THE INFLUENCE OF SOIL FACTORS ON YIELD DIFFERENCES AMONG LANDSCAPE POSITIONS IN AN APPALACHIAN CORNFIELD

The topography of the Appalachian region strongly influences the environment for plant growth. We conducted a field study in 1984 and 1985 on a Gilpin silt loam soil association in Preston County, West Virginia, to determine soil and environmental factors controlling corn (Zea mays L.) yield differences among landscape positions. Four plots were established at each of nine locations including summit, shoulder (N, E, S, W aspects), and backslope (N, E, S, W aspects). Athough common management practices were used throughout the field, silage, yields (65% moisture) were 15.3 to 43.0 Mg/ha in 1984 and 22.2 to 36.6 Mg/ha in 1985. Grain yields (15% moisture) were 3.1 to 8.2 Mg/ ha in 1984 and 4.0 to 7.6 Mg/ha in 1985. Poor silage and grain yields were associated with higher clay content and lower organic C in the A horizon, lower plant “available water” in the 0− to 15-cm depth interval, and possible subsoil acidity problems. Mean “available water” as represented by the difference between gravimetric water determined over time and water retained at 1500 kPa was a good predictor of silage yield. Soil water was apparently the most important factor controlling corn production differences in this study. The ability to predict soil water relationships on the landscape would hasten the development of successful agronomic management practices for the hilly Appalachian region. © 1990 Williams & Wilkins.