Contamination of freshwater bodies by excess nutrients is a critical water quality issue in Delaware. Improving the management of nutrients in crop production is an important step toward addressing this issue. Corn growers in the Mid-Atlantic base nitrogen (N) inputs on the following recommendation formula: 1 lb N/bu expected yield, where expected yield is determined by their knowledge of the field. This formula does not consider soil N content or variations in soil N over the field. While a sufficient quantity of N is critical for profitable corn production, appropriate application (timing and placement) of this N is critical for minimizing nitrate contamination of ground and surface waters.

Applications of nutrients to cropland usually are guided by soil tests, but how these samples should be collected is still a matter of much debate. New research indicates that grid sampling at an extremely small scale, possibly less than two meters, may be necessary to characterize spatial variability in soil nutrient availability. Such intense sampling is clearly not practical for most producers. This problem can, however, be addressed by using remote sensing, which has the potential to gather large amounts of data efficiently and effectively.

The objectives of this study were to 1) test the effectiveness of remote sensing in identifying the variability of N content within a production cornfield, 2) develop an image-based technique for site-specific mid-season nitrogen fertilizer management of corn in the Mid-Atlantic, 3) evaluate the use of previous yield maps for applying site-specific N fertilizer to corn at sidedress, and 4) evaluate the economic viability of prescription based site-specific N fertilization to corn in the Mid-Atlantic using remote sensing and previous yield maps.