Nitrogen Benefits of Winter Cover Crop and Fall-Applied Poultry Litter to Corn

Nitrogen from manures and fertilizers requires careful management to maximize efficiency and minimize losses. Cover crops may conserve nutrients from fall-applied manure and cycle N to corn (Zea mays L.). To quantify N benefits from winter cover crops (CC) and poultry litter (PL), fertilizer nitrogen equivalence (FNEQ) was calculated. Cover crop treatments included Rye (Secale cereale L.), Legume (Trifolium incarnatum L. and/or Vicia villosa Roth), LegumeRye, and winter fallow (WF) with and without fall-applied PL (2 Mg ha(-1)). Corn grain yield and grain N response to fertilizer N rates from 0 to 224 kg N ha(-1) served as the basis for calculating FNEQ. Cover crop N content, whole corn plant N content, grain yield, and grain N contents were measured. Across years, N content of Legume residue was 22% greater with PL than without. Without CC, PL failed to result in an N credit to corn. Poultry litter coupled with Legume CC resulted in increasing fertilizer N credit from Year 1 to 3 from 25 to 117 kg N ha(-1). Rye resulted in negligible FNEQ for the duration of this study. For biculture, FNEQ ranged from a deficit of -12 to a credit of 75 kg N ha(-1). Coupling PL with CC improved apparent PL N recovery, while a more immediate and synergistic N benefit was observed when Legume was combined with PL. These results suggest legume may effectively scavenge PL N in low N systems and result in increased residual soil N availability over time.