Modeling of Nitrogen Use Efficiency in Lettuce Culture (Lactuca sativa): Isotopic Nitrogen (15 N) and AquaCrop

The present study is highlighted through an experiment carried out over two consecutive years 2014–2016, in the sub humid region of Algiers. The methodology adopted concerns the variation of optimal nitrogen doses and their effects on the evolution of lettuce (Lactuca sativa L.) cultivation, whose socio-economic impact is proven, using isotopic nitrogen (15 N) and the AquaCrop model. The experimental design adopted is of the complete randomized block type, with four (04) levels: 0 (control), 60, 120, and 180 kg N/ha with four (04) replicates. The results obtained showed that the 120 kg N/ha dose is the efficient dose to cover the nitrogen requirements of lettuce with an efficiency of 74.48%. The accuracy of the model in calibration was tested using the following statistical indicators: R2, nRMSE, and d, which are, respectively, 0.64 < R < 0.81; 18 < nRMSE <46.3 and 0.78 < d < 0.94 for canopy coverage and 0.92 < R < 0.98; 21.6 < nRMSE <34.5 and 0.91 < d < 0.96 for dry biomass. The AquaCrop model could be recommended as a practical tool to better manage agricultural practices including fertilization.