Growing Season Nitrous Oxide Emissions from a Gray Luvisol as a Function of Long-term Fertilization History and Crop Rotation

A field study conducted over three growing seasons (2013–2015) assessed the effect of long-term fertilization history and crop rotation on growing season nitrous oxide (N2O) and carbon dioxide (CO2) emissions, wheat yield, wheat N uptake, N2O emission intensity, and soil properties on a Gray Luvisol soil. Long-term fertility treatments included check, manure, NPKS, NPK, and PKS fertilizers in two contrasting crop rotations: 2 yr wheat (Triticum aestivum L.) – fallow (WF), and 5 yr wheat (T. aestivum L.) – oat (Avena sativa) – barley (Hordeum vulgare L.) – alfalfa (Medicago sativa) – brome (Bromus tectorum) hay (WOBHH). Rotation significantly affected cumulative growing season N2O emissions, and within each rotation, long-term fertilizer or manure N additions increased N2O emissions over the check. Average, cumulative growing season N2O emissions in the 5 yr rotation were 1.29 kg N2O-N ha-1, significantly higher than the 0.58 kg N2O-N ha-1 in the WF rotation, but N2O emission intensities were comparable between the two rotations. Cumulative N2O emissions were positively correlated to total soil N (0–15 cm) and wheat N uptake, but N2O emission intensities were negatively correlated to total soil N. However, it is uncertain whether this result extends to annual emission intensities because of a lack of nongrowing season measurements.