Issue |
Agron. Sustain. Dev.
Volume 29, Number 2, April-June 2009
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Page(s) | 353 - 362 | |
DOI | https://doi.org/10.1051/agro:2008056 | |
Published online | 17 December 2008 |
DOI: 10.1051/agro:2008056
Effect of mulching dates modified for nature conservation on the yield and nitrogen fixation of green manure lucerne crops
G. Pietsch1, R. Hrbek1, D. Laubhann2 and J. K. Friedel11 Division of Organic Farming, Department of Sustainable Agricultural Systems, University of Natural Resources and Applied Life Sciences, Vienna
2 Institute of Botany, Department of Integrative Biology and Biodiversity Research, University of Natural Resources and Applied Life Sciences, Vienna, Gregor Mendel Strasse 33, 1180 Vienna, Austria
Accepted 3 October 2008; published online 17 December 2008
Abstract - Organically managed fields are highly attractive for wild animals of open
agricultural landscapes because of a high percentage of green covered
fields; for example, by green manures, catch crops and underseeds. Forage
legumes are the main source of nitrogen in organic farming. Forage legumes
are also important habitats for wild animals. The main ecological
disadvantage is frequent mowing of forage crops. Increasing the time without
disturbance in favour of wild animals may also decrease crop productivity
and increase weed pressure. Here, we studied the effect of modified mulching
dates on yield, nitrogen fixation and weed colonisation of lucerne green
manure under pannonian site conditions during two vegetation periods in
Eastern Austria. We compared a natural treatment, where the first mulching
took place two weeks earlier and the second mulching two weeks later than in
a conventional treatment with the latter. While in the first year the shoot
dry-matter yield (–1.5 t ha-1), nitrogen yield and the amount of fixed
nitrogen (–44 kg N ha-1) in lucerne were significantly lower in the
natural than in the conventional treatment at the first cut, no differences
could be detected in the second year. The seasonal amount of nitrogen
fixation as well as the percentage of N derived from the atmosphere
(N
at both cuts did not differ between the treatments. The natural
treatment also had no disadvantageous effects on weed coverage. Our results
show that prolonging the period without disturbance in lucerne crops had no
adverse agronomic effects with only one exception: the 14-day shorter
development period in the natural treatment at the first cut decreased shoot
yield and nitrogen fixation compared with the conventional treatment in the
first year, when weather conditions were humid before the first cut and dry
afterwards. We therefore recommend shifting mulching dates and prolonging
cutting intervals in lucerne on organic farms under pannonian site
conditions in favour of wild animals.
Key words: Lucerne / nitrogen fixation / nature conservation / mulching regime / wild animals / weed pressure
Corresponding author: gabriele.pietsch@boku.ac.at
© INRA, EDP Sciences 2008