Submitted to: Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 23, 2003
Publication Date: October 16, 2003
Citation: Lehrsch, G.A., Wright, J.L., Westermann, D.T. 2003. Nitrate-N and bromide breakthrough measured in the field under intermittent sprinkler irrigation. In: Proceedings of Agronomy Society of America Annual Meeting, November 2-6, 2003, Denver, Colorado. 2003 CD-ROM. Technical Abstract: Excessive irrigation can leach agricultural chemicals and nutrients through the vadose zone to contaminate ground water. A three-year field experiment near Kimberly, ID, was designed to study the transport of water, using applied Br as a tracer, and native nitrate through a Portneuf silt loam (Durinodic Xeric Haplocalcid) cropped to dry bean, then a fescue-ryegrass mix when irrigated judiciously, moderately, then heavily using a solid-set irrigation system. We estimated drainage using a water balance, with evapotranspiration (ET) calculated using ET crop coefficients. We measured precipitation and irrigation using rain gages, soil water contents using a neutron probe, and solute concentrations in soil solution samples taken from depths of 0.3 to 4.3 m. Solute movement and dispersion by depth were characterized using breakthrough curves of relative concentration plotted versus time. Bromide peak concentration decreased and movement slowed as the water pulse passed through the profile. Nitrate-N and Br moved preferentially through 50% of monitored sites and to depths from 0.5 to 4.3 m. Preferential solute transport occurred more at shallow than deep depths. Nitrate-N was transported through this irrigated and cropped silt loam by both matrix flow and spatially varying preferential flow.