Poultry Litter Time and Method of Application Effects on Corn Yield.

Adopting efficient management practices for utilizing poultry litter (PL) is critical for increased N use efficiency, for maximum yield and minimal negative environmental impacts.  This 3-year study investigated effects of application time (fall and spring), and method of application (surface broadcast and soil incorporation) of three PL rates and NH₄NO₃ (146 kg N ha^-1) on availability of selected soil nutrients and corn (Zea mays L.) grain yield.  The target plant available N rates supplied by the poultry litter were 68 kg N ha^-1 (low rate), 135 kg N ha^-1 (medium rate) and 270 kg N ha^-1 (high rate).  Grain yield, grain nutrient uptake, soil inorganic N, mehlich-3 P (M-3P) and available K which were measured before planting in April, mid-season in June or July, and post-harvest in October or November.  When averaged across the 3 years, grain yield from the high PL rate was similar to the medium PL rate when spring-applied.  The Medium PL rate resulted in 600 kg ha^-1 greater grain yield than NH₄NO₃ from both spring and fall applications.  Relative to surface broadcast, incorporation of the medium PL rate increased grain yield 590 kg ha^-1 and NH₄NO₃ by 480 kg ha^-1.  There was no grain yield advantage of incorporating the low and high PL rates.  At the end of the study, inorganic N, M-3P and available K increased by 438%, 91% and 75% respectively.  Grain N uptake was greater from spring than fall-applied PL, but P and K were affected similarly from all fertilizer treatments. When N sources were incorporated, the medium PL rate resulted in greater N and P uptake. A greater uptake of K was observed from spring than fall application of NH₄NO_3.