The objective of this study is to develop a simple landscape model within a Geographical Information Systems framework to evaluate the effects of spatial variability of topographic factors on soil genesis. Results indicate that the spatial distribution of E horizons can be estimated from surface curvature, slope, and aspect. The study also shows that contrasting soils that are in close proximity to each other, too close to be separated on conventional soil maps, can be detected with the help of landscape parameters. Big map units that extend over several hillslope positions can be further divided into smaller units to receive separate agricultural management based on soil water relationships defined by these landscape parameters. 150 soil cores were collected on a 50 m grid from a 32 ha field containing most slope facets found in the Palouse region of eastern Washington.
Results are pending analysis of soil cores and development of surface curvature maps.
In the 1997 crop year, they looked at soil test data, variable and fixed rate fertilizer applications, and yield monitoring on 2 fields. Data is being compiled and plans are in progress for efforts for 1998. Efforts are also ongoing on this project to develop variable rate water applications through pivot systems as well as variable rate pesticide applications through a fixed boom attached to the pivot. The remainder of the field was fertilized at using variable rate application equipment based solely on soil test P value. The remainder of the field was harvested with yield monitoring equipment.