STAGE SPECIFIC ACTUAL CROP EVAPOTRANSPIRATION OF BT. COTTON UNDER DIFFERENT MULCH CONDITIONS

Acquaintance of the exact water loss through actual evapotranspiration is necessary for sustainable development and environmentally sound water management to avoid the underestimation or overestimation of crop water consumption. An accurate estimation of crop evapotranspiration is important for better irrigation scheduling and water management. An attempt has been made to estimate actual evapotranspiration (ETa) at different growth stage of Bt. cotton under silver black plastic mulch, biodegradable plastic mulch, wheat straw mulch and no mulch condition using soil moisture sensor and it was compared with crop evapotranspiration (ETc) estimated using Penman- Monteith and Pan Evaporation method. Results revealed that Pan evaporation and Penmen Monteith approach over estimated cumulative ETc under by 46.11%, 45.84%, 39.33%, 56.10%and 22.89%, 22.50%, 13.19%, 39.42% than sensor based ETc under silver black plastic mulch, biodegradable plastic mulch, wheat straw mulch and control respectively at initial stage of Bt. cotton which was followed by development stage, mid stage and end stage of Bt. cotton. Sensor based approach estimated lower cumulative ETcat all growth stagethan Penmen Monteith method and Pan ETc approach.