Investigation of a simple method to estimate daily crop water requirement and crop coefficient of sugarcane

Upgrading the crop coefficient from FAO-56 is strongly recommended for locally determining crop water requirements. A low-cost and simple method should be practiced in place of a costly lysimeter. The trial was conducted under glasshouse conditions to estimate daily crop water requirements and create the crop coefficient based on water balance under the small pot scale. Soil pots with and without plants were daily weight to calculate soil evaporation, water loss, and transpiration. Reference crop evapotranspiration was computed based on meteorological data following Penman-Monteith equations. The result showed similar trends in crop water requirements and crop coefficient compared to that under the actual field conditions with the highest values at the grand growth phase. To apply the result from the pot experiment, the plant density could be involved in the crop coefficient corrected formula. The extra water estimated based on plant height increasing rate (6 g cm− 1 for the establishment phase and 12 g cm− 1 for the later phase) should be a component of crop water requirement.