Changes in crop productivity and the harvested area of rice grown in Sri Lanka over the last four decades (1979-2021) as affected by the season, district, and water management system

In Sri Lanka, rice (Oryza sativa L.) is cultivated during two seasons, known as Yala and Maha, across 25 districts either with or without access to irrigation water. However, variations in crop productivity and harvested extent in the last few decades remain unknown, particularly in relation to the district, season and water management systems (minor and major irrigation schemes, and rainfed). In this context, we conducted this study to determine the changes in rice crop productivity and harvested extent during the last forty years, and how they are affected by the season, district and water management systems. The relevant data for the period from 1979 to 2021 were obtained from the Department of Agriculture. Results revealed that rice crop productivity remained unchanged or increased with time for all the districts, seasons and water management systems, except for Galle where productivity declined under the major irrigation scheme during Yala. The harvested extent increased over the years for most districts, seasons and water management systems with a few exceptions. These exceptions were rainfed and minor irrigated paddy lands in the wet zone districts. Development and adoption of new improved varieties, better agronomic and management practices, use of modern technology and effective extension services have contributed to productivity improvement. In order to secure the harvested extent for the future, district, season and water management method-based recommendations are required apart from the common policies applicable at the national level.