Understanding the role of carbon in agriculture – Part 3
Ecosystem services—can you have your cake and eat it, too?
Part 2 of this series introduced a futuristic scenario of carbon (C) negative farming, whereby above ground biomass is used to displace fossil fuels and below ground crop root systems are used to capture and store excess CO2 carbon from the atmosphere. Of course, with our current reliance on fossil fuels, we’re a long way off from that scenario today. Nonetheless, a quick review of the ecosystem services provided with C-smart farming using best management practices is probably worth the effort. In this day and age, industries touting their environmental friendliness do so at the risk of being accused of “greenwashing” by pundits. Perhaps with agriculture though, society may take for granted certain ecosystem services because they’ve always been there, unbeknownst to the casual observer.
Let’s start with perhaps the most overlooked or taken for granted agricultural ecosystem service of oxygen (O2) generation. Using our example corn field from Part 1, we can calculate the amount of O2 generated. Recall we calculated 34,679 pounds of CO2 assimilated by a typical (180 bushel per acre) mid-Michigan corn farm. From our high school biology lessons, we learned that for every mole of CO2 autotrophically fixed, a mole of O2 is released. This gives us an O2 generation of 25,200 pounds per acre. Amped up to the 2020 national corn growers champion yield of 476 bushels per acre, 66,640 pounds per acre of O2 are generated.
Another often overlooked method of providing ecosystem service by capturing and storing carbon is inherent in the livestock sector of agriculture. In the simplest form, livestock harvest autotrophically (photosynthetically) derived C by consuming plants and in turn produce food products and manure. By applying C-smart best management practices to manure handling and application, C can be effectively captured and stored. A good example of this is in using anaerobic digestion to produce biogas used to generate electricity and offset fossil fuel use. This is currently being done at the Michigan State University Dairy Facility. Electricity generated is used on campus displacing fossil fuel consumption and emissions. Furthermore, residuals from the anaerobic digestion process are land applied to agricultural land using C-smart best management practices enabling a fraction of the remaining C to be incorporated into soil organic matter for long-term C storage.
Many ecosystem services generated from the implementation of C-smart best management practices relate directly to increasing soil organic matter levels. These include decreasing soil erosion, increasing water permeability, conserving water for crop uptake, improving soil structure, increasing the rate of spring soil warm up, etc. All of these agronomic and environmental ecosystem services have value to farmers and/or society as a whole. And if the current private and public sector policy discussions on carbon credits, carbon financing, and carbon payments bear fruit, direct monetary benefits may be available to farmers in addition to the agronomic benefits already realized. It appears you can have your carbon cake and eat it, too!