Nitrous oxide emissions and wheat yield responses to nitrogen rate and source in contrasting rainfed cropping systems in Morocco

The use of nitrogen (N) fertilization in agricultural production contributes to soil nitrous oxide (N 2 O) emissions, yet data on the magnitude of those emissions are scarce for rainfed cropping systems in North Africa. This study quantified N 2 O fluxes under five fertilizer regimes in two contrasting Moroccan agroclimatic zones: a wetter site (Larache) and a drier site (Settat). Treatments included current farmer practices (CFP), regional recommended rates with a conventional source (RFP), RFP plus a urease inhibitor (MCDHS), a high N level (HNL), and unfertilized control. Results showed contrasting responses between sites: in Larache, N 2 O emissions increased exponentially when N input exceeded 140 kg ha -1 (RFP), peaking at 7.14 kg N 2 O-N ha -1 under HNL, with an average emission factor of 1%; While in Settat, emissions rose with the application of N but plateaued beyond the N rate of 39 kg N ha -1 (CFP), with a mean EF of 0.6%. The urease inhibitor (MCDHS) increased grain yield by 27% in Larache without reducing emissions, whereas, in Settat, it had no significant effect on yield or cumulative N 2 O emissions compared to RFP. A generalized additive model identified soil water-filled pore space (WFPS) as the main driver of N 2 O fluxes across both sites. Overall, these findings indicate that yield and N 2 O responses to fertilization are strongly regulated by environmental conditions and that the IPCC Tier 1 emission factor underestimates emissions in Morocco wheat systems, highlighting the need for region-specific Tier 2 emission factors. • First field-based N 2 O emission study from rainfed wheat systems in North Africa • Site-specific N responses reveal divergent emission patterns in contrasting rainfed wheat agroecosystem in Morocco. • Yield-scaled N 2 O emissions were high and NUE is low in wheat cropping system in Morocco. • Soil moisture, expressed as water-filled pore space, is the primary environmental driver of N 2 O fluxes.