Corn Production on a Subsurface‐Drained Mollisol as Affected by Fall versus Spring Application of Nitrogen and Nitrapyrin

Abstract

Nitrogen management strategies that affect corn (Zea mays L.) production and loss of NO3–N to subsurface, tile drainage often include decisions of when to apply N (fall or spring) and whether to use a nitrification inhibitor. A field study was conducted from the fall of 1993 through 2000 on a tile‐drained Canisteo clay loam [fine‐loamy, mixed (calcareous), mesic Typic Endoaquolls] to determine the influence of fall vs. spring application of N and nitrapyrin [2‐chloro‐6‐(trichloromethyl) pyridine] on yield of corn and soybean [Glycine max (L.) Merr.] in rotation. Four anhydrous ammonia treatments [fall without nitrapyrin (NP), fall with NP, spring preplant without NP, and spring with NP] were replicated four times and applied at 134 kg N ha−1 (120 lb acre−1) for corn each year. Fall applications occurred between 20 October and 1 November when soil temperatures generally were ≤10°C. Six‐year average corn grain yields were least for fall N without NP [10.10 Mg ha−1 (161 bu acre−1)] and greatest for fall N with NP [10.72 Mg ha−1 (171 bu acre−1)], spring N without NP [10.82 Mg ha−1 (172 bu acre−1)], and spring N with NP treatment [11.03 Mg ha−1 (176 bu acre−1)]. Year‐to‐year variation in yield response to the treatments was great and was characterized by above‐normal May rainfall affecting the performance of the fall treatments while above‐normal June rainfall affected both fall and spring treatments. Apparent N recovery ranged from 47% for fall N without NP to 61% for spring N with NP. Annual economic return to fertilizer was greatest for spring N with or without NP. Based on the dominating effect of spring rainfall, this study suggests growers consider a spring preplant N strategy either with or without NP as an alternative to fall N for greatest economic return and least N loss to the environment on these Mollisols.