Adapting the nitrogen replacement approach to dryland spring wheat in the Pacific Northwest

Authors: Long, Daniel; McCallum, John; Reardon, Catherine - Kate; ENGEL, RICHARD - Montana State University

Submitted to: American Society of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2017
Publication Date: 8/3/2017
Publication URL: http://handle.nal.usda.gov/10113/5934973
Citation: Long, D.S., Mccallum, J.D., Reardon, C.L., Engel, R. 2017. Adapting the nitrogen replacement approach to dryland spring wheat in the Pacific Northwest. American Society of Agronomy. 50(5):34-37. doi:10.2134/cs2017.50.0503.
DOI: https://doi.org/10.2134/cs2017.50.0503

Interpretive Summary: Grain quality analyzers have become commercially available for combine harvesters to enable on-the-go mapping of grain protein levels across farm fields. A map of grain protein is potentially useful for post-harvest assessments of N management programs and development of future fertilizer N recommendations. Further, the grain protein concentration at harvest provides a qualitative index of N nutrition sufficiency, or deficiency, based on whether the protein level is above, or below, an established critical level. However, critical grain protein levels vary geographically across North America and need to be established for unique climate regions such as the PNW. The deficit in grain protein concentration below the critical level can also be used as a predictive tool to further refine future fertilizer N needs to maximize production or economic return based on the fertilizer N equivalent (FNE) required to raise protein to an acceptable level. This magazine article summarizes results of a study we conducted in eastern Oregon to define the critical protein levels for spring wheat and their FNE values. With this knowledge, dryland farmers in the lower rainfall areas (<14 in.) of the region could use yield and protein maps obtained with on-combine sensing equipment to estimate both the N-removed by a previous wheat crop and the N-required to raise protein to a desired level in the next crop.

Technical Abstract: Grain quality analyzers have become commercially available for combine harvesters to enable on-the-go mapping of grain protein levels across farm fields. A map of grain protein is potentially useful for post-harvest assessments of N management programs and development of future fertilizer N recommendations. Further, the grain protein concentration at harvest provides a qualitative index of N nutrition sufficiency, or deficiency, based on whether the protein level is above, or below, an established critical level. However, critical grain protein levels vary geographically across North America and need to be established for unique climate regions such as the PNW. The deficit in grain protein concentration below the critical level can also be used as a predictive tool to further refine future fertilizer N needs to maximize production or economic return based on the fertilizer N equivalent (FNE) required to raise protein to an acceptable level. This magazine article summarizes results of a study we conducted in eastern Oregon to define the critical protein levels for spring wheat and their FNE values. With this knowledge, dryland farmers in the lower rainfall areas (<14 in.) of the region could use yield and protein maps obtained with on-combine sensing equipment to estimate both the N-removed by a previous wheat crop and the N-required to raise protein to a desired level in the next crop.