117-6 The Effect of Water Management On Rice Yields and Greenhouse Gas Emissions.



Monday, October 17, 2011
Henry Gonzalez Convention Center, Hall C, Street Level

Takashi Kato and Kosuke Noborio, Meiji University, Kawasaki, Japan
Because rice paddy fields could be under either an aerobic or an anaerobic condition, they are one of the major sources of methane and nitrous oxide. This study was examined the effect of water management by measuring rice yields and greenhouse gas emissions during rice cultivation under different water management conditoins. The aim of this study was to advance water management in rice paddy fields to mitigate greenhouse gas emissions (CH4, N2O and CO2) and maintain rice yields. Rice plants were cultivated in 1/2000-a Wagner pots and three water management practices, continuous flooding and two kinds of intermittent irrigations. The measurements of gas emissions, volume water content and soil temperatures were made using a closed chamber method, TDR sensors and thermocouples, respectively. Gas concentrations at 14 cm below the soil surface were measured using gas permeable tubes. Results showed that CH4 flux was negative, but CH4 concentrations in soil were much higher than that in the atmosphere under flooding conditions. CO2 flux was negative by reflecting photosynthesis in rice plants, and positive in fallow. CO2 concentrations in soil were higher under flooding conditions than under drainage conditions. N2O flux was positive due to nitrification under drainage and denitrification under flooding conditions. N2O concentrations in soil were higher under drainage conditions than under flooding conditions. Rice yields did not differ in water management practices. This study showed that CH4 was produced in the soil under flooding conditions, but was not emitted to the atmosphere. Further research was needed to investigate CH4 dynamics in soil.
See more from this Division: S01 Soil Physics
See more from this Session: General Soil Physics: II (Includes Graduate Student Competition)