Effect of soil and topographic properties on crop yield in a north-central corn-soybean cropping system

Understanding the variability of soil and landscape properties and their effect on crop yield is a critical component of site-specific management systems. The objectives of this study were to identify yield-limiting soil properties and to investigate the relationship between soil properties and topographical variables and their relationship to crop yield. Two corn (Zea mays L.)-soybean [Glycine mar (L.) Merr.] fields in Michigan were sampled, and 23 soil properties from the top two horizons up to 50 cm deep were examined. Corn and soybean yield data were collected from 1996 through 2001 using a combine yield monitor. A multivariate statistical model, principal-component analysis (PCA), was used to identify important soil properties based on their potential to affect crop yield. Soil properties identified by PCA to be important to yield and two topographic variables, elevation and slope, derived from a high-resolution digital elevation model (DEM), were investigated for their effect on crop yield. Correlation analysis was used to examine the relationship between soil properties and field topography and between crop yield and both soil and topographical variables. Principal-component analysis was useful in identifying important soil variables. Slope and very fine sand content were two major yield-limiting factors during the study period. Other soil variables such as base saturation, pH, clay content, and elevation were helpful in explaining yield variability. The combined effect of both soil and topography varied by year and explained 28 to 85% of the observed yield variability.