Carbon Farming as a Carbon Negative Technology

Abstract:

Carbon farms have a pivotal role in national and international efforts to mitigate and adapt to climate change. A carbon farm in its broadest sense is one that reduces greenhouse gas (GHG) emissions or captures and holds carbon in vegetation and soils. Their capacity to remove carbon from the air and store it safely and permanently, while providing additional human and ecosystem benefits, means they could contribute significantly to national efforts to stabilize or reduce GHGs.

We examine carbon farms in the context of corn and soybean production agriculture. We illustrate, using Iowa data but with relevance across United States corn and soybean production, the potential for carbon farms to reduce human GHG emissions and sequester carbon permanently at a rate that has meaningful impact on global greenhouse gas concentration. Carbon has been viewed as a next generation cash crop in Iowa for over a decade. The carbon farm perspective, however, goes beyond carbon as cash crop to make carbon the center of an entire farm enterprise. The transformation is possible through slight adjustment crop practices mixed with advances in technology to sequester carbon through biochar.

We examine carbon balance of Iowa agriculture given only the combination of slight reduction in fertilizer and sequestration by biochar. We find the following.

• Iowa carbon farms could turn Iowa agriculture into a carbon sink. The estimated range of GHG reduction by statewide implementation of carbon farms is 19.46 to 90.27 MMt CO₂-equivalent (CO₂-e), while the current agricultural CO₂-e emission estimate is 35.38 MMt CO₂-e.
• Iowa carbon farm GHG reduction would exceed Iowa GHG reduction by wind energy (8.7 MMt CO₂-e) and could exceed combined reductions from wind energy and corn grain ethanol (10.7 MMt CO₂-e; 19.4 MMt CO₂-e combined). In fact, Iowa carbon farms alone could exceed GHG reduction from national corn grain ethanol production (39.6 MMt CO₂-e).
• A carbon price accessible to agricultural producers could generate revenue at carbon price of $15 per t CO₂-e and $45 per t CO₂-e in the range of $415 - $475 ha^-1 and $440 - $620 ha^-1, respectively.
• As a carbon negative technology, carbon farms could provide the backbone technology for a carbon neutral transportation biofuel through reduced indirect land use change.