Response of soil characteristics and bacterial communities to a gradient
of N fertilization rates for coastal salt-affected Fluvo-aquic soil
under paddy rice-winter wheat rotation
Abstract
Excessive salts in soil inhibit enzyme activity, decrease microbial
growth and constrain biochemical functioning, which could be alleviated
by soil management and fertilization. However, the effect of consecutive
chemical fertilizer on soil bacterial community structure under saline
environment is poorly understood. Here, a field randomized block design
under four nitrogen fertilization rates (0, 150, 300, and 450 kg N hm-2
y-1) was conducted on coastal salt-affected Fluvo-aquic soil. Effect of
nitrogen fertilization rates on soil properties and bacterial community
was characterized using Illumina Miseq sequencing for 16S rRNA gene.
Results indicated that consecutive chemical N fertilization accelerated
the improvement of soil chemical and microbial properties under the
paddy rice - winter wheat rotation. Soil bacterial community well
responded to the nitrogen fertilization and community richness and
diversity increased with the nitrogen rates. Predominant bacterial phyla
belonged to Proteobacteria, Chloroflexi, Acidobacteria, Actinobacteria
and Planctomycetes, whereas Deltaproteobacteria, Anaerolineae,
Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria,
Actinobacteria and Planctomycetia were dominant bacterial classes.
Increasing nitrogen fertilization resulted in an elevation in the
relative abundance of classes Alphaproteobacteria, Gammaproteobacteria,
Planctomycetia and Nitrospira, and a decline in Anaerolineae,
Acidobacteria_Gp6, Cytophagia, Bacilli and Acidobacteria_Gp10. Clear
separations in the bacterial communities at class level were observed
under different nitrogen fertilization rates. Community structure of
classes Alphaproteobacteria, Planctomycetia and Nitrospira was
significantly influenced by potential nitrification rate (PNR), and
community structure of class Actinobacteria was significantly influenced
by carbon mineralization rate (CMR). The results demonstrated that
nitrogen fertilization improved nutrients and metabolic activities to
more suitable bacterial microhabitats for saline soil.