A COMPARISON OF DIFFERENT TILLAGE SEEDING SYSTEMS - THE INTERACTION OF TILLAGE AND TIME OF SOWING ON SANDPLAIN SOILS IN WESTERN-AUSTRALIA

The effects of tillage-seeding method and 2 times of sowing on yields of wheat (Triticum aestivum) were examined on the sandplain soils in t he northern wheatbelt of Western Australia. Four methods were compared : sowing after cultivation, sowing followed by deep ripping, direct dr illing (i.e. single-pass seeding with a tined drill), sowing with a ne w cultivation depth modified drill (CDM) modified to cultivate up to 1 4 cm deep while sowing at 4 cm. Crops direct-drilled with the CDM prod uced more grain than crops established with conventional direct drilli ng or-crops sown later using the cultivate-sow method and had similar yields to late-sown deep-ripped crops, where appropriate cultivars wer e used. Early sowing followed by deep ripping produced the highest gra in yield. However, increasing the depth of soil disturbance while sowi ng early with the CDM in a 1-pass system resulted in a progressive inc rease in grain yield. When the cost of the extra ripping or cultivatio n operation is taken into account, early direct drilling with the CDM drill is likely to be more profitable than either conventional direct drilling or sowing with deep ripping or cultivation.