Ecological weed management as an interdisciplinary approach to overcome the herbicide lock-in

Senast ändrad: 09 september 2022

Alexander Menegat.

Since the beginnings of sedentary agriculture and the end of the hunter-gatherer era, weeds have been one of the major factors limiting the productivity of arable land and the quality of our agricultural produce. For millennia farmers relied on soil tillage as well as on cultural and mechanical methods for weed control until, in the middle of the 20th century, the first herbicide was introduced to the market. Herbicides have radically changed the way we produce crops, allowing for large-scale and highly mechanised farming systems that are heavily reliant on mineral fertilisers and chemical crop protection products.

Although herbicides considerably improved agricultural productivity, their excessive use has also caused a cascade of new and very complex problems, namely the selection and spread of herbicide resistant weed populations, contamination of soils, water bodies and the food chain and not least health risks for farmers and end consumers. Recent research could also show that the unselective eradication of weeds from our farmland is significantly contributing to the decline in biodiversity and wildlife we are currently observing in agroecosystems and beyond.

Sweeping changes in crop production systems are required to master the twofold challenge of producing enough food for a growing world population while sustaining ecosystems and biodiversity. Today’s food value chains are highly specialised in both the produce that are demanded as well as in the services and inputs that are provided. This is leaving very little room for farmers to change and diversify their cropping systems, leaving them in a technological lock-in situation where they continue using herbicides despite their questionable ecological, economic and social sustainability. Reducing farmers’ reliance on herbicides requires rethinking our definition of weeds and the way we are managing them, helping to facilitate the required changes in decision-making and farming systems design.

Integrated weed management, the combined use of agronomic, biological, and direct means for weed control was suggested as a potential way forward in reducing the reliance on herbicides. Despite decades of research and a comprehensive legal framework supporting its implementation, this approach has not resulted in the desired reduction in herbicide dependency. Further advanced and interdisciplinary approaches for weed management are sought after, where ecological principles and mechanisms are utilised for cropping system designs and where all actors of the food value chain are considered.

In this lecture I will present ecological weed management as a potential way forward, comprising the informed and targeted manipulation of agroecosystems, aiming for reducing the negative impact (ecosystem disservices) of weeds on crop production while regenerating biodiversity and ecosystem services. One central point of this approach is the paradigm shift from eradicating weeds from our agricultural fields, towards cropping systems that are resilient against weed competition and that favour the provision of ecosystem services. I will show insights from my ongoing and planned interdisciplinary research projects with examples of how cropping system diversification, minimal soil tillage practice, weed seed predation and detailed knowledge about weed functional traits can be utilised in future cropping systems. My research approaches are aiming to combine ecological and biological knowledge with soil sciences, economy and social sciences, acknowledging that weeds are not an individual rather than a collective dilemma that requires actions by all actors along the food value chain.