Journal of Biology, Agriculture and Healthcare www.iiste.org ISSN 2224-3208 (Paper) ISSN 2225-093X (Online) Vol.6, No.5, 2016 128 A Review Paper on: The Role of Agroforestry for Rehabilitation of Degraded Soil Nebiyou Masebo 1 Muluneh Menamo 2 1.Lecturer at department of Natural Resource Management, college of agriculture, Wolayita Sodo University, Ethiopia, P.O.Box 138, Wolayita Sodo, Ethiopia 2.Lecturer at department of plant science, college agriculture, Wolayita Sodo University, Ethiopia, P.O.Box 138, Wolayita Sodo, Ethiopia 1. Introduction The world population growth is steadily increasing and the situation is even more alarming in developing countries /third world continents. For instances, Ethiopia is characterized by a great bio-physical diversity, dividing the country in several agro-ecological zones, each with a specific fauna and flora. It therefore is an important centre of biodiversity and endemism (Zewge and Healey 2001). Due to the out going population (76 million) growth of Ethiopia (CSA 2008) and overgrazing and deforestation for agricultural activities, fuel wood and construction material, overall natural forest cover had decreased to a level of 2.5 percent of which only one twelfth has a dense forest structure (Zewge and Healey 2001). The combination of high endemism and fast habitat degradation in Ethiopia leads to a great risk of species extinction (Zewge and Healey 2001). Poverty and natural resources/environmental degradation tend to negatively reinforce each other; that is, as the land is degraded, agricultural productivity is lowered, resulting in decreasing incomes and food security and vise versa (Eyasu 2002, Selamyehun 2004; Wakeneand Heluf2000). This has resulted in migration of rural poor to urban centers; increased cultivation of marginal lands; encroachment into forest regions; and depletion of land resource base of small holders (Demelet al., 2000). Moreover, the country’s topographic nature has made it more liable to degradation (Girma 2000). To overcome this problem, agroorestry has been proposed as one of the options for its positive influences on soil fertility, mainly due to tree components (Kamara and Haque 1992; Campbell et al., 1994). The inclusion of compatible and desirable species of trees/woody perennials in agroforestry can result in marked improvement in soil fertility by: (i) increasing organic matter content of soil through addition of leaf and roots litter as well as other plant parts (Young 1997; Rao et al., 1998), improving organic matter status, which can in turn result in increased activity of micro-organisms in the root zone (Khanna 1998; Young 1997), (ii) enhancing efficient nutrient cycling within the systems (Khanna 1998), and (iii) controlling soil erosion (Young 1997; Rao et al., 1998). The objective of this seminar is to review the role of AF towards cease soil degradation. 2. Concept of Soil Degradation Land degradation is a composite term; it has no single readily- identifiable feature, but instead describes how one or more of the land resources (soil, water, vegetation, rocks, air, climate, relief) has changed for the worse. On the other hand, according to Hurni (1993) the unhindered degradation of soil can completely ruin its productive capacity for human purposes and may be further reduced until steps are taken to stop further degradation and restore productivity.According to UNEP (1999), land degradation is the temporary or permanent lowering of the productive capacity of land. It is one of the biggest problems in the world particularly at third world countries, threatening the lives of millions of people in the humid, sub humid and dry lands, albeit/although at different levels Robert .J; et al (2008). Degradation commonly occurs when negative human activities become supplemental to the natural factors. The main human activities include overgrazing, over-cultivation, inefficient irrigation systems that do not correspond with soil water requirements and deforestation as well as industrial pollution, population increases is also the other drivers of land degradation (UNCCD 2003). Erosion as one of a number of forms of soil degradation, including deterioration of physical, chemical and biological properties (Young 1989) all of which require attention. Therefore, the problem of soil erosion could be socioeconomic and/or environmental issue andit has become a global issue widely considered in management and conservation of natural resources (Morgan, 1995). More over, one of the main objectives of land resource management is aimed at soil conservation, since maintenance of integrity of soil quality, properties, process, and diversity is deemed essential to ensuring sustainable land use (Hurni, 1993). As well known land degradation has a vast side effect on the earth. The main consequences of land degradation, which impact negatively on human livelihoods and on the environment, are generally well known. They include: shortages of firewood and other wood, shortages of (NTFP) non-timber forest products (EFAP, 1994), increased sediment deposits, floods and land slides, drying up of springs and water bodies; siltation of dams, increased incidence of water-borne diseases, loss of biodiversity, climate change, desertification, all these reduce land productivity and affect food security (Robert.J et al., 2008). CORE Metadata, citation and similar papers at core.ac.uk Provided by International Institute for Science, Technology and Education (IISTE): E-Journals