Introduction ield experience and research demonstrate that manure nutrients can be readily substituted for commercial fertilizer. Fertilizer needs depend on soil test levels. Substituting manure at a lower cost than commercial fertilizer can result in signifi cant savings if relatively uniform application and distribution can be maintained. The less nutrient-dense manure requires more hauling o...

Estimating crop nitrogen (N) status with sensors can be useful to adjust fertilizer levels to crop requirements, reducing farmers’ costs and N losses to the environment. In this study, we evaluated the potential of hyperspectral indices obtained from field data and airborne imagery for developing N fertilizer recommendations in maize (Zea mays L.). Measurements were taken in a randomized field ...