(2020) Diminished Rice Yield by Coupled Impact of Climate Change and Soil Arsenic Contamination
Wang T, Muehe EM & Fendorf S
13m: Room 4, Tuesday 23rd June 00:30 - 00:33
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Excellent poster and important topic. In what form was the arsenic in the soil used in the experiments and how does that affect the phyoavailability?
Thanks for your interest in our work and your question. We use native Bangladeshi soil which has a relatively low background As concentration and amend them with double-distilled water containing 80% arsenite and 20% arsenate to simulate the As composition from local irrigation water. The soils are then left to equilibrate and dry under corresponding climate conditions. The type of iron minerals in the native soils are mainly affecting the phytoavailability of As. If they are easily reduced and we've observed in Californian soils, As will be released into porewater in earlier growth stages of rice, whereas in Bangladeshi soil, As release is a bit retarded.
Which mechanisms are likely to be involved in making As more available under proposed future climatic conditions?
Thank you for the question. We posit that elevated temperature will stimulate the reductive dissolution of As-bearing iron (hydr)oxides, so more As will partition from solid phase to porewater, increasing the phytoavailability of As. Elevated atmospheric CO2 might also stimulate microbial respiration.
Thank you for this very interesting project. I am interested in the porewater arsenic concentrations in the manipulated treatments. Your poster only reports porewater arsenic for the future climate vs. the current climate. Did you also measure porewater arsenic separately for high-co2 and high-temperature? And, what mechanism do you think might be increasing the porewater arsenic concentrations under the future climate? I also have an unrelated rice agronomic question. If high temperature is so disadvantageous to grain yield, how is rice grown today in very hot tropical areas? Thank you again.
Thanks for your interest in our project and your question. We also measured As porewater concentration in elevated CO2 and elevated temperature treatment. Elevated temperature showed similar trend to future climate, suggesting that elevated temperature is liberating more As into porewater and peaks earlier in the rice growth season. I'm not an expert in agronomy, but I think breeding more heat-tolerant rice varieties could be helpful. Farmers don't have direct and effective measures to combat heat stress, but ensuring sufficient irrigation water might be helpful to decrease canopy temperature a little bit through transpiration.
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