HIGH INPUT SUGARCANE PRODUCTION SYSTEMS CAN MASK THE ADVERSE EFFECTS OF POOR SOIL HEALTH

BREAKING the sugarcane monoculture or fumigating long-term sugarcane land enhances crop establishment. In many situations, enhanced establishment is instrumental in ultimately producing higher cane and sugar yields. However, recent studies in rotation experiments in the Burdekin have shown that with full irrigation and high inputs of nitrogen fertiliser, tillering can be increased to the extent that poor primary shoot establishment can be compensated by the production of more tillers. This results in the ultimate yield difference between breaks/fumigation and sugarcane monoculture being substantially reduced. The relatively good yields that can be produced with sugarcane monoculture in the Burdekin has led to a general conclusion that yield decline (poor soil health) is not an important issue in this region. However, research by the SYDJV has shown that soil health is as much an issue in the Burdekin as anywhere else, but the ultimate effect on crop yield can be masked by irrigation and high inputs of nitrogen fertiliser. The results of this research emphasise several important implications associated with management of high input systems. Although the adverse effects of poor soil health can be masked, the long-term consequences of ignoring soil health need to be seriously considered. Further, the excessive use of resources such as nitrogen fertiliser and irrigation water, have both economic and environmental consequences. In this paper we demonstrate that yields can be maintained with lower inputs in situations where soil health has been maintained through rotation breaks and the build-up of soil carbon (organic matter) levels. Further, it is argued that substituting high inputs to mask the effects of poor soil health is very much against the development of more sustainable sugarcane farming systems.