Maximising productivity while reducing impacts

Headshot of Bob Garnant
Bob GarnantCountryman
Department of Primary Industries and Regional Development officer David Rodgers.
Camera IconDepartment of Primary Industries and Regional Development officer David Rodgers. Credit: Countryman

A Great Southern land and water expert aims to improve agriculture soil nutrition to maximise farm productivity while reducing off-site impacts.

Department of Primary Industries and Regional Development officer David Rodgers has worked in a range of areas including biosecurity and soil nutrition for the past 26 years.

He is involved in uPtake, a joint project with government and industry investigating critical values for phosphorous on high rainfall pastures in the South West.

The project, now two years on, was initiated to build confidence in fertiliser recommendations, particularly with excess phosphorus levels now a common occurrence.

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“We’ve been doing trial work for last decade, sampled over 1200 farms and 25,000 paddocks,” he said.

“This has created a good snapshot of what the fertility of soils in the South West are like.”

Mr Rodgers, pictured, said the project worked on critical values, a level of soil fertility that would allow a 90 to 95 per cent potential dry matter yield.

“This requires a range of trial sites to define a curve, to give a 1.0 relative yield,” he said. “We measure what nutrient is already in the soil.”

Mr Rodgers said the phosphorus critical value required a range of different curves for a range of different buffering indexes.

“The amount required changes depending on the soils ability to hang onto to phosphorus,” he said.

Mr Rodgers said phosphorous was one of the nutrients that had created off-site impacts, it gets into waterways and affects water quality.

“We have 70 to 80 per cent of paddocks above that optimum and some of them go up to 20 times as much as is needed,” he said. “We have the opportunity to redirect some of the spending on phosphorous into other things.”

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