Response of Nitrifier and Denitrifier Abundance and Microbial Community Structure to Experimental Warming in an Agricultural Ecosystem

Abstract

Soil microbial community plays an important role in terrestrial carbon and nitrogen cycling. However, the response of the soil nitrifier and denitrifier communities to climate warming is poorly understood. A long-term field warming experiment has been conducted for 8 years at Luancheng Experimental Farm Station on the North China Plain; we used this field to examine how soil microbial community structure, nitrifier, and denitrifier abundance respond to warming under regular irrigation (RI) and high irrigation (HI) at different soil depths (0-5, 5-10, and 10-20 cm). Nitrifier, denitrifier, and the total bacterial abundance were assessed by quantitative polymerase chain reaction of the functional genes and 16S rRNA gene, respectively. Bacterial community structure was studied through high throughput sequencing of the 16S rRNA gene. Under RI, warming significantly (P < 0.05) increased the potential nitrification rate and nitrate concentration and decreased the soil moisture. In most of the samples, warming increased the ammonia-oxidizing bacteria abundance but decreased the ammonia-oxidizing archaea (AOA) and denitrifier (nirK, nirS, and nosZ genes) abundance. Under HI, there was a highly increased AOA and 16S rRNA gene abundance and a slightly higher denitrifier abundance compared with RI. Warming decreased the bacterial diversity and species richness, and the microbial community structure differed greatly between the warmed and control plots. The decrease in bacterial diversity was higher in RI than HI and at the 0-5 cm depths than at the 5-10 and 10-20 cm soil depths. Warming led to an increase in the relative abundance of Actinobacteria, Bacteroidetes, and TM7 but a decrease in Acidobacteria, Alphaproteobacteria, Deltaproteobacteria, Nitrospira, and Planctomycetes. The greater shift in microbial community structure was observed only in RI at the 0-5 cm soil depth. This study provides new insight into our understanding of the nitrifier and denitrifier activity and microbial community response to climate warming in agricultural ecosystems.

Terrestrial N2O emissions and related functional genes under climate change: A global meta‐analysis

“…With the assembled data sets presently available, we were not able to pinpoint the soil microbial mechanisms underlying positive temperature effects on N 2 O emission at a global scale (Figure 4) (Waghmode et al, 2018). Additionally, enhanced plant growth with increased temperature may increase inorganic nitrogen uptake by the plants, thereby reducing soil nitrogen availability for N 2 O production through nitrification and denitrification (Carter et al, 2012;Dijkstra et al, 2012Dijkstra et al, , 2013Pereira et al, 2013;Zhu et al, 2015).…”

Elevated temperature shifts soil N cycling from microbial immobilization to enhanced mineralization, nitrification and denitrification across global terrestrial ecosystems

“…The amoA gene in ammonia-oxidizing bacteria (AOB) and archaea (AOA) regulates inorganic N availability and N 2 O production via nitrification, while the nirK and nirS genes participate in NO 3 − consumption and N 2 O production, and the nosZ gene mediates conversion of N 2 O to N 2 in the denitrification process. Previous studies reported that elevated temperature did not change the abundance of amoA genes, or found inconsistent responses of AOA and AOB amoA genes to elevated temperature (Liu et al, 2015;Waghmode et al, 2018). Additionally, elevated temperature was found to increase the abundances of nirK and nosZ genes (Kai et al, 2016;Schölkopf & Smola, 2014;Xue et al, 2016), while nirS-containing denitrifiers were reported to be more sensitive to temperature increases than those containing nirK and nosZ genes (Cui et al, 2015).…”

Effect of root exudates of Eucalyptus urophylla and Acacia mearnsii on soil microbes under simulated warming climate conditions

“…Plenty of experimental results have shown that global warming has direct impacts on soil microbial respiration, activities, composition and as well as the process rates [4, 5, 12, 13]. However, there is also evidence of indirect effects of climate warming, such as affecting plant photosynthesis and respiration, changing the ratio of carbon and nitrogen nutrition in plants and associated root exudates inputs to the rhizosphere, witch lead to changes in soil microbial community structure [14–16].…”