Corn production on a subsurface-drained mollisol as affected by time of nitrogen application and nitrapyrin

Time of N fertilizer application to corn (Zea mays L.) and use of a nitrification inhibitor are management strategies that can affect corn production and loss of NO,,N from the soil profile via subsurface, tile drainage. A field study was conducted from the fall of 1986 through 1994 on a tile-drained Canisteo clay loam soil [fine-loamy, mixed (calcareous), mesic Typic Endoaquolls] to determine the influence of time of N application and nitrapyrin [2-chloro-6-(trichloromethyl) pyridine] on yield of corn and soybean [Glycine max (L.) Merr.] in rotation and N uptake of corn. Four anhydrous ammonia (AA) treatments [(fall without nitrapyrin (NP), fall with NP, spring preplant, and split (40% preplant and 60% sidedress at V8 stage)] were replicated four times and applied at 150 kg N ha(-1) (135 lb N acre(-1)) for corn each year. Fall applications occurred between 19 and 28 October when soil temperatures generally were : less than or equal to10degreesC. Seven-year average corn grain yields were least for fall N without NP (8.27 Mg ha(-1), 131 bu acre(-1)), intermediate for fall N with NP and spring N (8.72 Mg ha(-1), 139 bu acre(-1)), and greatest for the split N treatment (9.11 Mg ha(-1), 145 bu acre(-1)). Corn N uptake was not different among treatments in drier years but was generally greatest for the spring and split treatments in wet years. Apparent N recovery ranged from 31% for fall N without NP to 44% for the split treatment. Economic return to fertilizer was greatest for the split treatment ($239.40 ha(-1) yr(-1)) and lowest for fall N without NP ($166.70 ha(-1) yr(-1)). Application time strategies for AA considered to be best management practices for these poorly drained Mollisols include fall N with NP, spring preplant, and split application.