Whoa boys: small structures doing a mighty job
If you searched a telephone directory for “Mr Whoa Boy”, you should find Collinsville businessman and part-time grazier, Barry Collett.
When it comes to whoa boys, Barry has learnt almost everything there is to know about what works, what doesn’t and the extraordinary things these fairly innocuous structures can achieve.
Barry has used whoa boys and variations of the whoa boy design to remediate some of the paddocks on his 750acre block near Scottville.
Erosion control is a big part of his earthmoving business and whoa boys protecting roads, tracks and fencelines, represent a significant portion of that work.
He has three pieces of advice for anybody wanting to know how to install whoa boys:
• there’s not a one-size-fits-all solution;
• dirt is not soil; and
• soils ain’t soils.
“This paddock, for instance, [about 35 acres], has probably five different soil types in it,” he said.
Barry and NQ Dry Tropics Soil Conservation Officer Bernie Claussen were the presenters at a Save Your Soil workshop on Barry’s Todsure property near Scottville.
The workshop, attended by representatives from several properties in the region focused on designing and installing whoa boys to prevent erosion along property roads, tracks and fencelines.
Bernie and Barry stressed the need to understand the soil type in the location for the whoa boy.
“I dig a lot of potholes to investigate the soil before doing any work,” Barry said.
He said it was also important not to over-complicate assessing different soil types.
“We can do some basic tests and learn a lot from them,” he said.
Attendees at the workshop heard that designing and installing whoa boys involved balancing a lot of factors to arrive at a location and design that would effectively prevent water from flowing too rapidly along roads, tracks and fencelines.
Bernie led the group through some theory before sending them out in groups to get hands-on experience.
She said the most important consideration was to begin at the top of the catchment and build structures that would catch the damaging rapidly-moving run off, slow it down and divert it into a shallow pit from which it could overflow gently across a broad level sill and onto the landscape.
This allowed sediment to fall out and provide a chance for the water to infiltrate.
Bernie said the paddock in which they were sitting was a perfect example of the effect that well-placed, well-designed and well-constructed whoa boys could have.
When Barry started with a moonscape, bare paddock six years ago, the whoa boy-style interception banks he built at the top of the paddock provided the opportunity for grass to re-establish after rain.
The interception banks prevented the water from gathering speed and becoming damaging on the unprotected ground.
Now, the slowly-moving water had a chance to infiltrate and bring the soil to life.
Barry accelerated that process by shallow ripping between the structures and spreading a rich mix of pasture grass seeds.
As the grass grew in the areas where water could finally infiltrate, it added to the effect of slowing and spreading water running off after rain and the lush growth spread right down the paddock.
There’s now only a 20-30m strip at the bottom of the paddock that isn’t 100 per cent covered with a knee-high mix of the resident couch that returned but now had to compete with urochloa, seca, buffel, and Rhodes.
With the evidence of their effect all around them, attendees at the workshop were enthusiastic about what they learnt.
Tim Close from Warrigal, near Guthalungra, said he was keen to put the knowledge to practical use when he got back to the property.
Glenore Station brothers Aaron and Deane Casalegno were also looking forward to a lot of measuring, marking out and construction.
Bernie and Barry emphasised the necessity of accurate measuring and marking out.
“It’s impossible to do it by eye, no matter how much practice you get,” Barry said.
That was illustrated for the Casalegnos when the whoa boy they marked out looked to be level, rather than having the required 0.2 per cent slope towards the borrow pit and the level sill.
They measured again and proved the position of their original markout was correct.
Bernie took the group through the necessary maths to calculate spacing, using diagrams and the real data collected by the group as they used a laser level for the first time to measure the slope and find contours.
The combination of theory and hands-on backed up by the practical classroom exercise using the real measurements gathered in the paddock meant everybody “got” it.
This workshop was supported by the Landholders Driving Change (LDC2) project, funded by the Queensland Government through the Queensland Reef Water Quality Program.
