ESTIMATION OF THE AMOUNT AND RATE OF PEDOGENIC CARBONATES ACCUMULATION IN IRRIGATED AND NON-IRRIGATED DRYLAND SOILS OF SW IDAHO

Pedogenic carbonates are characteristic of arid to semi-arid climates and recognized as an important global carbon (C) pool. However, the CO₂ exchange from atmosphere to land, the age, amount and flux of inorganic carbon associated with natural dryland soils and dryland agriculture is poorly known. The amount of carbon sequestered by pedogenic carbonates in dryland soils varies with the amount of time the soil has been forming, climate conditions, dust influx, crops, agricultural practices, fertilizers and soil properties. Therefore, a reliable history of formation of pedogenic carbonates is needed to predict and model the past and future accumulation of these carbonates in the context of C sequestration, agricultural intensification, and climate change.

This study is focused on two areas; the non-irrigated sites of the Reynolds Creek Experimental Watershed (RCEW), and both the irrigated and non-irrigated sites of Kimberly Northwest Irrigation and Soils Research Laboratory (NWISRL), SW Idaho. Primarily, this research will address that how much inorganic carbon is sequestering in irrigated, pasture, and natural dryland soils and how has agricultural impacted carbon fluxes in the drylands. The total soil carbon storage in non-irrigated and irrigated sites at RCEW and NWISRL will be determined by measuring the soil inorganic carbon (SIC) and soil organic carbon (SOC) in these soils and in combination with OSL dating of soil profiles, it will provide the amount and rate of pedogenic carbonates over time. The comparison of SIC and SOC between native and managed sites, and dating from both RCEW and NWISRL will be helpful to determine the influence of human induced changes (tillage, irrigation, and fertilizer) on pedogenic carbonate formation.

Keywords: Soil total carbon, pedogenic carbonates, irrigated and non-irrigated soils, OSL dating