Update: 08.12.2017

Soil carbon is the largest terrestrial pool of carbon.

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The International Union of Soil Sciences (IUSS) is the global union of soil scientists. The objectives of the IUSS are to promote all branches of soil science, and to support all soil scientists across the world in the pursuit of their activities. This website provides information for IUSS members and those interested in soil science.

GLOBAL SOIL CHANGE: Time-Scales and Rates of Pedogenic Processes

Mexico City, March 10-18, 2005

This meeting was organized by two Commissions 1.3, Soil Genesis and Commission 1.5, Paleopedology together with La Sociedad Mexicana de la Ciencia del Suelo, Instituto de Geologia, Universidad Nacional Autonoma de Mexico (UNAM), Colegio de Postgraduados, Montecillo, Mexico, and Institut de Recherche pour le Developement (IRD), in France. It was well attended by the international and Mexican participants of about 60 scientists from 13 countries (Argentina 2, Canada 1, Cuba 1, China 1, Germany 11, Hungary 1, Italy 4, Rumania 1, Russia 6, Spain 1, Taiwan 3, USA 6, Mexico 22). The objective of the meeting was to increase our understanding of the pedosphere. It was recognized that the pedosphere and biosphere accelerating changes rapidly require more in depth understanding from the Earth and Life sciences stand point of view. This is the reason why this International IUSS Conference was held in Mexico. The Conference focused attention on time scales and rates of both natural and humanly induced pedogenic processes in relation to the global soil change.

Scientific sessions included were:

1. Main concepts of soil systems behavior in time.

2. Chronosequences of soils and paleosols: time-scales for natural pedogenic processes.

3. Rates and characteristic times for modern and ancient human induced pedogenic processes.

4. Time scales of soil geoforms biota interactions

5. Experimental modeling of pedogenic processes.

6. Soil dating methods: advances and limitations.

In a final session, a round-table discussion will examine the question:

“What are the important gaps in our knowledge on soil and time problem?”

The Conference had a three-day program of oral and poster sessions and two (pre and post) conference tours. Organizers have done a superb job.

Four day pre-conference field excursion


The Nevado de Toluca paleosol sequence was visited, with ages covering the last 50,000 years, formed from pyroclastic materials. During this excursion the soil diversity and landscape evolution in a typical mountain landscape at the western portion of the Transmexican Volcanic Belt (Michoacin state) and soils develop on a wide range of volcanic rocks from Tertiary dacites to Quaternary basalts and alluvium were examined. Participants enjoyed the area of the Paricutin volcano, that erupted in 1943. Soil chronosequences in this volcanic field and their relation to site quality for forest management were evaluated. Finally, they looked at soil erosion on lower slopes and piedmonts of volcanic mountains and its implications for surface water quality in the Cointzio watershed near Morelia, Michoacin. This excursion had 21 participants.

Two days post-conference field excursion

Two days post-conference field excursion

The participants have visited the area of Texcoco ex-lake, from the slopes of the Sierra Nevada to study the soil topo-chrono-climo-sequence on volcanic and lacustrine sediments, bearing effects of human impact of different age and duration (prehispanic, colonial, and contemporary). This excursion was plenty of cultural aspects, including the archaeological site in Huexotla and a Franciscan convent built in the XVI century. The participants enjoyed the paintings of Diego Rivera in the School of Agronomy (Universidad Autonoma de Chapingo); and finally the 28 participants enjoyed the famous archaeological site of Teotihuacan.The following individuals should receive special thanks for the excellent work and dedication for making the meeting a great success: Christina Siebe, Lorenzo Vazquez, Carmen Gutierrez, Sergey Sedov, Jorge Gama, Maricela Coronado, Guadalupe Maturano

Elizabeth Solleiro-Rebolledo
Victor Targulian
Ahmet R. Mermut