HR: 15:25h
AN: H32D-07    [PDF]
TI: Attenuation of Nitrate-15N by Vegetated Buffers in an Irrigated Pasture System
AU: * Haughn, A B
EM: bedardhaughn@ucdavis.edu
AF: Agronomy and Range Science, University of California One Shields Avenue, Davis, CA 95616 United States
AU: Tate, K
EM: kwtate@ucdavis.edu
AF: Agronomy and Range Science, University of California One Shields Avenue, Davis, CA 95616 United States
AU: Kessel, C v
EM: cvankessel@ucdavis.edu
AF: Agronomy and Range Science, University of California One Shields Avenue, Davis, CA 95616 United States
AB: Irrigated pastures are found within watersheds providing much of Western North America's surface drinking water supply. Vegetative buffers are often proposed to attenuate nutrient pollutants in runoff, but there is limited information on the mechanistic functioning of buffers adjacent to irrigated pastures. This study is intended to fill this gap in knowledge by examining specific vegetation, soil, and landscape characteristics controlling buffer efficiency and capacity. At the University of California Sierra Foothill Research and Extension Center, established flood-irrigated plots with three different buffer treatments are being used to characterize the attenuation of N, P, and sediment by buffers. Stable 15N isotope tracer was applied to quantify the fate of nitrate moving through the pasture and buffers. In the first 10 days following application of the 15N tracer, 2% of the tracer was lost as runoff, with more than half of the total loss occurring from plots with no buffers. Of the remaining tracer, 47% was taken up by grass in the zone of application, 3% was taken up by vegetation within the buffers (primarily in the first 4m of buffer), 20% was stored in the A horizon of the soil, and 28% was lost via leaching and/or gaseous losses. Results presented will include the effect of buffer length on nutrient attenuation and the relative importance of different N pools for nitrate retention. This research will allow land managers to maximize efficiency of riparian buffers adjacent to irrigated pasture, potentially increasing the adoption of vegetated buffers as a management tool.
DE: 1842 Irrigation
DE: 1860 Runoff and streamflow
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2003 Fall Meeting