New trick helps show value of conservation tillage
Carbon sequestration -- storing soil carbon using conservation tillage practices -- is a slow process that can take years to show results. But there is a way to measure soil carbon value more quickly.
Ohio State University agricultural engineers and soil fertility specialists have found that breaking down total soil carbon into its various components and analyzing each one provides a more immediate picture of carbon sequestration and its benefits. Randall Reeder, an Ohio State University (OSU) Extension agricultural engineer and conservation tillage specialist, says the information could help growers see the value of conservation tillage practices when it comes to carbon sequestration efforts.
"If you are just measuring total soil carbon, you don't see much difference between no-till and intensive tillage practices when it comes to carbon storage. It may take 10 or 20 years to show a significant change," Reeder says. "But by measuring the components of soil carbon, you can see that good things are happening in no-till fields. The results verify that no-till has value without having to wait so many years to prove it."
Reeder and his colleagues (OSU Extension educator Alan Sundermeier and Rafiq Islam, an OSU South Centers at Piketon soil fertility specialist) compared carbon sequestration between no-till and tilled fields after five years at OARDC's Northwest Agricultural Research Station near Hoytville, Ohio.
They found no difference between tilled and no-till fields when total soil carbon was measured. However, when the carbon was broken down into fractions (microbial carbon, active carbon, particulate organic matter and extractable carbon) and each one was measured, researchers found signficant results with carbon storage in no-till fields.
"Everyone hears about total carbon, but what really counts is the components of carbon and how those change based on specific production practices," says Reeder. "We couldn't see the differences when we measured total carbon, but when we tested the soil for components of carbon we found that they can be early indicators of carbon sequestration."
Islam, who analyzed the soil samples at his lab in Piketon, says measuring total carbon alone doesn't provide the full picture because much of the carbon is locked in the soil and unavailable for plants. Certain fractions of carbon, however, such as microbial carbon, are available for plants to use. The most significant measure of carbon sequestration came from microbial carbon.
"For every 100 pounds of total carbon in soil, about one pound is microbial biomass carbon, 10 to 30 pounds are active carbon and 40 to 50 pounds are particulate organic carbon," Islam says. "Increasing microbial carbon, even doubling it, is good for plant growth even though it may increase total carbon very little."
Reeder and his colleagues will also present findings on the impacts of compaction on carbon sequestration. By analyzing the components of carbon, the researchers found that compaction reduces carbon sequestration.