Researchers at the University of Illinois and the University of Central Florida reviewed physical conditions (such as soil productivity, land slope, and climate) to estimate land available to grow second-generation biofuels crops (see map).
The 2010 study found that between 320 and 702 million hectares of marginal land, including abandoned and degraded crop lands, may be available in the six most productive regions of the world without affecting currently productive crop and pasture land.
There are many ways in which land types and land uses are described and this can add complexity and confusion to any discussion about potential use of the world’s land. There is no agreed upon definition of “available” land, for example. The descriptions at right reflect definitions that are commonly used by such international agencies as the United Nations’ Food and Agricultural Organization and the UN’s Environment Programme.
- Abandoned land has been previously used for agriculture or pasture, but has been abandoned and not converted to forest or urban areas.
- Agricultural land is the sum of arable land, land under permanent crops and permanent pasture.
- Arable land is under temporary agricultural crops, temporary meadows for mowing or pasture, land under market and kitchen gardens and land temporarily fallow.
- Degraded land is a long-term loss of ecosystem function and services that cannot be recovered without aid.
- Fallow land is cultivated land that is not used for crops for at least one but not more than five growing seasons.
- Idle land and unused land are often used synonymously. These include all types of unused land – abandoned farmland, degraded, devastated and waste land, and land taken out of production for environmental and other reasons.
- Marginal agricultural land refers to an area where cost-effective production is not possible for such reasons as soil productivity (salinity), cultivation techniques (steep slopes), or agriculture or legal policies.
- Waste land is land with physical and biological characteristics that make it unfavorable for agricultural use. It is sometimes defined as land that can’t be used for cultivation under any conditions.