Submitted to: Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/4/2007
Publication Date: 6/1/2008
Citation: Steenwerth, K.L., Drenovsky, R.E., Lambert, J.J., Smart, D.R., Kluepfel, D.A., Scow, K.M. 2008. SOIL MORPHOLOGY, DEPTH AND GRAPEVINE ROOT FREQUENCY INFLUENCE MICROBIAL COMMUNITIES IN A PINOT NOIR VINEYARD. Soil Biology and Biochemistry. 40:1330-1340. Interpretive Summary:
Technical Abstract: Microbial community composition responds to soil resource availability, and has been shown to vary with increasing depth in the soil profile. Soil microorganisms partly rely on root-derived carbon to (C) for growth and activity, and roots in woody perennial systems like vineyards have a deeper vertical distribution than grasslands and annual agriculture. Thus, we hypothesized that vineyard soil microbial communities along a vertical soil profile would differ from those observed in grassland and annual agricultural systems. In a Pinot Noir vineyard, soil pits were excavated to ca. 1.6-2.5m and microbial community composition in 'bulk' (i.e., no roots) and 'root' )i.e.. roots present) soil was described by phospholipid ester-linked fatty acids (PLFA). Using Canonical Correspondence Analysis (CCA), soil microbial communities were more similar to each other in the Ap horizon than in the lower horizons, and they tended to cluster by soil morphology in the lower horizons. Soil resources comprised the primary gradient explaining the distribution of soil microbial communities along the first CCA axis. Total PLFA (i.e., labile C), soil C and nitrogen, and exchangeable potassium were enriched in the surface horizons and significantly explained the distribution of soil microbial communities. Along the second CCA axis, soil chemical properties represented the secondary gradient explaining the distribution of soil microbial communities. The distribution of PLFA biomarkers differed from previous studies in grasslands and annual agricultural systems. They were closely correlated to the distribution of roots in the vineyard soil profile, and regressions of biomarkers on vertical root distributions were significant, suggesting deeper root distribution in the vineyard was related to the distinct pattern in PLFA biomarker distribution.