Role of no-till in mitigating climate change may be overstated

Monday, October 6, 2014

A report published in the journal Nature Climate Change argues that no-till, often championed as a way to fight climate change, actually has limited potential to do so.

The report challenges the assumption, recently restated in the United Nations' Emissions Gap Report 2013, that no-till causes an accumulation of organic carbon in soil. The Biotechnology and Biological Sciences Research Council (BBSRC) reports that researchers led by Prof. David Powlson found that, while there was sometimes a small accumulation of carbon in no-till soils, most of the perceived extra carbon was just a redistribution, with more organic carbon near the surface and less deeper in the soil. The BBSRC also says "soil sampling methods normally used tend to exaggerate the effect" of carbon sequestration.

This larger concentration of organic carbon near the surface does often result in higher quality soil and better water retention, so no-till is still a good strategy for global food security and the protection of soils, especially in dry climates. No-till soils may also be better able to withstand the effects of climate change. Therefore, no-till's climate change mitigation properties should be viewed as merely the cherry on top of the soil-health sundae.

Powlson told the BBSRC that presenting a falsely optimistic picture of no-till is a serious matter and that, if this study proves robust, "there is even more pressure to decrease greenhouse gas emissions from other aspects of agriculture, and from other sectors of human activity." BF