Let's say you're a corn farmer and you're farming on low-fertility land. How do you make this soil healthier and more fertile? Many farmers think that if they add a lot of nitrogen fertilizers, those nutrients will be stored in the soil along with carbon as organic matter when microbes break down crop residues. But new research from the University of Illinois suggests those efforts may not work for poor soils. A new study published in Soil Science Society of America Journal compared the decomposition of corn residues at high and low fertility, p nitrogen fertilizers and without them. The results were a surprise. "Corn residue decomposes significantly faster in poor, low-nitrogen soils compared to fertile soil , especially when we added nitrogen, which stimulated microbial activity. This was a surprise, based on our earlier findings showing that high-nitrogen corn residues broke down faster," said study author Tanjila Jesmin, a doctoral student in the Department of Natural Resources and Environmental Sciences (NRES), which is part of the University of Agricultural, Consumer and Environmental Sciences (ACES) at the U of I. Richard Mulvaney, a professor at NRES and co-author of the study, explained that poor soils have fewer aggregate particles, the small rocky nuggets that house soil microbes and give the soil its structure. With fewer aggregates, free-living microbes move freely in the soil, encounter carbon more often, absorb it, and produce carbon dioxide as a byproduct.

(of Illinois in Urbana-Champaign)