Soil organic matter and the abundance of subterranean termites were measured at 89 locations spaced at 30-m intervals from the bottom to the top of a small desert watershed. There was no correlation between soil organic matter content and topographic position on the watershed. Analysis by autocorrelogram demonstrated that the soil organic matter content was randomly distributed on the watershed. There was a highly significant negative correlation between termite abundance and soil organic matter, r = -0.97. Soils characterized by horizon in soil pits within each vegetation type (soil type) showed some relationships to erosion-deposition areas on the watershed, with surface organic matter contents varying between 3.4% in the playa basin where termites were absent to 0.4% in a sparse shrubland on erosional soils. In the northern Chihuahuan Desert, subterranean termites appear to be responsible for most of the variation in soil organic matter.