Source: UNEP (2010): The GEO Data Portal, as compiled from FAO, TERRASTAT I Global GIS Databases Poverty and Food Insecurity Mapping Project. United Nations Environment Programme.
One of the core determinants of agricultural output is the time available for normal crop growth with photosynthesis. The length of growing period (LGP) is such a proxy that combines temperature and moisture considerations. It is the number of days under rain-fed conditions with temperatures above 5°C (minimum temperature for wheat to grow) and excludes periods which are too cold, too dry, or both. 90 days is considered the minimum period to grow crops.
Areas of the world that have above 200 days of LGP are among the most potentially productive. However, such areas are also supporting complex ecosystems (e.g. rain forests), implying the competition between land used for agriculture and land used by natural ecosystems. It is in the area of intermediate growing season and biodiversity that agricultural systems have been the most extensively developed.