Corn yield, nitrogen use, and corn rootworm infestation of rotations in the northern corn

Crop rotation may improve production efficiency and reduce fertilizer N requirements for corn (Zea mays L.). Objectives were to determine effect of rotation and N on corn yield, efficiency of water use (WUE) and N use (NUE), and corn rootworm (Coleoptera: Chrysomelidae) beetle populations (CR). Rotations (started in 1990) were continuous corn (CC), corn-soybean [Glycine mar (L.) Merr.] (CS), and a 4-yr rotation of corn-soybean-spring wheat (Triticum aestivum L.) companion-seeded with alfalfa (Medicago sativa L.)-alfalfa hay (CSWA). Nitrogen treatments for corn were corn fertilized for a grain yield of 8.5 Mg ha(-1) (highN), 5.3 Mg ha(-1) (midN), and no N fertilizer (noN). Average yield (1992-2003) was greatest (p = 0.003) under CS and highN (7.0 Mg ha(-1)). Yield differences (p = 0.001) among rotations increased with decreased fertilizer N. Average (1992-2003) yield with noN fertilizer was 5.8 Mg ha(-1) under CSWA, 4.5 Mg ha(-1) under CS, and 2.8 Mg ha(-1) under CC. Nitrogen use efficiency differed (p = 0.096) only under midN with CSWA = CS > CC. Soil water (upper 1.8 m) for corn measured on 1 June (average of N treatments) was 55, 54, and 45 cm for CC, CS, and CSWA, respectively. For CSWA under highN, available water limited yield in 3 of 6 yr. At highN, CR adult populations were greater under CS compared with CC and greater at higher N fertilizer levels within CC. Rotations have potential to improve production efficiency; however, there is potential for reduced corn yield after alfalfa due to less available soil water.