Comparison of Crop Water Productivity by Rice Ecologies (In Japanese with English abstract)

Abstract

The experiments are carried out in a rainy season in 2008 to compare the differences of crop water productivity by three rice cultivation methods, which are rainfed upland, rainfed lowland and irrigated rice. Three study sites, Ashaiman, Nyankpala and Kpong are selected from three different agricultural climate zones in Ghana. The following findings are obtained from the experiments. 1) The water productivity of rice was shown as 0.02-0.40kg/m3 in rainfed upland, 0.28-0.53 kg/m3 in rainfed lowland and 0.24-0.66 kg/m3 in irrigated rice. There was a significant difference on water productivity due to differences of rainfall in upland rice. On the other hand water productivity of rainfed lowland indicated that it does not compare favorably even irrigated rice. 2) Although water productivity was higher with increasing water input, it has shown the peak in 650mm of water input and it tended to be lower with increasing of water input in this experiment.