil fertility in the cathode area of paddy fields after electrostatic remediation:
[0042] The first step involved taking soil samples from the cathodic area of a cadmium-contaminated paddy field in southern China after electrokinetic remediation. Tests showed that the soil had a pH of 8.6, a available nitrogen content of 28 mg / kg, an available phosphorus content of 3.2 mg / kg, a available potassium content of 62 mg / kg, and a moisture content of 48%.
[0043] The second step is to adjust the pH of the sample: prepare a compound aqueous solution with a mass ratio of lactic acid to citric acid of 1.5:1, spray it while tilling the soil until the soil pH reaches 7.2;
[0044] The third step is nutrient supplementation: based on the amount of nutrient deficiency, apply 130 kg / hm² of urea, 90 kg / hm² of potassium dihydrogen phosphate, and 55 kg / hm² of potassium chloride, and mix them evenly after tilling.
[0045] Step 4, Soil Improvement and Maintenance: Add 25g / kg of 325-mesh straw biochar to the soil, plow to a depth of 15cm, adjust the soil moisture content to 50%, and cover with film for maintenance for 12 days.
[0046] It should be noted that the regulation mechanism used in the cathode area is different from that in the anode area. The lactic acid and citric acid applied in the cathode area are natural small-molecule organic acids that can quickly neutralize OH⁻. Their decomposition products are carbon dioxide and water, which do not cause secondary pollution. At the same time, they can activate the phosphorus and potassium elements fixed in the soil and improve the availability of nutrients.
[0047] It should be noted that biochar has a porous structure and a huge specific surface area, which can adsorb acid and alkali ions in the soil and prevent pH rebound; at the same time, it provides a habitat for soil microorganisms, promotes microbial activity, accelerates soil nutrient cycling, and improves soil fertility in the long term.
[0048] Example 3
[0049] For soil fertility restoration in anode zones without biochar addition:
[0050] The first step involved taking soil samples from the anode area of a cadmium-contaminated paddy field in southern China after electrokinetic remediation. Tests showed that the soil had a pH of 4.8, available nitrogen content of 32 mg / kg, available phosphorus content of 4.5 mg / kg, available potassium content of 58 mg / kg, and a moisture content of 45%.
[0051] The second step is pH adjustment: Prepare a compound aqueous solution of ammonium carbonate and potassium phosphate in a mass ratio of 2.5:1, and spray it while tilling the soil until the soil pH reaches 6.5; it is calculated that this adjustment introduces 18 mg / kg of nitrogen, 12 mg / kg of phosphorus, and 15 mg / kg of potassium.
[0052] The third step is nutrient supplementation: based on the amount of nutrient deficiency, apply 120 kg / hm² of urea, 80 kg / hm² of superphosphate, and 60 kg / hm² of potassium chloride, and mix them evenly after tilling.
[0053] Step 4, Soil Improvement and Maintenance: Till the soil to a depth of 15cm, adjust the soil moisture content to 50%, and cover with mulch for 10 days.
[0054] Comparative experiment:
[0055] Comparative Example 1: For the anodic acidified soil after electro-remediation (same as the soil in Example 1), no improvement treatment was performed, and it was left to stand for 10 days;
[0056] The purpose of the experiment was to obtain data on the original deteriorated soil substrate after electro-remediation, to serve as a benchmark for all improvement groups, to visually demonstrate the degree of damage to soil fertility caused by electro-remediation itself, and to make comparisons based on the specific plant growth status.
[0057] Comparative Example 2: For the anodic acidified soil after electro-remediation (same as the soil in Example 1), apply 150 kg / hm² of urea, 120 kg / hm² of superphosphate, and 90 kg / hm² of potassium chloride in one application, mix well, and let stand for 10 days;
[0058] Experimental objective: In the traditional method, simply applying chemical fertilizers without pH adjustment, and observing fertilizer utilization and plant growth status in subsequent experiments, to prove that it is impossible to effectively restore the fertility of acidified soil after electro-remediation.
[0059] Comparative Example 3: For the anodic acidified soil after electro-remediation (same as the soil in Example 1), pH adjustment treatment was performed using an ammonium carbonate-potassium phosphate compound solution to adjust the pH to 6.5, without adding any additional nutrients, and left for 10 days; no additional nitrogen, phosphorus, or potassium nutrients were added, and no soil conditioner was added;
[0060] Experimental objective: Although the acidification problem was solved, the electro-remediation process resulted in a significant loss of basic nitrogen, phosphorus, and potassium nutrients in the soil. Adjusting the pH alone did not address the nutrient deficiency in the soil, which could not meet the needs of crop replanting.
[0061] Performance testing:
[0062] Soil physicochemical properties: After the curing period, the soil pH value, available nitrogen, available phosphorus, and available potassium content were measured.
[0063] Rice growth experiment: Rice seedlings were planted in soil that had been treated with preservatives and cultured. After 14 days of culture, plant height, root length and above-ground dry weight were measured.
[0064] Test results showed that the soil pH of both Example 1 and Example 2 remained stable between 6.5 and 7.2, and the contents of available nitrogen, available phosphorus, and available potassium all met the standards for paddy field recultivation. The rice plant height increased by more than 75% compared with the control group, the root length increased by more than 60%, and the aboveground dry weight increased by more than 80%. Moreover, the cadmium content of the rice plants was not significantly different from that of the soil planting group after simple electric remediation, and all met the national food safety standards.
[0065] The soil pH in Example 3 showed a slight rebound after 30 days of cultivation, and the rice biomass was slightly lower than that in Example 1, demonstrating that biochar has the effect of stabilizing pH and long-term improvement.
[0066] The following is a record of the experimental comparison:
[0067] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 pH value 6.6 7.1 6.9 4.8 4.9 6.5 Alkaline nitrogen (mg / kg) 94.5 92.4 91.5 32.0 98.4 37.3 Available phosphorus (mg / kg) 13.1 13.5 12.7 4.5 15.1 5.4 Available potassium (mg / kg) 114.2 117.3 111.3 58.0 136.3 74.5 Plant height (cm) 19.4 18.8 16.8 10.2 12.5 13.8 Root length (cm) 12.1 12.5 9.9 7.1 8.1 8.8 Dry weight of aerial parts (mg) 26.7 24.9 20.1 14.7 15.4 16.7
[0068] Compared with the above embodiments, the pH value of Embodiment 1 and Embodiment 2 can be maintained between 6.5 and 7.2. Moreover, the plant height and root length in Embodiment 1 and Embodiment 2 both exceed those of traditional fertilization methods. Therefore, in this application, the area is first divided by pH value, and then the pH value is adjusted to the range of 6.0-7.5. Combined with the soil nutrient deficit and the nutrients brought in by pH adjustment, nitrogen, phosphorus and potassium fertilizers are applied. After adding soil conditioner and adjusting the moisture content, the soil is covered with film for maintenance, thus completing the fertility restoration method. This method can restore soil fertility quickly and improve soil structure simultaneously.
[0069] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.
Claims
1. A method for restoring soil fertility after electro-remediation of soil, characterized in that, Includes the following steps: S1. Soil basic parameter testing: The soil after electro-remediation was divided into zones, and the pH value, available nitrogen, available phosphorus, available potassium content and moisture content of the soil in each zone were tested. S2, Precise pH Adjustment: Based on the soil pH value of each region, differentiated reagents are used to adjust the pH to achieve the suitable growth range for crops; S3. Precise Nutrient Supplementation: Based on the detection and analysis of nutrient deficit, combined with the nutrient amount brought in during pH adjustment, calculate and supplement nitrogen, phosphorus, and potassium fertilizers; S4. Soil structure improvement and maintenance: Add soil conditioner to the soil, till and mix evenly, adjust soil moisture content, cover with film for maintenance, and complete soil fertility restoration.
2. The method for restoring soil fertility after electro-remediation of soil according to claim 1, characterized in that, In step S1, the soil is divided into three zones: an anode zone, a transition zone, and a cathode zone.
3. A method for restoring soil fertility after electro-remediation of soil according to claim 1, characterized in that, In step S2, the soil pH value is adjusted to the suitable growth range of crops, which is 6.0-7.
5. When adjusting the pH of the anode zone: when the soil pH is <5.5, a compound solution of ammonium carbonate and potassium phosphate is used for adjustment, with a mass ratio of (2-3):
1. The adjustment method is as follows: spray and stir simultaneously during the adjustment process until the pH reaches 6.0-7.
0.
4. A method for restoring soil fertility after electro-remediation of soil according to claim 3, characterized in that, In step S2, when adjusting the pH of the cathode area: when the soil pH > 8.0, a compound solution of lactic acid and citric acid is used for adjustment, with a mass ratio of (1-2):
1. The adjustment method is as follows: spray and stir simultaneously during the adjustment process until the pH reaches 6.5-7.
5.
5. A method for restoring soil fertility after electro-remediation of soil according to claim 4, characterized in that, In step S2, if the pH of the transition zone soil is between 5.5 and 8.0, no additional adjustment is required, as it will be naturally buffered by the subsequent nutrient replenishment process. A method for restoring soil fertility after electro-remediation of soil according to claim 1, characterized in that, in step S3, the adjusted soil alkaline nitrogen is ≥90mg / kg, available phosphorus is ≥10mg / kg, and available potassium is ≥100mg / kg.
6. A method for restoring soil fertility after electro-remediation of soil according to claim 1, characterized in that, In step S3, the nitrogen source is selected from at least one of urea and ammonium carbonate. The phosphorus source is selected from at least one of superphosphate and potassium dihydrogen phosphate; The potassium source is selected from at least one of potassium chloride and potassium phosphate; In step S3, the nitrogen introduced by ammonium carbonate and the phosphorus and potassium introduced by potassium phosphate during the pH adjustment process need to be deducted from the total amount of fertilizer applied.
7. A method for restoring soil fertility after electro-remediation of soil according to claim 1, characterized in that, In step S4, the soil conditioner is a biochar made from fruit shells or straw, with a particle size of 300-400 mesh, and an application rate of 10-30 g / kg of soil.
8. A method for restoring soil fertility after electro-remediation of soil according to claim 1, characterized in that, The soil moisture content is adjusted to 40%-60%, and the soil is covered with film for 7-14 days for curing.
9. The method for soil fertility restoration after electroremediation of soil according to any one of claims 1 to 8 is applied to the restoration of soil fertility after electroremediation of heavy metal pollution in farmland.