Normalized difference vegetation index and soil color-based management zones in irrigated maize
Spectral vegetation indices such as the normalized difference vegetation index (NDVI) have been shown to be useful for indirectly obtaining crop information such as photosynthetic efficiency, productivity potential, and potential yield. The objectives of this study were (i) to examine the relationships among NDVI determined early in the growing season, soil color-based management zones (SCMZ), and relative maize (Zea mays L.) grain yield and (ii) to determine if coupling soil color-based management zones with NDVI improves the accuracy of soil color-based management zone precision crop management strategy. Remotely sensed imagery was acquired by aircraft at approximately the eight-leaf crop growth stage (V8). Kappa statistics and percent areal agreement suggested a slight to substantial areal association among NDVI and relative grain yield (K = 0.10 to 0.63; % areal agreement = 13–67). Regression models were variable and explained among 25 to 82% of the variability in relative grain yield. Inclusion of soil color-based management zones in the regression models resulted in marginal improvements. When the affects of soil color-based management zones were removed, NDVI accounted for among 10 to 47% of the variability. The NDVI determined early does have potential to be useful in irrigated maize cropping systems. Coupling NDVI and SCMZs did not bring additional benefits to our soil color-based management zone strategy.