Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 25, 2001
Publication Date: October 25, 2001
Citation: BURKART, M.R., TOMER, M.D., JAQUIS, R.J., KRAMER, L.A. QUALITY OF WATERS FOUND AT DEPTH WITHIN A LOESS-HILLS AGRICULTURAL LANDSCAPE. ASA-CSSA-SSSA ANNUAL MEETING ABSTRACTS. 2001. CD-ROM. MADISON, WI. Technical Abstract: Concerns about nitrate-N in ground waters of Midwest agricultural watersheds have increased during the past few decades. We installed a transect of multi-depth piezometers and lysimeters across two adjacent first-order watersheds in the loess hills of southwest Iowa, and monitored NO3-N concentrations each month since 1997. Three transects of multi-depth piezometers were also installed across the riparian zone of one of these watersheds, and these have been monitored since late 1999. There were large variations in NO3-N concentrations, and temporal trends varied according to depth and landscape position. Concentrations ranged from non-detectable (<0.1 mg/L) to nearly 130 mg/L, but are most commonly between 10 and 30 mg/L. The largest concentrations (>40 mg/L) were in upper (divide and backslope) positions. The least concentrations were in the deepest ground waters, but this was not always consistent in the riparian zone. Seasonal trends in concentration were not observed. In the riparian area, concentrations were relatively stable with time on the west side of the stream, but commonly showed consistent increases on the east side. Temporal trends in upland positions often showed increases, but not consistently. Results highlight spatial and temporal complexity of nitrate contamination, which may be influenced by piezometric differences and, in the riparian zone, denitrification.