%0 Journal Article
%T Conversion of a Semiarid Nevada Soil to Irrigated Agriculture Preferentially Removes Labile Carbon
%A Brittany R. Trimble
%A Francisco J. Calderon
%A Paul S. J. Verburg
%A Simon R. Poulson
%J -
%D 2018
%R https://doi.org/10.3390/soilsystems2030038
%X Abstract Due to the scarcity of arable land, semiarid rangelands are often converted to irrigated croplands, which is likely to affect soil organic carbon (SOC) due to changes in C inputs into the soil and environmental factors regulating decomposition. In this study, soil density and particle size fractions as well as their C and N contents, stable isotopic composition, and chemical characterization by mid-infrared spectroscopy were measured in a native shrubland and an adjacent agricultural site under alfalfa cultivation for at least 50 years in western Nevada. Cultivation significantly reduced the amount of C and N in the surface soils and the proportion of C present in the labile fractions. The ¦Ä 13C and ¦Ä 15N values of the SOC reflected dominant vegetation types at each site, and suggested most SOC was root-derived. The potential decomposition rate of SOC was higher in the shrubland than in the alfalfa surface soil reflecting the larger amount of labile C present in the shrubland soils. Spectroscopy results suggested that the greater recalcitrance of the alfalfa soils was due to insoluble SOC moieties. Additional analyses of buried, SOC-rich, A horizons at both sites showed that slower decomposition of ¡®deep¡¯ SOC was due to lower substrate quality supported by fractionation and spectroscopy data. The results of this study showed that converting a semiarid shrubland into irrigated cropland significantly reduced SOC content but increased overall stability of residual SOC. View Full-Tex
%K land use change
%K semiarid rangeland
%K irrigated agriculture
%K soil organic matter
%K labile carbon
%K stable carbon
%K particle size fractionation
%K density fractionation
%U https://www.mdpi.com/2571-8789/2/3/38