Killing Weed Seeds with Exhaust Gas from a Combine Harvester

Abstract

We investigated if hot exhaust gas from a combine harvester could be used to reduce germination or kill weed seeds during the harvesting process. During the threshing and cleaning process in the combine, weed seeds and chaff are separated from the crop grains. After this separation, weed and crop seeds not collected can be exposed to exhaust gas before seeds are returned to the field. Seeds of some common weed species (Alopecurus myosuroides, Centaurea cyanus, Geranium pusillum, Lapsana communis, Lolium perenne, Rumex crispus, Spergula arvensis, and Tripleurospermum inodorum) were treated with exhaust gas at temperatures of 75 °C or 85 °C, 110 °C, and 140 °C for 2, 4, and 6 s, respectively. Afterwards, the seeds were germinated for 16 days. We found that 75 °C and 85 °C were insufficient to significantly reduce germination of the seeds after three durations. Some seeds were still able to germinate after 4 s exposure of 110 °C. An exposure of 140 °C for 4 and 6 s repressed germination of all species. We conclude that there is potential to develop combine harvesters that exploit the exhaust gas to either kill or reduce the ability of weed seeds to germinate before seeds are returned to the field.