Cover crops and drains help win a dry argument
GroundCover™ Issue: 111 | Author: Rebecca Thyer
Western Australian grower Stott Redman has decided to find out for himself if the cover crops he has read so much about will work in his high-rainfall region to improve soils, limit waterlogging and ultimately lift crop productivity
For the past two seasons, Western Australia grower Stott Redman has planted millet as a cover crop in a bid to address declining soil health on his white sandy soils. It has been a learning curve with mixed results.
“The first time we planted millet it got waterlogged, but the second time we managed to achieve a good cover. We know cover crops have been proven around the world so we want to make them work for us,” he says.
Cover cropping is part of Stott’s strategy to improve soil health on his 6500-hectare farm. Managing soils can be a challenge given the farm’s variability: “We have almost every soil type that the Department of Agriculture and Food, WA, has identified,” he jokes.
His farm’s soil types range from sand to sandy/gravel to clay, heavy loam and, the most problematic of all, about 300ha of deep-white sand.
On the upside, he says they have come to know their soils well and manage them accordingly: “For example, on our sandier soils we spread potassium and lime, while on our clay soils we spread gypsum, and our heavier, loam soils have less need for phosphorus. It’s a matter of matching inputs to soil type.”
Stott bought the farm, 590 kilometres south-east of Perth at Hopetoun in south-eastern WA, 10 years ago with his wife Charmaine and parents Bill and Yvonne.
“It was a run-down sheep farm and although things have improved in the decade since we bought the farm, our sandier soils haven’t. That’s probably due to the continuous cropping on that soil type. It just depletes the organic matter.”
This is why he is trialling a cover crop – millet – as a means of adding organic matter. The millet fits into the rotation on these sandy soils, which account for about 20 per cent of the farm. The millet follows lupins.
“In October, lupins are desiccated then harvested, which makes the perfect seedbed. We then seed the millet straight in, often with a full profile because the lupins don’t use much water. We take the millet through to February or March and then again desiccate and use it as a brown manure before planting canola in mid-April.”
Although only two seasons into testing millet’s value as a cover crop, Stott can already see some limitations – mostly to do with equipment shortages.
Cover crops need to be planted when his winter crops (wheat, barley and canola) are being harvested. “We ideally need another tractor for harvest time. We are trying to get the winter crops off while also keen to get our summer cover crops down. Not having the machinery is holding us back.”
Stott says that while the cost of another tractor might not seem much, the farm business has also been investing in other areas to improve productivity – mainly by reducing waterlogging.
The farm receives 475 millimetres of mostly winter-dominant, annual rainfall. While Stott says he is lucky to crop in a mid-to-high-rainfall zone, the rain has to be managed. The ground often becomes waterlogged, leading to stressed crops.
To address this, raised beds were used for about three seasons, but waterlogged tramlines slowed down operations: “I felt we were always driving through water,” Stott says.
After three years of engineering work, Stott believes he may have a better alternative: an intensive drainage system across 80 per cent of the farm.
The drains were designed by feeding real-time kinematic data – showing elevation and topography – into a software program (called Grade Design, from PAA Technology). This information was then relayed to the tractor, which pulled a scraper to cut drains to the desired levels. A contracted excavator cut drains that were too deep or rocky for the scraper.
Scraper-cut drains are mostly found in the paddocks. At three to four metres in width with a flat bottom, cropping machinery can still drive through them. They range from as shallow as 20 centimetres to as deep as one metre.
Excavator-cut drains are 1.5m wide and range from 0.5 to 3m in depth. They are shaped in a ‘V’ with a flat bottom and located mostly on hills and in swamps, not crop land.
“Where we have had to use excavator drains in the paddocks, we have run them with the tramlines so that they essentially run in line with the edge of the seeder.”
The farm runs equipment on 12m tramlines, with a 12m seeder and harvester and a 36m sprayer.
Stott says the drains let the water gently run off into natural water courses without impeding their cropping work.
The difference has been clear: “In conditions where we would have had waterlogging, stressed plants and a below-average season, we now have an average season.”
Stott is happy with the results, which have lifted his optimism for the farm’s potential.
“We are lucky,” he says. “We have the rainfall, we have shown we can innovate and we’ve got the scale to make it cost-effective.”
He also credits the farm’s progress to good staff and off-farm advisers – his agronomist, bank manager, accountant and business analyser – all of whom he says have been involved in the decision-making process, “contributing to making sure we do things right”.
More information:Stott Redman,
0429 351 475,