PARENT SESSION
Oral Session #25: Soil Ecology: Microbial and Invertebrate. Presiding: W. Parsons.
Tuesday, August 7, 2001. 8:00 AM to 12:00 PM. Hall of Ideas G.
Management effects on soil microbial biomass and the microbial community structure.
HU, SHUIJIN1, PARKER, KAREN1, RISTAINO, JEAN1, 1
ABSTRACT- Tillage practices and soil amendments profoundly affect the biomass and assemblage of the soil microbial community. We investigated the effects of tillage and four soil amendments on the soil microbial community in a sandy loam soil. The treatments were assigned in a split-plot design with conventional tillage and surface-mulch in the main plots and four soil amendments in the subplots. The four amendments were inorganic N fertilizer, cotton trash, manure and cover crop. After three consecutive years, the treatments were terminated in early 2000 and a cover crop (sudangrass) was planted. In samples collected in May, 2000, soil microbial biomass C, N and C:N ratios were significantly higher under surface mulch than under conventional tillage. Significant higher microbial biomass C:N ratios under surface-mulch than tillage suggest that fungi may become more dominant in the soil microbial community. However, treatment effects on the soil microbial community were not significant in the samples collected in August, 2000, suggesting that other factors such as soil temperature and moisture might become the dominant factor impacting the soil microbial community.
KEY WORDS: microbial biomass, microbial community structure, tillage, soil amendments