Elisha C. Delminguez, an undergraduate student from the University of the Philippines Los Baños, is currently working on her undergraduate thesis on the determination of soil organic carbon for selected sites within the Agno River Basin. The soil samples were collected during a Project PAMANA field campaign in 2022. Elisha conducted her soil sample preparation and analysis at the Soil Laboratory in UPLB Institute of Renewable Natural Resources.

Elisha used two processes to determine the soil organic carbon content: oven-drying of bulk density and the Walkley-Black method. For the oven-dried weight bulk density method, samples were taken at two distinct soil depths (topsoil at 0-20 cm and subsoil from 21-50 cm depth). These samples were then weighed after they were placed in the oven for 24 hours. The Walkley-Black method was applied to soil samples from the same soil layers. This procedure is one of the most widely used methods for determining soil organic carbon and is generally given as a percentage. The Walkley-Black process involves the organic soil component being wet-combusted using a combination of potassium dichromate (10 mL) and sulfuric acid (20 mL). The residual dichromate is titrated against ferrous sulphate after the reaction.

Currently, Elisha is in the process of analyzing and interpreting the data acquired from these measurements – we look forward to seeing the results 😊

~ Elisha C. Delminguez – Undergraduate student UPLB