Newdegate, around 400 kms southeast of Perth. In this part of Western Australia's grain
belt water repellent soils are a common challenge for growers.
Local farmer Steve Thompson is hosting a small-scale trial
investigating the effectiveness of wettings agents or surfactants on sandy non-wetting soils.
The trial, looking at different surfactants, or soil wetters,
interests me. We're doing it ourselves and I just wanted to see results from different products
and different methods of doing it to see if we could improve our system.
On Steve's farm about 25% of his lighter soils are non-wetting and in a low rainfall zone,
soil moisture is a valuable commodity. While surfactants can benefit
non-wetting Forest gravels their effectiveness on sandy soils needs more scientific evaluation.
So, you can see Kylie the plant densities in these plots are
quite acceptable any grower would be pretty pleased with that, yeah.
TrialCo is facilitating the trial with GRDC investment.
It's a two-year study and there are 5 trial sites in all.
At these sites crops have been sown on different stubbles and a number of surfactants applied.
However, an unusually wet April and May, has masked the effectiveness of the surfactant trial.
We've tried to select the trial set in both years to capture different crop types on
different stubble types so we've got canola on a cereal stubble, we got cereal on a canola stubble,
we've got cereal on lupin stubble, we've also got cereal on a cereal stubble so we were hoping that
we could try and tease out any relevance of the impact of stubble on the effectiveness of the
surfactants but due to the lack of responses it's been hard to make those comparisons.
It's obviously very wet here. And they haven't had to work too hard this year.
Just add water to get good germination and crop establishment.
But it's under normal seasonal conditions when these soils are hard to wet,
that surfactants are meant to make a difference and it's also why canola was the primary focus.
Of the 5 trials we've done this year 3 of them are canola.
And the reason for that is because canola is the crop that's generally seeded earlier in
seeding program, so quite often its seeded under marginal conditions or even dry, whereas when you
start moving into the cereal seeding there s been more chance of rainfall events to occur.
Another consideration in making the trial as relevant as possible
was to use commercial surfactants. Those with the highest adoption amongst growers
in this part of WA's grain belt were selected. Common practice was also applied to surfactant
placement, so it was banded with the seed. But it wasn't the only application method.
There's a product that we've trialled that we've both applied on top of the furrow,
so behind the press wheel as opposed to having it in the soil layer at seeding,
and the same product we've also applied with nozzles as a boom sprayer application.
By comparison Steve Thompson who's been using wetters for more than a decade
has customised his approach to application.
Ours, we have to place it as close to the seed as possible, so we run
two liquid systems on our seeder, one to put
liquid fertiliser below the seed and one to put the wetting agent as close to the seed as we can.
I think that is working better than what we used to do, but it's still not 100%.
So what we're looking at here is the plant numbers per sm.
Plant counts and bio production assessment
are some of the other data sets the trial was designed to analyse.
That profile is wet, all the way as far as I've dug anyway.
If there's a scenario where post seeding, we had a 4-mill rain event I think that's when
you re more likely to tease out a response. And this year it's been wet from the start.
As frustrating as it is, there will be outcomes when the trial winds up after this harvest,
though possibly not the outcomes anticipated at the start of the trial.
Despite the setbacks and challenges
there's at least one known according to TrialCo's Kylie Lockyer.
Basically when there's rainfall, that surfactants aren't
giving a return to the grower. Without science to sway him otherwise
grower Steve Thompson will maintain his long-established program of surfactant use.
We are still going to keep using it because I can see a response in certain areas.
However, he concedes, that while yield response would increase
if the non-wetting soil issue could be overcome, it would offer a limited benefit to him.
If we could improve our crop establishment through getting over the non-wetting issue,
it's probably only going to have a 5-10% impact on yields because
it's not our whole program as it's only areas of the farm.
It's a home truth that reflects the complexity of the non-wetting soils issue.
And underlines the need to adapt the use of wetting agents to your own situation.
I think Growers need to look at surfactants as just part of techniques to overcome non wetting
soils and they need to know their soil type and know what best will suit their farming system.
Try and talk to growers who've done it and had success I think.
We've done it for a long time and getting to the stage where
we think we've almost got our system worked out as good as we can do here.