Journal article
Turnover of grain legume N rhizodeposits and effect of rhizodeposition on the turnover of crop residues
The turnover of N derived from rhizodeposition of faba bean (Vicia faba L.), pea (Pisum sativum L.) and white lupin (Lupinus albus L.) and the effects of the rhizodeposition on the subsequent C and N turnover of its crop residues were investigated in an incubation experiment (168 days, 15 degreesC).
A sandy loam soil for the experiment was either stored at 6 degreesC or planted with the respective grain legume in pots. Legumes were in situ N-15 stem labelled during growth and visible roots were removed at maturity. The remaining plant-derived N in soil was defined as N rhizodeposition. In the experiment the turnover of C and N was compared in soils with and without previous growth of three legumes and with and without incorporation of crop residues.
After 168 days, 21% (lupin), 26% (faba bean) and 27% (pea) of rhizodeposition N was mineralised in the treatments without crop residues. A smaller amount of 15-17% was present as microbial biomass and between 30 and 55% of mineralised rhizodeposition N was present as microbial residue pool, which consists of microbial exoenzymes, mucous substances and dead microbial biomass.
The effect of rhizodeposition on the C and N turnover of crop residues was inconsistent. Rhizodeposition increased the crop residue C mineralisation only in the lupin treatment; a similar pattern was found for microbial C, whereas the microbial N was increased by rhizodeposition in all treatments. The recovery of residual N-15 in the microbial and mineral N pool was similar between the treatments containing only labelled crop residues and labelled crop residues + labelled rhizodeposits.
This indicates a similar decomposability of both rhizodeposition N and crop residue N and may be attributable to an immobilisation of both N sources (rhizodeposits and crop residues) as microbial residues and a subsequent remineralisation mainly from this pool.
Language: | English |
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Publisher: | Springer-Verlag |
Year: | 2004 |
Pages: | 153-164 |
Journal subtitle: | Cooperating Journal of International Society of Soil Science |
ISSN: | 14320789 and 01782762 |
Types: | Journal article |
DOI: | 10.1007/s00374-003-0694-2 |
15N, C and N mineralisation 8-B gen Microbial biomass Microbial residues Residue turnover Rhizodeposition