Are rice systems sustainable in Sri Lanka? - A case of Deduru Oya reservoir irrigation scheme

Sustainable rice systems play a crucial role in achieving sustainable development goals, particularly in countries like Sri Lanka that heavily rely on paddy production. The study aims to examine the economic, social, and environmental sustainability gaps of a rice production system at various spatial scales using the Sustainable Rice Platform (SRP) framework v2.1 and identify interventions that can address these gaps. Data for the study was collected through a structured questionnaire, which incorporated the 12 performance indicators of the SRP framework, including profitability, labor productivity, grain yield, water productivity, nutrient use efficiency, biodiversity, greenhouse gas emission, food safety, health and safety, child labor and youth engagement, and women empowerment. The survey was conducted over two consecutive cropping seasons, in 2019 dry and 2019/2020 wet seasons, in selected paddy fields representing three topo-sequences within the Deduru Oya irrigation project in Sri Lanka. The study's findings revealed that the rice systems' profitability ranges from 475 ± 45 to 642 ± 59 USD/ha across seasons and topo-sequences, and a yield gap of approximately 33% was observed. Substantial exploitable gaps were observed in labor productivity (67%–77%) and water productivity (58%–68%). Additionally, there was significant variability in nutrient use efficiency and greenhouse gas emissions due to variations in water management practices. The social sustainability of rice systems has received lower scores, particularly for health safety and women empowerment. The study attributed most of the economic and environmental sustainability gaps in the agricultural practices of cultivators, while various socio-political and cultural factors influenced the social sustainability gaps. This study offers valuable insights to policymakers and practitioners in countries with extensive rice systems, aiding their efforts toward achieving sustainable development goals.