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More cattle and forage would yield less greenhouse gasMore cattle and forage would yield less greenhouse gas

New ISU research shows more cattle in Iowa would limit ag-related greenhouse gas emissions.

April 18, 2016

3 Min Read

A new study co-authored by an Iowa State University researcher indicates that an increase in cattle production, and associated forage land, on Iowa’s agricultural landscape could lead to lower greenhouse gas emissions. The research, published recently in the peer-reviewed Journal of Soil and Water Conservation, found that cattle production yields a smaller percentage of greenhouse gas emissions than row-crop cultivation. 


That suggests integrating more cattle production into Iowa’s agricultural portfolio may cut the state’s greenhouse gas emissions and lead to other environmental benefits, says Mark Rasmussen, director of the Leopold Center for Sustainable Agriculture at ISU and co-author of the study.

More forage would raise the land’s carbon storage capacity
But those benefits largely would depend on new forage land on which the cattle would feed, Rasmussen says. More forage and pasture land means more roots in the ground holding soil in place and increasing the land’s capacity to store carbon, he explains.

“Our research paper shows that bringing more cattle back to Iowa and, as a consequence, adding more land for forage and perennial grasses, would actually be beneficial in the context of greenhouse gas emissions that result from agricultural activities,” he says. “It’s a way of putting more carbon away than you’re putting into the atmosphere.”

Cattle produce the greenhouse gas methane through their ruminant digestive process. But those emissions make up a smaller percentage of anthropogenic, or man-made, emissions than row-crop production, Rasmussen says. The study found that ruminants generate 11.6% of total anthropogenic emissions, while cropping and soil-associated emissions contribute 13.7%.

Converting row-crop acres into forage would cut carbon emissions
On the other hand, converting acres currently devoted to crops into forage land would cut down on carbon emissions that result from organic matter released by soil erosion, Rasmussen says. More forage or perennial grasses would improve the environment in other ways as well.

Less runoff from fields would protect water quality, and more grazing land would create new habitat for pollinating insects, he notes. And adding forages such as alfalfa in longer crop rotations can actually build organic matter in the soil over the course of a few years. “Soil degradation is a long, gradual process so it’s easy to ignore sometimes,” Rasmussen says. “Soil has been ignored for a long time, but this might be a way of rehabilitating vulnerable land.”

Converting ground from row crop to cattle grazing wouldn’t be easy
Rasmussen acknowledged that serious challenges stand in the way of integrating more cattle into Iowa’s agricultural infrastructure. “It would take a drastic change in current agricultural practices to produce the result suggested in this report,” he says.

Converting land from row crops to grazing land for cattle would require a significant investment in new facilities and equipment. And grass-fed cattle take more time to get to market than grain-fed cattle and require different genetics. He also cautions that the best results depend on cattle production that practices responsible use of forage land. Overgrazing a section of land can actually result in more soil erosion, he notes.

He says prior research into the impact of agriculture on greenhouse gas emissions focused too much on cattle emissions and not enough on soil erosion. “I’m sure there will be criticisms and discussions on this study, but that’s great. We need to talk more about the idea of bringing soil into this overall equation,” says Rasmussen. 

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