CROP YIELD VARIATION ASSOCIATED WITH COASTAL-PLAIN SOIL MAP UNITS

A 4-yr field study at an 8-ha research site near Florence, SC was conducted to quantify yield variation for a southeastern Coastal Plain field. Nineteen soil map units, classified as Ultisols and representing seven soil series were identified. Corn was grown in 1985, 1986, and 1988, while in 1987 wheat and grain sorghum were double-cropped. Crop yield was measured by harvesting transects throughout the field and subsequently identifying soil map units for each plot. Extractable P, K, Ca, Mg, Mn, and Zn; soil organic matter and pH; and depth to an argillic horizon (Bt) were measured to identify causes for yield variation among soil map units. Results demonstrate how measurements of crop yield by soil map unit can be determined and used to study soil variation. They also provide a data base that can be used to evaluate plant growth and soil management models for individual soil map units. -from Authors