Microbial biomass and numbers of denitrifiers related to macropore channels in agricultural and forest soils

摘要: Abstract In clay and loamy soils the vertical flow of dissolved particulate matter primarily takes place through macropore channels supplying attached microorganisms with nutrients substrates for their growth. Consequently walls may have a higher microbial biomass rate potential processes, e.g. denitrification, than soil matrix not affected by macropores. This was tested determining content NO 3 − -N, water-soluble carbon (WSC) size in bulk soil, adjacent to (macropore soil) macropores (matrix from one agricultural site forest located Jutland, Denmark. Determinations bacterial profile (0 250 cm) generally showed following sequence abundance: acridine orange direct counts>most probable numbers>total plate counts>nitrate reducers>denitrifiers. The numbers culturable bacteria were 1 2 orders magnitude lower profile. There tendency slight decrease increasing depth. comparison clearly that contained larger concentrations -N WSC biomass. average contents 6.7 3.7 μg g −1 dry respectively, whereas very low ( resulted smaller differences between soils. 51 40 C at 33 19 site, respectively. With respect results only four exceptions, samples out 44 analyses this difference statistically significant. These measurements substantiate role as preferential pathways transportation solutes such nitrate organic compounds. Consequently, cells environments be attributed better substrate supply channels.