The effect of nitrogen fertilizer rates and timing on cranberry yield and fruit quality

To examine the impact of N fertilizer rates and timing on cranberry (Vaccinium macrocarpon Ait.) yield and the fruit quality factors total anthocyanin, average berry weight, and field and storage rot, plots were established for 3 to 4 years, The cranberries received a total of 0, 22, or 44 kg N/ha over the growing season applied in three, four, or five applications, which varied by growth stage. There were eleven possible treatment combinations in Massachusetts on 'Early Black' and 'Howes' and in Wisconsin on 'Stevens' and 'Searles', and seven possible treatments in New Jersey on 'Early Black' and in Washington on 'McFarlin', The results showed a nationwide response to N that suggests the experimental middle rate of 22 kg . ha(-1) would result in high yields with moderate rot, However, the best timing for applying the fertilizer varied by both state and cultivar, where three late season applications were best on 'Early Black' in New Jersey versus four early season applications on the same cultivar in Massachusetts, and applying N fertilizers across five applications was optimal for 'Stevens' in Wisconsin.