UWA research fellow Wesley Moss looks at harvest sub-clover seeds

A research fellow with The University of Western Australia's (UWA) Centre for Engineering Innovation: Agriculture and Ecological Restoration, Dr Moss was using his mechanical engineering degree in the oil and gas sector in Queensland when he was taken aback by the impact agriculture had on the landscape.

Having been born in South Africa and then living in the suburbs of Perth since he was nine, he knew very little about the industry but seeing the extent of the operations he became fascinated by the big challenges agriculture was facing.

"I knew it was important to grow food to feed people, but I had no idea of the challenges in terms of the land, energy, water and resources needed to feed the world," Dr Moss said.

"I was captivated by the fact that it would all need to be increased to feed a growing planet and started speaking to people back at UWA and eventually ended up completing a PhD in agricultural engineering."

Simply put, agricultural engineering is using engineering to solve problems or increase efficiencies in agriculture and Dr Moss' PhD took a deep dive into pasture legume seed harvesting, primarily subterranean clover, supervised by Andrew Guzzomi and Phil Nichols.

Sub-clover is the biggest annual pasture legume used in Australia and around the world.

It works very well in a pasture cropping system, mainly because it buries its seed under the soil which means animals can graze it and the seed itself is protected the whole time.

The challenge is that if you're a farmer and you want to grow sub-clover, you first need to plant the seed somewhere, but harvesting that seed is incredibly difficult as it's below the ground.

Currently it is harvested by old machines, known as Horwood Bagshaw Clover Harvesters, which are essentially giant vacuum cleaners that suck up the seed from the soil.

"It is a slow and labour intensive process and there are issues around that practice, so my PhD was part of a project funded by AgriFutures Australia to look at solutions to that seed harvesting problem through the use of new technology," Dr Moss said.

As part of the project, he spoke with different seed producers around the country and held workshops in WA, South Australia and New South Wales to find out what their issues were, what works and what doesn't.

After that, a survey was sent out and one of the biggest takeaways was quantifying the scale of how much work goes into the sub-clover harvest process.

"For a normal broadacre crop, you pass over it with the header once, but for sub-clover they have to do about 11 passes," Dr Moss said.

"That includes using rakes and tynes to dig up the seed to the surface, passing over it with the suction harvesters and repeating that process a couple of times before trying to do something to the bare paddock to prevent erosion."

The Horwood Bagshaw was invented by a WA farmer in the 1950s and is still used today, even though it hasn't been manufactured in 30 years, so farmers are using machines at least 30 and in some cases up to 60-years-old.

Dr Moss also became fascinated by what had happened in the past and ended up writing a paper on the history of sub-clover seed harvesting.

"It's such a rich Australian industry and a lot of the innovations came directly from farmers - 75 per cent of the patents filed in this area were by farmers," he said.

"They had spent a lot of time harvesting sub-clover seed, primarily in the summer when it's hot and dusty, and were continually thinking of better ways to do it."

Sub-clover seed harvesting was a vibrant industry for a long time, until about the 1960s when the Horwood Bagshaw Clover Harvester came to market.

That worked well, dominated the industry and from there, future developments stagnated.

After that, the wool price collapsed in the 1990s, which decreased the market for pasture seeds and the millennium drought further affected the industry, meaning there were few new innovations coming through.

"It's a very niche group of people who are harvesting the seed and the fear from the industry is that when those people retire, the supply of seed for what is the largest annual pasture legume market in the country will disappear with them," Dr Moss said.

One of the other reasons for the stagnation was that there wasn't a lot of commercial support, so Dr Moss started a mission to find a compatible and commercially available technology that already exists.

It led him to discover peanuts were similar to sub-clover, as they grow under the soil and have a very well-established harvesting system all around the world, but primarily in the United States.

They are able to harvest peanuts in two passes, as opposed to the 11 used for sub-clover.

The first pass is with a digger which cuts underneath the soil just below the peanut root, pulls up the plant, turns it upside down and leaves the peanut seeds facing up to dry for a few days.

After that, another machine comes along for a second pass and picks them up.

"We've procured a peanut digger and for the past two years have been doing testing with it and making modifications to see if it is a viable mechanism for sub-clover," Dr Moss said.

"The big challenge we identified with sub-clover seed was getting it out of the ground in an efficient way and we have been able to make progress to doing that with the peanut digger.

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"There have been some promising results so far and now we need to start trying it in different conditions, soil types and varieties of sub-clover crops."

Dr Moss and his research colleagues have also been looking at ways to make improvements to the existing Horwood Bagshaws and while they realise that it's not a long-term solution, it is a quick fix until a better solution is found.

In the long run, the goal is to entirely replace those with other technologies and the hope is that by the end of the project in 2025, Dr Moss will have some tangible solutions for the sub-clover seed production industry.