Variability in Canada Western Red Spring wheat yield response to applied nitrogen in Manitoba soil landscapes

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Durand, Laurent (Larry) David Joseph
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Increasing economical and environmental pressures has sparked a great deal of interest in precision agriculture. Thus, a great deal of research has been initiated in order to gain a greater understanding of how existing technologies such as global positioning systems, geographic information systems, and equipment with variable rate capabilities can be used to manage agricultural amendments at a site specific level. In 1996 and 1997, small plot trials were established at six sites in Southern Manitoba. Four of these sites were located on glacial till landscapes of the Newdale Association and the other two were located on lacustrine landscapes of the Red River Association. A variety of soil and crop parameters were examined throughout the study. Replicated small plots with fertilizer N rates ranging from 0 to 200 kg N ha-1 were established in various positions in the landscape based on relative elevation, slope morphology, and slope aspect. The objective of the study was to determine if there were any significant differences in yield response to applied N in Canada Western Red Spring wheat in these landscapes. In the glacial till landscapes, a number of the soil parameters were found to be strongly associated with landscape position. Among these parameters, electrical conductivity, depth of A horizon, solum depth, NO3- -N, volumetric water content, and growing season N uptake tended to demonstrate the most consistent differences among landscape positions. However, yield and grain protein responses to applied nitrogen were extremely inconsistent throughout the study in these landscapes. The soil parameters studied in the lacustrine landscapes demonstrated very different trends than those observed at the glacial till landscapes... The use of landscape position as the only variable in determining differences in yield responses to applied N proved to be ineffective in the glacial till landscapes studied. In these landscapes, more comprehensive models with various other soil parameters may need to be developed in order to make variable rate nitrogen decisions. However, the use of landscape positions to make variable rate nitrogen decisions in lacustrine landscapes may be more promising.