Ironstone gravel soils are often considered by grain growers to be problematic.
But a GRDC investment is enabling the University of Western Australia, to combine chemistry
and physics to help scientists - and growers, understand potential water and nutrient absorption
by these gravelly soils in an effort to increase crop profitability.
Ironstone gravel in contrast to other gravels is porous, which means they have a pathway
for water and gas which can transport as a conveyor belt for micronutrients.
They can store water, hold it and release it again.
You can see these tiny little bubbles, this is our ironstone gravels still intact and
once those erode and mix with the soils we get our ironstone gravel soils.
Around 9% of Australia's cropping soils contain ironstone gravels mainly in southern WA and
South Australia.
They are commonly aluminum, silica, or iron based.
The more you go east the less percentage of ironstone gravels.
Scientists are determining if regional distribution of ironstone requires differences in how they're
treated along with absorption mechanisms.
They are more like this brick with a lot of pores so they're porous with pathways basically
then for the water and the gases to flow.
How they infiltrate, we don't know in which pore sizes the water sits, can it be released,
is it trapped in there and plants can't even use that do microbes for example colonise
these gravels, are they building a hub for microbes to sustain hot dry summer periods?
These are specific questions we want to ask and resolve within the GRDC funded project.
In addition to high tech science, unique geological expertise and technology from the mining industry
is being applied to the ironstone gravel project aiming to deliver practical and ultimately
profitable outcomes to grain growers.
This is ground-breaking research, never looked in this detail before from an agriculture
perspective and this is the beauty if we can harvest some of the results from the mining
industry and use and apply it to an agricultural context as well.
The project has just kicked off.
In the lab, researchers are analysing samples, sizing gravel and running hydrology tests,
is water tightly bound or, can it be released?
All of this requires some heavy-duty technology like CAT scanners; we're using nano Sims;
electro microscopy to understand the fine details and the mechanisms actually behind
these processes.
So inside the Xray machine we have a piece of gravel it's sitting in water and we can
watch as the water penetrates into that pieces of gravel.
This is a 3-dimensional piece of gravel cut through the middle this is approx 8 millimeters.
I don't think anyone has studied soils and gravels in this amount of detail before and
there's heaps we can find out - information on the properties of the soil we can ascertain
from these studies.
We want to provide clear advice for the farmer, based on their region which is a really beneficial
iron stone gravel.
We want to advise them on fertiliser, on water management to better understand their soils.
Potential research outcomes could be to increase crop yield by using more, or perhaps less,
fertiliser on gravel soils, or determine whether lower yields are the cost saving reality with
these kinds of these soils.
Either way growers are set to benefit from the findings.
I've driven through the southwest and a lot of wheat belt areas and see all the fields
growing there and it's good to be sitting here in the lab knowing that you are going
to be contributing to some of the benefits of growing better crops.
I think we have not closely looked enough at our gravel soils we know there are crops
growing in there, roots love to grow in between the gravels as well, so let's wait one or
two years to get the real basics of these gravels and then look for the advice they're
waiting.
But I think there is some potential we can increase the yield for the future.