Topic: Lecturer: Presentation: Introduction Soil degradation is the process through which soil loses value and productivity as a result of exposure to human and environmental influences. There are many forms of soil degradation. However, this paper will focus on soil erosion which is a major factor that affects soil productivity. Human activities are among the underlying causes of soil erosion. These activities have been highlighted. The impact of soil erosion has been discussed in detail. The paper also presents various methods that are being used to reduce or reverse its impact.
The relevance of soil erosion to the sustainable use of soil has been discussed. Soil Erosion Soil erosion is a phenomenon that has been taking place for many years. Loose soil on the earth surface is moved by water and wind especially where the ground is bare. As the soil is formed, it is moved away to a different place if it is not covered or held tight by vegetation (Toy et al 2002). Intense human activity has caused soil in the recent past to be moved at a higher rate than its formation.
Some activities such as overgrazing and inappropriate farming practices have increased the vulnerability of soil to erosion. Soil that is left bare is carried away by strong wind or rainfall and deposited in rivers and water masses (Cox and Ashley 2000). Rain splash is among the causes of soil erosion whereby very strong rain drops fall on bare soil detaching and moving it for a short distance. The effects of splash erosion are usually in-situ since the soil is only moved over a minimal distance. Moreover, the rain must fall with significant intensity for erosion to take place.
The soil is re-distributed on the surface unless if the area is sloping. Rill erosion may occur when the soil is moved along channels down slope. When the intensity of rainfall is high, the channels may enlarge to form gullies. Gulley erosion is more pronounced in many parts of the world and is associated with mass movement of soil (Bathgate and Pannell 2002). Generally, when the rain falls on soil, a substantial amount of water is absorbed until the soil is saturated.
It takes time for the water to infiltrate and therefore the more time the water remains on the soil surface the greater the possibility of absorption. Soil erosion is mainly attributed to overland flow, which is the water that does not infiltrate in to the soil. This occurs mostly when the rainfall is sudden and with high intensity giving little time for absorption.
Abel, D. 2001 Environmental Issues: Measuring, Analyzing, Evaluating, Prentice Hall, New Jersey.
Alexander, J. Roberts, A.M. and Pannell, D.J. 2010. Victorian Catchment Management approaches to salinity: learning from the National Action Plan experience, Australasian Journal of Environmental Management 17(1), 45-52.
Bathgate, A. and Pannell, D.J. 2002 Economics of deep-rooted perennials in southern Australia. Agricultural Water Management 53(1), 117-132.
Boardman, J. 2006 Soil erosion science: Reflections on the limitations of current approaches. Catena 68(3), 73-86.
Cox, J.W. and Ashley, R., 2000 Water quality of gully drainage from texture-contrast soils in the Adelaide Hills in low rainfall years. Australian Journal of Soil Research, 38(2), 959-972.
Dilly, O. and Pannell, D. 2009 Editorial: Sustainability impact assessment and land-use policies for sensitive regions, Environmental Science and Policy 12(8), 1075-1076.
Harmon, R. S. & Doe W. W. 2001 Landscape erosion and evolution modeling, Springer, New York.
Pannell, D.J. and Vanclay, F.M. 2011 Changing Land Management: Adoption of New Practices by Rural Landholders, CSIRO Publishing, Canberra.
Philip, R. & Morgan C. 2005 Soil erosion and conservation, John Wiley and Sons, New Jersey.
Rouhipour, H., Ghadiri, H., and Rose, C.W. 2006 Investigation of the interaction between flow-driven and rainfall-driven erosion processes. Australian J Soil Research, 44, 503-514.
Sanjari, G., Yu, B., Ghadiri, H., Ciesiolka, C.A.A., and Rose, C.W. 2009 Effects of time-controlled grazing on runoff and sediment loss. Australian Journal of Soil Research. 47, 796-808.
Seymour, E., Curtis, A., Pannell, D., Allan, C. and Roberts, A. 2010 Understanding the role of assigned values in natural resource management. Australasian Journal of Environmental Management 17, 142-153.
Toy, T. J. Foster, G. R. Renard, K. G. 2002 Soil erosion: processes, predicition, measurement, and control, John Wiley and Sons, New Jersey.
Troeh, F. 2003 Soil and Water Conservation for Productivity and Environmental Protection, Prentice Hall, New Jersey.
Vaclav, S. 2000 Feeding the world: a challenge for the 21st century, MIT Press, Cambridge.