Within the international project Sweedhart different measures and concepts are investigated to reduce weeds on agricultural fields without using herbicides. During harvesting three main fractions are produced – grain, chaff with weed seeds and straw. Conventional combine harvesters return the chaff and weed seeds to the fields and the seeds become a problem in future growth seasons. In Sweedhart, the effect of removing chaff from the field and utilize it energetically and/or materially is investigated. The possibility to kill the weed seeds in the chaff fraction thermally directly in the combine harvester before it is returned to the field is investigated as well. All measures intend achieving a reduced weed pressure on the field in the following growth seasons. Field tests were carried out in 2016 and 2017 to assess the concepts. While the long-term effect of reducing weed by the proposed measures remains object to future evaluation, the basic principles have been approved successfully. Applicable thermal treatment parameters were defined and an energetic utilization pathway including applicable pelletizing conditions for chaff was worked out. The project shows that chaff containing weed seeds can be converted into an unexploited biomass feedstock.

Proceedings of the 26th European Biomass Conference and Exhibition, 14-17 May 2018, Copenhagen, Denmark, pp. 64-71