Agricultural research in broadacre farming in Western Australia has a strong history, resulting in a significant public resource of knowledge about biophysical processes affecting crop performance. However, translation of this knowledge into improved on-farm decision making remains a challenge to the industry. Online and mobile decision support tools to assist tactical farm management decisions are not widely adopted, for reasons including: (1) they take too much time and training to learn; and (2) they aren’t integrated with the data they need or with each other, making their use too time-consuming.

Meanwhile, as farmers accumulate more data from their machinery, they find themselves unable to use that data to inform decision making. In an ideal future, variable rate technology (VRT) could be programmed to apply optimal rates of fertilisers. However, the existing suite of models and tools are derived from small-scale controlled field experiments and are not suitable for fine-scale paddock management.

Using 14 years of data from a farm in the eastern wheatbelt of Western Australia, we investigate the calibration and extension of an agro-economic model for spatial prediction of the effects of nitrogen applications on wheat yield and gross return. We use a simple response curve model, NP-Decide, that was developed in Western Australia and remains in common use.