Weed Suppression in Only-Legume Cover Crop Mixtures

Elsalahy, Heba, Döring, Thomas, Bellingrath-Kimura, Sonoko and Arends, Danny (2019) Weed Suppression in Only-Legume Cover Crop Mixtures. Agronomy, 9 (10). p. 648. ISSN 2073-4395

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Official URL: https://doi.org/10.3390/agronomy9100648


Weed suppression is a potential benefit of cover crop mixtures, as species diversity may allow for combining early and late-season competition with weeds. Here, we studied if this is possible for only-legume mixtures containing species with different growth rates, by testing two legumes, alsike clover (AC; Trifolium hybridum L.) and black medic (BM; Medicago lupulina L.) in two field trials sown in 2016 and 2017. Five AC:BM ratios (100:0, 67:33, 50:50, 33:67, and 0:100) were grown at three densities (50%, 100%, and 150% of recommended seed density). Cover crop and weed aboveground biomass (CCB and WB, respectively) were harvested three times, after establishment in spring (H1), in summer (H2), and in autumn after mulching (H3). Compared to fallow plots, all monocultures and mixtures showed early-season weed suppression in terms of biomass production and more efficiency over time with an average reduction of 42%, 52%, and 96% in 2016, and 39%, 55%, and 89% in 2017 at H1, H2, and H3, respectively. Out of 54 mixture treatments, only eight mixtures showed stronger weed suppression than monocultures. Mixtures reduced WB by 28%, as an average value, in 2017 compared to the respective monocultures, but not significantly in 2016, indicating that the crop diversity effect on weeds was dependent on the growing environment. Weed suppression was significantly higher at 100% and 150% seed density than 50%, but no significant differences were determined between 100% and 150% seed density. After mulching, no density effect was observed on CCB and WB. In conclusion, AC and BM can be used as a keystone species on weed suppression for sustainable agriculture as they possess plasticity to suppress weeds when higher biomass productivity is limited by environmental conditions. However, their diversity effects are time and condition dependent. Appropriate seed density and mulching can successfully be employed in weed management, but seed density may not have an effect after mulching.

Item Type: Article
Additional Information: Funding information: This research was funded by the Jameel Scholarship at Humboldt-University, Berlin, Germany [Ph.D. project].
Uncontrolled Keywords: asynchrony, crop diversification, forage legume, functional traits, interspecific interaction, mixed cropping, weed control
Subjects: C100 Biology
C200 Botany
C500 Microbiology
Department: Faculties > Health and Life Sciences > Applied Sciences
Depositing User: Rachel Branson
Date Deposited: 16 Sep 2022 13:52
Last Modified: 16 Sep 2022 14:00
URI: https://nrl.northumbria.ac.uk/id/eprint/50162

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