The benefits of cover crops to soil health and, consequently, farm productivity are well discussed and widely known among scientists and farmers alike. Increasing soil’s organic carbon through cover cropping reduces erosion, fixes atmospheric nitrogen, reduces nitrogen leaching, improves soil health and structure, and increases soil’s water holding capacity. Cover crops can also make farms more resilient to extreme weather events associated with climate change. But, cover crops do much more than serve farmers’ benefit.
Cover crops hold organic carbon in the soil where it can promote crop growth rather than releasing it to the atmosphere where it will contribute to climate change. A single tonne of soil-sequestered carbon reduces atmospheric carbon dioxide by 3.67 tonnes. Currently, climate change mitigation lies outside of the common list of cover cropping benefits. However, as climate change becomes an increasing concern for ordinary citizens and governments around the world, Farmers will have an increasing role to play in countering greenhouse gases.
Measuring the actual amount of carbon captured in soil and plants is extremely challenging, which is one of the reasons cropping-based carbon credits haven’t yet been widely offered. However, the Soil Conservation Council of Canada estimates that Canadian cropland can store as much as 22 million tonnes of atmospheric carbon dioxide annually through the use of zero tillage, cover cropping and other best management practices.
In late 2015, the United States’ National Resource Defense Council released a report outlining the climate change mitigating benefits of cover crops. According to the report, 19 million metric tons of carbon – equivalent to the emissions of four million cars – could be sequestered annually if cover crops were grown on half the corn and soybean acres in the U.S.’ 10 highest producing agricultural states. The report also stated that using cover crops and other soil stewardship methods to increase soil’s organic matter by one per cent on these same acres would help that soil hold an additional trillion gallons of water: equivalent to the annual needs of 33 million people.
Given that cover crops offer far-reaching benefit, farmers should be rewarded for the effort they make to grow them. Governments should encourage cover crops through the use of a carbon credit in a carbon-priced economy. As well, provincial governments must implement measures to lessen future carbon tax impacts on the agriculture industry. Being an energy intensive industry, agriculture could be heavily impacted by carbon tax legislation. Together, these legislative supports for agriculture will ensure farmers will be able to maintain a key and growing role in climate change mitigation into the future.