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ISU study casts carbon sequestration claims into doubt

Livestock manure as an alternative to commercial fertilizer has been hailed as a net good for crops and soil alike – especially when combined with cover crops.

However, a study from ISU might poke holes in any “silver bullet” claims about the combination of longer, more diverse crop rotations fertilized with manure. It’s not that the practice is not beneficial, the study claims, but carbon sequestration might not be as beneficiary as some have asserted.

The findings, published recently in Nature Sustainability, counter long-standing assumptions and could have implications for various carbon-market initiatives designed to help mitigate climate change, said Wenjuan Huang, assistant professor of ecology, evolution and organismal biology.

Carbon levels in the soil didn’t change over 20 years, said Huang, one of the study’s lead co-authors, in a post on the study. She adds, however, that there is value to the practice.

The study is based on data collected from the ongoing field trial at Iowa State’s Marsden Farm just east of Boone, which since 2001 has compared a traditional two-year corn-soybean rotation to three- and four-year systems that mix in a year or two of alfalfa, clover or oats and replace most of the synthetic nitrogen fertilizer for corn with cattle manure.

Read more on the study here.

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