Experimental Investigation on Role of Root Mucilage on Soil-Water retention Dynamics

Using a considerable amount of energy, soil microbes and plant roots release organic molecules in order to adapt to their surroundings.  Our hypothesis is that the organic molecules deposited on the soil surface are able to alter the soil water retention curves (SWRC) of the rhizosphere, relative to the bulk soil. By altering the make-up of the soil, more energy is provided for biogeochemical processes. For experimentation, glass beads of size 40 microns are used to imitate soil. These glass beads are saturated with various concentrations of polygalacutronic acid (PGA) to represent the organic exudates from plant roots.  PGA at varying concentrations are used to replicate the amount of organic matter released depending on the condition of the soil. The mixture is allowed to dry slowly in order to develop complete deposition of organic matter at the surface of the glass beads, just as it would on the soil surface.  To determine the soil water retention curves, measurements of water outflows at different suction levels will be recorded.  We will present the effects that the different concentration levels have on the changing retention curves by determining the SWRC for each sample and the rate of drying at numerous time intervals.