Improving Salt Leaching in a Simulated Saline Soil Column by Compost and Biochar in Vietnamese Mekong Delta

The problem of seawater intrusion in recent years has been serious in the coastal provinces of the Vietnamese Mekong River Delta. For rice cultivation in salt-affected areas, more effective techniques are required to remediate the saline soils for lowing salinity to secure rice growth and productivity. The objective of this study was to evaluate the potential reclamation of compost and biochar in laboratory experiment using a saline soil sample from the rice cropping system. Our hypothesis was that the addition of compost and biochar might improve the infiltration rate, resulted in more effectively salts removing from saline soil. The experiment was set up with compost and biochar at rates of 5 g kg-1, 10 g kg-1 and 20 g kg-1, respectively and 10 g kg-1 compost combined with 10 g kg-1 biochar. Soil chemical characteristics such as amount of Na+, K+, Ca2+, and Mg2+ cations removed from soil into eluent by leaching, soil availabe N, P after finishing leaching were analyzed. Results indicated that all compost and biochar amendments enhanced Na+ leaching process. This study proved that material amendment such as 20g kg-1 biochar and 10g kg-1 compost plus 10g kg-1 biochar could speed up water infiltration. Compost additions increase the available N and P content in the soil after leaching. Available N and P contents have not been improved in treatments supplemented with biochar.