Runoff and sediment yield from snowmelt and rainfall as influenced by forage type and grazing intensity
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Authors: S. I. Gill, M. A. Naeth, D. S. Chanasyk, and V. S. Baron
Date: 1998
Journal: Canadian Journal of Soil Science
Volume: 78
Number: 4
Pages: 699-706
Summary of Methods: The effects of grazing on sediment yield and runoff from annual and perennial forages were examined at the Agriculture and Agri-Food Canada Research Centre at Lacombe, Alberta (52° 27.5' N, 113° 44' W). Carlton smooth bromegrass, Paddock meadow bromegrass, Pika triticale, and Pika triticale/AC Lacombe barley mix plots were planted in May, and grazed with yearling crossbred beef replacement heifers at 3 grazing intensities (Heavy, Medium, and Light). Grazing occurred two to eight times in a growing season, dependent upon grazing treatment. Snowmelt runoff was collected in March, and rainfall runoff was collected in May 1994, and April 1995 after each precipitation event. Bare ground was assessed once annually in mid-July and litter biomass was assessed before first grazing period and after the last grazing period. Guelph Rainfall Simulator was used in fall of 1996 and spring of 1997 to simulate a rainfall event of greater than 100 years on meadow bromegrass, smooth bromegrass, and triticale treatments to examine water runoff and infiltration. Runoff was collected and measured every five minutes.
Article Summary / Main Points: Total annual runoff was dominated by snowmelt (>80%). Heavily grazed barley/triticale experienced higher total rainfall runoff in 1994. Total rainfall runoff increased with grazing intensity in perennials in 1995, but didn’t differ amongst annuals. Total sediment yields and average sediment concentrations were low, and no clear trend with grazing intensity was apparent. Litter decreased with increased grazing intensity on all forages, with perennials accumulating more litter by the end of 1995 than annuals (litter was incorporated into the soil at planting every year for annuals). When tested with the rainfall simulator, meadow brome had the highest infiltration rates followed by smooth brome and then triticale. Tested species exhibited highest infiltration rates under light grazing, followed by medium and heavily grazed speices, with the exception of triticale which had lowest rate of infiltration under medium grazed treatments.
Vegetation Types: Tame Pastures
MLRA Ecoregions: Not Applicable
Agrovoc Control Words: Grazing Watersheds Erosion
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: forage, soil erosion, sustainability, rainfall simulation, sediment yield, grazing
Annotation: Results from the rainfall simulation corroborated those observed under natural rainfall conditions and indicated that the tested grazing systems at this site properly prevent runoff and ensure conservation of soil. These findings are applicable to regions which exhibit similar slope, soil type, and grazed species.
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