Soil quality index of an Oxisol under different land uses in the Brazilian savannah

One of the challenges of Soil Science in the last 20years has been the development of soil quality indicators and indices that are sensitive, integrative, universal, and accessible to different users. However, some of the existing indices are not comprehensive, and others lack the simplicity to be applicable in developing countries. The objective of the present study was the development of a soil quality index-SQI that incorporates those criteria, and to apply it to an Oxisol under different land uses in the Brazilian savannah. The proposed SQI is based on relevant soil functions, assessed by chemical (organic matter, CEC, pH, total phosphorous, and base saturation), physical (soil infiltrability and modified penetration index), and biological (percent soil cover and number of dung beetles captured) attributes. The index was normalized by the number of attributes utilized, so that none of the three soil disciplines was over or underestimated. To illustrate the utilization of the SQI, it was applied to six experimental areas, varying from natural forest to cropland, in the region of Planaltina-DF (Central Brazil). The soil was a sandy-clay-loam ‘Latossolo Vermelho-Amarelo distrófico típico' (Typic Haplustox), and the local climate type is Aw (Köppen). The SQI scores and their respective classification were: ‘Cerradão' (natural woodland): 5.0 – high soil quality; 10yr-old Reforestation: 3.2 – medium; ‘Cerrado sensu strictu' (natural savannah): 2.9 – medium; Maize: 2.5 – medium; Pasture: 2.2 – low; and 1yr-old Reforestation: 2.2 – low. A similar trend in soil quality was found by other authors in the tropics, studying other Oxisols, and using different indices. © 2017 Elsevier B.V.