THE move four years ago to soil test at depth revealed a significant acidity problem for Miling farmer Tony White, but opened the way for a liming treatment program which has bolstered yields even in low rainfall years.
Mr White had been a regular participant in on-farm trials and routinely tested his soil to a depth of 10 centimetres.
But his management practices had been based on an incomplete picture, until he discovered soil acidity was his biggest yield limiting factor.
“I couldn’t work out why some of my neighbours were getting better yields with the same rainfall. The only difference was they were running their own road train to the beach and bringing back lime sand for a pH fix,” Mr White said.
“For years we were testing the top 10 centimetres of soil and getting told everything was okay. Once we went from 10 – 20 centimetres down we found trouble and once we went from 20 – 30 centimetres we found real trouble.
“Each year now we cart back over 1000 tonnes of lime sand and our crop yields are far better, even on less rain.”
Located in the region’s northern grainbelt, Mr White with his partner and family, run a 2000-hectare property that grows export hay and malt barely as well as canola, lupins and wheat, depending on paddock suitability.
Mr White said his soil types range from yellow sand plain to heavy grey clays and has an average rainfall of 320 millimetres.
Non-wetting and acidic soils are common for Mr White’s area, which prompted the change in direction four years ago, based on advice from the Grains Research and Development Corporation (GRDC), which recommends soil testing to a depth of 30cm to identify and address subsoil constraints as well as top soil deficiencies.
The information provided allowed him to address both problems in tandem. His first move was to address the non-wetting soils by trialling a deep ripping strategy.
“We didn’t get the results we were expecting, so we jumped into spading which gave us 700 kilograms a hectare difference compared with our un-spaded paddocks,” he said.
“The following year we trialled spading and mouldboarding and we found the mouldboarding was slightly better for the same operating costs.
“Mouldboarding enables us to bury weed seeds, get the ripping of the hardpan, get an inversion with the lime sand as well as treating non-wetting soils in the one pass.
“It’s costing us $120 a hectare for the mouldboarding and another $60 a hectare for the lime, but we’re growing an extra tonne per hectare of grain so we’ve recouped our costs back in the first year.
“We’ve got one paddock up the other end of the farm last year that went 3.4 tonne of wheat and I think this year it’s probably going to do over 4-tonne barely crop which is quite okay on 200 millimetres of rain.”
The GRDC has been supporting the adoption of mouldboard ploughing in sandy regions like the northern grainbelt of WA to reduce the impact of non-wetting soils and improve on-farm productivity.
Research supported by the GRDC has demonstrated the practice improves soil moisture penetration, reduces weed regeneration and assists in lime dispersal.
However, with the added heavy machinery operating on his farm, Mr White has started to see the effects of compaction. Controlled traffic farming (CTF) will be the next practice change that he explores, he said.
“We hadn’t noticed compaction so much over the years because the soils hadn’t been ameliorated to this extent, but now we’re using the mouldboard plough and we’re fluffing up the soil we can really see where the tracks have gone,” he said.
“If I could give advice to anyone I’d say, whatever type of crop you’re going to grow or whatever soil amelioration you’re going to do, it all comes down to the economics of each paddock.
“I think you’ve got to be pretty careful with what sort of soils you’re dealing with and what benefit is going to be gained.”