Traffic control and tillage strategies for harvesting and planting of sugarcane (Saccharum officinarum) in Australia

Two separate field trials were conducted at two sites; one trial determined the effect of matching crop row spacing and equipment track width on soil physical properties in the crop row and subsequent crop performance (Tully and Ingham, Qld, Australia). The second trial examined the effect of cultivating the old crop row only compared with cultivating the whole field on seedbed parameters for planting sugarcane (Feluga near Tully and Bundaberg, Qld, Australia). The trials were designed to test components of a potential new farming system for the sugar industry. The Australian sugar industry practices a form of controlled traffic in that harvesting traffic occurs in about the same position for up to four years. However, there is a mis-match between crop row spacing (1.5 m) and equipment track width (1.83 m). Single rows grown at 1.5 m spacing (random traffic, RT) were compared with dual rows (0.3 m between dual rows) grown at 1.8 m spacing (controlled traffic, CT). Soil bulk density and penetrometer resistance in the row was greater and saturated hydraulic conductivity was lower under the random traffic rows compared with the controlled traffic rows. Crop yields were variable, but tended to be greater under controlled traffic than random traffic conditions. It is thought that the benefits of controlled traffic in the sugar industry would increase with time. A field trial compared conventional land preparation with intensive cultivation and a 6–10 month bare fallow and three different types of reduced tillage. Treatments included mechanical stool removal with a 6–10 month bare fallow, chemically spraying the stool with a 6–10 month fallow period followed by cultivating the row prior to planting and mechanical stool removal and replanting with no fallow period. The crop was planted directly back into the previous crop row in all treatments. Reducing the number of cultivations did not compromise seedbed conditions, since similar aggregate size distributions were measured under all tillage strategies. Stalk counts and final yields indicated that crop response was not significantly (P < 0.05) affected by reducing the number of tillage operations. Soil fauna counts showed that there were higher numbers under reduced tillage compared with conventional cultivation. Our results indicate that controlled traffic and reduced tillage improves soil properties in the crop row compared with random traffic and conventional tillage as currently practiced, and we think that further improvement over time can be expected if controlled traffic and reduced tillage is continued. It is suggested that the combination of controlled traffic and reduced tillage could form the basis of a farming system for the Australian sugar industry to protect the soil resource and maintain long-term productivity.