Influence of Tillage on Hydrology in Western Iowaby Allen T. Hjelmfelt, Jr.,
Larry A. Kramer,
Abstract: USDA Agricultural Research Service has operated four field-sized watersheds in the deep loess soils of western Iowa since 1964. Throughout this time, two watersheds were cropped to corn using conventional tillage. One watershed was in bromegrass pasture with controlled grazing from 1964 to 1971. In 1972, it was converted to corn using a ridge till-plant system. The fourth watershed was cropped to corn using conventional tillage with level terraces from 1964 to 1971. There was less total runoff from the brome grass than from the corn watersheds, but there was more runoff from the ridge tilled than from the conventionally tilled watersheds due to reduced evaporation from the soil surface. The level terraces watershed exhibited flood hydrographs which were influenced predominantly by the area below the last terrace. Flood hydrographs from the parallel terraced field showed the influence of pipe flow through slightly increased peak discharge rates and greatly extended flow recessions.
Subject Headings: Hydrology | Watersheds | Crops | Floods | Runoff | Hydrographs | Vegetation | Pipe flow | Irrigation water | Iowa
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