CN-122003998-A - Soda saline-alkali soil improvement method for electrodynamic combined aluminum sulfate application

CN122003998ACN 122003998 ACN122003998 ACN 122003998ACN-122003998-A

Abstract

The invention discloses a soda saline-alkali soil improvement method by electrodynamic combined aluminum sulfate application, which comprises the steps of applying an aluminum sulfate modifier to soda saline-alkali soil to enable the aluminum sulfate modifier to be distributed in surface layer or plough layer soil, burying an anode on the soil surface layer of the soda saline-alkali soil, burying a cathode below a target improvement depth to form a vertical or approximately vertical electrode system, and applying a direct current electric field to the soil to realize electric improvement of the soda saline-alkali soil, wherein moisture replenishment is provided for the soil in the electric improvement process. The method improves the soil structure by aluminum sulfate, combines electroosmosis effect and electromigration effect generated under the action of an external electric field, enhances migration capability of moisture and salt in low permeability soil, and transfers aluminum-based ions to the cathode side under the action of the electric field, so as to relieve the problems of salt enrichment and aggravation of alkalization degree which are easy to occur in the cathode region in the electric improvement process, thereby realizing effective removal of salt and exchangeable sodium in soda saline-alkali soil.

Inventors

DU CHENXIN
ZHANG ZIJIE
Jia Renhao
LI XIAOPENG
LIU JIANLI
ZHANG JIABAO

Assignees

中国科学院南京土壤研究所

Dates

Publication Date: 20260512
Application Date: 20260206

Claims (7)

1. A method for modifying soda saline-alkali soil applied electrokinetically in combination with aluminum sulfate, characterized in that the method comprises the steps of; (1) Applying aluminum sulfate modifier in soda saline-alkali soil to make it be distributed in surface layer or cultivated layer soil; (2) Burying an anode on the soil surface layer of soda saline-alkali soil, burying a cathode below the target improvement depth, and forming a vertical or nearly vertical electrode system; (3) And applying a direct current electric field to the soil body so as to realize electric improvement of soda saline-alkali soil, and supplying water to the soil body in the electric improvement process.
2. The method for improving soda saline-alkali soil according to claim 1, wherein the application amount of the aluminum sulfate improver is 0.1-2.0 wt.% based on dry weight of soil.
3. The method for improving soda saline-alkali soil according to claim 1, wherein the DC electric field is formed by connecting a stabilized DC power supply with an anode and a cathode.
4. The method for improving soda saline-alkali soil according to claim 1, wherein the potential gradient of the direct current electric field is 0.6-2.4V/cm, and the duration of the power-on is 7-60 days.
5. The method for improving soda saline-alkali soil according to claim 4, wherein sufficient water is supplied to the soil body by means of surface irrigation or shallow water maintenance during the electric improvement.
6. The method for improving soda saline-alkali soil of claim 5, wherein the criterion for providing sufficient water supply is to maintain the soil moisture in a saturated or substantially saturated state.
7. The soda saline-alkali soil improvement method as claimed in any one of claims 1 to 6 wherein a drain structure is provided at the cathode to drain water and salt migrating to the vicinity of the cathode.

Description

Soda saline-alkali soil improvement method for electrodynamic combined aluminum sulfate application Technical Field The invention relates to a soda saline-alkali soil improvement method for electrodynamic combined aluminum sulfate application, and belongs to the technical field of soil improvement. Background Soil salinization is a major problem related to agricultural production safety, and the saline-alkali soil area of the world is about 1.1 multiplied by 10 9hm2 at present, and the saline-alkali soil area of China is about 3.69 multiplied by 10 7hm2. The saline-alkali soil has the characteristics of poor pore connectivity, aggregate structural damage, low organic matter content and the like, is typical low-and-medium-yield field soil, and restricts the land productivity and agricultural sustainable development. The improvement of the saline-alkali soil has important significance for improving the agricultural productivity and guaranteeing the grain safety. Soda saline-alkali soil contains a large amount of exchangeable Na +、HCO3- and CO 32-, and soil has higher pH and ESP (soil alkalization degree). The Na + in the soil has the advantages that the soil colloid is easier to disperse when meeting water, the macropores of the soil are reduced, the water permeability is poor, the CO 32- is alkaline after hydrolysis, the electrostatic repulsive force among soil particles is increased under the high-pH environment, and the aggregate structure of the soil is further destroyed, so that the ideal effect is difficult to achieve when the traditional irrigation salt washing is applied to soda saline-alkali soil improvement. Meanwhile, the high pH and the contents of HCO 3- and CO 32- also reduce the activity of metal cations in the modifier, which leads to the need of increasing the application amount and increasing the input cost when the chemical modifier (gypsum, aluminum sulfate, ferrous sulfate and the like) is applied to severe soda saline-alkali soil. In recent years, electrokinetic improvement technology has been applied to the field of soil remediation as a means for promoting ion migration and electroosmotic flow using a direct current electric field, and has shown a potential in low permeability soil improvement. The electric repair has the advantages that the in-situ repair of the soil can be performed, the physical disturbance in the soil repair process is reduced, and meanwhile, the movement of water in the low-permeability soil can be remarkably enhanced. The electric improved saline-alkali soil achieves good salt removal and alkali reduction effects at the anode, but the electrode reaction generates a large amount of OH - at the cathode, salt ions migrate from the anode to the cathode and accumulate at the cathode, so that the further increase of the salt content of soil near the cathode and the aggravation of the alkalization degree are caused. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a soda saline-alkali soil improvement method for electrokinetic combined aluminum sulfate application. The invention adopts the technical scheme that: a method for modifying soda saline-alkali soil applied electrokinetically in combination with aluminum sulfate, the steps comprising; (1) Applying aluminum sulfate modifier in soda saline-alkali soil to enable the aluminum sulfate modifier to be distributed in surface layer or plough layer soil, and uniformly mixing the aluminum sulfate modifier in modes of ploughing, mechanical mixing and the like; (2) Burying an anode on the soil surface layer of soda saline-alkali soil, burying a cathode below the target improvement depth, and forming a vertical or nearly vertical electrode system; (3) And applying a direct current electric field to the soil body to realize electric improvement of soda saline-alkali soil, and providing water supplement for the soil body in the electric improvement process so that the electrolysis reaction can be continuously carried out. Preferably, the application amount of the aluminum sulfate modifier is 0.1-2.0 wt.% based on the dry weight of the soil. Preferably, the direct current electric field is formed by connecting a stabilized direct current power supply with an anode and a cathode. Preferably, the potential gradient of the direct current electric field is 0.6-2.4V/cm, and the duration of the direct current electric field is 7-60 days. Preferably, during the electrokinetic remediation process, sufficient water supply is provided to the soil body by surface irrigation or by maintaining shallow water. Preferably, the criteria for providing adequate moisture supply is to maintain the soil moisture in a saturated or substantially saturated state to maintain a continuous pore water path for current conduction. Preferably, a drain structure is provided at the cathode to drain moisture and salt migrating to the vicinity of the cathode. The beneficial effects of the invention are as follows: