Ambrose Evans-Pritchard writes: American scientists have made an unsettling discovery. Crop farming across the Prairies since the late 19th Century has caused a collapse of the soil microbia that holds the ecosystem together.
They do not know exactly what role is played by the bacteria. It is a new research field. Nor do they know where the tipping point lies, or how easily this can be reversed. Nobody yet knows whether this is happening in other parts of the world.
A team at the University of Colorado under Noah Fierer used DNA gene technology to test the ‘verrucomicrobia’ in Prairie soil, contrasting tilled land with the rare pockets of ancient tallgrass found in cemeteries and reservations. The paper published in the US journal Science found that crop agriculture has “drastically altered” the biology of the land. “The soils currently found throughout the region bear little resemblance to their pre-agricultural state,” it concluded.
You might say we already knew this. In fact we did not. There has never before been a metagenomic analysis of this kind and on this scale. Professor Fierer said mankind needs to watch its step. “We really know very little about one of the most productive soils on the planet, but we do know that soil microbes play a key role and we can’t just keep adding fertilizers,” he said.
The Colorado study has caused a stir in the soil world. It was accompanied by a sobering analysis in Science by academics from South Africa’s Witwatersrand University. They fear that we are repeating the mistakes of past civilisations, over-exploiting the land until it goes beyond the point of no return, and leads to a vicious circle of famine, and then social disintegration.
Entitled “Dust to Dust“, the paper argues that the erosion of soil fertility has been masked by a “soup of nutrients” poured over crop lands, giving us a false sense of security. It said 1pc of global land is being degraded each year, defined as a 70pc loss of the top soil.
Once the top soil crosses a crucial threshold, the recovery rate plunges. Chemicals can keep crop yields high for a while but the complex ecology beneath is being abused further. Yields have already fallen 8pc across Africa as a whole. The paper calls for a complete change of course as the “only viable route to feeding the world and keeping it habitable.” [Continue reading…]