An irrigated site and a dryland site associated with the AG-CARES facility in Dawson Co., Texas were grid-sampled in 1990 and 1995, respectively. The irrigated site was sampled on a 2-acre grid and the dryland site was sampled on a 0.5-acre grid. Samples were analyzed for Soil-test nitrogen (N) and phosphorus (P), and were subjected to geostatistical analysis.