Plant cane responses to silicated products in the Mossman, Innisfail and Bundaberg districts

Within the Australian sugar industry there is a lack of infonnation on potential sources of silicated matelials and on their rates of application. Field experiments were established during the 1999 planting season to quantify responses in cane yield and CCS to different rates of application (rates trials) and to assess the suitability of a number of silicon sourCes (products trials). Experiments were established in the Mossman, Innisfail and Bundaberg districts on a Tenosol, Ferrosol and Hydrosol respectively. In each case the soils had sub-optimal levels of available Si « 10 mg Si/kg soil as extracted by 0.1 M CaCb). The rates trials comprised of varying amounts (0. 1.5, 3.0, 4.5, 6.0, 9.0 and 12.0 tlha) of Ca-silicate applied to soils and incorporated to a depth of 100-200 mm prior to planting. The products trials evaluated various locally available sources of Si. including mill ash. mud ash, Ca-silicate. cement, cement building board by-products and rock dust. Harvests of the plant crops at 8 and approximately 12 months (final harvest) revealed significant increases in milJable stalk yields with increasing rates of Ca-silicate at both the Mossman and Innisfail sites. The greatest response was measured at Mossman where 9 tlha Ca-silicate increased yield from 51 tiha in the control to 90 tiha at 8 months. These initial responses were carried through to final harvest with the highest rate of Ca-silicate application (12 t/ha) resulting in a 58% increase in yield. CCS was not affected by rates of application and the increase in sugar yield at Mossman was 4.2 tlha. At Innisfail and Bundaberg, cane yield increases were 22 tiha and 18 tfha. respectively for rates of application of 9 and 12 tiha Ca-silicate. respectively. Significant yield responses were also recorded in the products trials. At Mossman, Ca-silicate and cement resulted in significant increases in yield over the control. while mud ash at a rate of 50 tiha (dry weight) resulted in significant increases in yield over the control at the Bundaberg site. The responses support current soil test results.