Residual Poultry Manure Nitrogen Supply to Corn the Second and Third Years after Application

Only a fraction of total N from poultry manure is plant available during the first year of application, and residual N may become available in subsequent years. The objective of this study was to evaluate the residual supply of plant‐available N from poultry manure to corn ( Zea mays L.) in the second and third years after application. Two poultry manure sources were applied at two rates, targeting 84 and 168 kg total N ha −1 . The fertilizer equivalence approach was used as reference to estimate residual fertilizer equivalent values. Soil samples were collected at 0 to 30 cm for NO 3 –N in early June in the second year. Grain yield and chlorophyll meter (CM) readings at the R1 growth stage were collected to evaluate corn response to fertilizer and residual manure N. Based on corn grain yield, 3 to 12% of poultry manure total N was plant available in the second year after application, and 4 to 20% based on CM readings. In the third year, plant‐available N ranged from 0 to 4% of total manure N. Soil NO 3 –N was not successful in detecting possible N supply from poultry manure in the second year after application. Suggestions for residual poultry manure N supply to corn should not exceed approximately 10% for the second year and 4% for the third year.