Soil Quality Assessment Strategies for Evaluating Soil Degradation in Northern Ethiopia

Gebreyesus Brhane Tesfahunegn

doi:10.1155/2014/646502

Abstract

Soil quality (SQ) degradation continues to challenge sustainable development throughout the world. One reason is that degradation indicators such as soil quality index (SQI) are neither well documented nor used to evaluate current land use and soil management systems (LUSMS). The objective was to assess and identify an effective SQ indicator dataset from among 25 soil measurements, appropriate scoring functions for each indicator and an efficient SQ indexing method to evaluate soil degradation across the LUSMS in the Mai-Negus catchment of northern Ethiopia. Eight LUSMS selected for soil sampling and analysis included (i) natural forest (LS1), (ii) plantation of protected area, (iii) grazed land, (iv) teff (Eragrostis tef)-faba bean (Vicia faba) rotation, (v) teff-wheat (Triticum vulgare)/barley (Hordeum vulgare) rotation, (vi) teff monocropping, (vii) maize (Zea mays) monocropping, and (viii) uncultivated marginal land (LS8). Four principal components explained almost 88% of the variability among the LUSMS. LS1 had the highest mean SQI (0.931) using the scoring functions and principal component analysis (PCA) dataset selection, while the lowest SQI (0.458) was measured for LS8. Mean SQI values for LS1 and LS8 using expert opinion dataset selection method were 0.874 and 0.406, respectively. Finally, a sensitivity analysis (S) used to compare PCA and expert opinion dataset selection procedures for various scoring functions ranged from 1.70 for unscreened-SQI to 2.63 for PCA-SQI. Therefore, this study concludes that a PCA-based SQI would be the best way to distinguish among LUSMS since it appears more sensitive to disturbances and management practices and could thus help prevent further SQ degradation.

Highlights

Declining in soil quality (SQ) has posed a tremendous challenge to increasing agricultural productivity, economic growth, and healthy environment [1, 2]
This study demonstrated that natural forest land systems (LS1) have relatively good soil quality (SQ), whereas uncultivated marginal land systems (LS8) have a seriously degraded soil within the Mai-Negus catchment of northern Ethiopia
soil quality index (SQI) values for LS8 and LS6 provided an early warning regarding the severity of soil degradation since more than 50% of the original soil is degraded when compared to LS1

Summary

Introduction

Declining in soil quality (SQ) has posed a tremendous challenge to increasing agricultural productivity, economic growth, and healthy environment [1, 2]. Most of the causes are resulted from a desperate attempt by farmers to increase production for the growing population which aggravate SQ degradation more in the developing countries, which mainly depend on natural resources (agriculture) [1, 4]. SQ degradation by soil erosion such as soil nutrient depletion and changes in soil physical indicators is largely recognized as a principal cause aggravated by the effect of inappropriate land use and soil management in the developing countries like Ethiopia [6, 7]. The soil can maintain equilibrium by pedogenetic processes [9,10,11] This equilibrium is disturbed by anthropogenic activities (e.g., agricultural practices, deforestation, and overgrazing), and such effects are mainly noticed in the developing countries with poor

Objectives

Methods

Results

Conclusion