The Effects of Duration, Timing and Chemical Amelioration of Short-term Waterlogging During Furrow Irrigation of Cotton in a Cracking Grey Clay

摘要

The effects of the duration, timing and chemical amelioration of short-term waterlogging during nfurrow irrigation of cotton in a cracking grey clay soil were investigated at Narrabri, N.S.W. Water nwas run in furrows for 4, 8, 16, 32 and 64 h at each of the three crop irrigations. In other treatments, nwatering was extended from 4 to 16 h either at the first, second or third irrigation, to establish at nwhich irrigation waterlogging had the most effect. Soil applications of hydrogen peroxide and foliar nsprays of urea were evaluated as chemical ameliorants of short-term waterlogging. nIncreasing the period of inundation from 4 to 32 h reduced green bolls m-2 by 17.5 %, open bolls nm-2 by 20.6 % and final lint yield by 300 kg ha-' or 18.3 %. No further decreases were observed nby increasing the period of inundation to 64 h. Extended waterlogging was equally damaging at each nof the three irrigations. nThe rate of recovery from waterlogging to an air-filled porosity of 0.10 cm3 cm-3 in the top n20 cm of soil was highly correlated with lint yield, and was consistent with results from a previous nseason. nSoil applications of hydrogen peroxide did not ameliorate waterlogging damage, whereas sig- nnificantly higher lint yields were obtained from foliar sprays of urea applied prior to each irrigation. nThe results confirmed that cotton should be irrigated and thereafter drained rapidly in this soil nto minimize loss of yield. This could be achieved by increasing the rate of application of irrigation nwater and by using shorter fields and steeper slopes. The use of chemical ameliorants requires nfurther investigation.