Native grains cannot be harvested using conventional grain harvesters due to their variability and differences from introduced species. This means that Dan and Warren rely on the small range of technologies that have been designed or adapted for the industry or that they have developed themselves.

Dan’s harvester was a machine towed behind his ute with a series of rotating brushes to collect seeds from the grass and flick them into a collection box. These brushes allowed seeds to be harvested without damaging or cutting the grass but also meant that the only control over what is harvested is set by the brush height. As most native grains harvesting is done opportunistically from existing stands of grass that can naturally contain many species, this means that the harvested material can contain a range of different seed species as well as plant stems and leaves. Dan also spoke about the dangers they could encounter in grains harvesting as the brushes could throw pointed, spear like seeds into the air which could become lodged in skin, eyes and clothing, potentially causing serious injuries.

After harvesting, we were given a demonstration of how the seeds are cleaned and sorted. Depending on the application, the level of sorting needed for orders could range from the bulk mixture of seeds and plant matter directly from the harvester, known as mulch, only seeds with their husks on, or singular seed species with all other parts removed. For larger, round seeds this sorting can be done with a series of hand-held sieves adopted from the mining industry that separate grains of different sizes. Dan and Warren demonstrated the process of seed sorting by spreading mulch from the harvester onto one of these screens and moving the mixture around until the seeds become caught, before shaking the remaining plant material off the screen. Manual processes such as these mean that for seed harvesters like Dan, sorting can be time consuming and labour intense. This can mean high workloads to satisfy large orders, which can limit their output, even if the seed stock is available for harvest. As plants grown in native grasslands are rarely of a single species, this can mean even more labour if buyers are looking for only a single type of seed. Because of this, Warren will harvest seeds by hand to get singular species for nursery orders. Another challenge Dan talked about was the cost and uncertainty that he faced in prospecting native seed harvests. Dan harvests seeds all across Australia and will often have to travel to visit prospective harvest sites. The time when grasses are prime for harvesting is short and can change quickly depending on the weather. This means that Dan may have to make multiple trips to visit a site before travelling up with his harvester when he thinks that the seeds will be ready for harvest. CEAT is currently developing research collaborations focussing on remote sensing that could allow trips like these to be reduced, so that harvesters could travel to sites when they know that seeds will be ready for harvest.

One value that Dan and Warren strive to uphold in their work, which could pose some challenges in a scalable Australian native plants industry is the classification of grains as native. Selective breeding and migration of seeds from their natural growing region may be necessary for a commercial grains industry, but to Dan and Warren this would mean that they are no longer “native” grains. Warren told me about how native plants have evolved to adapt to the exact environment they live in, and to move or breed them would be to remove the “intelligence” that these plants have developed for their environment. One example of this is when native grasses find themselves surrounded by a high density of their own species, they will stop producing seeds to prevent competition with themselves. Although in natural environments this is beneficial, this may have to be selectively bread out of the plans if seeds were to be grown specifically for harvest. The challenge of maintaining a native classification could pose difficulty for a growing commercial bush foods industry where monocultures and selective breeding for more consistent height, or larger seeds could make the yield more efficient and profitable. Whilst this is one important perspective in the industry, it does not necessarily represent all stakeholders and it is possible that we may see a difference in the native plants for land regeneration and those bred and used for food production.

Throughout the many complexities and challenges, they shared with us, Dan and Warren expressed a strong interest in the potential for engineers to work with them to develop new technologies that could help improve their harvesting, to grow the native plants industry and help regenerate Australian land.

Full article found here.

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