Abstract
The cropping of perennial wildflower mixtures to produce biomass for use in biogas plants is one option for breaking maize’s dominance as a bioenergy feedstock. The aim of this study was to investigate the development of weeds in commercially produced perennial wildflower mixtures. Weed control during the establishment of perennial wildflower mixtures is very difficult to manage and raises the issue of the development of new weed problems when cropping perennial wildflower mixtures. In a three-year field experiment with staggered starts in four sites in northeast Germany, a perennial crop mixture was sown each year. The weeds and sown crops were surveyed annually in June. Plant densities and species numbers were counted and diversity indices calculated. Data were analysed using linear mixed models. Across all sites, weed density decreased significantly over the years of use (=cropping seasons), while weed species richness in the perennial mixture remained unchanged. The sown crop species richness significantly decreased, while the sown crop densities increased with cropping seasons. Weed density did not increase at any of the experimental sites. Although weed densities were high and crop establishment was poor in the first growing seasons, the perennial mix was able to suppress weeds in the following growing season. It was concluded that the cropping of perennial flower mixtures could contribute to biodiversity without causing new weed problems.
Highlights
The stated aim of the European Commission is to reduce greenhouse gas emissions by at least 40% compared with 1990 and increase the share of renewable energy to meet its obligations under the Paris Convention and create a fossil-free future
Short-lived species decreased from the first cropping season to the third cropping season (Arabidopsis thaliana Heynh., Chenopodium album L., Amaranthus retroflexus L.)
In the third cropping season, about 50% of the recorded weed species were perennials, with grass species occurring in higher densities (Anthoxanthum odoratum L., Apera spica-venti Beauv., Poa annua L.)
Summary
The stated aim of the European Commission is to reduce greenhouse gas emissions by at least 40% compared with 1990 and increase the share of renewable energy to meet its obligations under the Paris Convention and create a fossil-free future. Bioenergy production has increased since the EEG came into force in 2000. Maize is widely used as a biomass feedstock for bioenergy production. The area cropped with maize has increased over the past twenty years and led to landscape changes. In Germany, the cultivation area for maize for use in biogas plants is 2,720,500 hectares, more than double that in 2000. Maize cultivation often requires higher inputs of agrochemicals [1,2]. Owing to its possible negative effects on the environment, such as soil erosion, nitrate leaching, intensive use of pesticides and fertilisers and declining agrobiodiversity, more maize cropping or even monocropping is being debated throughout Europe [3,4]. It would appear that alternative crops for biogas production are needed to slow this trend for more maize
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
