Increased nitrogen enrichment and shifted patterns in the world's grassland: 1860–2016

Rongting Xu,Yonglong Lu,Hanqin Tian,Francesco N Tubiello,Bowen Zhang,Ute Maria Skiba,Jinfeng Chang,Jian Chen,Shree R S Dangal,Shufen Pan

doi:10.5194/essd-11-175-2019

Abstract

Abstract. Production and application to soils of manure excreta from livestock farming significantly perturb the global nutrient balance and result in significant greenhouse gas emissions that warm the earth's climate. Despite much attention paid to synthetic nitrogen (N) fertilizer and manure N applications to croplands, spatially explicit, continuous time-series datasets of manure and fertilizer N inputs on pastures and rangelands are lacking. We developed three global gridded datasets at a resolution of 0.5∘ × 0.5∘ for the period 1860–2016 (i.e., annual manure N deposition (by grazing animals) rate, synthetic N fertilizer and N manure application rates), by combining annual and 5 arcmin spatial data on pastures and rangelands with country-level statistics on livestock manure, mineral and chemical fertilizers, and land use information for cropland and permanent meadows and pastures. Based on the new data products, we estimated that total N inputs, the sum of manure N deposition, manure N application and fertilizer N application to pastures and rangelands, increased globally from 15 to 101 Tg N yr−1 during 1860–2016. In particular during the period 2000–2016, livestock manure N deposition accounted for 83 % of the total N inputs, whereas manure and fertilizer N application accounted 9 % and 8 %, respectively. At the regional scale, hotspots of manure N deposition remained largely similar during the period 1860–2016 (i.e., southern Asia, Africa and South America); however, hotspots of manure and fertilizer N application shifted from Europe to southern Asia in the early 21st century. The new three global datasets contribute to the filling of the previous data gaps of global and regional N inputs in pastures and rangelands, improving the abilities of ecosystem and earth system models to investigate the global impacts of N enrichment due to agriculture, in terms of associated greenhouse gas emissions and environmental sustainability issues. Datasets are available at https://doi.org/10.1594/PANGAEA.892940.

Highlights

Livestock production has increased substantially in response to growing meat consumption across the globe in the past century (Bouwman et al, 2013; Dangal et al, 2017)
Land used by livestock for permanent meadows and pastures is the largest component, using 25 % of the total land earth surface (FAOSTAT, 2018) to generate 33 %–50 % of world total agricultural GDP (Herrero et al, 2013)
We developed datasets for major sources of N inputs in agriculture, using the recently published FAOSTAT statistics on manure N use in agriculture (FAOSTAT, 2018)

Summary

Introduction

Livestock production has increased substantially in response to growing meat consumption across the globe in the past century (Bouwman et al, 2013; Dangal et al, 2017). Land used by livestock for permanent meadows and pastures is the largest component, using 25 % of the total land earth surface (FAOSTAT, 2018) to generate 33 %–50 % of world total agricultural GDP (Herrero et al, 2013). Livestock production plays a major role as a driver of global change in land use and nutrient cycles (Havlík et al, 2014; Herrero et al, 2013; Zhang et al, 2017). There is a growing recognition that livestock production is linked to increasing global greenhouse gas (GHG) and ammonia emissions (Tian et al, 2016; Tubiello et al, 2018; Xu et al, 2018, 2019). Growing global demand for livestock products has increased grain production for feed in many regions, and has become a global driver of fertilizers trends, through an increase in manure availability and synthetic fertilizer N use (FAOSTAT, 2018)

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Discussion

Conclusion