In a unique farm-level study, researchers at the University of Minnesota and Colorado State University have shown that best farming practices can significantly reduce the carbon footprint of corn production. Detailed production data from family farms in and around southwest Minnesota were analyzed to model carbon emissions under various scenarios while maintaining high yields. Thousands of scenarios were evaluated. The study shows that by applying fertilizer at optimal rates and using tillage practices that minimally disturb the soil, corn production can capture carbon rather than emit it.
In 2011, researchers collected and analyzed detailed, three-year survey data from 40 large, family owned farms supplying a biorefinery in southwest Minnesota. The study published in 2013 showed the respondents had a 25% lower carbon footprint than the USA corn average.
In the current study, the data from these farms was modeled by CSU to assess the effect of best management practice scenarios. GHG emissions could be reduced by 46% simply by limiting nitrogen fertilizer application from current rates of 225 kg per hectare (ha) to the optimal rate of 150 kg. In addition, by using minimal tillage practices, carbon emissions could be reduced 65% compared to current practices. If fertilizer application rates were managed at the 150 kg/ha rate and no-till practices were used, the CSU DayCent model showed carbon sequestered at the rate of 55g of carbon per bushel of corn.
The principle author of the study was John Sheehan, PhD. The CSU team, led by Keith Paustian, PhD included Kendrick Killian and Stephen Williams of the Natural Resources Ecology Laboratory. A review panel included experts from the World Wildlife Fund (WWF), The Nature Conservancy and the Environmental Defense Fund (EDF.)
The CSU team modeled over 2000 farm practice scenarios to determine that nitrogen application rate and tillage practice were the two most important. Displacing some portion of synthetic fertilizer with manure had a positive impact on GHG emissions in all scenarios. But, prudent use of nitrogen fertilizer trumps all! Above around 150 kg N per hectare, no further yield benefit occurs.