The role of agriculture

Not only forests emit VOCs. Every kind of vegetation is a potential producer of these compounds. This is why researchers are interested in other environments such as, for example, cultivated land which often raises questions about the impact of farming on the composition of the atmosphere. The Unit of Biosystems Physics installed equipment in the middle of a field in Lonzée (province of Namur): this was an anemometer which measured the strength of the wind twenty times a second, and an air sample linked to instruments on the ground capable of measuring the chemical composition of the air. This equipment system made it possible to analyze the flow of the different compounds, CO2 in particular (Read : Forests and grasslands : carbon sinks), but also, over a two-year period, a bouquet of VOCs. In this semi-natural environment, where wheat and corn are growing, the researchers from Gembloux demonstrated that these plants emitted mostly methanol. While these two crops are the most important in terms of surface area on a global scale, they have remained virtually unstudied up to the present. These results are therefore very important for scientists attempting to estimate the quantity of VOCs released into the atmosphere on a global scale.

The researchers from Gembloux have now turned their attention to another environment: pastureland. They are going to deploy their equipment in a meadow in the Dorinne area, to the south of Namur. A farmer grazes a herd of  Belgian blue breed cattle on this land for six months of the year. The study aims to measure the flow of VOCs in this meadow, and the impact of certain stress-factors on the production of VOCs. For example, grazing by the cattle causes the emission of VOCs from the wounded plants when cows cut grass blades. The researchers want to know in what quantities VOCs are emitted during this activity. Droughts, heat-waves or peaks in the concentration of ozone gas can also modify the emissions. Expected climate change for the coming decades predicts more and more extreme events of the kind mentioned above. Will such events increase the emission of VOCs or reduce them? And by how much will they do so? Will the type of VOCs emitted change in these conditions? There are so many pressing questions with regard to the reaction of the ecosystems of our regions that can be answered by carrying out measurements in the natural environment in perfectly realistic conditions. The first measurements will be revealed in the spring of 2014.