Above ground biomass and water use efficiency of crops at shallow water tables in a temperate climate

Field plots had lower drainage and subirrigation intensity than lysimeters and thus indicated both waterlogging and drought stress. This resulted in significant and strong correlations between groundwater table and biomass of arable crops. As in lysimeters, the highest WUE occurred with the highest crop biomass, it may be concluded that in field situations, highest WUE can be achieved with controlling an optimum range of water table. Crops of highest WUE, maize and winter wheat, had optimum water tables in the range of 80-160 cm on soils of higher water storage capacity. Grassland required water tables less than 80 cm. Creating rewetted areas of water tables less than 20 cm would mean a very low efficiency of water use.