N2O emission in maize-crops fertilized with pig slurry, matured pig manure or ammonium nitrate in Brittany

N2O is a potent greenhouse gas and solutions have to be sought to reduce its emission from agriculture. This work evaluates N2O emission from maize-crop (Zea mays) fields submitted to different organic or mineral fertilizers (pig slurry, matured pig manure or ammonium nitrate) in Brittany (France). N2O emission was evaluated along a year in two experimental sites receiving 110 or 180 kg N ha(-1) as ammonium nitrate or pig slurry and 180 or 132 kg N ha(-1) as ammonium nitrate or matured pig manure at Champ Noel and Le Rheu experimental plots, respectively. N2O emission was evaluated by interpolation method of periodic fluxes on the field scale and by simulation with NOE algorithm using measured soil characteristics such as N content and gravimetric moisture and other soil biological properties determined in a previous study (potential denitrifying activity, N2O/[N2O + N-2] ratio during denitrification) or drawn from literature. On the whole N2O emissions vary between 0.3 kg N ha(-1) year(-1) in an unfertilized plot and 2-4 kg N ha(-1) year(-1) under ammonium nitrate fertilization. They were higher under N fertilizer application than without N fertilizer but no significant effect of type of N fertilizer was observed on either site. However, N2O losses immediately after fertilizer application were higher under pig slurry and matured pig manure, while measured and predicted fluxes showed that greater N2O losses occurred from summer to winter under ammonium nitrate application. This could be mainly explained by higher mineral N contents at Le Rheu and higher N2O/(N2O + N-2) ratio at both sites. The NOE model predicted higher annual N2O emission and emission factor with ammonium nitrate at Champ Noel only and similar emissions for both treatments at Le Rheu. These results suggest that in this climate and soil context the use of pig slurry or matured pig manure did not have a stimulating impact on N2O emissions in comparison with a plot receiving a mineral fertilization. (c) 2007 Elsevier B.V. All rights reserved.