To develop concepts that will help solve the conflict and competition for land between food production and biofuel production reliable figures are needed about how much surplus land or residual areas are available for energy-plant cropping. But such figures are lacking.
In the current debate on biofuel it is often proposed that such surplus or residual land should be used more intensively to grow energy plants, and thus mitigate land-use competition with food production. To date, however, no uniform definition is on hand for what “surplus” fallow land is, nor is it clear how much land is indeed available and what yield potential it has. Specialist literature contains assumptions ranging from 250 million to 1,580 million hectares. This enormous bandwidth comes from the fact that different types of residual areas are included and are calculated with different potentials and very often, the social constraints to exploiting the given areas are not sufficiently taken into account.
Scientists propose, therefore, that the term „surplus land “ be given a clearer definition and that both the constraints and the opportunities for sustainable biofuel land-use be considered. Moreover, a global, high resolution database has to be developed for the sustainable use of land, because present-day data on land use, ownership, climate and soil are often too roughly estimated for use in regional planning.
Scientists at the University of Hohenheim are currently developing a mathematical model to calculate how much cropland for energy plants would remain worldwide if top priority is given to world food supplies (see article: “What is the real potential of biofuels?”)
The scientists involved in the study „Bioenergy from “surplus” land: environmental and socio-economic implications“ list a number of criteria in their publication that must be taken into account when estimating the potential of residual areas, but also indicate how some of these rather constraining factors could be mitigated or, through the skillful growing of energy plants even generate positive effects.