Investigation of Soil Suction Characteristics Induced by the Degradation of Organic Matter

Total soil suction is considered to be the accumulative influence of matric and osmotic suction, assuming that the soil is biologically inert. However, there are several biological activities occurring in soil media, which result in the degradation and precipitation of organic/inorganic substances in the soil pores and around the soil surface. These biological activities may influence the soil pore structure and hence, the water retention of the soil. This study investigates the influence of the most common biological activity, degradation of organic matter in the soil pores, on the suction characteristics of the soil. The water retention behavior of the soil admixed with 10% (by weight) organic waste (banana peel, genus Musa) is estimated at different time intervals during the degradation process using dewpoint PotentiaMeter. Marginal changes in the water retention behavior were observed up to 14 days degradation period, however the soil tend to regain its initial suction characteristics after the degradation stabilizes. The organic content decreased from 10 to 3.23% during 14 days of degradation period and a marginal change in the van Genuchten fitting parameters n and α parameters were recorded. The n parameter varied only 4% in 14 days degradation period while corresponding change in α was recorded from 2.7 × 10^–4 to 2.2 × 10^–4. This study reports no significant change in the water retention behavior of soil during the degradation period of 28 days.