Motivation: Soil vulnerability, climate crisis, and human health
Soil resources are under increasing pressure due to population growth and intensified agricultural and urban uses. While best known for its role in agricultural production of foods, soil is equally fundamental for waste disposals, ground water purity and recharge, and climate impact. The thin soil vadose zone regulates water and chemical fluxes between the atmosphere and water aquifers and thereby controls their quality. Vital economic, environmental, and human health issues are linked to the biophysical properties and functionality of the soil vadose zone.
The increasing public concern on continued quality of soil is reflected in the final reports of major international conventions (the European Soil Charter, 1972, the Rio Convention, 1992, and the Kyoto Protocol, 1997). The European Union (EU) addressed the threats to soil quality by formulating a Soil Thematic Strategy by the interaction of a large number of soil scientists, stakeholders, and NGOs. A Soil Framework Directive will be approved by the European Council in 2007 and provides a guideline to soil protection strategies to be implemented by the member countries. The increased awareness of soil vulnerability is further strengthened by the pending climate crisis.
Soil contributes significantly to global warming, an effect not only related to CO2. The quantities of methane and nitrous oxide emitted from soil are relatively small compared to CO2, but their warming potentials are 20 and 300 times higher. Around one third of global CH4 emissions and two thirds of global N2O emissions come from soil. The exchange of these greenhouse gases between soil and atmosphere depends heavily on soil management and soil physical conditions. The gradual change in climate is anticipated to affect the moisture conditions in the soil vadose zone in currently dry as well as wet climate zones. As projected by the Fourth Assessment Report on the UN Intergovernmental Panel on Climate Change 2007, parts of Europe will see increasingly warm weather periods with high evaporation, causing extreme moisture gradients in the top soil and dramatic changes in soil structure. These climate changes will cause all vital soil functions including productivity and filtering of pollutants to be affected with yet unknown consequences for ecosystem and human health.
A positive human control of the soil vadose zone requires detailed knowledge and quantification of the physical and biological processes from nano to meso scale. Without knowing how gases, water, particles, and microorganisms move in natural soil systems with complicated soil inner space architecture - how can we predict and minimize gas emissions from soil to indoor air in buildings, suggest soil management strategies to limit chemical fluxes to groundwater, enhance crop productivity, design economically and remediation effective systems for cleaning up contaminated soil sites, or realistically try to estimate regional, national, and global trace gas exchange between soil and atmosphere? Today, we are trying to do all of this based on a fragmented and empirical knowledge of soil inner space, often resulting in erroneous predictions and expensive, ineffective solutions. Understanding and quantifying interactions between key soil processes and natural soil architecture is necessary to create a knowledge-based platform for turning soil inner space processes in the right direction for soil quality, human health, and climate. That is the motivation for the Soil-it-is project and the future of environmental soil science and engineering.