Five mesquite dunes were irrigated by pumping water from storage tank located 200 m from the site. Water was applied to the dunes with an overhead sprinkler (later replaced by a drip irrigation system to minimize wind drift) located at the apex of each dune. Irrigation began in March with approximately 2.5 cm applied 2-3 times/week for 6 weeks to initially wet the dry soil. Thereafter high water availability was maintained by weekly irrigation. Five nonirrigated dunes served as control. Soil samples were collected (hand augered) under mesquite (Prosopis glandulosa) trees at sand dune site on the Jornada LTER site to three depths, 0-50 and 50-100, and 100-150cm. Soil samples were placed in plastic bags, tied, and stored in portable coolers. These samples were later divided into subsamples for nematode investigations. Nematodes were recovered using semi-automatic elutriator with sugar flotation-sieving (Byrd et al. 1976), and Baerman Funnel Technique (Freckman and Virginia 1989). Nematodes were counted and separated into trophic groups (Freckman et al. 1987, Freckman and Baldwin 1990).