Quantifying nitrogen losses in oil palm plantations: models and challenges
- 1CIRAD, UPR Systèmes de pérennes, 34398 Montpellier, France
- 2ITK, CEEI CAP ALPHA Avenue de l'Europe, 34830 Clapiers, France
- 3UMR ECOSYS, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France
- 4World Agroforestry Centre (ICRAF), Southeast Asia Regional Programme, Bogor, Indonesia
- 5SMART Research Institute, Jl. Tengku Umar 19, Pekanbaru 28112, Indonesia
- 6College of Science and Engineering, James Cook University, Cairns QLD 4878, Australia
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.