LONG-TERM INGHAM AND MACKAY FARMING SYSTEM EXPERIMENTS: COMPARISONS BETWEEN PERMANENT NON-TILLED BEDS AND RE-FORMED BEDS

EXPERIMENTS involving row spacing and tillage, originally established in Mackay and Ingham in 2001, were planted to a second cycle of sugarcane in 2006 following a soybean break. In the second cycle 1.5 m and 1.8 m single and 1.8 m dual rows were established into fully prepared land or land that was kept in permanent beds, receiving no tillage since 2001. In the plant crop in both experiments, tillage produced a highly significant increase in cane and sugar yield but there was no effect of row spacing. The response to tillage could be attributed to the removal of compaction caused by harvester and haul-outs during the previous cycle. In the first ratoon there was again no effect of row spacing, and surprisingly, no effect of the tillage applied prior to planting in either experiment. The lack of a tillage response in the first ratoon suggests that much of the damage caused by compaction is inflicted during harvesting of the plant crop. Despite large yield differences, economic analysis indicated that there would be little difference in gross margins because of the much higher costs of the tilled system. It is concluded that without GPS guidance, as was the case with these experiments, cane yields are likely to be reduced with no tillage but these problems may well be overcome by implementing minimum strategic tillage to remove compaction from the planting row.