A new publication from Iowa State University researchers shares the average nitrogen use efficiencies (NUE) on a county-by-county basis in Iowa - allowing farmers and agronomists to compare their fields to those surrounding it.
A field’s NUE - the pounds of nitrogen applied per bushel of corn harvested - is associated with positive environmental and economic outcomes, according to ISU Extension and Outreach. This number can be affected by variables such as weather, management, crop genetics and soil type.
Data in the publication suggests a field’s NUE can be improved by nitrogen management, soil management and planting date. If you have a field that’s using more N than the county average, researchers advise you to ask yourself why that is and what management practices you can be doing to help reduce that amount.
Practices ISU Extension has found to be the most impactful to improve NUE are:
- Crop rotation
- Drainage improvement
- Shift from fall to spring fertilizer application
Cover crops and reduced tillage were found to be the least effective and had more variable results overall.
The research also shows the average bushel of corn contains 0.55 lb. of nitrogen, so applications less than that per bushel would be unsustainable as more is harvested than applied each year.
