Source of airborne sunflower dust generated during combine harvester operation

•Sunflower parts were compared to field sample to identify airborne dust source.•Analyses suggest inner stalk pith to be most likely origin of airborne dust.•FTIR analysis indicates similar carbon/oxygen bonding between pith and field sample.•The source of airborne dust, that lead to combine fires, is better understood.•Future combine harvester headers could be altered to prevent processing pith.

The sunflower harvest season presents challenges for many farmers when an abundance of airborne dust is carried by surrounding winds and allowed to relocate on equipment surfaces. Combine fires are a serious problem resulting from the ignition of biomass dust that settle and accumulate on the combine harvester. Farmers' anecdotal evidence indicates that harvesting sunflowers can produce more airborne dust than other commodity crops. The source of this airborne sunflower dust was investigated using various methods to analyse different parts of the sunflower: whole heads, outer stalk, and inner stalk pith. These samples were compared to a collected amount of bulk sunflower dust field sample taken directly from a horizontal surface on a combine harvester during the 2011 harvest season. All testing methods; proximate and ultimate analyses, biomass dust particle density analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy; suggest the sunflower bulk field sample is comprised of mostly inner stalk pith rather than dust particles from the outer stalk and whole sunflower heads. By confirming the source of the airborne sunflower dust field sample, the arrangement of combine harvester equipment could be modified to reduce the amount of sunflower dust generated during operation.