Environmental Humanities South (EHS) is excited to host Dr A.M Lawal from Federal University Gusau, who will be giving a seminar, titled "Controls on the Production and Distribution of Mineral Nutrients in Soils in Agricultural Karst Critical Zones". To attend in person or online, email zainab.adams@uct.ac.za 

DATE: 08 May 2025

TIME: 11 AM - 12:30 PM

VENUE: EHS Seminar Room, Level 4 Humanities Building, Office 4.19 Upper Campus.

ZOOM ID: [Meeting ID: 975 6309 0451 | Passcode: 515492]

ABSTRACT: Earth’s Critical Zone, the region encompassing the top of the vegetation canopy to the bottom of the weathering zone, which has, historically, been shaped by geologic and climatic forcings is now being impacted by anthropogenic activities. These activities have led to intensive competition for resources such as food and fibre resulting in unsustainable land use practices and soil degradation especially in the karst environments where lithology contributes to the formation of nutrient-poor soils. Here, we studied the impact of lithology and climate on the production of mineral nutrients in karst CZOs in Guizhou province, southwestern China and Crete, Greece that were impacted by intensive agricultural activities under different timescales and seasonality. Mineralogy and rock texture were analysed using SEM while soil and bedrock bulk chemistry were analysed by ICP-OES. The results indicated the influence of lithology and atmospheric deposition. Bedrock mineralogy and mass transfer profiles of the mineral elements have also indicated that in situ dissolution of carbonate minerals (calcite and dolomite) leaves soil matrix enriched with non-carbonate (mostly aluminosilicates) mineral impurities which control soil formation and mineral nutrient content in the soils. Mass transfer profiles show that the enrichment of the mineral nutrient elements (Ca, Mg, K and P) in the soil is attributed to atmospheric deposition and biolifting (a process in which plants scavenge and concentrate mineral elements on the surface). Variation in bedrock mineralogy between the two CZOs was attributed to the more prominent role of bedrock in Guizhou in controlling soil mineral profiles than Crete.