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Phosphorus major threat to organic farms?
20 Oct 2003
Phosphorus could be the single largest hurdle to the Australian organic industry's ambition of being a viable sustainable farming system. Organic producers are facing the challenge of being unable to use superphosphate because of organic certification restrictions on water-soluble fertilisers.
In a survey of 16 broadacre organic farms in southern and central NSW, researchers found all but one property registered less than six parts per million (ppm) of plant-available phosphorus. This is substantially less than the 15 to 20ppm considered in conventional agriculture to be the minimum level for optimum crop and pasture production.
One farmer said during nine years of organic production he had sometimes had to harvest crops of half the yield of his conventional neighbours. This is an unsustainable way to farm, he said. He's still committed to the organic ideal, but said he would have to revert to non-organic methods if he couldn't find a solution to phosphorus deficiency in his alkaline (pH 8.0) red sandy loams.
The Land, 16/10/03.
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