DO DRYLANDS SOILS ACT AS A NET SINK OF CO2 TO REDUCE ATMOSPHERIC CO2 IN THE GLOBAL CARBON CYCLE?
The Kimberly site in southwestern Idaho is a semi-arid dryland ecosystem with annual precipitation of ~300 mm. The parent material is loess on top of wavy basalt bedrock. This dryland region was converted to agricultural land in ~1904, including ~900 mm of supplemental irrigation water annually from the Snake River. Our preliminary results indicate the upper 100 cm of soil have accumulated SIC on an average of ~11% in the irrigated cropland and ~24% in the pasture land. The SIC appears concentrated at shallower depths in the soil profile and just above the loess/basalt boundary in irrigated soils.
The Kimberly soils have been irrigated for more than 100 years and whether this irrigation has caused an increase or decrease in SIC is still unknown. Addressing agriculture impacts on accumulation of SIC has its implications for climate change and agricultural communities. The present dataset and future research will further quantify SIC concentration in irrigated soils, CO₂ and water flux, and will address the issues of carbon and calcium provenances. Moreover, all the acquired results from Kimberly will be compared with prior SIC studies by Stanbery et al. (2017) as well as with the abundance and stable isotope composition (ẟ13C, ẟ18O) of CaCO3 determined from the nearby Reynolds Creek natural dryland ecosystem.