Cassava Water Footprint Assessment in Various Irrigation Management

Abstract

Water footprint is used as a tool to measure both direct and indirect water used by crops. Water footprint of cassava production was examined under 3 water managements, including irrigation condition (Nakornratsrima), limited-irrigation condition (Kampangpet) and rainfed condition (Rayong). One ton of cassava from 2 consecutive growing seasons between
2015 and 2018 was used to calculate water footprint. The study showed that the averaged water footprint of cassava was 147-366 m3/ton, comprised of 48-87% or 92-339 m3/ton green, 0-9% or 0-21 m3/ton blue and 13-48% or 29-97 m3/ton grey water. Irrigation conditions had low water footprint of 211 m3/ton, compared to 224 and 301 m3/ton of limited-irrigation and rainfed conditions, respectively. Higher yield gave low water footprint, whereas irrigation as crop water requirement gave a higher yield. Varieties and planting times were the main factors determining water footprint differences, although cassava was grown at the same farm. In water-limited area, planting in June caused crop water deficit. Optimum planting date and supplemental irrigation were needed, particularly at initial stages of growth.Growing in the late rainy season made water deficit during some growing periods. In limited water resource area, optimum growing period was a better choice. Planting in June should be avoided due to inadequate rainfall for crop water use. In rainfed area, planting in
November caused more severely water deficit during 3-5 months after planting, compared to growing in January. Use a suitable variety would increase yield.