Nitrogen Placement, Row Spacing, and Furrow Irrigation Water Positioning Effects on Corn Yield

Abstract

Furrow irrigation often leaches NO3–N. We hypothesized that banding and sidedressing N fertilizer on a nonirrigated side of a corn (Zea mays L.) row would maintain yield and decrease NO3–N leaching. In a 2‐yr field study in southern Idaho on a Portneuf silt loam (coarse silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid), we evaluated the effects of (i) N placement (broadcast vs. banded), (ii) row spacing (0.76 m vs. a modified 0.56 m), and (iii) irrigation water positioning (applying water to the same side or alternating sides of a row with successive irrigations) on field corn yield and N uptake. We irrigated every second furrow nine times in 1988 and seven times in 1989. Compared with broadcasting, banding maintained grain yield in 1988 and increased it by 11% in 1989. Where N was banded in 0.56‐m rows in 1989, silage yield when only the nonfertilized furrow was irrigated was 22.9 Mg ha−1, which was 22% greater than when alternating furrows were irrigated. Compared with 0.56‐m rows, the 0.76‐m rows had no effect on 2‐yr average grain yield but tended to increase 2‐yr average silage N. Banding N on one side of a row, rather than broadcasting, and applying water all season to the furrow on the other side of the row maintained or increased grain yield, increased silage yield by up to 26%, and increased N uptake in silage by up to 21%, particularly from N‐depleted profiles. Applying water to the same furrow, rather than alternating furrows, did not reduce yield or N uptake.