Quantitative estimation of water use efficiency and evapotranspiration under varying nitrogen levels and sowing dates for rainfed and irrigated maize.

Water is a key driver of agricultural production, the scarcity of which the production is adversely affected; hence, it is critical for the agriculture system and global food security. Water use efficiency (WUE) can be an effective measure to reduce water demand against crop yield as it depends upon water consumption. Thus, the purpose of this research was aimed to estimate the effect of variation in sowing time (timely and late) and nitrogen (N) level on the evapotranspiration (ET) and WUE for maize crop under irrigated (2013 and 2014) and rainfed (2012 and 2014) conditions. Two evapotranspiration (ET) approaches, i.e., Penman–Monteith (PM) and soil water balance (SWB), were used to estimate the evapotranspiration; thereafter, evapotranspiration was partitioned into soil evaporation (E) and transpiration (T). The results clearly indicated that cumulative evapotranspiration was higher for both rainfed (5.44–10.25%; N₆₀–N₁₀₀) and irrigated maize (5.87–13.77%; N₇₅–N₁₂₅) in comparison with N₀ nitrogen level. The delayed sowing dates gave on average a lower value (9.56%) and a higher value (15.68%) of ET for the rainfed and irrigated seasons, respectively, in comparison with timely sowing dates. Additionally, the WUE for maize grain yield was higher for both rainfed (251.12–346.06%; N₆₀–N₁₀₀) and irrigated maize (113.75–162.62%; N₇₅–N₁₂₅) in comparison with N₀ nitrogen level. The study further disclosed that a sowing date combination with nitrogen levels could be an effective management strategy to increase the crop yield by minimizing the water losses. [ABSTRACT FROM AUTHOR]