BACKGROUND TO THE STUDY
Erosion is recognized as one of the world’s most serious environmental problems (Pimentel et al., 2005, Shiferaw and Holden, 2009). Globally, about 80% of the current degradation of agricultural land is caused by soil erosion (Angima et al., 2003). Erosion by water, at a global scale, is the main soil degradation process in agricultural areas (Bewket and Sterk 2002). It generates strong environmental impacts and major economic losses from decreased agricultural production and from off-site effects on infrastructure and water quality by sedimentation processes (Zinabu et al., 2002; Daba, 2003; Haregeweyn et al., 2005; Amsalu et al., 2007).
Erosion creates severe limitations to sustainable agricultural land use, as it reduces on-farm soil productivity and causes food insecurity (Tadesse, 2001; Sonneveld, 2002; Beshah, 2003, Moges and Holden, 2006, Bewket, 2007). In most developing countries human activity triggers these losses (Mohammad et al., 2001, Belyaev et al., 2004, Bewket and Sterk, 2005, Hurni et al., 2005). This is associated with rapid population growth, inadequate attention to the basic natural resources (soils, water and vegetation), and the need to maximize production to meet the needs of the growing population (Shiferaw and Holden, 2009, 2000, Bewket, 2002, Feoli et al., 2002). This situation is more serious in poor developing countries where subsistence production predominates. The average farmer who cultivates one hectare of food crops and keeps some livestock, is nowadays dependent on natural conditions and cannot tolerate further deterioration of soil productivity (Sonneveld and Keyzer, 2003). Increasing population, intense land cultivation, uncontrolled grazing, and deforestation often lead to, or exacerbate, soil erosion (Tadesse, 2001 and Bewket, 2002). These factors undermine agricultural productivity and frustrate economic development efforts, especially in developing countries where there is heavy land dependence (Shiferaw and Holden, 2000) in low external-input farming systems.
Statement of Problem
Erosion is considered as one of major land degradation process in Emure Local Government Area of Ekiti State which is also the main source of environmental deterioration. It creates negative impacts on agricultural production, infrastructure and water quality (Vrieling, 2006). Erosion is also the natural phenomenon (geological process) which is caused by natural force; it can be more accelerated when the process is influenced by human activities (human-induced erosion). It is considered that the accelerated erosion is a serious global problem and widely recognized (de Graaf, 2006). With the accelerated erosion, it can affect agronomic/biomass productivity (on-site effect) and flooding, sedimentation of reservoirs, siltation of agriculture field and decrease of water quality downstream (off-site effects). The two important agents of erosion are wind and water (Hudson, 2006).
The study area is located in Emure Local Government Area, Ekiti State. This area is an intensive agricultural areas in Ekiti State for years now. The conversion of the tropical rain forest to agricultural system has been taking place. With the increasing population, the cultivation in the mountainous area has been taking place. The primary forest is replaced by the maize, plantain, paw-paw, yams, and other crop types. The removal of natural forest and vegetation cover in steep slope and followed by improper land use practices have led to the various land degradation problems in the area. Each year during the rainy season a lot of topsoil is eroded and the agricultural lands are affected. On the other hand; the eroded soil and sediments which are transported by the surface runoff affect the downstream cultivation land.