Winter Wheat Yield and Grain Protein across Varied Landscape Positions

Abstract

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) (r2 = 0.51) and by 706 kg ha−1 per 100 spikes m‐2 (r2 = 0.76). Grain protein concentration among landscapes increased by 2.7 g kg−1 per each increase of 10 kg residual soil NO3−N ha−1 (r2 = 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.

Impact of Climate Change Adaptation Strategies on Winter Wheat and Cropping System Performance across Precipitation Gradients in the Inland Pacific Northwest, USA

“…While a portion of this variability was teased out by differences in year-to-year precipitation, other environmental, genetic, and management factors contribute to within-site variability, such as landscape elevation, slope, aspect (Mulla et al, 1992;Fiez et al, 1994;Yang et al, 1998), subsoil constraints , spring rainfall , crop rotation (Hammel, 1995), nutrient availability (Fiez et al, 1995), onset of drought and temperature stress (Gizaw et al, 2016), and crop genetics . Despite the heterogeneity of the landscape, iPNW growers still commonly apply single rates of fertilizer, particularly in the higher precipitation areas (Mahler et al, 2014).…”

“…In addition to conserving soil water, the reduction or elimination of tillage is a strategy to combat water and wind erosion (Singh et al, 2012;Williams et al, 2014) in combination with continuous annual cropping (Thorne et al, 2003;Feng et al, 2011). Heterogeneous topography also challenges nutrient management due to significant variability in plant-soil-nutrient interactions and crop performance (Fiez et al, 1994(Fiez et al, , 1995 with opportunities for site specific N fertilizer management to mitigate differences in water and N use efficiencies across the landscape (Miao et al, 2011). A combination of these alternative cropping system strategies may increase productivity and economic returns (Tanaka et al, 2002;Alam et al, 2015;Babu et al, 2016), and multiple strategies may be needed (Kirkegaard and Hunt, 2010;Snapp et al, 2010).…”

Use of soil moisture data for refined GreenSeeker sensor based nitrogen recommendations in winter wheat (Triticum aestivum L.)

“…It is apparent that fertilizer use efficiency is a function of available water (Fiez et al 1994;Gutierrez-Boem and Thomas 1998). Thus, temporal variability in soil moisture (SM) clearly translates into temporal variability of crop response to N. It has been shown that crops response to N varies significantly from year to year, and that the magnitude of response is difficult to predict from 1 year to the next.…”

Managing nitrogen fertility of irrigated soft white spring wheats for optimum quality

“…In contrast to the body of literature on fertility management of hard wheat, relatively few studies have evaluated the effect of fertility practices on soft wheat yield and grain protein (Glenn et al 1985;Bole and Dubetz 1986;Bruckner and Morey 1988;Gravelle et al 1988;Carefoot et al 1989Carefoot et al , 1993Fiez et al 1994;Fowler 2003). These studies have demonstrated advantages to split applications of N in terms of improved crop yield and nitrogen use efficiency.…”