To grow sugarbeet ( Beta vulgaris L.) profitably, producers must effectively manage added N, whether from inorganic or organic sources. Our objective was to determine if equivalent sugarbeet root and sucrose yields could be achieved when substituting dairy cattle ( Bos spp.) manure, either composted or stockpiled, for conventional N (urea) fertilizer. First-year treatments at Site A (Parma, ID) included a control (no N), urea (202 kg N ha -1), compost (218 and 435 kg estimated available N ha -1), and manure (140 and 280 kg available N ha -1). Site B (Kimberly, ID) treatments were a control, urea (82 kg N ha -1), compost (81 and 183 kg available N ha -1), and manure (173 and 340 kg available N ha -1). Compost and manure were incorporated into two silt loams, a Greenleaf (fine-silty, mixed superactive mesic Xeric Calciargid) at Parma in fall 2002 and 2003 and a Portneuf (coarse-silty, mixed superactive, mesic Durinodic Xeric Haplocalcid) at Kimberly in fall 2002. Sugarbeet was planted the following spring. Sucrose yield averaged across years and organic N rates at Site A was 12.24 Mg ha -1 for urea, 11.88 Mg ha -1 for compost, and 11.20 Mg ha -1 for manure, all statistically equivalent. Doubling the organic N rates at Site A increased the yield of roots up to 26% and sucrose up to 21%. Applying organic amendments in place of urea affected neither root nor sucrose yields but, at one location, decreased sugarbeet quality, though without hindering sucrose recovery. Sugarbeet producers can use compost or manure to satisfy crop N needs without sacrificing sucrose yield.
