 |
| Titel |
Zoom in new insights of potential microbial control of N and CH4 gaseous losses induced by different agricultural practices in temperate paddy soils |
| VerfasserIn |
Maria Alexandra Cucu, Laura Bardi, Daniel Said-Pullicino, Dario Sacco, Luisella Celi, Roberta Gorra |
| Konferenz |
EGU General Assembly 2016
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250131980
|
| Publikation (Nr.) |
 EGU/EGU2016-12439.pdf |
|
|
|
|
|
| Zusammenfassung |
| Rice is the world’s single most important food crop and a primary food source for more than
a third of the world’s population. Usually, rice is grown in flooded paddies that result in
anoxic soil conditions throughout a major part of the cropping period. Redox processes in
wetland ecosystems combined with crop residue incorporation play an important role in
element cycling and ecological functions of rice ecosystems. Microbial communities are at
the basis of the functioning of wetlands and the ecosystem services they provide. Agronomic
management practices adopted in rice paddies may have important effects on microbial
biomass functionality and interactions, but these are largely unknown in situ. They mediate
important processes such as nitrification, anaerobic ammonia oxidation (Anammox),
denitrification, and methanogenesis that regulate ecosystem functioning and control
greenhouse gases (GHG) emissions. Therefore, it is crucial to comprehend the microbial
control of these processes as a function of different crop residue and water management
practices.
Here we highlight recent findings based on the exploration of microbial functional genes
as biogeochemical indicators. Through both lab and field experiments and by linking to GHG
emissions and soil chemistry, we evaluated niche differentiation between microbial
communities and the crucial role of agronomic management in regulating their potential
functionality.
Recent studies showed a high abundance of both 16S communities, bacteria and archaea,
confirming the high relevance of archaeal mediated processes in rice ecosystems. Our results
unravel the complete denitrification as key player in regulating major nitrogen (N) fluxes in
fertilized paddies. In a laboratory experiment this process was shown to be driven by both
archaea and bacteria harboring nosZ gene, but especially by archaea in the absence of
straw. In addition, part of the immobilized N was attributed to nitrous oxide (N2O)
reducing archaea, suggesting that the assimilation of N contributes to the last step of
archaeal denitrification. In a field experiment a high abundance of aerobic ammonia
oxidizers suggested nitrification as proxy for complete denitrification, highlighting the
importance of the latter in mitigating N2O emission from rice ecosystem. As a
new insight for temperate rice paddies, our data indicated a high abundance of
Anammox bacteria, suggesting this process to be very important in controlling N losses
independently of water and rice straw management. Characteristic treatment interactions and
cooperation were shown between aerobic and anaerobic ammonia oxidizers. Rice straw
incorporation and the increased rice biomass due to N fertilization supported the
methanogenesis. In this regard, a high abundance of mcrA gene was shown in situ
level.
Our findings highlighted the possibility of microorganisms niche differentiation not only
driven by differential responses to NH4+ concentration, but also through different organic C
substrates derived from more or less labile pools, and the contrasting straw C/N ratios in
different treatments.
The results provide novel insights into the influence of paddy soil management on
microbial communities dynamics, with important implications on their potential
functionality. These studies are a step forward in understanding the overall microbial control
in N and CH4 gaseous losses mitigation from rice fields. |
|
|
|
|
|
|