Nitrogen Use Efficiency
Soil organic matter increases crop yield amount and stability. Soil organic matter – not nitrogen fertilizer – is the largest source of crop nitrogen uptake and environmental nitrogen loss. For example, approximately 10% of Iowa corn acres are non-responsive to nitrogen fertilizer in any given year despite yields that exceed regional averages- however, predicting those acres is extremely challenging.
To increase nitrogen retention and nitrogen use efficiency, we must improve our understanding of the processes that control inorganic nitrogen fertilizer transformation to soil organic matter, and subsequent re-transformation of soil organic matter back to crop-available inorganic nitrogen (a process known as ‘mineralization’).