These paddocks 60kms north of Esperance have been transformed by soil amelioration.
What was typical Western Australian flat Mallee country, producing around 2 tonne to the hectare
cereal crops, is now delivering double those yields.
We’ve treated around 700 ha so far on the farm and we’ve still got probably around
500 – 600 ha to do maybe more.
When finished, it will mean about a third of Gavin’s 34,000 ha property will have
had a soil amelioration treatment.
On a property like Gavin’s in medium rainfall zone the main constraints
were, non-wetting and soil compaction.
They were identified by Gavin and we did some ground truthing work using EM and radio metrics
and just purely digging holes to work out what was going on, and then we developed strategies
around that to address those probably two key issues.
The strategy was to delve and rip the soils to break the compaction and bring clay to
the surface.
What those analytics told us was they gave us a fair idea of the depth of clay, so then
we could zone out the paddocks.
Where clay was deep we’d used clay spreading as the amelioration method and where the clay
was shallow enough to the surface we used delving as the method to bring clay to the
surface.
Topsoil that was 99 per cent sand now has 5 per cent clay mixed into it; pH has risen;
as well as Potassium levels.
According to consultant Quenten Knight, the cereal yield increases have been phenomenal.
So when I talk about phenomenal we were seeing yield increases of probably nearly 100 per cent.
So from country that was maybe only producing say two tonne of cereals now that’s got
up to the point where its regularly produces up to four tonne.
The Egan’s improved yields have come with some consequences such as needing a revised
farming strategy.
One of the challenges with doing this is getting seeding at the right depth.
We’ve got a parallelogram seeder, so the press wheels on the tyne and as long as we
run that with a low enough pressure we seem to manage to still get a 90 per cent job of
what we’d expect on untouched country.
Another consequence of disturbing the soil and covering stubble is exposure to wind erosion.
It’s a risk Gavin Egan has minimised by monitoring soil moisture levels and being
selective about sowing times.
That’s been our main issue is if we get a blow after seeding and fill the furrows.
But that’s only happened on small areas a couple of times, not the whole area that
we’ve been doing.
Below the soil surface there are other needs to satisfy.
As we started to increase yield potential obviously we had to re-address our nutrition package
because once we feeding for a 2.5 tonne crop now we’ve got to start feeding for a 3.5
to 4 tonne or better crop. So it’s a continually evolving thing and once our production levels
increase our agronomy around that whole system needs to continually change.
Quenten and Gavin are working on herbicide strategies as well.
Post amelioration we get some good consistent germinations of weeds and knockdowns are effective
and our pre-emergent herbicides are a whole lot more effective because they are operating
in soil moisture where previously they weren’t.
Gavin Egan’s soil amelioration program started seven years ago.
Now he believes he’s drought-proofed a lot of his farm and given himself options.
What we do know now is that we can seed earlier with longer season varieties that will yield
more in this Esperance area.
The soil health is better, the earth worms are there and increasing again now that we’ve
fixed the non-wetting issue and these areas that we’ve been targeting in a dry type
year we’ve been struggling to get a yield of grain off, where as now its as good as
if not better than our good country and we just know we can produce grain each year which
is a real bonus.
With Gavin Egan’s experience at one end and the R&D generated by the Soil Constraints
West program run by WA’s Department of Primary Industries and Regional Development at the
other end, a lot of benefit has come from GRDC’s investment in soil amelioration.
Somewhere in-between there’s the promise of gain for all grain growers according to
consultant Quenten Knight.
The real proof will be the adoption on-farm so we’re seeing that as every year goes
by more and more growers are gaining confidence in the research that’s been getting done
and ultimately its making their businesses more profitable and more resilient.