Field-scale watershed evaluations on deep-loess soils: I. Topography and agronomic practices

D.L. Karlen; L.A. Kramer; D.E. James; D.D. Buhler; T.B. Moorman; M.R. Burkart

ABSTRACT:

Long-term field-scale watershed studies are needed to quantify productivity and environmental impacts of various farming practices. The objective for this study was to summarize geologic, topographic, and agronomic data for four deep-loess, field-scale Watersheds in western Iowa. Average corn grain yield for 1972 through 1995 on Monona (fine-silty, mixed mesic Typic Hapludollsj, Ida-Dow (fine-silty, mixed mesic Typic Udorthents), and Napier-Ken-nebec (fine-silty mixed mesic Cumulic Hapludolls) soils was 7.2, 6.7, and 7.9 Mg ha⁻¹ (115, 107, and 126 bu/ac), respectively. After more than 20 yr of continuous corn production, the weed community had reached a high density and was dominated by foxtail (Setaria) species. It is recommended that future soil and crop management practices on these watersheds should focus on increasing crop diversity to control weeds and reduce the apparent yield penalty associated with continuous corn. The management practices also should strive to develop a soil condition that is resilient and able to buffer periodic, but anticipated plant water and heat stress.

Footnotes

All six authors are with the U.S. Department of Agriculture Agricultural Research Service (USDA-ARS), National Soil Tilth Laboratory (NSTL). D.L. Karlen, D.E. James, D.D. Buhler, T.B. Moorman, and M.R. Burkart are located at the laboratory in Ames, Ia., while L.A. Kramer is located at the Deep Loess Research Station in Council Bluffs, Ia., Mention of trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the USDA, and does not imply its approval to the exclusion of other products or vendors that also may be suitable.
Copyright 1999 by the Soil and Water Conservation Society

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