he Eternal Search for Simple Methods to Assess Soil Quality/Degradation for a Sustainable Land Management

Manuel Pulido Fernandez, Susanne Schnabel, Jaoquin Francisco Lavado Contador, Jesus Barrena Gonzalez, Artemi Cerda

Abstract


Humanity has been always concerned about the measurement and evaluation of terrestrial processes as the final
mechanism for understanding nature and human driven phenomena and environmental systems. We summarize the main
contributions made by the GeoEnvironmental Research Group (GIGA) of the University of Extremadura to develop and
apply simple methods that allow assessing soil quality and degradation in Mediterranean agrosilvopastoral systems. The
achievements of the GIGA research group have been complemented with the research experiences carried out by the Soil
Erosion and Degradation Research Group (SEDER) in Mediterranean agricultural areas, where orchards and gardens are
the main subjects of the study. A total number of twenty relevant publications made by the GIGA research group were
analysed, along with other ten studies led by the SEDER research group. This paper reviews: (i) the pioneering works,
(ii) the studies carried out at the farm scale in rangelands of SW Spain, (iii) the soil quality/degradation system evaluation
based on eight indicators proposed by the GIGA group, (iv) research on soil erosion conducted by the SEDER group in
vineyards, citrus plantations and tobacco orchards and (v) ongoing research about integrated assessment of rangeland
farms and the definition of indicators and other studies on soil erosion in chestnut tree orchards. Some indicators such as
soil depth, Ah-horizon thickness, water content at field capacity, cation exchange capacity (CEC), exchangeable
potassium (K) and soil organic matter (SOM) from 0 to 5 cm depth were the most appropriate to assess soil quality in
rangelands. The percentage of bare soil and bulk density (BD) from 5 to 10 cm in depth were proposed to assess soil
degradation processes such as soil erosion risk and soil compaction. Furthermore, rainfall simulations and erosion plots
showed their effectiveness to measure soil erosion rates at the short-term and ISUM (Improved Stock Unearthing Method)
at the medium and long-term. Those methods are being used successfully on agriculture and forest land and on
silvopastoral land uses to assess the soil degradation and soil quality.

Keywords


GIGA, SEDER, indicators, assessment, research, rangelands, soil erosion.

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