Table 1.
A summary of data sources used for quantifying N deposition in global datasets.
| Datasets | References | Data Sources and Methods by Variable | |
|---|---|---|---|
| N Deposition | Land area | ||
| Zhang 2015; Zhang Reorganized† | Zhang et al.13 | Used deposition map from Bouwman et al.12 and cropland distribution map of Ramankutty et al.57 | Harvested area from FAOSTAT |
| Lassaletta | Lassaletta et al.39,40 | Dentener et al.30, Bouwman et al.58 | Used a combination of harvested area and cropland from FAOSTAT |
| Conant and Dorich | Conant et al.16 | Dentener et al.30 | Cropland area from FAOSTAT |
| Bodirsky with (or without) forage‡ | Bodirsky et al.11,17 | ACCMIP10, LUH221 | Cropland area from LUH221, based on Klein Goldewijk et al.59 |
| IMAGE | Bouwman et al.12 | Deposition map from Dentener et al.30 for year 2000. Using historical and projected emission, the deposition maps are scaled to other years. | Land cover data from HYDE 3.159 |
| Gerber and Mueller | Mueller et al.45,46, West et al.47 | Deposition map for 2000 from Dentener et al.30 | Cropland area: FAOSTAT, irrigated area: Portmann et al.60, crop area: Monfreda et al.61, pasture area: Ramankutty et al.57 |
| Chang et al. | Skalský et al.48, Herrero et al.49, Valin et al.50, Havlík et al.51, Chang et al.52 | Atmospheric N deposition for the year 2000 is derived from the International Global Atmospheric Chemistry (IGAC)/Stratospheric Processes and Their Role in Climate (SPARC) Chemistry-Climate Model Initiative (CCMI) N deposition fields62. | Harvested area from crop-specific and spatially explicit SPAM dataset is harmonized with cropland land cover from GLC200048. Further, at regional level to harvested area from FAOSTAT. Some additional adjustment of total cropland to total arable land from FAOSTAT. |
| FAO | FAOSTAT Soil N Budget Domain44 | Zhang et al.13 | Cropland area from FAOSTAT |
| Wang et al. | Wang et al.18, Shang et al.19, Wang et al.20 | Dry and wet N depositions for 1850–2100 simulated by the global aerosol chemistry climate model LMDZ-OR-INCA | Land cover data from HYDE 3.159 |
| Lu and Tian | Lu and Tian41, Zhang et al.42 | Not Available | Cropland area from HYDE 3.222 |
| Nishina with (or without) double cropping* | Nishina et al.43 | Not Available | Cropland area from the Harmonized Global Land Use map (LUHa) v1.063. |
†Both datasets were used by Zhang et al., using the same data processing steps, but with input data belong to different years from FAO. Zhang 2015 downloaded data from 2014, while Zhang Reorganized used data from 2018, respectively.
*Two datasets were used by Nishina. Double cropping region is based on global crop use intensity (CUI) map developed by Siebert et al.64. “Without double cropping” indicate excluding the N fertilizer input in double cropping region from the inputs.
‡Two datasets were used by Bodirsky, one dataset include forage crop, while other exclude it in the budget.