Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 16, 2004
Publication Date: November 1, 2004
Citation: Reeder, S.J., Grant, D.W. 2004. Differences in labile pool c and n dynamics in the surface soils of two-semi-arid rangeland ecosystems. American Society of Agronomy Abstracts. CD Reeder Abstract. Technical Abstract: Natural perennial grasslands are characterized by a high degree of spatial and temporal variability. This study quantified the spatial distribution and relationships between total and labile carbon (C) and nitrogen (N) in two semi-arid grasslands. Soil samples (0-5 and 5-10 cm depth) were collected in the early growing season from shortgrass steppe (SGS) and northern mixed-grass prairie (NMP) ecosystems and analyzed for total soil organic C (SOC), total N, water soluble organic C (WSOC), water soluble N (WSN), and potentially mineralizable C and N by 21-day aerobic incubation. Microbial activity in bare ground microsites was more C-limited than microbial activity in grass-occupied microsites. The NMP had greater microbial activity, root biomass and total SOM than the SGS, but lower levels of WSOC and inorganic N. Ratios of respired CO2 to net mineralized N and WSOC to WSN also were higher in the NMP than the SGS. These results suggest that N immobilization is likely more frequent in the NMP, while net N mineralization may be more frequent in the SGS ecosystem. The lack of plant-available N in the NMP may frequently limit plant growth.