PROJECT MATERIAL ON SOIL CHARACTERIZATION AND LAND SUITABILITY EVALUATION
ABSTRACT
This study assesses the agricultural potential of the land in Anuka, Nsukka Local Government Area, Enugu State, Southeastern Nigeria, characterized by a sub-humid tropical climate. Maize (Zea mays), cassava (Manihot esculenta), yam (Dioscorea spp.), and oil palm (Elaeis guineensis) cultivation were evaluated through field studies and laboratory analyses. Six pedons representing sampling units were dug and described: two for maize and oil palm fields each, and one each for yam and cassava fields. Auger samples were purposefully collected at depths of 0-20cm and 20-40cm to investigate nutrient distribution. Soil samples from the pedogenetic horizons of the pedons were collected, processed, and analyzed. Pedons were designated P01 = cassava field, P02 and P03 = maize fields, P04 = yam field, and P05 and P06 = oil palm fields. Soil texture varied, with the dominant class being sandy clay loam. Overall results indicated acidic soils with generally low phosphorus content, decreasing organic matter down the profile depth, and medium organic matter (>2.0 %) for epipedons. Exchangeable bases were generally low: low exchangeable Ca (<3.2 cmol kg-1), low to medium exchangeable Mg (0.2 -3.2 cmol kg-1), very low exchangeable Na (<0.70 cmol kg-1), and deficient exchangeable K (<2.0 cmol kg-1). Total nitrogen content ranged from moderately low to very low (0.042 % < N < 0.196 %). Soil classification indicated Typic Dystrustults (P01, P03, P04, P05, and P06) and Aquic Argiustults (P02) (Soil Taxonomy), correlating to Acrisols (FAO/UNESCO). Despite favorable climate and topography, there is currently no highly suitable (S1) soil unit for maize, cassava, and yam cultivation based on parametric and non-parametric suitability evaluation methods.
CHAPTER ONE
INTRODUCTION
It is important that the land that will be used for agricultural production should be used according to its capacity for optimization and sustainability of soil productivity (Adeboye, 1994). This becomes very vital at this time when precision farming is gaining wider acceptance and the relevance is particularly more now in the developing world where the use to which a land is put is very often not related to its capacity (Senjobi, 2001).
A major problem of agricultural development in Nigeria is poor knowledge and appraisal of suitability of parcels of land for agricultural production. The result is poor farm management practices, low yield and an unnecessary high cost of production (Aderonke and Gbadegesin, 2013). Land evaluation using a scientific procedure is essential to assess the potentials and constraints of a given land parcel for agricultural purposes (Rossiter, 1996). The knowledge of soil limitations arising from land evaluation reports aims at ameliorating such limitations before, or during cropping period (Lin et al., 2005). Therefore, soil as a main medium for cultivation needs to be assessed (surveyed / characterized) scientifically. The performance assessment is based on matching qualities of different land units in specific area with the requirements of actual or potential land utilization types. This assessment results in classification of lands as to their suitability to produce specific crops or combination of crops (Ezeaku, 2011).
Soil suitability evaluation involves characterizing the soils in a given area for specific land use type. The suitability of a given piece of land is its natural ability to support a specified land use such as rain-fed agriculture, livestock production, forestry, etc. The main objective of land evaluation is to predict the inherent capability of a land unit to support a specific land.
