title: Lessons from temporal and spatial patterns in global use of N and P fertilizer on cropland.
abstract: In recent decades farmers in high-income countries and China and India have built up a large reserve of residual soil P in cropland. This reserve can now be used by crops, and in high-income countries the use of mineral P fertilizer has recently been decreasing with even negative soil P budgets in Europe. In contrast to P, much of N surpluses are emitted to the environment via air and water and large quantities of N are transported in aquifers with long travel times (decades and longer). N fertilizer use in high-income countries has not been decreasing in recent years; increasing N use efficiency and utilization of accumulated residual soil P allowed continued increases in crop yields. However, there are ecological risks associated with the legacy of excessive nutrient mobilization in the 1970s and 1980s. Landscapes have a memory for N and P; N concentrations in many rivers do not respond to increased agricultural N use efficiency, and European water quality is threatened by rapidly increasing N:P ratios. Developing countries can avoid such problems by integrated management of N, P and other nutrients accounting for residual soil P, while avoiding legacies associated with the type of past or continuing mismanagement of high-income countries, China and India.
authors.affiliation: Department of Earth Sciences - Geochemistry, Faculty of Geosciences, Utrecht University, P.O. Box 80021, 3508 TA Utrecht, The Netherlands.|PBL Netherlands Environmental Assessment Agency, PO Box 30314, 2500 GH The Hague, The Netherlands.
authors.forename: A F
authors.initials: AF
authors.lastname: Bouwman
authors.affiliation: Department of Earth Sciences - Geochemistry, Faculty of Geosciences, Utrecht University, P.O. Box 80021, 3508 TA Utrecht, The Netherlands.|PBL Netherlands Environmental Assessment Agency, PO Box 30314, 2500 GH The Hague, The Netherlands.
authors.forename: A H W
authors.initials: AH
authors.lastname: Beusen
authors.affiliation: PBL Netherlands Environmental Assessment Agency, PO Box 30314, 2500 GH The Hague, The Netherlands.
authors.forename: L
authors.initials: L
authors.lastname: Lassaletta
authors.affiliation: Farming Systems Ecology group, Wageningen University, PO Box 430, 6700AK Wageningen, The Netherlands.
authors.forename: D F
authors.initials: DF
authors.lastname: van Apeldoorn
authors.affiliation: PBL Netherlands Environmental Assessment Agency, PO Box 30314, 2500 GH The Hague, The Netherlands.
authors.forename: H J M
authors.initials: HJ
authors.lastname: van Grinsven
authors.affiliation: Department of Earth Sciences - Geochemistry, Faculty of Geosciences, Utrecht University, P.O. Box 80021, 3508 TA Utrecht, The Netherlands.|Center for Earth System Science, Tsinghua University, 100084 Beijing, China.
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Plant Production Systems Group, Wageningen University, P.O. Box 430, 6700 AK Wageningen, The Netherlands.
authors.forename: M K
authors.initials: MK
authors.lastname: Ittersum van