Location: Agroecosystems Management ResearchTitle: Closed depression topography Harps soil, revisited) Author
Submitted to: Soil Horizons
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2014
Publication Date: 3/31/2014
Publication URL: http://handle.nal.usda.gov/10113/58654
Citation: Logsdon, S.D., James, D.E. 2014. Closed depression topography Harps soil, revisited. Soil Horizons. 55(2):1-7. Available at: https://www.soils.org/publications/sh/tocs/55/2. Interpretive Summary: Lime (calcium carbonate) accumulates at edges of field depressions as ponded water transports the lime out and up from the depressions. This study showed the lime was concentrated in the low-slope area at zones where the depression curled inward (inlets), rather than where the depression jutted out (peninsulas). Within buffers extending 164 feet from the depressions, the slope was significantly lower for areas that had the lime accumulation (1.36%) than for areas that did not have the lime accumulation (1.89%). The lime was present even though buried tiles and tile inlets associated with the depressions would be expected to drain water. The tiles do not always prevent ponding in the depressions after snow melt and intense rains, and ponding may remain for a few days to a few weeks. This information is primarily of interest for scientists who study how water transports chemicals in fields that have depressions.
Technical Abstract: Accumulation of carbonates around depressions indicates past or present water and solute flow paths out and up from the depressions. The purpose of this study was to determine the pattern of surface carbonates in relation to landscape parameters, depressions, and original Harps map units. Surface carbonates were determined around each depression or Harps map unit in adjacent field areas (around 1650 m wide and 2475 m long) by violent effervescence with 10% HCl. Elevation information for these fields was used to determine slope as well as profile and plan curvatures. A 50-m buffer around each depression was overlaid with zones that either had or did not have surface carbonates, and the two zones were compared for differences in slope or profile curvature. One third of the Harps map units overlapped the newly mapped carbonate areas. The newly mapped surface carbonates were located in low-slope regions at “inlet” areas around depressions. In contrast, the Harps map units often encircled depressions or overlapped the > 0.5 m depression areas. In the 50-m buffers around depressions, the newly mapped surface carbonates had significantly lower mean slope (1.36 m / 100 m) than did the non-carbonate areas (1.89 m / 100 m). There were no significant differences for profile curvature between the two zones within the perimeter. The surface carbonates were present even though the fields had subsurface tiles and tile inlets in the depressions, since the depressions can hold water for a few days to weeks following snow melt and intense rain.