Integrating perennial crops into corn and soybean rotations doesn’t consistently increase the ability of soils to store carbon, according to a new study that defies expectations for how diverse cropping systems affect carbon sequestration.
The study …. compares the carbon-storage performance of conventional corn-soybean rotations with cropping systems that incorporate perennials and small grains such as oats. Diversified crop rotations protect water quality and have other environmental benefits, but Michael Castellano, a professor of agronomy and co-author of the study, said recent experiments show that improved carbon storage isn’t necessarily among those benefits.
Atmospheric carbon acts as a greenhouse gas, but storing carbon in the soil keeps it out of the atmosphere. So researchers are analyzing various agricultural production methods that might enhance carbon storage.
…[The] findings run contrary to a widely held assumption that putting more roots in the ground for longer periods would increase the carbon content of soil, Castellano said.
The ISU experiments involved three research farms in Iowa where diversified crop rotations grew alongside corn-soybean systems for years at a time. The researchers compared soil carbon content from the corn-soybean systems with that of the diversified systems and found no consistent differences ….