Some conclusions from a six-year study of farming systems on Upper Eyre Peninsula led by John Hancock, Minnipa Agricultural Centre (from the 1999 project summary report).
On average, direct drilling has increased wheat yield by 56 kg/ha at Cungena (calcareous soils) and 41 kg/ha at Minnipa (moderately calcareous red sandy soils).
Direct drilling has been demonstrated to be a successful way to sow crops early and gain improved yield, providing this system is set up properly. The use of points that cultivate below the seedbed increases the success of this system by providing some control against Rhizoctonia.
The importance of zinc nutrition has been emphasised in this trial and it is vital to ensure that zinc nutrition is maintained in the adequate range so that plant growth is not impeded.
The results have shown that stubble retention has not led to any change to yield at Cungena or Minnipa. Retaining stubble does, however, have many advantages. The improvement to soil cover can help protect against wind erosion.
Preliminary data obtained so far reveal that stubble may also play a very important role in building up soil microbe levels in these light calcareous soils. In the long term, this may improve the health of the soil and reduce the prevalence of disease.