Assessing The Soil Carbon Sequestration Potential of Different Plant Residues

Abstract

Carbon is a major constituent of all living things and the cycling o f carbon between the atmosphere and the biosphere is one of the bases for life on earth. However, as a result of m an’s exploitative activities such as deforestation, automobile emission and power generation to increase productivity to m eet energy demands, the quality of the natural environment has and continues to deteriorate in many parts o f the world at a time when the human population is growing at an accelerated rate. The stable carbon dioxide concentration in the atmosphere has for a long time been 0.034 % (Alexander, 1977). Report by Paustian (1998) indicates that carbon dioxide in the atmosphere has increased by about 30 % since 1800 and continues to increase by about 0.5 % per year. According to a special report on the contribution o f carbon pool to the global carbon cycle by the Intergovernmental Panel on Climate Change (IPCC, 2000) over the period 1989- 1998, activities in the energy and building sectors o f the global economy increased atmospheric carbon levels by 6.3 Gigatonnes o f carbon per year (Gt C yr-1). Other reports from the Science Daily Magazine (1995 -2003) also indicate that deforestation and the use of fossil fuels release about 8 billion metric tonnes o f carbon dioxide into the atmosphere annually. Although most of the carbon dioxide gas is removed from the atmosphere by plants or by the w orld’s oceans, a significant portion remains air borne. The net result of these fluxes over the last 10-15 years is that atmospheric carbon levels have increased by about 3.3 Gt C yr - 1 Carbon dioxide addition to the atmosphere is caused not only by burning of fossil fuel through industrial and agricultural activities, but also by soil organic carbon decomposition and vegetation burning. Methane production, volatilisation and mineralization o f soil carbon can also lead to carbon loss from the soil. Consequently, atmospheric carbon dioxide continues to increase at the rate of 3.5 billion tonnes every year (Rice et al., 2004) which presents a problem of global wanning. 1.2 Problem specification Increased atmospheric carbon dioxide in the environment could lead to global warming and changes in climate pattern (Jenkinson et al., 1991; IPCC, 2001). To mitigate these effects various methods have been proposed to control carbon dioxide accumulation in the atmosphere. One of these is to legislate a policy framework, which ensures that the fossil burning industries change their technology to reduce carbon dioxide concentration in the atmosphere (Wise and Cacho, 1999). In other cases, heavy levying of culprit industries to deter their production of carbon dioxide has also not been effective. The Department o f Energy in U.S. A used carbon to bind common minerals like serpentine and peridotites and this was believed to result in a mineral carbonate which could be used to prevent carbon dioxide from fossil fuel from reaching the atmosphere (McNelly, 1999). This helps in reducing carbon dioxide concentration in the atmosphere. However, this method is very expensive and could not be used on a wide scale. Carbon credit trading, incentives for development and application of new technology, education and technical assistance for producers and tax credits for conservation practices are also being used (Bruce et al., 1999) as methods to reduce carbon load of the atmosphere.