Soil quality – A critical review

Else K Bünemann,Giulia Bongiorno,Zhanguo Bai,Rachel E Creamer,Gerlinde De Deyn,Ron De Goede,Luuk Fleskens,Violette Geissen,Thom W Kuyper,Paul Mäder,Mirjam Pulleman,Wijnand Sukkel,Jan Willem Van Groenigen,Lijbert Brussaard

doi:10.1016/j.soilbio.2018.01.030

Abstract

Sampling and analysis or visual examination of soil to assess its status and use potential is widely practiced from plot to national scales. However, the choice of relevant soil attributes and interpretation of measurements are not straightforward, because of the complexity and site-specificity of soils, legacy effects of previous land use, and trade-offs between ecosystem services. Here we review soil quality and related concepts, in terms of definition, assessment approaches, and indicator selection and interpretation. We identify the most frequently used soil quality indicators under agricultural land use. We find that explicit evaluation of soil quality with respect to specific soil threats, soil functions and ecosystem services has rarely been implemented, and few approaches provide clear interpretation schemes of measured indicator values. This limits their adoption by land managers as well as policy. We also consider novel indicators that address currently neglected though important soil properties and processes, and we list the crucial steps in the development of a soil quality assessment procedure that is scientifically sound and supports management and policy decisions that account for the multi-functionality of soil. This requires the involvement of the pertinent actors, stakeholders and end-users to a much larger degree than practiced to date.

Highlights

Soil quality is one of the three components of environmental quality, besides water and air quality (Andrews et al, 2002)
Statistical data reduction by multivariate techniques such as principal component analysis (PCA), redundancy analysis (RDA) and discriminant analysis (e.g. Andrews and Carroll, 2001; Lima et al, 2013; Schipper and Sparling, 2000; Shukla et al, 2006), and multiple regression (Kosmas et al, 2014) became more common. After this initial data reduction, simple or multiple correlation analysis can further decrease the number of indicators (Andrews and Carroll, 2001; Kosmas et al, 2014), sometimes followed by the use of expert judgement for choosing only one out of two or more highly correlated soil properties (Sparling and Schipper, 2002)
A number of steps are to be taken in soil quality assessment (Fig. 6), elements of which are addressed to very different degrees in the large number of approaches that have been developed during the past three decades and reviewed in this article

Summary

Introduction

Soil quality is one of the three components of environmental quality, besides water and air quality (Andrews et al, 2002). Soil quality is more complex than the quality of air and water, because soil constitutes solid, liquid and gaseous phases, and because soils can be used for a larger variety of purposes (Nortcliff, 2002) This multi-functionality of soils is addressed when soil quality is defined from an environmental perspective as “the capacity of the soil to promote the growth of plants, protect watersheds by regulating the infiltration and partitioning of precipitation, and prevent water and air pollution by buffering potential pollutants such as agricultural chemicals, organic wastes, and industrial chemicals” (National Research Council, 1993 as cited in Sims et al (1997)). Given the scope and readership of this journal, the “nonecological functions” of soil sensu Blum (2005), such as the physical basis of human activities, source of raw materials, and geogenic and cultural heritage, are beyond the scope of this review

Objectives

Methods

Findings

Conclusion