The effects of duration, timing and chemical amelioration of short-term waterlogging during furrow irrigation of cotton in a cracking grey clay

Abstract

The effects of the duration, timing and chemical amelioration of short-term waterlogging during furrow irrigation of cotton in a cracking grey clay soil were investigated at Narrabri, N.S.W. Water was run in furrows for 4, 8, 16, 32 and 64 h at each of the three crop irrigations. In other treatments, watering was extended from 4 to 16 h either at the first, second or third irrigation, to establish at which irrigation waterlogging had the most effect. Soil applications of hydrogen peroxide and foliar sprays of urea were evaluated as chemical ameliorants of short-term waterlogging. Increasing the period of inundation from 4 to 32 h reduced green bolls m-2 by 17.5 %, open bolls m-2 by 20.6 % and final lint yield by 300 kg ha-1 or 18.3 %. No further decreases were observed by increasing the period of inundation to 64 h. Extended waterlogging was equally damaging at each of the three irrigations. The rate of recovery from waterlogging to an air-filled porosity of 0.10 cm3 cm-3 in the top 20 cm of soil was highly correlated with lint yield, and was consistent with results from a previous season. Soil applications of hydrogen peroxide did not ameliorate waterlogging damage, whereas significantly higher lint yields were obtained from foliar sprays of urea applied prior to each irrigation. The results confirmed that cotton should be irrigated and thereafter drained rapidly in this soil to minimize loss of yield. This could be achieved by increasing the rate of application of irrigation water and by using shorter fields and steeper slopes. The use of chemical ameliorants requires further investigation.