The effect of short-term waterlogging during furrow irrigation of cotton in a cracking grey clay

Abstract

A crop of cotton cv. Deltapine 61 was waterlogged in the field by running water in furrows for 4, 8, 12 or 16 h at each of three crop irrigations in a cracking grey clay soil at Narrabri, N.S.W. The season was hot and dry, and rainfall did not influence waterlogging treatment. Increasing the inundation period from 4 to 16 h reduced lint yields by 15.9 g m-2 or 8%. Waterlogging treatment had little effect on leaf area, plant height, dry matter and boll size. Lint yield loss from waterlogging was largely associated with reduced boll number m-2. Soil aeration results showed that treatment affected the rate of recovery from waterlogging, and that recovery rate was also a function of soil depth. On taking an air-filled porosity of 0.10 cm3 cm-3 as limiting for growth of roots in soil, the surface 0-10 cm layer was always adequately aerated. However, increasing the inundation from 4 to 16 h delayed soil recovery at 10-20 cm from 0.85 to 1.54 days, and at 20-30 cm from 3.83 to 4.20 days. Multiple regression analysis showed that 77 % of the variation in lint yield could be accounted for by the lengths of time taken for the 10-20 cm and 20-30 cm layers to recover from waterlogging. However, associated yield losses were 2.5 times greater for the 10-20 cm layer than for the 20-30 cm layer for each day of waterlogging in the two layers. The results indicated that lint yield is likely to increase if cotton crops are irrigated and drained faster to reduce contact time. The farmer may achieve this by using larger siphons, more siphons per furrow, shorter furrows or steeper furrows.