Sulfur deficiency in rice grown on the alkaline soils of the Ord Irrigation Area, Western Australia

Abstract

Nutrient and acidification effects of sulfur (S) on the growth of flooded rice on Cununurra clay from the Ord Irrigation Area, Western Australia. were studied in pot experiments. An acute S deficiency in the surface horizon of Cununurra clay was found. This deficiency was extreme on virgin soil but was also evident on cropped soil that had received substantial amounts of S as superphosphate and ammonium sulfate in the past. The major effect of an application of elemental S on rice growth was as a nutrient. Irrigation water appears to be an important source of nutrient S in this remote area where annual atmospheric accessions of S are estimated to be about 1 kg ha-1. The S content of Ord irrigation water from Lake Argyle is relatively low (mean ¦ s.e. sulfate3 = 1.7 ¦ 0.05 mg L-1) by world standards. Nevertheless. in this study, 62% of the S added with the Ord irrigation water was recovered in the plant tops. This indicates that factors which determine the amount of irrigation water applied are likely to affect the field incidence of S deficiency. In particular, decreased usage of irrigation water during the December-March wet season (when average rainfall is 630 mm) may increase the likelihood of S deficiency in rice.