H3 Study for Greenhouse gas Reduction through Agricultural Carbon Enhancement network in Mandan, North Dakota Greenhouse gas management and understanding the carbon emissions associated with land management decisions is a growing public concern and an increasingly important component to sustainable agricultural systems. Fertilization with nitrogen is known to influence emissions of greenhouse gases from soils. Less clear is how the timing of fertilization impacts emissions. We performed an experiment to determine if emissions could be reduced by adjustment of fertilization timing alone using a maize field in production. We found fertilization of plots with urea in the early-spring resulted in lower greenhouse gas emissions than fertilization of similar plots with urea in the late-spring. This was primarily due to greater emissions of carbon dioxide at the soil surface when fertilized at temperatures greater than 10°C. The difference between treatments, when integrated over a 5-month growing season, was 548 kg C ha-1. Yields were similar for both treatments. Fertilizing at cooler temperatures resulted in a substantial carbon “savings” without affecting yield. This study indicates fertilization timing may be a management option for reducing soil carbon losses and greenhouse gas emissions. Additional study is needed to determine if this effect is consistent across years.