Commentary on four publications testing the effectiveness of biostimulant products on pasture recovery from pasture dieback: an agronomy viewpoint

Pasture dieback is a disorder of tropical perennial grass species leading to the death of susceptible species and a reduction in feed for livestock. The spread of the disorder into north-eastern NSW in 2020 has led graziers in the region to search for management strategies to help combat the effects of dieback. Four individual publications based on data from central Queensland have drawn conclusions that commercial biostimulant products promote pasture recovery from dieback. In the mind of the public and landholders suffering from the effects of pasture dieback, these have created a reasonably compelling case for the use of such products in the management of dieback. In this perspective paper, we critically examine the agronomic methods, statistical analyses, data presented, and conclusions drawn across these four publications. We make the case that many of the methods are poorly described or inappropriate, the statistical analyses and means comparisons are largely invalid and the conclusions drawn do not align with the data presented. We conclude that, on the whole, the four publications present little compelling evidence for any agronomic benefits of the biostimulant products tested, and that the conclusions drawn by the authors of these publications are over-optimistic and misleading.