Agriculture is the focus of a new report on climate change and greenhouse gases, showing the industry's role in the problem and how it can be part of the solution.
Bruce Babcock, an Iowa State University economics professor and director of the Center for Agricultural and Rural Development, co-chaired a 15-member task force that developed the Council for Agricultural Science and Technology report. "It's a reference guide on both the science and the policy issues that surround greenhouse gas emissions," he says.
The report shows three gases - carbon dioxide, nitrous oxide and methane - have risen dramatically during the past century. These account for more than 80 percent of the human-induced global warming that's occurring.
Greenhouse gases stem from many different sources, but Babcock says agriculture is linked to these top three. "We need to take into account the multiple gases that result from soil fertility and livestock production, and the net emissions that are tied to agriculture," he says.
While agriculture is a source of greenhouse gases, it also can serve as a "sink" by removing carbon dioxide from the atmosphere and storing the carbon in the soil. The report shows this practice, known as carbon sequestration, can be achieved through management practices such as crop rotations with high-residue yields, conservation tillage, conservation reserves on marginal cropland, grassland and grazing management improvements and rehabilitation of degraded land.
The report also highlights steps producers can take to reduce emissions. These include increasing the efficiency of farm inputs such as fuel, fertilizers and pesticides, increasing the production of agricultural biofuels to replace fossil energy emissions, and capturing or preventing emissions from animal manure storage.
"This report shows it is technically feasible for farmers to sequester carbon in the soil and reduce other emissions," says Babcock. "But there isn't an economic incentive for them to do so. Until the United States is obligated through an international agreement, or we adopt a goal to reduce greenhouse gas emissions, it's not going to happen."
The report does outline possible contracts that would allow farmers to receive payments if they store carbon in soil on their land. "But the process could be reversed simply by tillage," he adds. "Incentives will be needed to keep the carbon sequestered."
The report is available online at http://www.cast-science.org or by calling CAST at 515-292-2125.