Effects of time-controlled grazing on runoff and sediment loss

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Title Effects of time-controlled grazing on runoff and sediment loss
Author Sanjari, Gholamreza; Yu, Bofu; Ghadiri, Hossein; Ciesiolka, Cyril A.A.; Rose, Calvin Wyatt
Journal Name Australian Journal of Soil Research
Year Published 2009
Place of publication Australia
Publisher CSIRO Publishing
Abstract The time-controlled grazing (TC grazing) has become popular in Australia and elsewhere in the world to provide graziers and ranchers with improved productivity over traditional practices. However, this grazing system, which involves short periods of intensive grazing, has raised concerns about the sustainability and environmental impacts on water and soil resources and ecosystem health generally. A runoff catchment experiment at the catchment scale was established on the grazing property 'Currajong' in the south-east region of Queensland, Australia to investigate the effects of continuous and TC grazing on runoff and sediment generation from 2001 to 2006. Sediment loss reduced significantly under TC grazing compared with continuous grazing irrespective of the size of runoff events. This effect is more pronounced in the catchments with soils of gentler slopes and greater depths. The reduction in soil erosion was achieved despite the fact that the increase in ground cover under TC grazing had little effect on runoff coefficient or runoff. Decrease in runoff in relation to the increase in surface cover only occurred for small events, whereas for large rainfall events, runoff generated irrespective of the level of ground cover. This study showed that ground cover is a key driver in reducing sediment concentration, resulting in a significantly lower sediment loss under TC grazing. In the study area a minimum of 70% of surface cover as threshold appears to be needed to efficiently protect the soil surface from erosive forces of rain and runoff and to control soil erosion. The results also indicate that TC grazing has a superior capability to produce and maintain a higher level of ground cover (up to 90%) than continuous grazing (up to 65%). The long rest periods in TC grazing are seen as being the major contributor to soil and pasture recovery after intensive defoliations by grazing animals, leading to an increase in above-ground organicmaterial and thus surface cover over time.
Peer Reviewed Yes
Published Yes
Alternative URI http://dx.doi.org/10.1071/SR09032
Copyright Statement Copyright 2009 CSIRO. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.
Volume 47
Issue Number 8
Page from 796
Page to 808
ISSN 0004-9573
Date Accessioned 2010-03-04
Date Available 2010-06-23T05:23:46Z
Language en_AU
Research Centre Environmental Futures Research Institute; Atmospheric Environment Research Centre
Faculty Faculty of Science, Environment, Engineering and Technology
Subject Natural Resource Management
URI http://hdl.handle.net/10072/29407
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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