Corn Yield and Nitrogen- and Water-Use under No-Tillage Rotations

Increased crop diversity and length of rotation may improve corn (Zea mays L.) yield and water-and nitrogen-use efficiency (WUE and NUE). The objectives of this study were to determine effects of crop rotation on corn yield, water use, and nitrogen (N) use. No-tillage (NT) crop rotations were started in 1997 on a Barnes clay loam (fine-loamy, mixed, superactive, frigid Calcic Hapludoll) near Brookings, S. D. Rotations were continuous corn (CC), corn-soybean [Glycine max (L.) Merr.] (CS), a 3-year rotation of corn-soybean-oat/pea (Avena sativa L. and Pisum sativum L.) hay (CSH), a 3-year rotation of corn-soybean-spring wheat (Triticum aestivum L.) (CSW), and a 5-year rotation of corn-soybean-oat/pea hay companion seeded with alfalfa (Medicago sativa L.)-alfalfa-alfalfa (CSHAA). Fertilizer N was applied to corn on all rotations at planting (16 kg N ha(-1)) and side-dressed (64 kg N ha(-1)). Average corn grain yields (1998-2007) were greatest under CSW (7.38 Mg ha(-1)) and least under CC (4.66 Mg ha(-1)). Yields were not different among CSH, CSW, and CSHAA rotations. Water-use efficiency of rotation was ordered as CSW > CSH > CSHAA > CS > CC. Nitrogen-use efficiency was greatest under CSW and least under CC. There were no differences in yield advantage (YA) among crop rotations during years with plentiful early-season rainfall (May 1-July 31). In years with low spring rainfall, YA was greatest under CSW (54%) and least under CSHAA (33%). Corn yields under extended rotations (CSH, CSW, and CSHAA) were greater than under CC and CS, but lack of rainfall may result in reduced yields under CSHAA.