CANE TRASH AND CALCIUM-BASED SOIL AMENDMENTS: A COMBINATION TOO GOOD TO MISS

GREEN cane trash retention and acidic soils occur widely in the Australian sugar industry. Although both have received individual attention over the years, little information is available on the interaction between trash and the calcium-based ameliorants routinely applied to sugarcane producing soils. For this reason, the effects of applying amendments to trash were explored in terms of decomposition of the trash and the release and availability of associated nutrients. Pot experiments were conducted in subtropical and moist tropical conditions using various amendments and common soi types. A field trial, aimed at validating the results from the pot experiments, was conducted. The results showed that certain calcium-based amendments, especially lime and millmud, accelerated trash decomposition. Differences in rates of decomposition in simulated subtropical and moist tropical conditions suggested that temperature and water availability were important factors for decomposition. Amendments applied to the surface of the trash layer were found to have the ability to ameliorate conditions in the underlying soil. Although millmud and mill ash applied to trash increased the amount of N, P and K removed by the harvested cane, these elevated levels could either have been the result of the amendments themselves, or due to enhanced decomposition of the trash, or a combination of both of these. The combination of trash retention and the application of calcium-based soil amendments enables the advantages of both practices to be harnessed for sustainable sugarcane production.