Aim Anthropogenic additions of nitrogen (N) are expected to drive terrestrial ecosystems toward greater phosphorus (P) limitation. However, a comprehensive understanding of how an ecosystem's P cycle responds to external N inputs remains elusive, making model predictions of the anthropogenic P limitation and its impacts largely uncertain. Location Global. Time period 1986‐2015. Major taxa studied Terrestrial ecosystems. Methods We conducted a meta‐analysis including 288 independent study sites from 192 articles to evaluate global patterns and controls of 10 variables associated with ecosystem P cycling under N addition. Results Overall, N addition increased biomass in plants (+34%) and litter (+15%) as well as plant P content (+17%), while decreasing P concentrations in plants and litter (−8% and −11%, respectively). N addition did not change soil labile P or microbial P, but enhanced phosphatase activity (+24%). The effects of N addition on the litter P pool and soil total P remained unclear due to significant publication biases. The response of P cycling to N addition in tropical forests was different from that in other ecosystem types. N addition did not change plant biomass or phosphatase activity in tropical forests but significantly reduced plant P and soil labile P concentrations. The shift in plant P concentration under N addition was negatively correlated with the N application rate or total N load. N‐induced change in soil labile P was strongly regulated by soil pH value at the control sites, with a significant decrease of 14% only in acidic soils (pH < 5.5). Main conclusions Our results suggest that as anthropogenic N enhancement continues in the future it could induce P limitation in terrestrial ecosystems while accelerating P cycling, particularly in tropical forests. A quantitative framework generated on the basis of this meta‐analysis is useful for our understanding of ecosystem P cycling with N addition, and for incorporating the anthropogenic P limitation into ecosystem models used to analyse effects of future climate change.

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Abstract. Increases in observed atmospheric concentrations of the long-lived greenhouse gas nitrous oxide (N 2 O) have been well documented. However, information on eventrelated instantaneous emissions during fertilizer applications is lacking. With the development of fast-response N 2 O analyzers, the eddy covariance (EC) technique can be used to gather instantaneous measurements of N 2 O concentrations to quantify the exchange of nitrogen between the soil and atmosphere. The objectives of this study were to evaluate the performance of a new EC system, to measure the N 2 O flux with the system, and finally to examine relationships of the N 2 O flux with soil temperature, soil moisture, precipitation, and fertilization events. An EC system was assembled with a sonic anemometer and a fast-response N 2 O analyzer (quantum cascade laser spectrometer) and applied in a cornfield in Nolensville, Tennessee during the 2012 corn growing season (4 April-8 August). Fertilizer amounts totaling 217 kg N ha −1 were applied to the experimental site. Results showed that this N 2 O EC system provided reliable N 2 O flux measurements. The cumulative emitted N 2 O amount for the entire growing season was 6.87 kg N 2 O-N ha −1 . Seasonal fluxes were highly dependent on soil moisture rather than soil temperature. This study was one of the few experiments that continuously measured instantaneous, high-frequency N 2 O emissions in crop fields over a growing season of more than 100 days.