Overseer is pleased to announce that we have completed three science research projects investigating and updated where necessary the Overseer science model. The completed projects include:
• Comparing N-leaching estimates using different climate datasets
• Crop model update to incorporate deeper rooted plants
• Overseer model sensitivity and uncertainty analysis for N-leaching estimates.
Overseer undertook a series of sensitivity and uncertainty analyses focusing on nitrate leaching. Our findings confirmed that the model is most sensitive to climate and soil inputs and that these factors contribute the most to the average uncertainty of N-leaching estimates. The uncertainties associated with Overseer estimates are on par with other environmental models and were comparable for dairy, beef and sheep and cropping farms. More model sensitivity and uncertainty work is planned for next year to continue to inform confidence in the Overseer model estimates.
The Overseer model currently uses long-term average monthly climate data. Comparisons of this dataset with other combinations of climate data, including daily climate inputs, concluded that the current climate dataset remains fit for purpose.
Assessment of the impact of N-uptake below 600 mm by deeper-rooting plants showed that N-uptake will generally occur only when there is sufficient nitrogen available above 600 mm. Based on this, OverseerFM has now been updated to incorporate N-uptake by deeper rooted plants. You can read the release notes for this update here.
We are still working on two science model research projects which are part of our current science programme of work. If you are interested in finding out more about our science projects contact us at science@overseer.org.nz
Why is this research important?
We know some farmers and growers have had some questions about OverseerFM following the technical review of the Overseer model released last year.
This research increases the confidence in OverseerFM. It also shows that OverseerFM remains a useful decision support tool that allows farmers and growers to make informed decisions about their farm management practices.
Overseer Limited will continue to work hard to improve the understanding of OverseerFM and the way it should be used. One way to think about OverseerFM results is to view them more like a weather forecast than a measure you might obtain from a rain gauge or thermometer. Weather forecasts provide valuable insights and are continually improving, but nobody expects them to be 100% right 100% of the time. Whether a weather forecast, or any environmental model, is ‘good enough’ depends on how you propose to use the results, the decision you are making and what is at stake. Inevitably, there will always be a degree of uncertainty associated with modelled results, so it is vital users understand OverseerFM’s limitations and consider what else is known about the farm being modelled.
As we look forward to 2023, Overseer Limited is committed to continuing to improve OverseerFM for the benefit of our farmers and growers, the wider primary sector and New Zealand. We will continue to develop OverseerFM to improve its utility, reliability, and usability. This will include providing ways to provide insights and information to enable farmers to evaluate their progress over time so they can better tell their story and be recognised and rewarded for the hard work and investment.
