ESTIMATION OF CROP EVAPOTRANSPIRATION OF Bt. COTTON UNDER SILVER BLACK PLASTIC MULCH USING VARIOUS APPROACHES
Most fundamental requirement of scheduling irrigation is the determination of crop evapotranspiration (ETc). Over estimation of crop evapotranspiration leads waste of scarce water and under estimation leads to the plant moisture stress and decreased crop yield. In order to avoid the underestimation or overestimation of crop water consumption, knowledge of the exact water loss through actual evapotranspiration is necessary for sustainable development and environmentally sound water management. The Penman-Monteith method is maintained as the single standard method for the computation of reference evapotranspiration (ET0) from complete meteorological data but, it requires large number of climatic parameters that are not always easily available for many locations. Pan evaporation method is susceptible to the microclimatic conditions under which the pans are operating and the rigour of station maintenance. An attempt has been made to estimate actual evapotranspiration (ETa) of drip irrigated Bt. cotton under silver black plastic mulch using soil moisture sensor. ETa(ETc) at different growth stage of Bt. cotton was estimated using soil moisture sensor and it was compared with ETc estimated using Penman-Monteith and Pan evaporation method. Results revealed that Pan evaporation method and Penmen Monteith method over estimated ETc by 19.26% and 13.78% than sensor based ETc respectively. Sensor based method estimated lower cumulative ETc at initial stage, development stage, mid stage, and end stage by 46.11%, 33.70%, 18.83% and 17.93%, and 22.89%, 17.80%, 16.09% and 14.89%over Pan evaporation and Penmen Monteith method respectively.
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