The influence of dissolved gypsum on pasture establishment on irrigated sodic clays

Abstract

The heavy grey and brown soils of the Riverine plain have been considered to have a low irrigation potential primarily because of the difficulty of pasture establishment. A series of experiments has indicated that satisfactory establishment can be achieved by the application of gypsum. For increased emergence the most efficient method of applying gypsum was to dissolve it in the first irrigation water. The reason for adding gypsum in solution was to obtain flocculation rather than calcium saturation of the soil colloids. This represents a novel approach to the reclamation of sodic soils and is clearly different from the procedure used in the United States, where smaller quantities of gypsum are added to the irrigation water to adjust the sodium : calcium ratio of the water. The treatment with gypsum leads to a more friable soil surface, increases the rate of water entry, and results in increased yields per plant.