Agricultural practices in oil palm plantations and their impact on hydrological changes, nutrient fluxes and water quality in Indonesia: a review
Résumé
Rapid expansion of oil palm (Elaeis guineensis Jacq.) cultivation in Southeast Asia raises environmental concerns about deforestation and greenhouse gas emissions. However, less attention was paid to the possible perturbation of hydrological functions and water quality degradation. This work aimed to review (i) the agricultural practices commonly used in oil palm plantations, which potentially impact hydrological processes and water quality and (ii) the hydrological changes and associated nutrient fluxes from plantations. Although many experimental trials provide clear recommendations for water and fertilizer management, we found that few studies investigated the agricultural practices actually followed by planters. Our review of hydrological studies in oil palm plantations showed that the main hydrological changes occurred during the first years after land clearing and seemed to dissipate with plant growth, as low nutrient losses were generally reported from plantations. However, most of those studies were carried out at the plot scale and often focus on one hydrological process at a single plantation age. So, there is insufficient information to evaluate the spatiotemporal fluctuations in nutrient losses throughout the entire lifespan of a plantation. Furthermore, few studies provided an integrated view at the watershed scale of the agricultural practices and hydrological processes that contribute to nutrient losses from oil palm plantations and the consequences for surface and groundwater quality. Future research efforts need to understand and assess the potential of oil palm plantations to change hydrological functions and related nutrient fluxes, considering agricultural practices and assessing water quality at the watershed scale.