For each grid cell of 5 arc-minute, whose size is approximately 10 x 10 km at equator (and less the further away from the equator) the following variables are calculated for each crop/input system:
- Harvested area (ha)
- Physical area (ha)
- Production (mt)
- Yield (kg/ha)
Harvested Area
Example: Maize harvested area (Full-version of maps for other crops available at [Download] - [Maps])
Amount of area where a specific crop in a given input system is being cultivated and harvested in the year 2000 (average 1999 - 2001). If a crop is being harvested more than once, the harvested area increases as well. Data for harvested area is collected at national and sub-national level for all SPAM crops. Harvested area is expressed in hectare.
Physical area
Example: Maize physical area (Full-version of maps for other crops available at [Download] - [Maps])
Area where a specific crop in a given input system is being cultivated in the year 2000. Multiple harvesting seasons in one year are not taken account of. Intercropping or successive planting of different crops on the same physical area do not increase the physical area. Cropping intensity factors convert harvested area into physical area.
Physical area is expressed in hectare.
Production
Example: Maize production area (Full-version of maps for other crops available at [Download] - [Maps])
Production of a specific crop in the given input system. Production is calculated by multiplying harvested area by yield. Since harvested area and yield refer to the year 2000, so does production. Production is expressed in metric tonns.
Yield
Example: Maize yield (Full-version of maps for other crops available at [Download] - [Maps])
The yield of a crop in the given input system is the amount of production per harvested area.Yields are given for the year 2000. Yield data is collected at national and sub-national level for all SPAM crops. Yield is expressed in kilogramme per hectare.
Note
Harvested area, yield and cropping intensity factors are also input parameters (at national and sometimes sub-national level). Physical area and production are calculated at those levels as well. SPAM processing further allocates physical area and calculates harvested area, yield and production for each cell.
