ASA Southern Branch 2007 Annual Meeting
February 4-6, 2007
Mobile, AL

Sunday, 4 February 2007

Effects of irrigation and fertilizer application on soil microbial biomass and activity in an intensively managed loblolly pine plantation.

Reji Mathew1, Yucheng Feng1, Michele Owsley1, Lisa Samuelson2, Thomas Stokes2, and Mark Coleman3. (1) Agronomy and soils, Department, Auburn University, Auburn, AL 36832, (2) Department of Forest Sciences, Auburn University, Auburn, AL, (3) Southern Research Station, PO Box 700, New Ellenton, SC 29809

Forest management practices may influence greenhouse gas emissions and soil carbon sequestration. The overall goal of this study was to improve understanding of soil carbon cycling in an intensively managed loblolly pine plantation. The specific objective of the study was to determine the influence of irrigation and fertilization on basal respiration, soil microbial biomass and activity in a six-year-old loblolly pine plantation. Field experiment plots were established in 2000 on a Blanton sandy soil near Aiken, South Carolina. The experiment was arranged in a randomized complete block factorial design with three blocks and irrigation and fertilization as factors. Soil samples (0-15 cm) were collected from different positions (North, Center and South) with respect to planting rows on a monthly basis beginning in February, 2006. The soil samples were analyzed for basal respiration, soil microbial biomass carbon and fluorescein diacetate (FDA) hydrolysis. The preliminary results show that basal respiration and soil microbial biomass carbon were significantly higher (P=0.05) in fertilized plots than in control plots. The correlation analysis showed that there was significant correlation (P=0.05) among basal respiration, soil microbial biomass carbon and FDA hydrolysis. Significant differences were observed among sampling positions for all three parameters. The results indicate that fertilization increased basal respiration and soil microbial biomass.

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