|Herrick, Jeffrey - Jeff|
Submitted to: Environmental Pollution
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/21/2001
Publication Date: 3/1/2002
Citation: BIRD, S.B., HERRICK, J.E., WANDER, M.M., WRIGHT, S.E. SPATIAL HETEROGENEITY OF AGGREGATE STABILITY AND SOIL CARBON IN SEMIARID RANGELAND. ENVIRONMENTAL POLLUTION. 2002. V. 116 P. 445-455. Interpretive Summary: Accurate estimates of soil carbon are needed to evaluate changes in carbon sequestration. Soil organic matter is closely related to soil structure. We found that both soil carbon and soil aggregate stability are extremely variable at multiple scales, from plant-interspace to the landscape, even on similar soils under similar vegetation cover. These patterns need to be taken into account in the design of any soil carbon monitoring program, an in the application of management practices designed to improve soil structure or enhance carbon sequestration.
Technical Abstract: To measure and manage for C sequestration in heterogeneous rangeland systems, we need to more fully understand spatial patterns of soil resources. Spatial distributions of aggregate stability and soil carbon were investigated in a semiarid rangeland in New Mexico, U.S.A. Soil was analyzed from plant interspaces, black grama (Bouteloua eriopoda (Torr.) Torr.), and mesquite (Prosopis glandulosa Torr.) in a landscape-replicated study. Aggregate stability at the 250 micro meter scale, carbonate C, organic C and N, C:N ratio, and glomalin, were all highest under mesquite. Soil C:N ratio was the best predictor of aggregate stability. Estimates of metric tons of C per hectare in the top 10 cm were highly variable at patch and landscape scales, varying from 10.5 under mesquite to 3.0 in interspaces. High variability of aggregate stability and soil C has important implications for C sequestration. We argue that this multi-scale soil heterogeneity must be considered when measuring and managing for C sequestration.