Canopy reflectance informs in-season malting barley nitrogen management: an ex-ante classification approach data

Malting barley (Hordeum vulgare) requires precise nitrogen (N) fertilizer management to achieve a narrow range of grain protein content (≈9–10.5%) while maintaining yields, but practical tools to accomplish this are lacking. This study hypothesized that canopy reflectance (Normalized Difference Vegetation Index (NDVI)) measured at tillering (Feekes 2–3) and expressed as a sufficiency index (SI), can estimate the likelihood of a site-specific response to in-season N fertilizer in malting barley. Canopy reflectance was measured from plots at tillering with a GreenSeeker and unmanned aerial vehicle (UAV) borne multispectral cameras in trials across heterogeneous California agroecosystems. Field experiments included a range of N fertilizer application rates (0–168 kg N ha-1) and timings (pre-plant, tillering, or evenly split), and resulted in a range of crop N sufficiency/deficiency. NDVI-based SI measurements were categorized into one of three quantitative categories (low, medium, and high..., , The .Rmd file details how the data was analyzed and used in the manuscript.