Measuring global soil changes

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Global change is increasingly affecting important terrestrial ecosystem functions such as the filtering and buffering capacity of soils, the supply of clean water, soil fertility, and consequently, the production of food, feed, and fiber.

Recent studies and reports from the United Nations indicate that water and soil resources are both heavily under pressure. Worldwide about 2 billion ha of land (15% of the total land surface and 40% of agricultural land) is affected by degradation caused by, e.g., deforestation, poor land and watershed management, and dumping of contaminants. In addition, clean water may become a scarce resource for many people, especially those living in developing countries.

 It is expected that by 2025, nearly 2 billion people will live in countries or regions with absolute water shortages. In these regions, water resources per person will fall below 500 m3 yr–1, which is the recommended minimum amount of water a person needs for healthy and hygienic living.

In order to manage water and soils in our terrestrial systems in a sustainable way, and to mitigate or adapt to the impact of global change, a fundamental understanding of the key processes at scales relevant to management practices is required. Therefore, in addition to the improvement of process understanding, research in terrestrial systems (e.g., the vadose zone) will need to bridge the gap between the measurement or observation scale and the regional (or sometimes even continental) management scale at which regulatory measures are being implemented. As more and more information about the state of the terrestrial system is becoming available, the development of methodologies that bring together different types of information (direct and indirect) with different spatial and temporal resolutions and coverage will become a major issue.

A special section in the August issue of Vadose Zone Journal presents results of research at the Agrosphere Institute in the Forschungszentrum Jülich (Jülich, Germany) that is addressing these issues. The institute is conducting research along three major directions: functional analysis of soils and sediments, development of sensing methods to explore terrestrial systems, and modelling of flow and transport processes of water and matter in terrestrial systems. In order to bridge the above gap, mathematical models in combination with high resolution measurements and observations of the state of the terrestrial system play a crucial role.

Despite the progress made, most of the models need extensive calibration and so there is still a need for more efficient and novel upscaling and downscaling strategies to derive effective parameters, state variables, and fluxes, and to improve process descriptions. This need for calibration indicates that the adopted parameterizations, model structures, and process descriptions are still insufficient to predict real-world behavior. Furthermore, data assimilation to predict soil water fluxes and soil moisture content will become more important as more and more data become available from new sensors and observation platforms.

Therefore, the Agrosphere Institute aims to contribute to the sustainable management of soil and water resources in terrestrial systems by providing new knowledge with respect to the functioning of those systems. A better understanding of terrestrial system function will come from the development of (i) novel sensing methodologies for process studies and the characterization and observation of terrestrial systems and (ii) appropriate mathematical models to deal with the problem of scaling.

Vereecken, H., P. Burauel, J. Groeneweg, E. Klumpp, W. Mittelstaedt, H.-D. Narres, T. Pütz, J. van der Kruk, J. Vanderborght, and F. Wendland. 2009. Research at the Agrosphere Institute: From the process scale to the catchment scale. Vadose Zone J. 8(3).

The full article will be posted online by mid-August at http://vzj.scijournals.org/content/vol8/issue3 

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