Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2005
Publication Date: 11/7/2005
Citation: Long, D.S., Kozar, B.J., Wraith, J.R. 2005. Evaluating variability of soil water in hummocky glaciated landscapes of northern Montana. Agronomy Abstracts. American Society of Agronomy. Madison, WI. CDROM
Technical Abstract: The interest in precision agriculture has drawn attention to yield differences within farm fields, which are largely due to variability in soil water. The objective of this study was to evaluate the influence of topography on soil water distribution in gently undulating and rolling terrain of northern Montana. The prairie soils (Ustolls and Usteps, frigid) have developed from loamy, glacial till parent material. Neutron scattering was used to monitor soil water distribution over two growing seasons within four dryland fields. Geographic Information System (GIS)-based digital terrain modeling was used to compute the compound terrain index (CTI), which specifies that that soil water content will decrease as flow lines are retraced upslope higher within a watershed. Relationships between CTI and soil water varied from field to field and were poorly correlated. The strongest correlation occurred at the end of the growing season at the 20-cm soil depth in one study site (r^2 = 0.40, P<0.05). The results indicated that topographic features in the driest portions of the northern Great Plains have little influence on soil water distribution because of absence of abundant precipitation or shallow impeding subsoil layers that would create conditions for lateral surface or subsurface flow.