Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: 11/10/2005
Publication Date: 11/10/2005
Citation: Tomer, M.D., Cambardella, C.A., James, D.E., Moorman, T.B. 2005. Variation in surface-soil properties and water contents across two watersheds with contrasting tillage histories. In: Proceedings of the Soil Science Society of America Annual Meeting. Soil Science Society of American Annual Meeting, November 6-10, 2005, Salt Lake City, UT. 2005 CDROM.
Technical Abstract: Spatial distributions of soil properties and water contents (SWC) have been examined in various landscape settings. However, soil management could alter spatial patterns. This study compared surface-soil properties and SWC in two small watersheds (30-43 ha) in Iowa's loess hills. Both watersheds were in continuous corn from 1972 through 1995, one (W1) under conventional tillage and the other (W3) under ridge tillage. In 1996, W1 was converted to no-till. Surface (0–0.2 m) SWC samples were collected along hillslope transects during 2002 and 2003, including four dates with sampling in both watersheds. Soil bulk density (BD), organic carbon (OC), and texture were determined, along with terrain attributes (elevation, slope, surface curvature, contributing area, wetness index). Accounting for effects of landscape position, W3 had more OC (2.1 versus 1.7%) and smaller BD (1.16 versus 1.25 Mg m-3) than W1 (p <0.001), showing differences found in 1995 persisted eight years after W1 was converted to no-till. Greater water contents occurred in W3 when SWC was >33% (p<0.001). Landscape position and terrain attributes more consistently explained variation in SWC in W3 than W1. Also, OC was correlated with SWC in W3, but not in W1. Pedotransfer functions, when applied to the soils data, confirmed that differences in SWC between watersheds should be most detectable under wet conditions, and that soil moisture should have a more distinct landscape pattern in W3. The impacts of long-term conventional tillage in W1 influenced SWC, and muted the effects of soil and terrain on its spatial pattern.