Reducing nitrous oxide emissions and optimizing nitrogen-use efficiency in dryland crop rotations with different nitrogen rates

Authors: Sainju, Upendra; GHIMIRE, RAJAN - New Mexico State University; MISHRA, UMAKANT - Argonne National Laboratory; JAGADAMMA, SINDHU - University Of Tennessee

Submitted to: Nutrient Cycling in Agroecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2020
Publication Date: 2/6/2020
Citation: Sainju, U.M., Ghimire, R., Mishra, U., Jagadamma, S. 2020. Reducing nitrous oxide emissions and optimizing nitrogen-use efficiency in dryland crop rotations with different nitrogen rates. Nutrient Cycling in Agroecosystems. https://doi.org/10.1007/s10705-020-10046-0.
DOI: https://doi.org/10.1007/s10705-020-10046-0

Interpretive Summary: Nitrous oxide is a potent greenhouse gas that contributes to global warming. Agricultural practices contribute 70% of the global nitrous oxide emissions. Improved management practices are needed to reduce nitrous oxide while enhancing crop yields. Researchers at ARS, Sidney, MT in collaboration with those from New Mexico State University, Argonne National Laboratory, and University of Tennessee reported that nitrous oxide emissions under continuous spring wheat and spring wheat-pea rotation can be reduced while crop yield can be increased using nitrogen fertilization rate at 100 kg N ha-1, regardless of crop rotations. Producers can sustain dryland crop yields while reducing nitrous oxide emissions using nitrogen fertilization rate at 100 kg N ha-1.

Technical Abstract: Information on management strategies to reduce N2O emissions and N fertilization rate while enhancing crop yield and N-use efficiency (NUE) under dryland cropping systems is limited. This study evaluated the effect of dryland crop rotation and N fertilization rate on N2O emissions, annualized crop grain yield, emission factor, and yield-scaled- and NUE-scaled N2O emissions from 2012 to 2016 in the northern Great Plains, USA. Crop rotations included continuous spring wheat (Triticum aestivum L.) (CW) and spring wheat-pea (Pisum sativum L.) (W-P) under the no-tillage system and N fertilization rates were 0, 50, 100, and 150 kg N ha-1 to spring wheat. The N2O fluxes were measured from April 2012 to March 2016 at 3 to 14 d intervals using static chamber along with soil temperature and water content throughout the year. The N2O fluxes peaked immediately following N fertilization, intense precipitation, and snowmelt, accounting for 75-85% of the total annual flux, as N input, soil temperature, and water content increased. Cumulative N2O flux usually increased with N fertilization rates, but varied with crop rotations for various N rates and years. Annualized crop yield and NUE were greater with W-P than CW for 0 kg N ha-1 in all years, but the trend reversed for 100 kg N ha-1 in 2013 and 2015. Crop yield was greater for 100 kg N ha-1 than other N rates. The NUE and N fertilizer-scaled N2O emissions decreased with increased N rate, but yield-scaled- and NUE-scaled N2O emissions were greater for150 kg N ha-1 than other N rates. The emission factor averaged 0.24 for all treatments. Nitrous oxide emissions can be minimized while dryland crop yields and NUE can be optimized for 100 kg N ha-1, regardless of crop rotations.