| AQUASTAT | 
FAO's global information system on water and agriculture | 
| FAOSTAT | 
Food and Agriculture Organisation | 
| GCMD | 
Global Change Master Discovery (NASA) | 
| HWSD | 
Harmonized World Soil Database | 
| IFA | 
International Fertilizer Industry Association | 
| IPG | 
Institute of Physical Geography Hydrology Group (Goethe-University Frankfurt) | 
| GDR | 
UC Berkeley Geospatial Data Repository | 
| USDA | 
United States Department of Agriculture; http://www.pecad.fas.usda.gov/cropexplorer/ | 
| EEA | 
European Environment Agency | 
| WRI | 
Earth trends The Environmental Information Portal | 
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