Study of microbial communities in Lusitanian organic and conventional agricultural soils by phospholipid fatty acid analysis

Abstract

The microbial community of a soil is determined by the soil properties and by the type of soil management. In this study, the microbial communities of several agricultural soils in the Lusitanian pedoclimatic zone, under two management systems (conventional and organic), were characterized by phospholipid fatty acids (PLFAs) analysis. Organic soils showed a higher amount of total PLFAs and PLFAs associated with bacteria and arbuscular mycorrhizal fungi. We observed that the amounts of these fatty acids were related to the amount of soil organic matter and total nitrogen. On the other hand, in conventional soils we found a higher amount of fatty acids related to ascomycetes and basidiomycetes and a higher fungi/bacteria ratio. This is directly correlated with a higher proportion of macro-aggregates (> 2 cm) and inversely correlated with the amount of nitrogen.