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United States Department of Agriculture

Agricultural Research Service

Research Project: SOIL CONSERVATION SYSTEMS FOR SUSTAINABILITY OF PACIFIC NORTHWEST AGRICULTURE

Location: Northwest Sustainable Agroecosystems Research

Title: Fifty Years of Predicting Wheat Nitrogen Requirements Based on Soil Water, Yield, Protein and Nitrogen Efficiencies)

Author
item William, Pan
item Schillinger, William
item Huggins, David
item Koenig, Richard
item Burns, John

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 11/1/2006
Publication Date: 12/1/2006
Citation: Pan, W.L., William Schillinger, David Huggins, Richard Koenig, and John Burns. 2006. Fifty Years of Predicting Wheat Nitrogen Requirements Based on Soil Water, Yield, Protein and Nitrogen Efficiencies. In Annual meetings abstracts [CD-ROM]. ASA, CSSA, and SSSA, Madison, WI.

Interpretive Summary:

Technical Abstract: During the early 1950’s synthetic N fertilizers were gaining widespread adoption in the wheat growing region of the inland Pacfic Northwestern U.S. Agronomists quickly recognized water and N as the two principal determinants of grain yield and quality Numerous N fertility trials across a range of climatic environments, soils and cropping systems provided the basis for estimating wheat yield potentials from root zone soil moisture, and N fertilizer recommendations were made from yield-based crop N requirements, estimates of soil N supplies and N use efficiencies. This N recommendation model based on the regional variations in crop-soil N budgets has stood the test of time for nearly 50 years, as confirmed by recent N fertility and agronomic trials. A recent data analysis of yield-water relationships reveals a remarkably similar slope but different y-intercept defining the lowest available water levels at which grain yields are obtainable. Spring soil moisture remains a reasonable predictor in this Mediterranean climate, but variable in-season rainfall is still a major source of error. Adjustments in the N recommendation model have been made to accommodate genetic, soil, management and climatic variables affecting water and N use efficiencies. However, limits in our ability to extrapolate the regional model to site specific applications are restricted by our ability to predict landscape processes that control the water-yield and the yield-nitrogen use relationships defining the unit N requirement. The generalized 50% single season N uptake efficiency used in the model is adjustable with improved N management, but much higher rotational N uptake efficiencies need to be recognized and taken into account.

Last Modified: 8/24/2016
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