ARS | Publication request: LIGNIN DEGRADATION IN GRASSLAND, FOREST, AND SHRUB-STEPPE SOILS

Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: March 10, 2003
Publication Date: N/A

Technical Abstract: Lignin decomposition was studied in soils from research plots in 5 locations in the US: restored tallgrass prairie, farmland (grain), semiarid shrub-steppe, and loblolly pine and Douglas fir forests. Soils were amended with 14C- lignocellulose and incubated for 6 months during which total- and 14C-CO2 evolution were monitored and some replicates sampled for analysis of POM-C and microbial biomass. Soils that respired the most CO2 did not have the highest specific activities (14C activity/total CO2; dpm/(mg CO2-C)) during the incubation, nor were the specific activities for any soil constant through the incubation. Thus, it appears that in different soils and at different timepoints, C was mineralized to CO2 disproportionately from the labeled and residual C in the soil. For example, a tilled soil had an initial specific activity of 90 and decreased to 50 by 7 d. In contrast, the tallgrass prairie had an initial specific activity of 5, and then peaked at 7 d at 20. The specific activity of the CO2 evolved from all soils reached approximately constant values for all soils after 8 wk suggesting that the perturbation of the stable soil C caused by addition of fresh C was not permanent.