Weed reduction potential of cover crop mixtures

Publication Type

Contribution to conference

Authors

Schappert, A., Gerhards, R.,

Year of publication

2018

Conference name

18th European Weed Research Society Symposium

Conference location

Ljubljana, Slovenia

Conference date

17-21 June 2018

Weeds are a major determinant of grain yield reduction worldwide. Cover crops (CC), as a component of integrated weed management, can provide several advantages, like increasing the soil organic matter content, reducing the soil erosion and stabilizing the N content. Furthermore, CC are an opportunity to reduce the herbicide input into cropping systems, especially in spring crops.
The aim of this study was to analyze the potential of i) CC mono-cropping and ii) CC mixtures on
weed reduction. The main idea was to i) use and ii) combine CCs to suppress weeds using only
physical (e.g. Phacelia) or with reported allelochemical mechanisms (e.g. Raphanus sativus).
The experiments were conducted at the Agricultural Station Ihinger Hof from August until December 2016 and 2017 (Renningen, Germany). After winter cereal harvesting, the experiment was set up as a randomized complete block design. The development stages and the biomass accumulation of the different CC treatments were determined every second week. Weed amounts and composition, along with relative coverage were measured twice, 7 and 12 weeks after sowing.
As expected, high biomass CCs are more competitive and have a higher weed suppression outcome.
CCs like Raphanus sativus (2016) and Avena strigosa (2017), which combine chemical and physical suppression mechanisms showed the best weed reduction results, between the mono culture treatments. Moreover, mixtures with a high content of allelopathic CC species were able to reduce weeds more effectively compared to other treatments.
The gained dataset helped to evaluate the effect of CC mixtures in comparison to mono-cropping
as an option for biological weed control. Weed suppression was correlated with CC biomass and soil coverage, but combining different CCs with dual suppression mechanisms achieved even better results.