An assessment of current silicon status of sugar cane production soils from Tully to Mossman

A survey of soils currently used for sugarcane production on the wet tropical coast of north Queensland was undel1akcn during the 1999-2000 growing season. The regions surveyed included the Atherton Tablelands, Mulgrave, South Johnstone, Babinda, Mourilyan, Mossman and Tully mill areas. More than 85 percent of all wils tested had sub-optimal or marginal soil Si levels (20 mg/kg Si). In all regions, with the exception of the Atherton Tableland, more than 50 percent had levels of plant available silicon that could be considered sub-optimal « 10 mg/kg Si). Plant Si levels, measured on the top visible dewlap leaf from sugarcanc at all sites, were colTelated with available soil levels. As part of the project, comparisons were made between different chemical methods for extracting soil silicon in order to identify the most robust method, and one that was best correlated with tissue levels.