Nitrogen Recommendation Recalibrations for Wheat in North Dakota
A multiple year research study updating N response and recommendations for wheat in various agro-ecological areas of North Dakota.
IPNI-2007-USA-ND15
15 Feb 2010
2009 Annual Interpretive Summary
Nitrogen Recommendation Recalibrations for Wheat in North Dakota, 2009
The objective of this project was to review current N recommendations for wheat to determine profitable N recommendations for spring wheat and durum in North Dakota. Over 100 site-years of data were collected during this project from archived studies and recent N-rate studies. Soil test nitrate improved the relationship between available N and yield. The Return to N approach was used to establish relationships between yield/protein response and economics of N application. This approach was modified for wheat by adding the criteria for the protein relationship. In the economic analysis, a 50% per point premium was provided between 14 to 15% protein, and a 50% per point dockage for any protein below 14%. The large number of sites made it possible to segregate different agri-climatic zones and determine whether the responses to available N were similar or different. The state was separated into the Langdon region, Eastern North Dakota, and Western North Dakota. When using the newly re-calibrated recommendations, a grower is asked to look exclusively at past field yield history and select productivity levels of low, medium, or high. The table values determined by region, productivity, wheat price and N cost are gross N requirements determined using return to N relationship equations. From this, the soil test nitrate will be subtracted. Other adjustments include previous crop N credits, additions due to short-term no-till adoption, credits due to long-term no-till adoption, and organic matter if greater than 5.9%.
The opening segment of the “North Dakota N Rate Calculator,” is available on the web at this: www.soilsci.ndsu.nodak.edu/franzen/franzen.html. The final recommendation is usually plus/minus 30 lb N/A. Adjustments based on the common sense of the grower/consultant and their experience with the field area will dictate the final rate. Consideration due to protein property of the wheat variety, N application techniques that might not be 100% efficient, excessive previous year straw, and other considerations may play roles in defining the final rate. The recommendations were made available December 1, 2009, in both print form and as the web-based N calculator. ND-15