Optimizing Water Productivity in Cassava Production: Comparative Water Footprint of Drip and Furrow Irrigation in Humid Tropics of India

Efficient irrigation strategies are essential for optimizing water use in cassava production. This study evaluated the water footprint of cassava under five irrigation regimes—drip irrigation at 100%, 80% and 60% of crop evapotranspiration (ETc), furrow irrigation, and rainfed conditions—using field data from 2008 to 2012 validated with 2021–2023 data from humid tropical India. The crop ETc showed a decreasing trend, peaking at 378.8 mm in 2008–2009 and reaching its lowest value (307.6 mm) in 2021–2022. Drip irrigation at 100% ETc significantly reduced water use and blue water dependency compared to furrow irrigation, which exhibited high inefficiencies due to surface evaporation and runoff. The blue water usage under furrow irrigation (7200 m 3 in 2021–2023) was reduced to 2065 m 3 with drip irrigation. This efficiency resulted in higher cassava yields, with drip irrigation at 100% ETc achieving the highest yields (45.5 ± 7.3 t ha −1 in 2008–2012 and 46.7 ± 3.5 t ha −1 in 2021–2023), surpassing furrow (~26%–27% lower) and rainfed (~59% lower) conditions. Drip irrigation also led to the lowest total water footprint (80.9 ± 7.0 m 3 t −1 ), representing a 65% reduction compared with furrow irrigation and a 28% reduction compared with rainfed conditions (112.2 m 3 t −1 ). These findings provide crucial insights for sustainable cassava intensification.