Quantification and simulation of soil water on grazed fescue watersheds
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Authors: D. S. Chanasyk, E. Mapfumo, W. D. Willms, and M. A. Naeth
Date: 2004
Journal: Journal of Range Management
Volume: 57
Number: 2
Pages: 169-177
Summary of Methods: The Versatile Soil Moisture Budget (VB2000) is a model that was developed to describe soil water movement in one dimension through the use of meteorlogical and soil/crop properties. It was used in a 2-year study at the Stavely Range Station located 100 km south of Calgary ( 50° N; 114° W).,The soil water status of small grassland watersheds under 3 grazing intensities and 4 topographic positions (upper, middle and lower slope positions and 5 m from collector drains). Grazing treatments were defined as: ungrazed (control), heavy grazing (2.4 AUM ha1), and very heavy grazing (4.8 AUM ha1). Soil water measurements were taken every 2 weeks in 1998 and 1999, with daily air temperature and precipitation being measured on site from mid-April to mid-November.
Article Summary / Main Points: In both 1998 and 1999, grazing treatments did not affect the total soil water for the 0-50 cm interval (TSW50) in upper, middle, and lower slope positions, but close to the collector drain the very heavy grazed treatment had significantly lower TSW50 than the ungrazed treatment. In both 1998 and 1999, grazing treatment did not have an effect upon TSW50 in the upper 3 slope positions. In 1998, TSW50 differences among the four slope positions occurred under the heavy grazed treatment. In 1999, TSW50 was significantly lower for very heavy grazed versus controlled or heavy grazed treatments. The heavy grazed treatment had a greater TSW50 next to the collector drain compared to the other three slope positions. Grazed treatments generally had lower TSW50 than the ungrazed treatment. The overall performance of the model indicated a slight over-prediction of the soil water content, and under prediction of soil moisture for the area studied.
Vegetation Types: All Grasslands
MLRA Ecoregions: Not Applicable
Agrovoc Control Words: Grazing Rangelands Watersheds
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: total soil water, moisture budget, runoff, slope position, water infiltration, grazing, model performance
Annotation: Model has potential for further use in many grazed grassland watersheds when area specific data, grass species permanent wilting point and crop coefficients, are available to plug into the model. Spatial variation due to presence of rocks or cracks as well as averaging across slope may partly contribute to discrepancies between model results and observed data.
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