Irrigation Energy Consumption in a Tropical Lowland Rice Field

Abstract

Available and limited water resources are seeing high demand from many sectors such as agriculture, industry and domestic households. In water allocation, the quantification of water in terms of energy used for water supply is more appropriate in terms of economic aspects. This study was undertaken to assess the embodied in irrigation for a lowland tropical rice production system. The irrigation energy requirements for the off and main cropping seasons were estimated based on crop water requirements at different cropping stages. Experimental results indicate that there are significant differences among the irrigation energy requirements of the various cropping stages, with the highest values of 4625.34 MJ ha-1 and 3843.93 MJ ha-1 observed for the mid-season stage in the off-season and main season, respectively. The off-season irrigation energy requirements for the rice variety MR 219 were found to be 32.6%, 26.8%, 20.3% and 271.7% higher than the main season for the initial stage, crop development stage, mid-season stage and late-season stage, respectively. There is a significant difference in irrigation energy requirement among the seasons and crop growth stages. Crop Water Use Efficiency (CWUE) in the off season (0.26 kg/m3) is higher than the CWUE in the main season (0.23 kg/m3) which is attributed to better water management and yields during the off season due to water shortage. Irrigation energy productivity (IEP) of rice in the off season and the main season at Tanjong Karang is 0.26 and 0.29, respectively. In terms of irrigation energy spent, the main season shows better performance where a part of irrigation requirement is met by rainfall. Irrigation energy, CWUE and IEP can be used in decision making on the profitability of growing rice in different seasons.