Surprising crop growth over fox holes in the middle of a cereal paddock has seen Rankins Springs producer Michael Pfitzner re-examine the way he undertakes his cropping program.
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Mr Pfitzner has been focusing on lifting poorer performing areas to be more productive on his 2800-hectare northern Riverina property.
Soil studies found the pH in these areas was lower, with the associated acidity and aluminium toxicity problems.
“Certainly something that opened our eyes was about three years ago we had some fox holes on the sandy soils and we filled them in prior to sowing,” Mr Pfitzner said.
“We sowed barley in that particular paddock and we noticed where these fox holes were the crop was every bit as good as the heavy parts of the paddock.
“We investigated that further and did some soil testing, expecting the difference to be phosphorus or nitrogen.”
In fact the foxes had changed the soil type by digging and bringing alkaline soil closer to the surface.
“To our surprise the only difference was the pH, where the fox hole had brought some more alkaline soil up. The fox holes soil had a pH of 7.8 and right next to it was a pH of 5.4,” Mr Pfitzner said.
In conjunction with the yield mapping, this provided a good picture of where these problem areas were.
The property mainly consists of red sandy loam soils that are generally flat with sand hills in amongt some of the paddocks.
Mr Pftizner grows wheat and barley and when the opportunity exists, canola, field peas and lupins as well as some vetch for green manure and safflower.
The last decade of mostly dry autumns has made it difficult to plan and maintain a rotation on the property.
“The likes of the early sown crops like lupins and canola that has been difficult but we’ve overcome that a little bit with vetch as a brown manure crop,” Mr Pfitzner said.
“The vetch is conserving a bit of moisture by not allowing it to mature, is creating a bit of nitrogen and provides weed control by spraying it out later.
“This is one way of being flexible in these difficult times.”
He’s also done a lot of general soil testing and over the last 12 years has been yield monitoring, with a strong focus on good performing areas and poor performing areas.
Mr Pfitzner has found there are differences in soil types and soil pH across each paddock.
“What we’ve found in these different areas is there is quite different management required,” he said.
“I guess the initial step was with variable rate phosphorus, cutting back the phosphorus where the production areas were less.
“That has been a stepping stone to work out what have been the drivers behind why these poor areas are performing poorly.”
A trial project has been organised by Central West Farming Systems (CWFS) and the Southern Precision Agriculture Association (SPAA) group with funding from the Grains Research and Development Corporation (GRDC).
“This year we’re concentrating on a particular paddock that we know has issues with these sandy rises being a little bit more acidic,” Mr Pfitzner said.
“It’s a pretty basic form of variable rate and we’re just applying lime where we have noticed it needs it and not applying it where it doesn’t.”
It is not just lime which is being used on the trial site with chicken litter also used as an alternative.
This is the first year of the trial with some interesting results from a test strip last season.
“It showed to be quite promising with the chicken litter getting more of an instant response,” he said.
“We have a prescription variable rate for MAP and sulphate of ammonia that we are applying to this paddock.
“I guess we’re looking at addressing some of the issues with the lime and the chicken litter on the poor areas and then just backing off fertiliser rates in a prescription over the paddock.”
This has seen the better performing areas getting slightly more fertiliser and the traditional poorer performing areas getting slightly less but getting ameliorated with lime and chicken litter.
Last year’s test strip saw the crop go in on an 18-month fallow paddock which had some good stored moisture from summer rains.
“In the satellite imagery it showed we were getting a response, probably more so from the chicken litter than the lime but it showed we could actually fix up these sandy rises to some degree,” Mr Pftizner said.
“With the yield data on top of that we could see that these poor performing sandy rises were yielding the same as the rest of the paddock.”
While the initial results from the lime treatment were not as good as the chicken litter, Mr Pfitzner has decided to continue to investigate both techniques further.
“We know there are acidity issues there and aluminium toxicity type issues we need to address but we are seeing a quicker result by putting some chicken litter on it as well,” he said.
“The chicken litter works well possibly because of the organic matter and all the things which make it up but it is just not one thing.
“Certainly it can be a bit too strong in drier years where we’ve seen it burn crops off in patches which perhaps don’t need it.
“We’ve been a little bit wary in doing big blanket rates of it but I think in areas which do need a bit of a push it has certainly got a place.”
He’s also very conscious of the costs of undertaking the work to make sure the trial work is economically viable on a property wide basis.
“In the work we did last year, gross margin wise, they came out slightly behind the do nothing approach.
“I guess you have got to remember this is not just a one year hit so hopefully we can transfer those costs over a number of years.
“If the results we are seeing so far prove to continue then costs wise it will certainly be well worth it.”
