Submitted to: American Chemical Society Symposium Series
Publication Type: Abstract Only
Publication Acceptance Date: 4/8/2013
Publication Date: 4/10/2013
Citation: Chaney, R.L., Anders, M.M., Mcclung, A.M. 2013. Effect of water management variation on As and Cd accumulation or rice grain. American Chemical Society Symposium Series. Symposium on Arsenic Contamination of Food and Water. New Orleans, LA. April 10 and 11, 2013. #327.
Technical Abstract: Because of the current interest in As accumulation in rice, we examined rice grain As and Cd levels from a field test evaluating the effect of irrigation water management. The original study was conducted to test water saving production methods because limitation on water supply is constraining production in several US areas. Water saving production methods also impact greenhouse gas emissions and incidence of several rice diseases. Six irrigation methods and two cultivars were tested, from traditional permanent flood management (season long anaerobic conditions) to a furrow irrigation method (alternate wetting and drying) where water was supplied only when the soil reached 40% or 60% of water holding capacity. Brown rice grain from all treatments in 2011 and 2012 were analyzed for total As and Cd. Water management and cultivar significantly affected grain As and Cd while year had little effect. Grain As fell from 0.24 mg/kg DW to 0.04 mg/kg DW (for flood vs. most aerobic treatments), but the sharp decline occurred only with more strongly aerobic management. Grain Cd rose from 0.02 mg/kg under flood management to 0.06 mg/kg with aerobic soils, rising sharply with any increase in soil aerobic condition. US rice soils are low in Cd and it is not likely that aerobic production will cause grain to exceed CODEX Cd limits. The pH of the test soils was about 6.4. Some studies from China with more acidic soils showed rice Cd to rise above the CODEX limit of 0.4 mg/kg when grown under aerobic soils to limit grain As. Other research indicates that most US rice contains low levels of inorganic As regardless of production area. And although more aerobic soil production may reduce grain As, it needs to be managed carefully to not result in reduced yields and milling quality. Obtaining low grain As and Cd and high yields will require integrated production and breeding research to result in management practices that are economically viable while assuring a safe and nutritious cereal grain.