Rosemary Alphonse

Agricultural soils generate nearly 70% of global anthropogenic N2O emissions, while also serving as both a source and sink of CO2. This study aimed to test the impact of surface and subsurface drip irrigation and the number of laterals on N2O and CO2 emissions. A field experiment was conducted from April―June 2025 using Edamame (Glycine max L. Merrill) as the test crop. Four treatments were applied at the Neve Ya’ar Research field with five replications, combining surface and shallow subsurface (20 cm) drip irrigation (DI and SDI, respectively) and fertigation with and without nitrification inhibitors and bio-stimulants. GHG fluxes were measured weekly using a large chamber (1.2×1.2×0.5m3) on planting beds and a smaller chamber (0.21×0.68×0.29m3) between beds. In all the treatments, fertigation influenced N2O and CO2 emissions. In one lateral treatment, N2O emissions from DI were similar to SDI (~3.63±0.51ng cm-2 s-1), yet significantly lower than the two laterals SDI (6.45±1.04 ng cm-2 s-1). Subsurface fertigation with nitrification inhibitors and bio-stimulants had a positive effect by decreasing N2O emissions (20%) compared to regular subsurface fertigation. Spatial variation was also observed: N2O emissions were lower on the plant beds than between them, while CO2 fluxes were significantly higher on the beds (89.4±6.2 vs. 29.6±6.3 ng cm-2 s-1). Overall, our findings highlight that in drip irrigation, the number of laterals directly affects N2O fluxes and that fluxes may be reduced through the use of nitrification inhibitors. It also highlights that in shallow SDI the area between plant beds may be N2O hotspots.