CHAPTER ONE
1.0 INTRODUCTION
Land use can be defined as the arrangements, activities and inputs people undertake in a certain land cover type to produce, change or maintain it (Di Gregorio and Jansen, 1998). Changes of forests to rangeland and agricultural lands are one of the most concerns in environmental degradation and world climate change (Wali and Evrendilek, 1999; West and Watts, 1999; Pant and Gibbs, 1999; McClead, 1999).Recently, due to population growth; forest lands are degraded and converted to Agricultural lands. The anthropogenic changes in land use have altered the characteristics of the Earth’s surface, leading to changes in soil physicochemical properties, soil fertility, soil erosion sensitivity and content of soil moisture. Land use changes such as deforestation, conversion of rangeland to crop land and cultivation are known to result in changes in soil physicochemical and biological properties (Houghton and Hacker, 1999; Lawrence, 1999). Impact of these changes and their magnitude is according to land cover and land management (Nardi and Cocheri, 1996; Dell’Agnola, 1996; Baskin and Binkley, 1998). Land use changes and agricultural practices, especially cultivation of deforested land may rapidly diminish soil quality (Kang and Juo, 1986; Nardi and Cocheri, 1996; Dell’Agnola, 1996; Islam and Weil, 2000). Severe deterioration in soil quality may lead to a permanent degradation of land productivity. Transformation of one land use system into another system and different management practices can affect soil structure, soil organic carbon and other nutrients reserve (Yeshanew and Welfgang, 2004; Guggenbeyer and Tekalign, 2004)..
Land use types affects soil physicochemical and provide an opportunity to evaluate sustainability of land use systems and thus the basic process of soil degradation in relation to land use (Woldeamlak and Stroosnijder, 2003). However, the information about the effect of land use changes on soil physicochemical properties is essential in order to present the recommendations for optimal and sustainable utilizations of land resources. Due to an increasing demand for firewood, timber, pasture, food, and residential dwelling, the hardwood forests are being degraded or converted to cropland, housing, infrastructural and industries at an alarming rate, during the last few decades (Ayoubi et al., 2011). Forest coverage in this area has decreased in the last few years (Kiani and Jalalian, 2003; Pashae and Khademi, 2003).
1.1 Statement of the problem
Land use changes are one of the main drivers of many processes of environmental changes, as it influences basic resources within the landscape, including the soil resources. Poor soil management can rapidly damage vast amounts of land, which frequently becomes a major threat to rural subsistence in many developing countries. Conversely, impact of land use change on soil can occur so unnoticed that land managers hardly contemplate initiating ameliorative measures. Forest conversion to cropland and reduction of tillage intensity can prevail as main changes of land use in some region, whereas abandon of agricultural field can be a major concern in other regions. In a non-agricultural context, changes in land use are of major interests that are driven by urbanization, landscaping, engineering, and mining. Knowledge and understanding of soil properties and processes ensure remediation or reclamation of disturbed or damaged soil, here soil management system plays an important role in sustainable agriculture and environmental quality, management practices have greater effect on the direction and degree of changes in soil properties, if the conversion of native ecosystem to cultivated land may be the reason of soil degradation and decrease in quality.
According to(Marshall and Shortle, 2005) The effects of land conversion refers to the environmental impacts generated by the process of destruction and reconstruction involved in altering of land parcels, land cover and land use as well as providing services and access to that parcel. These impacts may be relatively long term, but the time within which they are generated is limited to the period of actual development. The most widely recognised impacts found are water and soil quality; impacts of road and parcel construction include increased soil erosion and run off due to temporary loss of vegetative cover. This effect is exacerbated by the fact that construction inevitably result in soil compaction, which compromises the soil ability to absorb water (Buol, 1994).
1.2 Scope of the study
The study is trying to explore through the variability nature of land use changes and cover types which includes its major uses (fallow land, rainfed cultivated land and irrigated land), in the area of study to assess and establish the best land use practices and its effects to the ecosystem.
1.3 Significance of the study
The study in particular, is investigating the fertility status of some selected soil under land use types which would assist farmers to have a baseline information on /or to improve the soil fertility and productivity of soil in the studied area and elsewhere with similar agro-ecology. Research on these land use types is of important as the result obtained from the studies could be used to determine the best agricultural practices and crop best grown on.
1.4 Aims and objectives
This study is aimed;
- To assess the fertility status under different land use systems
- To evaluate the effect of land use on the physical properties of the soils
- To compare and contrast land use changes on fertility depletion.
