Experimental and Numerical Investigation of the Drying of an Agricultural Soil

Due to climate change, soil desiccating became a serious concern in the agricultural area of Belgium. Knowing soil evaporation kinetic can help to elucidate and predict: the soil moisture regime, soil water retention and soil water content. Those parameters are vital for water use efficiency and sustainable agriculture. This research analysed the mechanism of soil evaporation both under laboratory experiment and numerical modelling. Soil samples (Luvisol) were collected from the agricultural field in Gembloux-Belgium, and processed in a small drying chamber. Sensors measured the chamber temperature and humidity, while digital camera monitored the soil surface throughout the experiment. HYPROP device recorded the water change, soil suction, and soil water retention curve. During three evaporation experiments, four periods were observed rather than three according to the common theory. The modelling considered thermo-hydro-mechanical framework for predicting the drying process of Luvisol. The model used the finite element code LAGAMINE created at the University of Liege. The Software aims at assessing the mechanism of water transport between soil and atmosphere. The results of the simulation showed major domination of Darcean flow during desiccating, while some short vapour diffusion occurred only after the soil surface began to de-saturate.