Biomass is king - that was the message shared to producers taking part in field days in the Balonne-Maranoa region that dug down into the soil to identify possible constraints to growing crops and pasture, and talk about how to manage them.
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Leading the discussion organised by ConnectAg was Dr Andrew Biggs, senior soil scientist with the state Department of Resources, who got down into pre-dug pits in three separate locations in the Nindigully-Thallon area on the first day, and who already had chemical analyses done to refer to.
At Leithmore, owned by Theresa and Anthony Pilcher, two pits were dug half a kilometre from each other, one on cropped land and the other on native vegetation.
The Pilchers have been farming on the country since 1970 and started zero till practices 10 years ago, mainly using a wheat-chickpea rotation.
Dr Bigg spoke about the interaction between gypsum, which was present naturally on brigalow belah soils, the soil's salt bulge, and the pH levels.
Among the questions thrown at him were the best ways to manage compaction, bearing in mind that aiding the entry of water through the top of the soil was what would govern growth.
"Compaction fixes itself via wet-dry-wet rain cycles, naturally," he said.
In response to queries about whether some crops might dry soils out, Dr Bigg said different crops acted as different 'vacuum cleaners'.
"Chickpeas don't suck terribly hard but sunflowers are at the other end of the system - they're a big plant with a big root system," he said.
There were also plenty of questions about the value of growing pasture phase crops in the area, which Dr Bigg said was a good idea in theory where rain was more guaranteed, but in regions where there wasn't that level of certainty, people would have to do their numbers.
"I wouldn't do it just for compaction - these soils fix themselves to an extent," he said, adding that what a pasture phase did was improve organic carbon in the soil.
"Here, it's 0.4 per cent - that's pretty typical. On the native vegetation it's 0.65pc.
"You're not going to get the gain from pasture phases that you get in a wetter climate."
A pasture phase was always guaranteed to improve soil carbon, but Dr Bigg asked whether it improved it significantly from an economic point of view.
He added that the biggest responses and the best gains in yield were always made on the worst soils.
"There is one universal - soil carbon is always a good thing," Dr Bigg said.
"The broad principles of regenerative agriculture - don't flog your country, maintain your biomass - have been promoted for decades.
"It's the law of diminishing returns.
"In the north, they have good biomass but it breaks down very quickly.
"Cape and Territory soils are so much harder because of the lack of organic matter - they call it the rice paddy effect.
"The thing is, you'll never achieve a number higher than Mother Nature."
In an interesting aside, Dr Bigg pointed out the presence of manganese in the soil, saying toxicity was a 'thing' in really acetic soils.
"There might be a deficiency - no-one's really looked into it," he said.
"It illustrates there's still a lot we don't know about plant roots and sub-soil interaction, despite years of GRDC research."
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Sally Gall
Based at Blackall, CW Qld, where I've raised a family, run Merino sheep and beef cattle, and helped develop a region - its history, tourism, education and communications. Get in touch at 0427 575 955 if you've got a story idea for me.
Based at Blackall, CW Qld, where I've raised a family, run Merino sheep and beef cattle, and helped develop a region - its history, tourism, education and communications. Get in touch at 0427 575 955 if you've got a story idea for me.
