Soil Salinity Levels Caused by Saltwater Intrusion in Coastal Paddy Areas of Sri Lanka: Soil salinity levels due to saltwater Intrusion in coastal paddy area

Rice is the staple food and main agricultural crop in Sri Lanka. Rice production is primarily concentrated in the dry zone of Sri Lanka, though it is also cultivated in the wet zone. The productivity of most of the paddy lands in the coastal zone of Sri Lanka has declined over the years due to salinization caused by tidal waves and sea water intrusion, both of which are linked to climate change-induced sea level rise. This study primarily focused on salinity-related issues in the coastal paddy fields due to saltwater intrusion. It was conducted in seven selected coastal districts of Sri Lanka, encompassing both the dry zone and wet zone of Sri Lanka. The dry zone districts included Jaffna and Mannar, which are located in the north of Sri Lanka, and the wet zone districts included Gampaha, Colombo, and Kalutara districts, located in the west of Sri Lanka, and Galle and Matara districts, located in the south of Sri Lanka. The soil samples were collected periodically during the dry season, between August to October in the year 2019 and checked for salinity levels using electrical conductivity measurements of 1:5 soil to water extract (EC 1:5). As per the results, the salinity levels within the study areas ranged from 0.105 dS m-1 (non-saline) to 4.002 dS m-1 (highly saline with significant impacts on paddy growth and yields). Over 70 percent of the sites in the wet zone districts and all the sites in the dry zone districts are found to be highly saline. According to the study, more than 50% of the land extent along the coastline of the study districts is severely affected by salinity.   Due to prevailing high salinity conditions, the productivity of these lands is heavily affected, with the high salinity stress in their early growth stages severely affecting the survival rate. Therefore, it is recommended that urgent, long-term precautionary action be taken for the optimal control of salinity in the coastal paddy fields before it gets worse with time.