Soil can help with climate change by storing carbon through a process called “carbon sequestration.” However, the amount of carbon soil can store depends on choices made by farmers and other landowners.
The choices farmers make—the crops they grow, whether or not they plow (till or no-till), and the amount of fertilizer they use—can influence both crop yields and greenhouse gas emissions. Soil organic matter has large amounts of carbon, which is also an important part of the greenhouse gases carbon dioxide and methane. Microorganisms decompose soil organic matter, obtaining energy and producing either carbon dioxide if there is lots of oxygen in the soil or methane if there is little oxygen. Tillage adds oxygen to the soil and increases soil organic matter decomposition rates. Other management choices, including combinations of the crops raised and the tillage methods chosen, have the ability to increase soil organic matter, effectively removing carbon dioxide from the atmosphere.
Until recently, most farmers chose to regularly plow their fields. Now however, no-till farming is becoming a more popular practice. When farmers decide to engage in no-till farming, they do not plow the soil in their fields. Instead, they plant their crops with minimal soil disturbance. By not plowing the soil, farmers release less carbon dioxide into the air. Additionally, by not plowing their fields, farmers decrease the likelihood of soil erosion occurring as well as store more water in the soil.
Another way that farmers can work with soils to help with climate change is by engaging in crop rotation. This involves planting a new crop in a new place every year or so. Different crops use different soil nutrients, so crop rotation improves soil health. Cover crops are also helpful for mediating climate change. The presence of the plant growth on the soil prevents erosion and can keep the soil cooler. Some cover crops, like alfalfa, even put nutrients back into the soil. This reduces the amount of fertilizer needed the following year. The application of fertilizer often requires the consumption of fossil fuels, which adds greenhouse gases to the atmosphere. In addition, a portion of the nitrogen fertilizer added to crops can be converted to greenhouse gases through soil processes.
Homeowners and landowners also have a role to play in keeping soil healthy. If you have a home garden, you, too, can practice no-till. Rotate your crops from year to year. If you have a lawn, use chemicals sparingly—if at all. And, consider planting a rain garden or other natural area on your land. Rain gardens capture water from rainfall and snowmelt, and allow the soil to clean the water naturally (for more information, see February’s blog post https://soilsmatter.wordpress.com/2015/01/21/how-do-rain-gardens-help-with-storm-water/ ).
In conclusion, soil can help reduce the effects of climate change. However, in order for the soil to help us, we need to keep the soil healthy through good practices.
-Answered by Eric Brevik, Dickinson State
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More educational materials can be found on various SSSA websites:
http://soils4teachers.org/ (K-12 Lesson Plans and Activities)
http://soils4kids.org (Just for kids!)
http://soils.org/iys (International Year of Soils, with a coloring book and monthly ideas for teachers and scientists!