Grains Research and Development

Date: 01.06.2003

Precision farming: culling the danger zone: paddock zoning could improve the average gross margin by $56 per ha by rationalising inputs in accordance with soil potential by Eammon Conaghan

WA PADDOCKS could soon have a flavour of Darwin in them. That is Darwin the philosopher; not Darwin, Northern Territory.

Survival of the fittest is the economists' catchcry and, with the price squeeze and lean margins endured by graingrowers, that sentiment must echo across the WA wheatbelt.

Grain paddocks should work for growers and, if they don't deliver, let's lay them off or withdraw privileges such as fertiliser.

At the western Crop Updates, John Blake of the Department of Agriculture profiled the 'invest, vary or cull' (IVC) system which he believes can help growers rationalise costs by identifying growing zones that refuse to deliver, even if well catered for with fertilisers.

Diagnostics to determine if these areas will respond to treatment provide a critical step and a focus of current and future research and development.

"Many years of yield mapping have proven that inherent soil properties have an overriding influence on crop performance. But if properly diagnosed, some of those properties, such as soil pH, traffic or plough pans and non-wetting, can be ameliorated," Mr Blake said.

"Paddock zoning is an effective tool for the future management of poor-performing areas. The decision to invest in amelioration, merely vary seasonal inputs based on current productivity potential or cull areas from the rotation can be supported by IVC in partnership with diagnostic programs."

Using yield maps, growers can identify which paddocks and areas within paddocks are not providing profitable yields. Those areas can then be diagnosed for the soil characteristics that are dragging crop production down.

"However, amelioration such as claying can cost up to $200 per ha, depending on the proximity of the clay source, so growers must predict whether they will recoup those costs with the interest needed to make it a wise business decision."

Matching inputs to zones

Mr Blake and his team, with consultancy support from PlanFarm, ConsultAg and CRT, worked with grower groups from Casuarina, Corrigin and Wongan Hills to develop prototype matrices of the return on investments for varying input levels across soils of three different production potentials (zones).

Results from the Casuarina group showed that paddock zoning could improve the average gross margin across the three zones by $56 per ha by rationalising inputs in accordance with soil potential.

However, Mr Blake warned that, as agronomy and management- affect yield, merely holding back inputs without diagnostics could make poor-performing crops a self-fulfilling prophecy.

If amelioration is not a viable option and crops do not respond to nutrient inputs, but can still return a profit with modest inputs, then growers might consider chopping back fertilisers to strike the greatest return on investment ratio.

If margins threaten to slip into the red, growers can cull trouble areas from the rotation altogether.

It is the accuracy and sensitivity of these diagnostic systems that underpin the success of rvc and consequent zoning programs. Paddock zoning delivered significant profit increases in five of the 12 in-field case studies undertaken.

While profit increases were not always achieved, crop performance varied as predicted across the zones, confirming that zone divisions are identifying important distinctions . between areas of the landscape and, with more fine-tuning, could provide new management insights.

"With improved prior-season diagnosis, zone management could lift profit, even in adverse seasons. That improvement will come as specific diagnosis processes are developed," Mr Blake concluded.

A key for diagnosing soils is being developed and information is available from Daya Patabendige at the Department of Agriculture on 08 96902174.

Program 4 Contact: Mr John Blake 0896902143 email

Region West