F. Walley et al., Spring wheat (Triticum aestivum) yield and grain protein responses to N fertilizer in topographically defined landscape positions, CAN J SOIL, 81(3), 2001, pp. 505-514
A 3-yr field study was initiated in 1996 to examine the different grain yie
ld and grain protein responses of wheat to varied N fertilizer rates in a t
ypical glacial till landscape in Saskatchewan, Canada. Our objective was to
assess the agronomic and economic feasibility of variable rate fertilizer
(VRF) N application for wheat. Results suggest that spring soil water statu
s largely determined the yield and the protein content of wheat both within
different years of the study and between different landscape positions wit
hin a given year. Although grain yield was strongly related to spring soil
water and was predictable on that basis, the grain yield response of wheat
to fertilizer N additions was highly variable due, in part, to the dual rol
e that N played in determining both grain yield and grain protein content.
As a consequence of the unpredictable nature of the varied response of whea
t to N fertilizer additions, there was little economic rationale for using
VRF strategies in the 3 yr of this study. However, in the long-term, we bel
ieve that VRF N application strategies can be employed to manage N inputs f
rom the perspective of managing and replacing harvested N.