Submitted to: Nonpoint Source Water Quality Monitoring Results Workshop
Publication Type: Abstract Only
Publication Acceptance Date: January 1, 1996
Publication Date: N/A
Technical Abstract: Improved N fertilizer placement and irrigation water management will decrease the potential for nitrate movement to groundwater. A two-year field study with field corn (Zea mays L.) grown on a Portneuf silt loam (Durixerollic Calciorthid) evaluated 1) broadcast and banded N placements, 2) row spacing, and 3) alternate-furrow irrigation management effects on soil nitrate concentrations. Soil nitrate was measured to 1 m (or more) under the plant row, about six days after each irrigation in 1988 and 1989. In 1988, nitrate moved laterally and concentrated under the row when water was applied first to one side of the row and then the other with consecutive irrigations. Regardless of water management, there was more nitrate at 0.6-0.9 m under 0.76-m rows in broadcast plots (10.4 mg/kg) than in banded plots (8.6 mg/kg), suggesting that more nitrate leached to this depth by broadcasting N than by banding. Nitrate concentrations at 0.6-0.9 m in plots irrigated only on the non-fertilized side of the row were 31% smaller than in plots irrigated on one side of the row then the other with consecutive irrigations. To reduce soil nitrate concentrations below 0.6 m yet maintain yield, the best treatment was to band and sidedress urea near a dry furrow and irrigate only the opposite furrow throughout the season.