On-farm assessment of sub-soil salinity and sodicity constraints to barley production in southern Australia

Abstract

Multiple factors contributing to subsoil constraints include salinity, sodicity, and high concentrations of chloride which are present in many rain-fed farming soils of Southern Australia. Identifying genotypes adapted to these adverse subsoil conditions and/or able to exploit subsoil water may be an option to maintain productivity of these soils. Field trials were carried out to evaluate the relative importance of high soil solution concentration of Na+ and Cl- ions on yield reduction of barley in 4 sites over 3 years in north-west Victoria and South Australia. All soils had high concentrations of exchangeable Na+ and Cl- in the subsoil and the variation in these levels were correlated with the spatial variation in yield. Grain yield was also greater in genotypes with the capacity to exclude Na+ and Cl- from their leaves. Measurement of ion concentrations from the upper two leaves of the main stem at Zadoks 65 were highly correlated with yield among 10 adapted varieties of barley and may be effective as screening criteria compared with those from the lower two leaves. The maintenance of low Cl- and Na+ concentrations in the upper two leaves offered the best guide to salt tolerance under both conditions. Potassium concentration was a poor criterion compared with the selectivity of K+ over Na+.