Food and Agriculture Organization of the United Nations (FAO).
Definitions & Technical notes:
Agricultural area refers to the sum of area under arable land, permanent crops, and permanent pastures.
refers to land under temporary crops (double-cropped areas are counted only once), temporary meadows for mowing or pasture, land under market and kitchen gardens and land temporarily fallow (less than five years). The abandoned land resulting from shifting cultivation is not included in this category. Data for "Arable land" are not meant to indicate the amount of land that is potentially cultivable.
under permanent crops refers to land cultivated with crops that occupy the land for long periods and need not be replanted after each harvest, such as cocoa, coffee and rubber; this category includes land under flowering shrubs, fruit trees, nut trees and vines, but excludes land under trees grown for wood or timber.
Land under permanent pastures
refers to land used permanently (five years or more) for herbaceous forage crops, either cultivated or growing wild (wild prairie or grazing land).
% change (of agriculture area) since 1990 and % total land area (covered by agriculture land) are calculated by UNSD based on FAO data.
FAO promotes national censuses of agricultural land use every 10 years, with varying degrees of success. Standardised definitions exist but can pose problems when land is used for multiple purposes. In many parts of the world, for example, livestock graze in orchards and among other permanent crops. Moreover, land removed from production under set-aside schemes intended to reduce overproduction, is not always reflected adequately in the figures.
Agricultural surveys and censuses are generally confined to farmland. However, in many countries common land is used for grazing and may or may not be included in the figures for permanent pastures.