Wheat straw or poultry Pinus-sawdust litter were added to a forest aci
d soil and changes in the microbial community were studied during a 3-
month soil incubation. Soil amendment did not alter the relationships
between microbial groups. In all the samples most microbes were aerobi
c heterotrophic bacteria which predominated over fungal propagules and
actinomycetes; fungal hyphae were relatively well developed, whereas
the densities of cyanobacteria and algae were relatively low Among the
N-cycle microbes, there was a relatively high number of ammonifiers,
while both ammonium- and nitrite-oxidizers were scarce. Although soil
amendment did not significantly alter the pattern of growth of most mi
crobial groups, it drastically changed their numbers, alterations due
to poultry addition being much more marked than those due to straw add
ition. Among the heterotrophic microbes, straw addition to soil increa
sed fungal population but decreased bacteria and especially actinomyce
tes, while those that were able to carry-out ammonification were unaff
ected. Conversely, poultry manure addition favoured all the microbial
groups, the increase in number following the order: bacteria > fungi >
actinomycetes, the ammonium-producers being particularly stimulated.
Autotrophic microbes, whether photo- or chemo-autotrophs, were decreas
ed by straw and manure. The response of microbes indicated that the us
e of wheat straw could lead to a reduction in taxonomic and functional
diversity in the microbial community and that, in general, poultry ma
nure seems to be better for applying to soil. Copyright (C) 1996 Elsev
ier Science Ltd.