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| Titel |
How does pyrogenic organic matter affect the N dynamic in agricultural soils? An incubation study |
| VerfasserIn |
Jose M. de la Rosa, Heike Knicker |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250045228
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| Zusammenfassung |
| Besides other environmental factors, N availability drives the carbon (C) and nitrogen (N)
cycles in grasslands. Since grass-dominated ecosystems cover approximately 40% of the
terrestrial surface and store more than 30% of global soil organic carbon (SOC), alterations to
those ecosystems could have significant consequences and potential implications for global C
and N cycles and climate (Schlesinger et al., 1990). Understanding the processes that govern
the efficient cycling of nutrients through soil/plant systems remains an important topic to
underpin the choice of strategies aimed at ensuring the long-term sustainability of
ecosystems.
In Mediterranean ecosystems, wild-fires occur frequently. Whereas factors such as
water shortage or erosion contribute to reduced N-availability by lowering the litter
input, burning additionally increase the refractory N and C-pools by charring litter
and humic material (charred pyrogenic organic matter-PyOM) (Gonzalez-Pérez,
2004).
In general, the addition of organic matter either as plant residues or farmyard manure has
been shown to significantly increase biological activity, microbial biomass and enzyme
activity in soil (Dick, 1992). Even in situations where microbial biomass appears to be
unaffected, the activity of specific processes (e.g. N mineralization) can be significantly
influenced by the addition of organic residues). However, little is known about the changes of
the N cycle caused by the addition of PyOM.
Therefore, the interest of our research was to study the impact of 15N enriched-biochars
either alone or in conjunction with a 15N enriched fertilizer (K15NO3) on aggregate stability
and organic carbon (C) and nitrogen (N) distribution among the different soil fractions. The
latter may help to elucidate both, the quality of the stored organic matter and if the
accumulation is related to interaction with the mineral matter.
Therefore, biochar derived from grass material grown on 15N-enriched fertilizer was added to
a typical Andalusian agricultural soil (calcareous Rhodoxeralf, FAO-UNESCO
classification). The bioavailability of the 15N from the biochars was tested by determining its
content in grass (lolium perenne) grown on this soil under defined conditions. Following the
15N within the soil fractions gave further information about some mechanisms involved in
N-partioning and stabilization. Chemical alteration of the 15N-containing organic
structures during mobilization/immobilization were followed by solid-state NMR
spectroscopy in order to obtain some more insights into the processes involved in the C and
N-sequestration.
References:
Campbell, C.A., V.O. Biederbeck, G. Wen, R.P. Zentner, J. Schoenau and D. Hahn, Canadian
Journal of Soil Science 79 (1999), pp. 73–84.
Dick, R.P., Agriculture Ecosystems and Environment 40 (1992), pp. 25–36.
González-Pérez, J.A., F.J., González-Vila, G., Almendros and H., Knicker, Environment
International 30 (2004), pp. 855–870.
Schlesinger, W.H., J.E. Reynolds, G.L. Cunningham, L.F. Huenneke, W.M. Jarrell, R.A.
Virginia and W.G. Whitford, Science 247 (1990), pp. 1043–1048. |
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