Effects of wet soil during early season ratoon establishment on sugarcane grown under different trash management systems in southern canelands

Abstract

Green cane trash blanketing (GeTB) has been rapidly adopted by the Queensland sugar industry on the wet tropical coast, but adoption has generally been much slower in the southern eanelands. The slower adoption in these areas appears due largely to perceptions of lower productivity under a GCTB system, particularly when ratooning occurs under cool and/or wet conditions. This work was initiated to examine the interactive effects of trash management and soil moisture status on ratoon establishment of carly harvested Q150 near Bundaberg. The paper also contrasts the Bundaberg results with data from similar experiments using Q124 in the Northern Rivers Region of NSW. Treatments were imposed during the establishment phase of three successive ratoon crops at Bundaberg, and on successive ratoons at Harwood and Broadwater. Trash management systems included burnt cane harvesting and green cane harvesting, with trash removed from the stool (stool raking), trash removed from the stool followed by incorporation of trash in the inter-row (trash incorporation, Bundaberg only) and a standard green cane trash blanket. Soil moisture during ratoon establishment was manipulated using trickle tape, micro-jet sprinklers and flood irrigation. After the establishment phase, all treatments at Bundaberg were irrigated until maturity On a common schedule using surface trickle tape. Trash management and soil moisture status during ratoon establishment significantly affected shoot numbers and crop growth at al sites. Early shoot numbers could be related to differences in accumulated thermal time and also to the rate of shoot addition per unit of thermal time, with thermal time calculated from soil temperatures at stool depth. There was no evidence of any interaction between soil moisture status and trash management on ratoon establishment at any site. There were no significant correlations between shoot numbers at 3.5 months and the numbers of mature stalks at harvest in any site. There were no correlations between early shoot numbers and yield at Bundaberg.