See more from this Session: Microbe, Plant , and Soil Interactions (Includes Graduate Student Poster Competition)
Decomposition of crop residues provides the primary source of new C in agricultural soil, and understanding residue C decomposition in different soils is important for developing and promoting practices that best sustain a soil's productive capacity. Stable isotope probing of the microbial community using 13C is a powerful tool for tracking residue C as it flows through the microbial biomass. As part of a larger long-term study that investigates the rate and pathways of litter decay, we studied the incorporation of 13C from barley residue into the microbial biomass using phospholipid fatty acid analysis (PLFA).
Study sites under contrasting climatic
conditions were located at
After about 1 yr, the proportion of residue-derived C that was assimilated decreased for fungi but increased for bacteria and was not affected by residue placement. Overall, the fungal biomass was more heavily labeled with 13C than the bacterial biomass. Residue placement affected microbial community structure even after 2 yr, and this effect was stronger under more arid conditions.