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| Titel |
The importance of plant-soil interactions for N mineralisation in different soil types |
| VerfasserIn |
Conor Murphy, Eric Paterson, Elizabeth Baggs, Nicholas Morley, David Wall, Rogier Schulte |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250077426
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| Zusammenfassung |
| The last hundred years has seen major advancements in our knowledge of nitrogen
mineralisation in soil, but key drivers and controls remain poorly understood. Due to an
increase in the global population there is a higher demand on food production. To
accommodate this demand agriculture has increased its use of N based fertilizers, but these
pose risks for water quality and GHG emissions as N can be lost through nitrate
leaching, ammonia volatilization, and denitrification processes (Velthof, et al., 2009).
Therefore, understanding the underlying processes that determine the soils ability
to supply N to the plant is vital for effective optimisation of N-fertilisation with
crop demand. Carbon rich compounds exuded from plant roots to the rhizosphere,
which are utilized by the microbial biomass and support activities including nutrient
transformations, may be a key unaccounted for driver of N mineralisation. The main aim of
this study was to study the impact of root exudates on turnover of C and N in soil,
as mediated by the microbial community. Two soil types, known to contrast in
N-mineralisation capacity, were used to determine relationships between C inputs,
organic matter mineralisation (priming effects) and N fluxes. 15N and 13C stable
isotope approaches were used to quantify the importance of rhizosphere processes on
C and N mineralisation. Gross nitrogen mineralisation was measured using 15N
pool dilution. Total soil CO2 efflux was measured and 13C isotope partitioning
was applied to quantify SOM turnover and microbial biomass respiration. Also,
13C was traced through the microbial biomass (chloroform fumigation) to separate
pool-substitution effects (apparent priming) from altered microbial utilisation of soil organic
matter (real priming effects). Addition of labile carbon resulted in an increase in
N-mineralisation from soil organic matter in both soils. Concurrent with this there was an
increase in microbial biomass size, indicating that labile C elicited real priming
effects that mobilised N from organic matter. The results from this experiment
indicate that rhizosphere processes play an important role in mediating rates of
C and N mineralisation and should be accounted for in estimating soil N-supply
capacities.
Velthof, G.L., Oudendag, D., Witzke, H.P., Asman, W.A.H., Klimont, Z., Oenema, O.,
2009. Integrated assessment of nitrogen losses from agriculture in EU-27 using
MITERRA-EUROPE. Journal of Environmental Quality 38, 402-417. |
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