Influence of land-use intensity on the spatial distribution of N-cycling microorganisms in grassland soils

A geostatistical approach using replicated grassland sites (10 m × 10 m) was applied to investigate the influence of grassland management, i.e. unfertilized pastures and fertilized mown meadows representing low and high land-use intensity (LUI), on soil biogeochemical properties and spatial distributions of ammonia-oxidizing and denitrifying microorganisms in soil. Spatial autocorrelations of the different N-cycling communities ranged between 1.4 and 7.6 m for ammonia oxidizers and from 0.3 m for nosZ-type denitrifiers to scales >14 m for nirK-type denitrifiers. The spatial heterogeneity of ammonia oxidizers and nirS-type denitrifiers increased in high LUI, but decreased for biogeochemical …

Regulation of bacterial and fungal MCPA degradation at the soil–litter interface

Abstract Much is known about mechanisms and regulation of phenoxy acid herbicide degradation at the organism level, whereas the effects of environmental factors on the performance of the phenoxy acid degrading communities in soils are much less clear. In a microcosm experiment we investigated the small-scale effect of litter addition on the functioning of the MCPA degrading communities. 14 C labelled MCPA was applied and the functional genes tfdA and tfdAα were quantified to characterise bacterial MCPA degradation. We identify the transport of litter compounds as an important process that probably regulates the activity of the MCPA degrading community at the soil–litter interface. Two possi…

Biogeography of microorganisms in grassland