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Winter Wheat Yield and Grain Protein across Varied Landscape Positions
Author(s) -
Fiez Timothy E.,
Miller Baird C.,
Pan William L.
Publication year - 1994
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1994.00021962008600060018x
Subject(s) - yield (engineering) , fertilizer , agronomy , grain yield , nitrogen , winter wheat , precipitation , environmental science , mathematics , chemistry , geography , biology , materials science , organic chemistry , meteorology , metallurgy
Winter wheat ( Triticum aestivum L.) yield varies greatly among landscape positions in the Palouse region of eastern Washington, yet N fertilizer is typically applied uniformly. Varying N fertilizer rates within fields to match site‐specific N requirements can increase fertilizer use efficiency; however, spatially variable N management programs are limited by their ability to predict site‐specific yield potentials and the resultant N requirements. The objective of this study was to ascertain the role of yield components and soil properties in determining soft white winter wheat grain yield and protein when N application rates are varied among landscape positions. Nitrogen fertilizer (0 to 140 kg N ha −1 ) was fall‐applied on footslope, south‐backslope, shoulder, and north‐backslope landscape positions at each of two farms in 1989 and in 1990. Grain yield among landscapes varied by up to 55% in 1990 and by up to 33% in 1991. Landscape position grain yields increased by 199 kg ha −1 /(cm precipitation + soil water reduction) ( r 2 = 0.51) and by 706 kg ha −1 per 100 spikes m‐2 ( r 2 = 0.76). Grain protein concentration among landscapes increased by 2.7 g kg −1 per each increase of 10 kg residual soil NO 3 −N ha −1 ( r 2 = 0.82). The large differences in grain yield among landscape positions may justify spatially variable N application. Improved N management should favorably reduce soft white winter wheat protein concentrations by minimizing high residual N levels as well as improve net returns and reduce environmental degradation. The basis for this improved N management may be site‐specific yield estimates calculated from soil water availability and spike density.