Nitrogen Utilization of Selected Cropping Systems in the U.S. Northeast: I. Dry Matter Yield, N Uptake, Apparent N Recovery, and N Use Efficiency

Excessive application of N‐containing fertilizers may result in high concentrations of soil nitrate. Soil nitrate levels can be reduced with cropping systems that best utilize N. Split‐plot design experiments were conducted in Connecticut from 1987 through 1990 on a Paxton fine sandy loam soil (coarse‐loamy, mixed, mesic Typic Dystrochrept) to determine the effectiveness of various cropping systems in utilizing N. Orchardgrass ( Dactylis glomerata L.), red clover ( Trifolium pratense L.), a doublecrop system of oat ( Avena sativa L.) followed by the forage brassica tyfon [ Brassica rapa L. × B. pekinensis (Lour.) Rupr.], and maize ( Zea mays L.) followed by a cover crop of winter rye ( Secale cereale L.) received preplant N at 0, 112, 224, 336, and 448 kg ha −1 . Cropping systems were tested three times for two consecutive growing seasons, with N applied only in the first season. Dry matter yield (DMY), N uptake (NUP), apparent N recovery (NREC), and N use efficiency (NUE) were determined. Maize‐rye produced the greatest DMY (18.3 to 22.8 Mg ha −1 ), followed by oat‐tyfon (9.8 to 16.5 Mg ha −1 ). Highest NUP (121 to 329 kg N ha −1 ) and NREC (46.5 to 81.7%) were obtained by oat‐tyfon. The greatest NUE was produced by maize‐rye and oat‐tyfon at 112 kg N ha −1 . The oat‐tyfon double crop provides the most effective means for preventing N loss among the systems evaluated for N rates > 112 kg ha −1 .