Soil properties impacting denitrifier community size, structure and activity in New Zealand dairy-grazed pastures
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Date
2017-09-22
Open Access Location
Journal Title
Journal ISSN
Volume Title
Publisher
Copernicus Publications
Rights
Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Abstract
Abstract. Denitrification is an anaerobic respiration process
that is the primary contributor of the nitrous oxide (N
O) produced from grassland soils. Our objective was to gain
insight into the relationships between denitrifier community
size, structure, and activity for a range of pasture soils. We
collected 10 dairy pasture soils with contrasting soil textures,
drainage classes, management strategies (effluent irrigation
or non-irrigation), and geographic locations in New
Zealand, and measured their physicochemical characteristics.
We measured denitrifier abundance by quantitative polymerase
chain reaction (qPCR) and assessed denitrifier diversity
and community structure by terminal restriction fragment
length polymorphism (T-RFLP) of the nitrite reductase
(nirS, nirK) and N
O reductase (nosZ) genes. We quantified
denitrifier enzyme activity (DEA) using an acetylene inhibition
technique. We investigated whether varied soil conditions
lead to different denitrifier communities in soils, and
if so, whether they are associated with different denitrification
activities and are likely to generate different N
2
O emissions.
Differences in the physicochemical characteristics of
the soils were driven mainly by soil mineralogy and the management
practices of the farms. We found that nirS and nirK
communities were strongly structured along gradients of soil
water and phosphorus (P) contents. By contrast, the size and
structure of the nosZ community was unrelated to any of the
measured soil characteristics. In soils with high water content,
the richnesses and abundances of nirS, nirK, and nosZ
genes were all significantly positively correlated with DEA.
Our data suggest that management strategies to limit N
O
emissions through denitrification are likely to be most im-
2
2
2
portant for dairy farms on fertile or allophanic soils during
wetter periods. Finally, our data suggest that new techniques
that would selectively target nirS denitrifiers may be the most
effective for limiting N
O emissions through denitrification
across a wide range of soil types.
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Citation
BIOGEOSCIENCES, 2017, 14 (18), pp. 4243 - 4253