The effect of nitrogen fertilizer and irrigation frequency on a semi-dwarf wheat in south-east Australia. 2. Water use

Abstract

The semi-dwarf wheat WW15 was grown under four irrigation frequencies and two nitrogen rates in the Murrumbidgee Irrigation Area of south-eastern Australia. The irrigation treatments, which were scheduled using pan evaporation and rainfall, ranged from natural rainfall alone to seven flood irrigations. Water use was determined using the water balance equation, and measurements or irrigation water applied, rainfall, change in soil-stored moisture, and surface drainage. The water-use figures were high in comparison with values obtained overseas, ranging from 408 mm with no irrigation to 818 mm at the highest irrigation frequency. Despite the high water use, water-use efficiency was comparable with that for semi-dwarf wheat in other parts of the world, with a mean value of 10.4 kg grain ha-1 mm-1. Nitrogen fertilizer had little effect on plant growth and no effect on crop water use.