Assessment and mapping crop evapotranspiration and green and blue water uses by major crops in trans Indo-Gangetic plains

Green crop water use, blue crop water use, virtual water content, and crop water footprint are now being used as indicators for quantifying the water embedded in agricultural produce. It helps in proper and equitable use of water resources and helps in deciding the cropping pattern in a geographical region. Realistic assessment and mapping of crop evapotranspiration in a geographical region is essential for estimation of green and blue water uses and crop footprint. Crop evapotranspiration (ETc), blue crop water use (CWUbₗᵤₑ) and green crop water use (CWUgᵣₑₑₙ) of 11 major crops cultivated in the states of Haryana in India were determined using CROPWAT model and spatial variability maps were prepared by kriging technique of geostatistics. The ETc of crops in different growing seasons was minimum in Northern Plains and maximum in Western Plain. The ETc in Central Highlands was in medium range. The ETcof sugarcane was highest and varied from 1707 to 2312 mm, followed by cotton (811–1154 mm), paddy (496–746 mm) and maize (453–705 mm). Barley and wheat had ETc in the range of 237–321 mm and 238–332 mm, respectively. In northern region, green crop water use was higher for all crops than the other AESR. Among the kharif crops, cotton and paddy used rainwater most effectively, with overall green water usage of 395 and 350.3 mm, respectively in the Northern region. The CWUblue was higher in the western region with a decreasing pattern towards the Northern regions for all the crops. Among all rabi crops CWUblue was highest for potato (206 – 371.5 mm) followed by black gram, barley, wheat and mustard. Among all kharif crops blue crop water use was highest for cotton (244–937 mm), followed by paddy, maize, sorghum and pearl millet. Highest blue crop water use was found for sugarcane (1098.9– 2052.7 mm).