ROW SPACING AND TILLAGE EFFECTS ON THE GROWTH AND YIELD OF SUGARCANE

THERE has been concern expressed in recent years as to what is the most appropriate row spacing and plant configuration to maximise yields in sugarcane. Much of this concern has resulted from the promotion and subsequent failure of high density planting, but has also been stimulated by a move towards a controlled traffic farming system which will necessarily involve wider row spacings than the current 1.5 m. In an attempt to clarify the situation, a row spacing/plant configuration experiment was established on Bundaberg Sugar’s Bingera plantation in September 2003. Eight bed/row combinations were established in December 2002 and planted to soybeans. These were two plots of 91 cm rows, one bed on a 1.5 m centre, 2 beds on 1.8 m centres, and three beds on 2.1 m centres. For cane planting, the 91 cm rows were conventionally prepared and planted with a whole stalk planter or a billet planter. The other six row spacing/configurations were split to surface tillage to incorporate the soybean residue or left untilled. Double disc opener planters were used to plant one row of cane on the 1.5 m beds, one or dual rows of cane on the 1.8 m beds and dual, triple or quad rows of cane on the 2.1 m beds. Crop growth, cane and sugar yields and yield components were measured. There was no significant difference in cane yield between 1.8 duals, 2.1 duals, 2.1 triples and the billet planted cane. However, lower yields were obtained with the conventional whole stalk planting, 1.5 m beds, 1.8 m beds with a single row, and the quad rows. The quad rows lodged badly and this was a major reason for their lower yield. Early shoot development was generally correlated with setts planted per unit area but tended to equilibrate across treatments at around 10 stalks per m2 at crop harvest. Individual stalk weight was an important determinant of yield and it decreased as planting rate increased. The results indicate that the development of a controlled traffic system based on 1.8 m dual rows is practical, will not result in yield loss, and will result in a minimal changeover cost from the current system. Although duals and triples on 2.1 m spacing can produce similar yields, they require greater capital investment in machinery as substantial modifications to harvesters and planters are necessary.