Mechanized relay-cropping in an irrigated red-brown earth in south-eastern Australia

Abstract. Machinery was designed specifically for relay-cropping on permanent raised beds (150 mm high and 1.5 m wide) in northern Victoria. This machinery enabled maize ( Zea mays ) to be successfully sown at 2, 4 and 5 weeks before harvest, and 1 day after harvest (Control), of wheat ( Triticum aestivum ). The sowing equipment consisted of a four-row cultivator, behind which were four precision seeders. The wheels (250 mm in diameter) were spaced at 1.5 m to track along the base of the furrows. In one pass on each bed, the sowing equipment tilled two strips (each 50 mm wide, 30 mm deep and 50 mm from the outer row of wheat) and sowed maize, with little damage to the wheat crop. We extended the axle of the trailed harvester so that the wheels (250 mm in diameter) were 3 m apart, and moved the drawbar 300 mm to one side so that all wheels ran along the base of the furrows. There were no significant differences between treatments in yield (mean 2.9 t ha^-1) of dryland wheat, in final emergence percentage (mean 89%) or in early growth of irrigated maize. The maize yielded significantly less grain in the treatment sown at 5 weeks (9.6 t ha^-1), but not 2 or 4 weeks (mean 10.6 t ha^-1) before the wheat was harvested, than in the Control (10.8 t ha^-1). The wheat and maize yielded more grain than those grown traditionally as sole crops in northern Victoria.