Soil constraints in Australian agriculture: Research priorities and approaches

In Australia, approximately 75% of agricultural soils have constraints that limit productivity (Dang and Moody 2016). Soil constraints can be any physical, chemical or biological characteristic that limits root access to moisture and nutrients or reduces plant function. Some examples of soil constraints include: low water and nutrient holding capacity, acidity, alkalinity, dispersion, salinity, compaction, non-wetting soils and hard-setting soils. Identifying, understanding and managing these constraints are major challenges to increasing agricultural productivity, especially when multiple constraints occur in the same soil. Soil constraints may occur in the surface, subsurface or subsoil, and throughout the profile. Although a number of amelioration strategies are available to manage some of these constraints, there are fewer technologies developed for ameliorating subsoil constraints compared to those that occur near the surface. Emerging technologies such as subsoil manuring and injection and addition of clay and organic matter (OM) into bleached horizons of lighter texture soils are currently being examined to manage subsoil constraints. This paper presents an overview of the cost-benefit analysis of methods to ameliorate soil constraints to agriculture and identifies the future research priorities to increase production on these soils.