Carbon balance is all about how much carbon a plant adds to soil and how much is lost to harvest and erosion. Add more than you take off the field, and you build soil carbon. Enlarge Unlike many crops, corn, a C4 plant, can be easily bred for key traits. With the rise of improved breeding and plant genetics came bigger corn crops and higher yields of overall biomass on a given amount of land. That has lead available corn stover residue to more than quadruple. That means more carbon from the atmosphere can be delivered to the soil. Enlarge