Lindsay W Bell 1, Rebecca Garrad 1
1 – CSIRO Agriculture and Food, Toowoomba Qld 4350, Lindsay.Bell@csiro.au
Perennial pastures offer potential to rebuild soil health in cropping systems, yet more knowledge is needed about the impacts that subtropical grass-based pastures have on soil borne pathogens, beneficial soil biology and soil structure. In this study, a range of soil health indicators were compared between 14 paired paddocks across southern Queensland and northern NSW. The paired paddocks had a common cropping history and they had either been returned to a 4-10 year phase of a perennial pasture or continued to be continuously cropped. We found much lower populations of root lesion nematodes and crop fungal pathogens (Fusarium spp and Bipolaris spp.) under pastures at sites where these pathogens were present. Soil under pastures had higher arbuscular mychorizae fungi populations at half the sites and free-living nematode populations were higher at all but one site. Soils under the pastures also had better aggregate stability, with the fraction of macro-aggregates 10-40% higher than under continuous cropping at 13 of the 14 sites. This study shows that pastures were consistently beneficial for soil health across many sites and different pasture mixtures in subtropical regions of Australia. However, the benefits that this improvement could have for subsequent crop productivity are yet to be confirmed.