咸淡轮灌和生物炭对滨海盐渍土水盐运移特征的影响

为利用滨海地区微咸水改良盐渍土,进行了不同咸淡水轮灌(淡淡、淡咸、咸淡、咸咸)和施用生物炭(0、15、30 t/hm2)的室内入渗试验,探讨了咸淡轮灌和生物炭施用下滨海盐渍土水盐运移过程.结果表明:滨海盐渍土水分运动主要受初始入渗水质的影响,先咸后淡的轮灌方式更有利于土壤水分入渗,入渗速率增加了8.2％～46.9％,并...

Effects of Cycle Irrigation with Brackish and Fresh Water and Biochar on Water and Salt Transports of Coastal Saline Soil

For saline soil reclamation using brackish water in coastal areas, indoor infiltration tests were carried out to investigate the water and salt transport processes of coastal saline soil under different cycle irrigations with brackish and fresh water and biochar application. There were four cycle irrigation treatments, that was, continuous freshwater irrigation (fresh-fresh), began with freshwater irrigation then brackish water irrigation (fresh-brackish), began with brackish irrigation and then freshwater irrigation (brackish-fresh), continuous brackish water irrigation (brackish-brackish). The biochar application rates were 0t/hm2, 15t/hm2 and 30t/hm2, respectively. According to the results, the water movement of coastal saline soil was mainly affected by the initial infiltration water quality. The cycle irrigation of brackish-fresh was more beneficial to soil water infiltration and increased the infiltration rate by 8.2%~46.9%. The cycle irrigation of brackish-fresh also slightly improved soil moisture content. Biochar promoted water infiltration under cycle irrigation with brackish and fresh water, and increased wetting front distance, accumulated infiltration amount, infiltration rate, and soil moisture content. Biochar application at 15t/hm2 was most conducive to soil water transport, increasing the infiltration rate by 3.5%~22.0%. The soil salt content of fresh-brackish and brackish-fresh was lower than that of brackish-brackish, while the desalinization rate and depth coefficient were higher. The cycle irrigation of brackish-fresh increased the desalinization rate, and the cycle irrigation of fresh-brackish could increase the desalinization depth. The addition of biochar was beneficial to soil salt leaching under cycle irrigation, which increased the desalination rate and desalination depth coefficient by 9.1%~15.0% and 1.1%~7.5%, respectively. Biochar also increased the content of Ca2+ and Mg2+, which promoted Na+ leaching and mitigated the risk of brackish water irrigation. The effect of biochar on salt leaching was limited when the biochar application rate was increased to 30t/hm2. The research result showed that 15t/hm2 biochar combined with cycle irrigation with brackish and fresh water improved infiltration characteristics, water holding capacity, and salt distribution of coastal saline soil, which could provide references for the development and utilization of saline soil and brackish water in coastal regions.