Paper submitted for the nineth international drainage workshop (ICID)

The environmental benefits of water table management (WTM), as a method to reduce nitrate pollution, are well known. However, there are few published studies on the effects of WTM on water use efficiency (WUE). This paper highlights the agronomic interest of WTM for increasing WUE of irrigated grain corn production. A field study was conducted in 2001 and 2002 at a large scale WTM research facility in Québec, Canada. The region experienced periods of drought during the two growing seasons. This study shows that, by keeping the water table at 0.80 m below the soil surface, there were on average 35% increases in grain corn yields, compared to conventional free drainage. The WUEs obtained with WTM (5.1 kg m⁻³ in 2001 and 7.1 kg m⁻³ in 2002) indicate that the method is generally more water efficient than conventional sprinkler and furrow irrigation. The WUE of WTM also compares well with that of water conservation methods such as alternate furrow irrigation and deficit sprinkler irrigation. Moreover, WTM requires low inputs in terms of equipment, energy, and labour, because it makes use of existing subsurface drainage systems, which are widespread in Eastern Canada due to the region's soils and climate, and because of its design, which does not necessitate high-pressure pumps and allows for automated management. Hence, WTM appears to be an interesting alternative to conventional irrigation methods due to its combined environmental and agronomical benefits.