Spatial and temporal variability in corn growth, development, insect pressure, and yield

To identify critical site-specific factors affecting crop production within a 16 ha central Iowa field, we quantified the spatial and temporal variability in corn (Zea mays L.) emergence and growth, insect pressure and damage, extractable soil nutrient levels, yield, and yield components. Principal components, simple correlation, and stepwise regression analyses were used to examine relationships among the various parameters. Spatial soil-test patterns were examined by overlaying data layers with a geographical information system. Analysis of data from 40 microplots showed that soil water content 10-d after planting, total organic C, and total organic N accounted for 21% of the variance. Data from individual plants within each microplot showed that early emergence and total soil N content accounted for 23% of the variance. Soil acidity may be a factor that can be corrected by site specific management, but water management and erosion control appear more important than variable fertilization.