Brave new world of spading revealed

30 Jul, 2010 04:00 AM

BINNU farmers Damian and Clara Harris have entered a brave new world.

They have no real reference points or definitive directions, which they hope will take them on a path towards building a sustainable and profitable farming enterprise.

But anecdotal information and trials on their property are convincing them they are on the right track.

And it's not hard to agree with their assessment once you pick the line in the trial paddock where they have spaded.

In fact the proverbial Blind Freddy would have had no trouble separating lush germinating Magenta wheat with non-spaded staggered germinations on classic non-wetting soils.

"It's an incredible result and it's a whole new story for me," Damian said as he crouched near the now famous "line" with his dog Tup for another photograph to record the "evidence".

"I actually should have done more than this 30 hectare trial judging by the results but it has given me confidence to expand the spading program on the property.

"It certainly has raised a lot of questions and there is really nothing to compare it with, in terms of a component of crop production.

"I don't know whether the cultivation effect of spading is the big factor but I suspect it has to play a major part because of improved mineralisation and amelioration of the soil that enhances moisture penetration."

Spading is basically incorporating any surface material into the top soil.

Commercial spader machines are capable of mixing soil to depths of 30cm to 35cm (12-14in) employing rotary spade sweeps with an optional power roller to level the soil.

Badgingarra farmers David Hayes and Dennis Martin put the system in the spotlight in WA last year and assisted farmers like Damian with on-farm trials.

Damian, who crops around 2450ha (6000ac), bought a Farmax spader last year, with a working width of four metres (13.5ft).

Small trials led to a more "ambitious" 30ha paddock trial this year.

"Basically I want to get more production out of our non-wetting soils and from what I'm seeing with the spader, I've got a chance to do that.

"I think we're on to something that will take away the frustration of watching crops struggle every year in non-wetting sands."

Damian has started by spading 1.2t/ha of lime sand and experimenting with naturally-occurring clay.

"We have house pad yellow sand with clay present around 300 to 400mm (12-16in) depth and high pH," Damian said.

"In our trials we have spaded to 400mm to mix up the top soil profile with clay and that has proved successful," he said.

"We spaded then seeded and it was easy to get across, not like going over deep tilled country.

"Interestingly on one pass we purposely sowed at 90 degrees to the way we were going and that produced a better response but I haven't got any answers yet as to why that has happened."

The trial was sown on May 26 after the property received 10mm on May 24.

"The spaded trial is visually about double what we achieved in the non-wetting sowings and we also noted faster germinations in the spaded area," Damian said.

Interestingly, sowing with a DBS, Damian said he didn't have to go deep with the leading blade.

"We didn't have to go deep and we ended up just tickling the surface," he said.

"That meant we didn't disturb existing deteriorating stubble in the soil profile and that has got to be a plus going forward in building up soil fertility."

Damian describes the action of the spader as digging up a vegetable garden.

"It's like a spade going into the soil and you lift and turn the soil," he said.

"It's not vigorous like a rotary hoe but it does a thorough job of mixing up the soil which eliminates the non-wetting soil surface allowing moisture to penetrate in the ground."

Damian is planning a "gradual process" to spade the whole property to lift crop productivity.

"Once the spading is done I don't think I'll have to do it again for awhile," he said.

"Some people have said it could be up to 10 years but I suspect there's no hard and fast time frame.

"The main focus will be on improving soil structure and soil fertility and that means lifting productivity by improving our non-wetting soils."

Three Springs machinery dealer Bruce Cunningham also has established spading trials this year after becoming an Imants spader dealer for South Australian importer Roger Groocock.

"We have established more than a dozen trials with each trial averaging between five and six hectares," Bruce said.

"The main interest in our area is to overcome non-wetting soils and raise soil pH.

"Treatments have included trials with incorporating between 0.5t/ha and 6t/ha-equivalent lime applications and mixing up clay in the topsoil.

"Where we have spaded it is quite evident we have got better germinations and healthier crop establishments.

"The spaded trials gave plants a better chance to get away in the dry and cold conditions this year whereas the unspaded treatments did poorly with staggered germinations.

"I think there is potential for spading in WA and theoretically it should assist in increasing soil structure and soil fertility."

For David Hayes, spading should become an integral part of WA's broadacre cropping system as well as being used to renovate and rejuvenate pastures.

He already has built his own spader and is doing contract work for a growing number of farmers.

"I knew non-wetting was an issue in our soils but it's bigger than I thought," he said.

"But there is no question in my mind that spading trials should be done under GRDC funding to properly quantify the benefits.

"Otherwise all we have is anecdotal evidence and that may not be enough to push the system."

According to David, spading will become part of a wider management program to make his farm more sustainable.

"With the spader, I have the ability to incorporate not only clay but straw, chicken manure, lime to depth in the first year and successfully establish perennials," he said.

"I thinking of mounting a combine seeder box on the spader to sow perennials while I'm effectively renovating pastures.

"But there is a warning to farmers going into spading and that is to watch wind erosion.

"That's why I am using press wheels behind my machine to create furrows to reduce wind erosion and create a water-harvesting effect at the same time."

David said he remained enthusiastic about spading, believing it will have a major impact on WA broadacre farming.

"When I compare a spaded area of crops on my property with unspaded crops it's chalk and cheese and that evidence is very compelling," he said.

David will exhibit his 4.5m-wide (15.2ft) spader, made by Bayswater engineering firm Profab, at next month's Dowerin GWN Machinery Field Days.



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