Functional design of smart evaporative irrigation for mina-padi system in Indonesia

The smart evaporative irrigation is offered as an appropriate option in regulating irrigation water more effective. Smart means the system of irrigation is automatically controlled by a floating ball valve based on evaporation and evapotranspiration rate without electrical power. The objective was to evaluate the functional design of the evaporative irrigation on water demand aspect particularly for Mina-padi (paddy–fish farming). The system was evaluated based on the experimental field in the lab-scale since 10 July 2020. There were three irrigation regimes, i.e., continuous flooded (CR), wet (WR), and dry (LR) regimes. During the vegetative growth stage, the smart evaporative irrigation worked well. The irrigation was supplied by a floating ball valve automatically according to the evapotranspiration rate. The actual water levels were well kept and fitted to the setpoint as indicated by low mean absolute error (MAE). The CR regime needs more irrigation water and evaporated more water through the evapotranspiration process. Its rate was highest ranged between 5.81 – 6.6 mm/day. On the other hand, the LR regime has the lowest evapotranspiration rate in between 1.65 – 4.09 mm/day. The irrigation control system became crucial for control the evapotranspiration rate in which less irrigation water evaporate less water.