Dynamics of Microbial Community in Japanese Andisol of Apple Orchard Production Systems.

In this study, two fields of temperate Andisols from high-input and low-input (zero-input) management practices of an apple orchard were selected to assess microbial community dynamics based on environmental variables. Soils from an Ap horizon were sampled in five consecutive months from May to September and assessed for phospholipid fatty acids as a biomarker of soil microbial community, soil hardness, bulk density, porosity, pH, electrical conductivity (EC), organic carbon (C), available nitrogen (N) and phosphorus (P), and exchangeable cations as soil environmental variables. For all sample dates, total phospholipid fatty acids (PLFAs), total bacterial PLFAs, fungal PLFA, mycorrhizal PLFA, PLFA for actinomycetes, and earthworm were higher in low-input management than high-input management. Total PLFAs showed a high degree of seasonality, having August maxima and May minima. Significant effect on the relationships among soil environmental variables and microbiological attributes were observed. Soil management practices also showed a remarkable effect on the relationships among microbiological traits, indicating that some mechanism regulated soil microbial dynamics under two soil management practices. Comparatively higher correlations among the microbiological attributes were observed in low-input management than high-input management. Irrespective of soil management practices, bacterial and fungal lipid biomarkers were negatively correlated, suggesting that these subsets of fatty acids are contrasting components of the microbial biomass. Bulk density has negative influence on all soil microbial communities except fungi. On the other hand, linoleic acid and organic C were positively correlated, referring to the distribution of soil organic C implying an upper layer of soils. Microbial community composition and structure were greatly affected by sampling date and to a lesser extent by long-term management practice. In this study, both ecosystems were characterized by a very diverse microbial community. [ABSTRACT FROM AUTHOR]