Chaff rescues saline soil

Crop growth in these areas stopped, leaving farmers searching for solutions to prevent the spread of salinity and make the soil fertile again.

Affected farmers Scott and Caroline Bussenschutt, Tickera, worked with Northern Sustainable Soils - a group of farmers and industry representatives targeting soil, pest and crop nutrition issues on the northern YP - to find an answer to the problem.

Chaff spreading proved very effective.

"We've been looking at this issue for five years or so," NSS executive officer Leighton Wilksch said.

"During that timeframe, farmers in the NSS have been trying different things to manage the rising salinity - spreading chaff is the main thing that's had the biggest impact in recent years.

"Salinity has always been managed by planting trees or fencing off certain areas, but to turn the land into higher production country, chaff and straw spreading has been the main focus.

"It's helping turn previously unproductive country back into something that will grow some grain."

The Bussenschutts coastal location meant that over the years winds were bringing salt into the soils, increasing salinity to problematic levels.

"Their country runs right along the coast near Tickera," Leighton said. "They had noticed an increase in saline patches in their paddocks, and a lot of that had to do with the fact that they were removing a lot of weeds out of their cropping system, which every farmer wants to do, but that was leaving bare areas that just didn't grow anything.

"The big factor that really exacerbated the rise in salinity was the dry run of seasons from 2006 to 2008."

Scott was first inspired to try spreading chaff after noticing plant growth in saline areas where chaff was deposited by the header at harvest.

Soil moisture probes placed at the NSS trial site on the Bussenschutts' property has shown the big difference chaff has made.

"The chaff has helped retain any moisture that falls over summer and autumn, providing an insulation mat," Leighton said.

"When the crop is planted in late autumn, the seeds tend to germinate immediately because there's moisture around them, whereas if that had been bare ground, the seeds don't germinate or take a lot longer to germinate. They have less vigour and grow less biomass and bulk, and therefore the ground is more prone to drying out. It's a cycle and it just gets worse and worse.

"The retention of the moisture in the soil is the first great step, and then the second fantastic thing is that once the crop is able to grow a bit of biomass, that stubble gets cycled back into the soil, which leads to beneficial microbes getting up and away, and that will then lead to a better crop. The benefits just keep building."

Leighton said the technique made use of equipment many farmers were already using at harvest.

"There are a lot of chaff carts used around the region to catch weed seeds at harvest," he said.

"Farmers are either manoeuvring that chaff onto these saline areas, or alternatively they are bailing straw out the back of a harvester, and then getting that straw and dumping it on top of those saline, poor production areas.

"There's a bit of a process to actually spread it out so that it's a more even mat, and also so that it's not too thick so that the seeder can actually get through and plant crop into the ground.

"That's being done with slashers or guys putting harvesters back through that straw and spreading it through the back. In some cases, there are also disc machines being used to disc it into the ground."

* Full report in Stock Journal, July 10, 2014 issue.