Mr Oswald's winning scores
Water-use efficiency: 11.99kg/ha/mm growing season rainfall. Based on a calculation of grain produced per hectare per millimetre growing season rainfall (adjusted April to October rainfall)
Cost efficiency: $ 1.71/ha/mm growing season rainfall. Based on a calculation of gross margin profit per millimetre of growing season rainfall.
How it was calculated
Kg/ha/mm is calculated by dividing grain yield by the number of hectares and by the figure for growing season rainfal1.
Cost efficiency was calculated by dividing gross margin profit per hectare by the figure for growing season rainfall.
Rainfall: Calculated on the basis of mm falling in the growing season. April to October or adjusted for your region. Subtract 110 mm (average in southern states) for evaporation losses and use the remainder in the equation.
Gross yield potential: It's quite common for actual yields to be less than 50 per cent of potential. Here's a rule of thumb for calculating the potential gross kg yield per hectare in relation to rainfall. Take your relevant growing season rainfall, subtract 110 mm (average) and multiply by 20.
(20kg/ha/mm rain fa ll has been shown in field trials to be achievable under ideal conditions such as getting the crop in by Ihe first rainy day to use full water potential)
Grain price: was calculated at Hard Wheat varieties 12 percent protein; ASW varieties 10 percent protein.
Expenses: included standard prices for seed, fuel, fertiliser and chemicals. Allowance was made for repairs and maintenance. Harvesting costs were not included.
Yield: judged by an outside assessor but you can judge your own.