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WP 6: Methods for regulating competition and control of perennial weeds

Barley undersown with a cover crop species mixture

With this work package OSCAR aims to improve the understanding how cover crops, main crops and weed plants compete with each other in cover cropping systems. This knowledge will be used to develop new cultivating methods and to inform the development of appropriate machinery for weed control.
Competition depends on interactions of many factors; the most important are the plant density, the spatial distribution pattern, acquired competitive advantages, the competing ability of the involved genotypes and environmental factors such as day-length, temperature, rainfall and nutrient availability.
Based on the Multi-Environment Experiment and additional field experiments, the factors determining competition in cover cropping and living mulch systems will be analysed and models of competition in these systems will be developed. OSCAR will use this information to design improved cover cropping systems.

Creeping thistle (Cirsium arvense) in a cover crop

The work package consists of five main elements:
1) Exploiting databases that list the properties of cover crops and living mulch species to identify underlying ecological principles and knowledge gaps.

2) Studying the competition between main crop and living mulches. We aim to analyse parameters of competition in the Multi-Environment Experiment. In particular, OSCAR studies the effects of environmental factors (such as climate, water dynamics, soil conditions, day length), as well as the degree of overlapping of the vegetation cycles, on the performance of cover cropping systems.

3) Investigating the effects of sowing techniques, sowing patterns, sowing time, and seed densities in cover cropping systems. Establishment of the main crops is the most critical factor if cover cropping cropping systems are to be successful. One of the leading underlying hypotheses is that increasing the density of the main crop (cereal) will increase the cereal portion of the total biomass both directly and through increased size-asymmetric competition. Uniform cereal spatial distribution is likely to lead to increased competitive dominance over the living mulch.

4) Monitoring weed communities with a special focus on perennial creeping species, such as couch grass (Elymus repens) and creeping thistle (Cirsium arvense). The monitoring will be performed in the Multi-Environment Experiment  and in the Long Term Experiments at early and late crop growth stages to evaluate the effect of systems with higher and lower crop density on weed populations; and the effectiveness of the novel machinery for weed control, compared to conventional methods (ploughing, no-till based on glyphosate); and the effectiveness of various cover crop species for weed control.

5) Studying the and innovative machinery for perennial weed control such as selective mowing of perennial weeds within cover crop and living mulch based systems.