Saltland Capability Assessment: Targeting Plants to Landscapes to Increase Profitability

Abstract

Saltland varies in its capacity for productive and profitable use. For example, in the Central Wheatbelt of Western Australia it ranges from being highly productive and profitable ($40-80/ha/yr) to being of negligible productivity and profitability. To reduce the spread and impact of salinity, perennial plants need to be planted on saltland to lower the watertable, but annual under-storey plants are essential to increase productivity and profitability through increased grazing opportunities. Clear guidelines are required so that interventions on saltland match the optimal combinations of plant species to the landscapes of different capability. Research conducted at four trial sites in the medium rainfall (350-550 mm/yr) zone of Western Australia, with river saltbush, small-leaf bluebush, samphire, Rhodes grass, saltwater couch, puccinellia, tall wheat grass and lucerne, led to the development of a saltland capability assessment tool based on the following assessments; 1) level of salinity in the subsoil (25–50 cm depth), 2) depth to the watertable, and 3) presence of plant “indicator species.” Results from the field trials combined with economic analysis suggested that profitability of the grazing system will be highest if plantings are confined to land with average ECe values less than 8 dS/m and watertables in summer deeper than ~1 m. The featured saltland capability assessment tool is a first step. However, the decision support tool needs to be validated across a wider range of saline sites and expanded to incorporate a wider range of plants. Farmer participation and validation is an essential component of this process; this participation will be continued through the Future Farm Industries CRC “Saltland Knowledge Exchange” and “SALTCAP” Projects.