 This study investigated the effectiveness of using multi-spectral vegetation indices and crop height derived from a compact camera mounted on a UAV to predict grain yield and determine if an additional side dress application of nitrogen fertilizer was needed just before flowering. The study found that the Wide Dynamic Range Vegetation Index, WDRVA, was the most effective index for predicting final grain yield. Additionally, it demonstrated that there was no significant response to extra nitrogen application at the economic optimum rate of fertilization, 239.8 kg.n.ha-1, for which a grain yield of 16.12 mg.ha-1 was obtained. Furthermore, a ranking of different vegetation indices and crop height was proposed to overcome the uncertainty associated with basing decisions on a single index. This article was authored by Angel Merezma, Mara Riza, Elias Martinez, and others.