The impact of grassland management regime on the community structure of selected bacterial groups in soils

Abstract

The impact of long-term grassland management regimes on microbial community structure in soils was assessed using multivariate analysis of polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) banding patterns of selected bacterial groups and PLFA (phospholipid fatty acid) profiling. The management regimes assessed were inorganic nitrogen (N) fertiliser application and soil drainage. PCR-DGGE profiles of the eubacteria, actinomycetes, ammonia oxidisers and pseudomonads were assessed by principal co-ordinate analysis of similarity indices which were generated from binary data using both Dice and Jaccard coefficients. The analysis of binary DGGE data revealed significant impacts of N fertiliser on the eubacterial and actinomycete community structure using the Jaccard coefficient, whilst N fertiliser had a significant impact on the actinomycete community structure only when using similarity indices generated from the Dice coefficient. Soil drainage had a significant impact on the community structures of the actinomycetes and the pseudomonads using both Dice and Jaccard derived similarity indices. Multivariate analysis of principal components derived from PLFA profiling revealed that N fertiliser had a significant impact on the microbial community structure. Although drainage alone was not a significant factor in discriminating between PLFA community profiles of the different treatments, there was a significant interaction with N fertiliser. Analysis of principal component analysis (PCA) loadings revealed that PLFAs i15:0 and i17:0 were partly responsible for the clustering away of the undrained-N fertilised treatment. Although soil management regime influenced some background soil data, correlation analysis using PC1 from PLFA data revealed no significant relationship with soil organic matter, pH, total C and total N. These results provide evidence that grassland management practices impact on the community composition of specific microbial groups in soils.

Soil Microbial Community Changes in Wooded Mountain Pastures due to Simulated Effects of Cattle Grazing

“…The lack of explanation by soil variables in the sunny situation is probably due to the high homogeneity of soil conditions. Similarly, Clegg et al (2003) showed no significant relationship between PLFA and soil variables such as organic matter, pH, total C and total N in grasslands. In our study, only pH explained part of the variation in the shady situation where soil conditions were slightly less homogeneous than in the sunny situation ( Figure 2 and Table 2).…”

“…Much research effort has been directed at understanding how agriculture and land use practice influence the structure and diversity of animal and microbial below-ground communities (Chabrerie et al, 2003;Clegg et al, 2003;Grayston et al, 2004;Larkin, 2003). The role of soil organisms in regulating ecosystem processes has received growing attention over the past several years and there is an increasing number of studies on questions such as how decomposers respond to disturbance regimes especially those related to agriculture (Guitian and Bardgett, 2000;Wardle et al, 1999;Yeates et al, 1997).…”

“…In addition, the field studies compared existing situations with little control over the fields and independent variables (pseudoexperiment) (e.g., Bardgett et al, 2001;Donnison et al, 2000;Grayston et al, 2004) and microcosms were usually used in experiments (e.g., Bardgett et al, 1999;Jordan et al, 2003). Only a few studies used controlled field experiments (Clegg et al, 2003;Harrison and Bardgett, 2004;Wardle et al, 1999;Williams et al, 2000).…”

Multivariate Analyses of Burkholderia Species in Soil: Effect of Crop and Land Use History

“…Although agricultural practices induce general changes in soil microbial communities, specific microbial groups may respond differently. Clegg et al (6) showed that the application of inorganic nitrogen had a significant impact on eubacterial and actinomycete community structures, whereas soil drainage significantly affected the community structures of actinomycetes and pseudomonads. In addition, continuous wheat cropping affected the community structure of pseudomonads, such that an increase in the population of antibiotic-producing Pseudomonas spp.…”

Opening the Black Box: Understanding the Influence of Cropping Systems and Plant Communities on Bacterial and Fungal Population Dynamics

“…Since microbial populations play an important role in plant residue decomposition and nutrient cycling, it has been an area of interest to study how fertilizers affect the structure and function of these microbes. By using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and phospholipid fatty acid (PLFA) profiling, Clegg et al, (2003) found that nitrogen fertilizer has a significant impact on the total bacterial and actinomycete community structures. It was also found that fertilizer amendment altered the abundance of bacterial groups throughout the agriculture soil in Watkisville, Georgia, USA by using both 16S rRNA gene clone libraries and PLFA (Jangid et al, 2008).…”