Irrigation energy consumption in a tropical lowland rice field

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 mainseason for the initial stage, crop development stage, mid-season stage and late-s eason 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(0.23kg/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

Land preparation water management by canal simulation in a paddy estate.

A canal simulation study was conducted in an intensively cultivated paddy estate in Malaysia. CanalMan software was applied to main and selected secondary canals that have difficulty in land preparation supply within the scheduled time periods. The study revealed that the CanalMan is capable of simulating different scenarios possible in the project area. Canal simulations also revealed that the land preparation supply management could be completed in three days, which is two days less than the current practice, when the canals are supplied with design discharges. Canal simulations combined with a water balance study revealed that a minimum of 20 mm of effective rainfall is needed to complete land preparation within the desired period. When the water levels along main canal drops, the required rainfall is much higher. This forces the management to start supply by pumping or shift land preparation water management in critical blocks to the drainage period soon after seeding in other blocks