ARE PEDOGENIC CARBONATES IN DRYLAND SOILS A SOLUTION TO CLIMATE CHANGE? EVALUATING THE AMOUNTS, RATES AND PROCESSES OF CARBONATE FORMATION IN AGRICULTURAL AND NATURAL CRITICAL ZONE SYSTEMS
Kimberly Idaho is a semi-arid xeric ecosystem ( ~300 mm of precipitation annually). The parent material is loess on top of wavy basalt bedrock. In ~1904, irrigation from the Snake River transformed this dryland ecosystem into an agricultural community with an average of ~900 mm of additional water input from irrigation annually. Research as part of a new NSF CZO project at Kimberly Idaho reveals intriguing results. Despite irrigation well in excess of the 500 mm pedocal/pedalfer threshold identified by Hans Jenny and others, and the observed annual threshold for SIC accumulation in Reynolds Creek, preliminary results from Kimberly Idaho show an average of ~11% CaCO₃ in the top meter of irrigated cropland soils and ~24% CaCO₃ from pasture soils. Notably, SIC in irrigated soils is concentrated at the top of the soil profile and just above the loess/basalt boundary.
Ongoing and future research will further quantify amounts of SIC in irrigated soils, as well as CO₂ flux, water flux and chemistry, dust flux and composition. Preliminary findings suggest irrigated farmlands have been sequestering inorganic carbon for >100 years, with important implications for mechanisms of both addressing climate change and supporting agricultural communities.