Nitrous oxide emission from forage plantain and perennial ryegrass swards is affected by resource allocation dynamics belowground- Dataset

The experiment was conducted in a greenhouse located in the University of Kiel, northern Germany. The experimental units consisted of a 3x3 factorial design, comprising three N fertilizer (urea) rates (0, 150 and 300 kg N ha-1 equivalents, subsequently called N0, N150 and N300) applied in three splits, and the three swards types (L. perenne (LP), L. perenne – P. lanceolata (LP+PL), and P. lanceolata (PL)), replicated four times and arranged in a completely randomized block design. Gas samples were analyzed for N2O through a gas chromatograph. N2O-N fluxes were calculated by linear regression between measured N2O-N concentrations and sampling time. Accumulated N2O emissions over the experimental period (83 days) for each replicate. Aboveground biomass (AGB) was harvested at a fixed time period of three weeks after the stabilization cuts while stubbles and belowground biomass (BG) measured at the end of the experiment. The ratio of N uptake by plants to fertilizer N input constituted N uptake efficiency (NUpE), and N use efficiency (NUE) was calculated as (treatment N uptake – control)/N applied. Soil samples were obtained at each biomass harvest using procedures described by Pijlman et al. (2020). The kinetics of hydrolytic enzymes involved in the N cycle was measured by fluorimetric microplate assays of 7-amino-4-methyl coumarin (AMC) (Marx et al., 2005; Stemmer et al., 1998).