Impacts of Livestock Grazing on Surface Water Quality in Tropical Pastures: Remediation and Mitigation Measures in Malaysia

Degradation of water quality in tropical pastures of Malaysia is of growing environmental concern.It is one aspect of the sustainability of livestock production that can cause many problems if maximum limitsare exceeded. This paper examines the peer reviewed literature dealing with livestock grazing and surfacewater quality in tropical pastures and introduces the Best Management Practices (BMPs) which could mitigatethe negative and enhance the positive impacts of grazing on surface water. Results indicate that the degradationof water quality in pasture ecosystem is mainly due to unrestricted animal access to streams, lack of adequatebuffer between the grazing land and streams, direct fecal defecation into the streams, increased runoff of fecalmaterial from the adjacent grazing land, and increased erosion of stream banks by animal traffic. In additionto grazing intensity and rainfall amount; a range of natural and human induced factors such as land type,vegetation cover, management practices, landscape scale, drainage network (natural or man-made), monitoringperiod are important factors in the assessment of livestock grazing impacts on surface water quality in pastures.Installation of removable water troughs and shade sources, streambank fencing particularly for severelydegraded stream banks and total cattle exclusion from streams were introduced as BMPs for reducing thenegative impacts of livestock grazing on surface water quality in pasture. It seems that the crucial knowledgegaps in current understanding of livestock grazing impacts on surface water quality are the effectiveness ofvarious practices in reducing the impacts of livestock on surface water, nutrients and sediment export to waterfrom various livestock concentration sites on pasture, impacts of stream banks and riparian areas grazing onstream habitat and aquatic life, and the lack of grazing management strategies with emphasize on theconservation of riparian areas and limiting animal direct access to streams.

Keywords:

best management practices (BMPs) , grazing ecosystem , livestock production , water quality index