MN Impact: Subfield level model for improved nitrogen fertilizer recommendations

Issue

Agroecosystem modeling, used for generating nitrogen (N) fertilizer recommendations, is traditionally performed at the field scale or larger. Such field level models result in an entire field getting the same fertilizing recommendation. Because of inherent variability within a field, these recommendations are not always accurate and could lead to using excess or insufficient fertilizer.  

What has been done

Researchers at the University’s Precision Agriculture Center have developed a novel approach that takes the traditional modeling one step further by performing a secondary calibration using data with high spatial resolution. The software integrates remote sensing and crop systems model to spatially determine in-season N stress. 

Results

The software integrates the EPIC (Environmental Policy Integrated Climate) field (or subfield) based agroecosystem model with a geographic information system (GIS) database. It creates a simulation “template” for every unique location in a field, whether large scale (e.g. hectares) or small scale (e.g. individual plant). For each unique location, it performs a secondary calibration using any spatially precise data available (e.g., crop yield maps, aerial images indicative of crop biophysical parameters or soil characteristics) collected over any time scale.

Overall, the new model integrates spatially precise data with GIS to provide better N fertilizer recommendations. These recommendations help growers made informed decisions that will ultimately improve crop N efficiency and reduce the likelihood of nitrate contamination of water resources.