Quantifying nitrogen losses in oil palm plantations: models and challenges
Lénaïc Pardon1,6,Cécile Bessou1,Nathalie Saint-Geours2,Benoît Gabrielle3,Ni'matul Khasanah4,Jean-Pierre Caliman1,5,and Paul N. Nelson6Lénaïc Pardon et al.Lénaïc Pardon1,6,Cécile Bessou1,Nathalie Saint-Geours2,Benoît Gabrielle3,Ni'matul Khasanah4,Jean-Pierre Caliman1,5,and Paul N. Nelson6
Received: 04 May 2016 – Discussion started: 17 May 2016 – Revised: 31 Aug 2016 – Accepted: 07 Sep 2016 – Published: 30 Sep 2016
Abstract. Oil palm is the most rapidly expanding tropical perennial crop. Its cultivation raises environmental concerns, notably related to the use of nitrogen (N) fertilisers and the associated pollution and greenhouse gas emissions. While numerous and diverse models exist to estimate N losses from agriculture, very few are currently available for tropical perennial crops. Moreover, there is a lack of critical analysis of their performance in the specific context of tropical perennial cropping systems. We assessed the capacity of 11 models and 29 sub-models to estimate N losses in a typical oil palm plantation over a 25-year growth cycle, through leaching and runoff, and emissions of NH3, N2, N2O, and NOx. Estimates of total N losses were very variable, ranging from 21 to 139 kg N ha−1 yr−1. On average, 31 % of the losses occurred during the first 3 years of the cycle. Nitrate leaching accounted for about 80 % of the losses. A comprehensive Morris sensitivity analysis showed the most influential variables to be soil clay content, rooting depth, and oil palm N uptake. We also compared model estimates with published field measurements. Many challenges remain in modelling processes related to the peculiarities of perennial tropical crop systems such as oil palm more accurately.
Oil palm is the most rapidly expanding tropical perennial crop, which raises environmental concerns, notably related to the use of nitrogen fertilisers and consequent pollution. We tested existing models to estimate N losses in plantations. Results were highly variable and highlighted the remaining challenges to improve the reliability of these models in order to steer towards more sustainable practices.
Oil palm is the most rapidly expanding tropical perennial crop, which raises environmental...