EFFECT OF DIRECT DRILL PLANTING INTO RAISED BEDS ON CANE GROWTH AND YIELD UNDER RAINFED CONDITIONS IN NORTH QUEENSLAND

DIRECT drill planting (DP) onto raised beds (RB) utilising the double-disc opener planter has been mainly tested where moisture could be controlled by irrigation, either full or supplementary. An experiment was conducted at Tully to compare the direct drill/double-disc opener planter system with a mouldboard furrow (MF) planting/conventional cultivation (CC) system under rainfed condition. Three varieties Q172A, Q181A and Q187A were planted in dual rows at 1.8 m centres. Shoot emergence in the MF/CC planting was almost double that in DP/RB planting in the first 52 DAP. This difference was due to about 23% less gaps >0.5 m in the furrow planted cane. This early growth advantage was maintained through to harvest at 9.5 months of age resulting in the MF/CC planted cane having about 26% higher cane yield than DP/RB planted cane. This was associated with higher stalk number, taller stalks and greater stalk mass with MF/CC planting. The poor result with DP/RB planting was considered to result from moisture stress due to variable soil cover at planting and less available soil moisture during crop growth. The results are discussed in relation to their applicability to the new sugarcane farming system. Suggestions are made as to how the DP/RB system using the double-disc opener planter may be adapted to better suit rainfed conditions in north Queensland.