The latter two were among alarming prospects raised by speakers at the third annual Carbon Farming conference in Orange last week.

“Peak oil” refers to the time, considered to be imminent if not already here, when the maximum rate of global oil extraction is reached, after which production would enter terminal decline, leading to increasing oil shortages and steadily rising prices.

One conference speaker suggested availability of phosphate to make fertilisers was facing a similar crisis, another that the world could run out of usable soil within about 60 years.

The possibility of “peak soil” was raised by Professor John Crawford, of the University of Sydney’s Institute of Sustainable Solutions, who said Europe was losing soil at the rate of 17 tonnes a hectare, and in China soil was being lost at 57 times the rate at which it could be replaced.

In NSW the rate of soil loss was five times the speed of replacement, he said.

The conference – organised by Carbon Farmers of Australia, which is headed by Goolma district farmers, Michael and Louisa Kiely – featured a strong bias towards biological farming and related alternative soil management practices.

There was more than a whiff of evangelical fervour about the potential of biological farming to create healthier soils that could store large amounts of carbon and produce healthier food for healthier people.

But there was also scientific support for the movement’s emphasis on farming in a way that enhances the number and variety of soil microbes deemed central to soil fertility.

About 300 attended the conference – well up on last year’s 220 – with a Carbon 101 workshop the previous day attracting about 100, compared with last year’s 35.