Document: BRI-3-59-44

Impact of five Carbon treatments on the labile nutrient Pools of historic Nitrogen and water manipulated plots.

FORD, B.E* ¹, J.EBARRETT ², I.CBURKE ³ and W.KLAUENROTH ³

Bard College, Annandale-on-Hudson, NY 12504 USA ¹
Dartmouth College Hanover, NH 07355 USA ²
Colorado State University, Fort Collins, CO 80523 USA ³

Abstract:
We assessed the influence of 5 carbon(C) treatments on the labile C and nitrogen (N) pools of historically N enriched plots on the Short Grass Steppe Long Term Ecological Research site in northeastern Colorado. We applied sawdust, sugar, industrial lignin, sawdust + sugar, and industrial lignin +sugar to plots that had received N and water additions in the early 1970's. Previous work has shown that the legacy of these water and N additions, altered plant species composition and enhanced rates of nutrient cycling, are still apparent twenty year after cessation of treatment. We hypothesized that C amendments would stimulate microbial activity and humification and suppress rates of N mineralization. We found that the historic water and N treatments continue to enhance C and N mineralization in the field and in laboratory incubated soils. Of the five current carbon treatments, sawdust and sawdust plus sugar stimulated potential C mineralization and suppressed N mineralization. In situ soil CO₂ flux suggests that precipitation plays a significant role in mediating the effectiveness of the current carbon treatments in stimulating microbial activity.

Keywords: C and N mineralization, precipitation, Short Grass Steppe

This abstract is being presented at: 3:30 PM in session:
Poster Session #15: Nutrient Cycling.