Salinity and waterlogging as constraints to saltland pasture production: A review

This review considers the issue of targeting plants for forage/fodder production in landscapes affected by dryland salinity, and two principal factors that affect saltland capability—salinity and waterlogging. Saltland differs in its capacity to support plant growth, and the species used differ in grazing value, so that greatest economic gain will be achieved by focusing revegetation into areas of highest capability. Both salinity and waterlogging are temporally and spatially variable: plant ecological zonation on saltland is a reflection of plant adaptation to these variable stresses. The review has three parts. First, we consider the case for ecological zonation to be caused by variation in salinity and waterlogging. Secondly, we review the current means by which salinity and waterlogging are measured and the suitability of these techniques for rapid field appraisal of saltland capability. Thirdly, we suggest three critical questions that need to be answered if we are to establish a framework to make rapid saltland capability assessments. These are: (a) can a plant use the groundwater, (b) is the soil water above the water table suitable for use, and for what period is it sufficient in volume to support growth, and (c) is the soil sufficiently aerobic for root-growth and function. We conclude with some recommendations about the types of data around which a saltland capability assessment protocol might be designed.