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Legacy effects of leguminous green manure crops on the weed seed bank in organic crop rotations

Melander, Bo; Rasmussen, Ilse A. and Olesen, Jørgen E. (2020) Legacy effects of leguminous green manure crops on the weed seed bank in organic crop rotations. Agriculture, Ecosystems and Environment, 302, p. 107078.

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Summary

Leguminous green manure crops are important for accumulating nitrogen by means of biological nitrogen fixation and for building up soil fertility in organic arable cropping systems. Whole-year green manure crops are also known to deplete the soil weed seed bank, e.g. by decaying and predation, but there is uncertainty about the magnitude of the legacy effect after termination of the green manure crop. This study sampled soil for weed seed bank assessment upon termination of a two-year leguminous green manure crop and then one, two and three years afterwards. The samples were taken from two five-year crop rotations (2011–2015) in a long-term organic crop rotation experiment in Denmark. One rotation (O2) had a two-year green manure crop followed by three years of annual cash crops, and the other rotation (O4) consisted only of annual cash crops, with four crop sequences in both rotations represented every year. In general, the weed seed bank of rotation O2 was 54 % lower than O4, with 5475 seeds m−2 versus 11,967 seeds m−2. Similarly the aboveground amount of weed biomass in O2 was lower than in O4 over the course of the five years. The legacy effect of the green manure crop showed a negative exponential rise in weed seed numbers with the increase in years after termination of the green manure crop. A biennial leguminous green manure crop can mitigate weed problems in organic annual crops. This effect adds to the benefits of including nitrogen fixing leys in crop rotations with limited access to animal manures.


EPrint Type:Journal paper
Keywords:Lucerne, Grass-clover, Broadleaved weeds, Grass weeds, Seed bank depletion, Seed decay
Agrovoc keywords:
Language
Value
URI
English
plant production -> crop production
http://aims.fao.org/aos/agrovoc/c_5976
English
crop rotation
http://aims.fao.org/aos/agrovoc/c_6662
English
green manures
http://aims.fao.org/aos/agrovoc/c_3375
English
legumes
http://aims.fao.org/aos/agrovoc/c_4255
English
weeds
http://aims.fao.org/aos/agrovoc/c_8347
English
clover-grass mixture -> grass clover
http://aims.fao.org/aos/agrovoc/c_cdb03095
English
lucerne -> Medicago sativa
http://aims.fao.org/aos/agrovoc/c_4693
Subjects: Crop husbandry > Composting and manuring
Crop husbandry > Weed management
Research affiliation: Denmark > AU - Aarhus University > Faculty of Science and Technology > Department of Agroecology
Denmark > ICROFS - International Centre for Research in Organic Food Systems
European Union > CORE Organic Plus > PRODIVA
DOI:10.1016/j.agee.2020.107078
Deposited By: Jakobsen, Malene
ID Code:40007
Deposited On:03 Jun 2021 19:52
Last Modified:03 Jun 2021 19:52
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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