What does Unknown mean for an uncertainty value?
The “Unknown” uncertainty value does NOT mean the model does not support or have have cropping system and tillage data for your area. Nor does it mean that the C changes and fuel usage reported are considered unreliable. It only means there is currently insufficient statistical accuracy to estimate the uncertainty for your selected management scenarios. The uncertainty calculation, not the COMET-VR model itself, has problems with dry, low productivity, and wet, high productivity environments. Soon we plan to address some of these issues with an upgraded statistical model. However, the basic limitation to the uncertainty is a lack of soil carbon studies coupled with the site, management and production data needed to validate the environmental extremes.
