Split Application of Urea Does Not Decrease and May Increase Nitrous Oxide Emissions in Rainfed Corn

• DOI: 10.2134/agronj14.0411
• Publication Date: 2014-12-16T18:11:21Z
• Authors: Rodney T. Venterea; Jeffrey A. Coulter
• Keywords: Nitrous oxide; Growing season; Rotation system

Modification of N fertilizer application timing within the growing season has potential to reduce soil nitrous oxide (N 2 O) emissions but limited data are available assess its effects. We compared cumulative (cN following urea applied corn ( Zea mays L.) in a single (SA) at planting or three split applications (SpA) over season. For both SA and SpA, granular was broadcast incorporated six rates phase corn–soybean [ Glycine max (L.) Merr.] rotation continuous system two seasons. Daily O flux measured using chambers on 35 dates 2012 40 2013 nitrate‐N concentration weekly. Split did not affect grain yield cN O. Across rotations, 55% greater with SpA 2012. Increased likely resulted from prolonged dry period before second followed by large rainfall events third application. years increased 57% when maximum rate applied. Exponential relationships between explained 62 74% variance area‐based 54% yield‐based Applying coincide periods high crop demand does necessarily may increase emissions.