CHAPTER ONE

INTRODUCTION

Parent material refers to the geology or superficial or drift deposit in which soil horizons form. The composition of parent materials has direct impact on the physicochemical, morphological, biological, and mineralogical characteristics of soils they give rise to. The variability of the soil from one part of a landscape to another is due to a number of factors such as parent material, topography, vegetation, land use and drainage Akamigbo and Asadu, 1983. Wilding et al., 1994 stated that causes of vertical and lateral anisotropy that yield variability of a random nature over short range or intermediate distances include: differential lithology, intensity of pedogenic weathering processes, hydrology, biological activity, erosion, deposition, pedoturbation, temporal effects of soil management and sampling as well as analytical errors.

Major differences in the appearance of profiles excavated close to one another are usually a reflection of the differences in the materials from which the soils were derived. The cause of variability of properties in soils have been outlined by Beckett and Webster 1971 as parent material, climate, living organism including management, topography, soil physical and chemical processes. Esu 1999 identified parent materials as the most dominant soil factor to contribute to differences in soil properties. Soils of any region are rarely formed from a single parent material. Usually intrusion and pockets of extraneous materials may be found in regions dominated by a particular rock type Ekwueme, 2003. Since parent material is the significant controlling factor of soil formation along with climate, topography, living organisms and time, caution must be exercised in identifying the native rock or parent material and kind of pedogenic process giving rise to the soil under investigation.

Soil Conservation Service 1994 reported that apart from bedrock parent materials, mineral soils could develop form other types of parent materials called recent cover deposit and these include alluvial, aeolian, glacial, lacustrine, loessal, marine deposit as well as volcanic ash deposits. The parent materials giving rise to soils in Central Cross River State include basalt, basement complex granite, gneiss, quartzite and schist, sandstoneshale intercalation and alluvium Ekwueme, 2003; Ibanga and Armond 1992. The soils of Central Cross River are currently under several agricultural activities by thousands of small holders growing tree crops: Theobroma cacao, Gemlina arborea and Oldfiedial Africana as well as food crops: yam Dioscorea spp, cassava Manihot spp and maize Zea mays Eshett, 1987; Esu 2005. The productivity of agricultural soils in Central Cross River is declining drastically following intensified land use under very poor management practices. Okpiliya et al., 2008 noted that agricultural productivity and food security in the savannah ecozone of northern Cross River are being seriously threatened by steady decline in soil fertility, defined as a net decrease in available nutrients and organic matter in the soil and caused by continued nutrient mining of already degraded soils. However, the use of soils amendments and best practices have resulted in significant increase in yield in the study area. Agba and Enya 2005 observed significant increase and profuse growth of cucumber Cucumis sativus in all cases of nitrogen treatment than where nitrogen fertilizer was not applied. This situation thus calls for investigation, which would provide proper evaluation that will lead to formulation of better land management practices to increase the productivity of these soils. The quest for wise ...Get Complete Material.