Final report SRDC Project CLW009 Improving yield and ccs in sugarcane through the application of silicon based amendments
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Under high leaching environments common to the wet tropics, soils undergo significant weathering, which, when combined with accelerated chemical and physical degradation due to soil perturbation and crop removal, results in increased soil acidification and dissolution of the alumino-silicate clay minerals (de-silication). The consequences are both a loss of plant available Si through leaching and a decline in cation exchange capacity and hence an inability to retain essential plant nutrients. The current project has highlighted that large areas of cane-growing soils in North Queensland have sub-optimal levels of plant-available Si. Based on the current soil test, some 85% of soils that were evaluated in the six mill areas on the wet tropical coast have sub-optimal to marginal levels of available Si. Hence the implications of silicon deficiency for substantial areas under sugarcane production, and therefore the benefit of prophylactic applications of silicate materials may have a significant impact of productivity. One of the primary objectives of this study was to quantify responses in cane yield and ccs to Si application. To address this objective, three field trials were established in Bundaberg, Innisfail and Mossman, using a range of application rates of calcium silicate slag. At Innisfail, over the 2 years of the trial, a rate of 9t/ha Ca-silicate gave a 32% increase in total cane yield (189 t/ha) when compared to the control treatment (128 t/ha). At Mossman, a rate of 12 t/ha gave a 35% total yield increase (161 t/ha) compared to the control (105 t/ha) over the same period. At Bundaberg, over a crop cycle of 3 years, the 12 t/ha rate of Ca-silicate resulted in a 23 % increase (278 t/ha) compared to the control (213 t/ha). The results clearly indicate that Si should be treated as an integral part of any fertilizer strategy associated with cane production on these soils.