Irrigation Practices on Rice Crop Production in Arsenic-Rich Paddy Soil

Abstract

Irrigation and water management are important cultivation practices, controlling rice crop production and regulating As concentration in both paddy fields and rice plants (Oryza sativa L.). This study investigated the impacts of various types of irrigation practices with As-contaminated groundwater on the extent of arsenic accumulation within rice plant parts during development and rice crop production at maturity. Three types of irrigation practices were applied to As-rich paddy fields: flooded irrigation, aerobic irrigation, and alternate wetting and drying irrigation (AWDI). The arsenic accumulation in various plant parts was monitored at 40, 54, 68, 82, 96, and 110 d after transplanting in the first (with 'Tainong 84') and the second (with 'Tainan 11') cropping seasons of 2013. Results show that the arsenic concentration in different parts of rice plants varied with growth stage and irrigation practices in both cropping seasons. There was a seasonal fluctuation of arsenic concentration within rice plants during plant development with flooded irrigation, which had the largest amount of irrigation input. Lower levels of As in rice were found in AWDI and aerobic irrigation than in flooded irrigation. Different irrigation practices can change the oxidation and reduction conditions of the paddy field, which lead to As release or absorption in the soil, thus influencing the uptake of As by plants.