Soil management | Extreme situations can require tillage, says Australian farmer and no-till advocate Bill Crabtree
Pragmatism should trump dogma when it comes to conservation tillage, says Australian farmer Bill Crabtree, better known as No-Till Bill.
There are scientists and farmers within the zero tillage movement who argue that fields should never be plowed, cultivated or disturbed, but Crabtree isn’t part of that camp.
“When do you cultivate when you’re a no-till farmer? When you have to. Be pragmatic,” said Crabtree, who attended the World Congress on Conservation Agriculture in Winnipeg June 22-25.
“A no-till organization is not a religious, fanatical, 10 commandments organization.”
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Crabtree, an agricultural consultant, farmer and no-till advocate, said there are several scenarios where cultivation is necessary in no-till systems. One example is from Western Australia, where many farmers have subsoil acidity.
“The pH and calcium chloride might be 3.9 at 20 to 30 centimetres, as it is on my farm…. I haven’t yet plowed, but I know I’m going to have to,” he said. “Another example is where we have wheel ruts from a wet year. There’s no way to fill them in except with tillage.”
No-till proponents have suggested that even one pass with a cultivator could threaten soil microbiology and endanger soil health benefits associated with zero tillage, thus undoing 10 or 20 years of soil improvements.
Crabtree said such arguments are extreme.
“That idea is a bit strong,” he said.
“If our soil was a two out of 10 when we started no-till and we’ve now got it up to eight, I think if you do one tillage you’re dropping it back to a six.”
Yash Dang, senior soil scientist for the Queensland science department, has investigated the impact of tillage on soil microbiology, soil organic carbon, water retention, fertility, yield and weed population.
He and his colleagues cultivated five long-term no-till fields in Australia’s northern grain region in 2012.
Dang said tillage affected the soil in several ways:
- reduced water retention
- slight impact on soil microbiology
- minimal improvement in grain yield
- slight decrease on soil organic carbon
- improved control of weed populations
- improved mobilization of phosphorus in the subsoil
He said there are several reasons why zero-till farmers may need to use tillage, including herbicide resistant weeds, an increase in stubble borne diseases and nutrient stratification in the top layer of soil.
