New research suggests rainfall and climate variability may play a larger role in soil carbon increases than land management, raising questions about carbon credit schemes.

Soil carbon has become a central pillar of Australia’s climate policy. Farmers are being encouraged – and in some cases financially rewarded – to increase soil carbon stocks through altered grazing and land management practices.

Carbon credits generated from soil projects are now traded in national and international markets, promoted as part of the solution to climate change. But do these schemes actually deliver additional, reliable carbon sequestration?

Substantial amounts of the world’s terrestrial carbon stores are in the soil. Maintaining appropriate levels of carbon and nitrogen in soils is essential for soil health and agricultural productivity. Yet scientific evidence on how land management affects soil carbon remains mixed, particularly in highly variable climates such as Australia’s.

To help address this uncertainty, we examined soil carbon and nitrogen levels at 50 farm sites in south-central New South Wales,........

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