Report on the international Conference “Soil geography; new horizons”, Huatulco, Mexico, November 2009

The international conference “Soil geography; new horizons” was held in Huatulco (Oaxaca, Mexico) from the 16th to the 20th November 2009, organized by UNAM (Universidad National Autonoma del Mexico) and INEGI (Instituto National de Estadistica y Geografia del Mexico), sponsored by IUSS (International Union of Soil Science), SLCS (Latin American Society of Soil Science), SMCS (Mexican Society of Soil Science), ECSSS (European Confederation of Soil Science Societies), and IES (Institute for Environment and Sustainability of the Joint Research Center of the European Union).

The scientific program considered the following sections:

 

More than 200 scientists from 50 countries attended the congress and presented various research works.

Prof. Blum’s presentation regarded an innovative theory, expressing the pedogenetic processes in terms of energy, which was found very provoking. This could be the subject of many research works in the near future.  

 

Many works in the following three sections stressed the importance of geomorphological analysis in the soil cartography process, as the pedogenetic factor relief was is among the most important in explaining the model of soil distribution in a region. The integration of geodatabases of soils and other natural resources was acknowledged as a fundamental step to improve soil cartography. Standardization and harmonization of data were also recognised in the digital storage process. The definition of a common ontology, including common rules and definitions in soil science, was also recognised, so more exchange between soil scientists is needed in the future. The final aim of this work should be to progressively reduce tacit knowledge, and to make pedology a science more user friendly and understandable to the overall public. The general use of the WRB classification in soil cartography at national and regional levels (1:250,000 and smaller scales) was one of the recommended standardization systems. In the long run, efforts are undertaken to develop a Universal Soil Classification as a world-wide accepted common language for soil classification and mapping.

 

During the 4th session Dr. Schad presented the “Guidelines for constructing small-scale map legends using the World Reference Base for Soil Resources”.  The reference WRB classification was the second version, published in 2006. In this version two new reference groups were created and a larger number of qualifiers for each reference group was added. Qualifiers were organized in prefixes and suffixes. For their use, rules and a fixed order were defined. The new concept presented by Dr. Schad during the congress included the possibility to give a different order to the qualifiers when using the WRB classification for profile classification or for creating mapping units, according to the cartographic necessities. The presented document was defined as an “in fieri” publication and everybody was invited to participate to its improvement, taking advantage of local experiences. During the discussion, which continued even in a special round table in the following day, the majority of the attending colleagues suggested not to classify profiles and types of map units in different ways, but they welcomed the possibility of using WRB flexibly to create cartographic units.

 

Another very interesting talk given by Dr. Wiesmeier and coll. about “Digital mapping of soil organic carbon in a semi-arid grassland of Northern China”. The research work concerned an innovative spatialization method which used random forest modelling and CART classification, in term of accuracy, better then those obtained by linear regression models.

 

During the following sessions the soil distribution of many environments and relative soil-landscape models were presented, such as of the karstic peninsula of  Yucatan (Mexico), the pingo-islands in Russia, the Cape region of South Africa, the tropical ambients of Sierra Madre del Sur (Mexico), and other Mexican, Russian and African environments.  Among the presentations, the one of Søren Torp titled “Soil mapping and N-leaching modelling of intensively managed farmland in the Norsminde fiord catchment (Denmark)” was particularly interesting. It dealt with an application of geo-electrical scanning with electromagnetic induction technology (EM38), aimed at large scale cartography of soil characteristics related to the N-leaching managing. Other examples of pedological cartography with deterministic approach were presented during the 4th, 5th and 8th sections. The relevance of the anthropogenic factor on pedogenesis was many times indicated as a disturbing agent in the natural evolution of soils, and thus it was suggested to properly consider this factor in the mapping process.  A considerable success was the work of Prof. Carmelo Dazzi and colleagues "Soilscape order and disorder: is land use change a cause of loss of pedodiversity?", in which a model of soil and landscape evolution for a whole Municipality in Sicily was proposed, which indicated for the coming years, the almost complete loss of natural soils and their replacement by anthropogenic soils, only suitable for viticulture.

 

In the Paleopedology session, titled “Paleosols in the present and past soilscapes” two interesting reports on the soils of the Mayan archaeological sites were presented, one of Dr. Timothy Beach "Ancient Maya wetland fields: two models based on multiple proxies" and the other by R. Terry and R. Burnett "Stable carbon isotope evidence of ancient Maya agriculture at Tikal, Guatemala These talks were followed by a methodological report of Edoardo Costantini and Simone Priori on "The pedostratigraphic study of the soil cover for the geomorphological, tectonic-stratigraphic, and paleoclimatic reconstructions”. The work of Daniela Sauer and collaborators about the pedogenesis on a marine terraces in southern Italy, and a series of case studies, including those by Cabadas –Báez and co-workers on "Pedosediments Karstic of sinkholes in the eolianites of the NE of Quintana Roo, Mexico”, where a model of the genesis of soils and forms in karst environment was described. The model predicts a small but variable contribution of the insoluble residue of limestone to the soil genesis during the Holocene, while the soil mass is by far constituted of aeolian and colluvial sediments. Other oral and poster presentations dealt with case studies covering a wide range of topics: reconstruction of Triassic (Arefiev and Kuznetsova) and MIS3 (Rusakov) soil scapes, soil-archaeological research in the Palaeolithic (Sedov), Medieval Russian (Egovatova and Golyeva) and Classic Mesoamerican (Rivera et al.) archaeological sites.

 

The session on pedodiversity attracted a large audience, a sign of the growing interest in this emerging subject. Of particular value was the paper by Viktor Targulian and Maria.Gerasimova "Soil geography: Geography of soil systems and soil bodies", where a distinction was made between the concepts of soil as a functional system and a natural (or artificial) body. It was shown how the two concepts may differ, and how this has profound implications for mapping and monitoring soil properties. In the case of soil as functional system, a much closer scanning time and space is required, that includes the multiple phases of soil, like moisture and temperature regimes, biomass production, biogeochemical cycles, the aeolian, fluvial, colluvial contributions etc.

 

The award for the best poster presented during the congress was won by the work "Soil organic carbon stocks variations in Italy during the last three decades," I which Fantappiè M. et al. documented losses of carbon in the '90s in Italy and the subsequent slight recovery.

During the field trip after the conference it was remarkable to observe the environmental unsustainability of many urban developments and farming systems that, just likewise in richer countries, cause soil degradation. In the case of Mexico, they have historically led to the abandonment of areas heavily populated, and now to a desertification that increasingly devastates large areas.