Exploring land quality effects on world food supply.

In a previous study, simulations of agricultural production potentials were made for different exploratory scenarios considering population growth, type of diet and low and high input agriculture. Results indicated that future world populations can be fed, but problems are likely in South Asia. The simulations involved gross generalizations for soil conditions. For example, possible effects of soil degradation were not expressed. The current study was made to explore the effects of the different types of soil degradation on agricultural production, using major soil groupings of the Humid Tropics and Seasonally Dry (Sub)Tropics as examples. Degradation (compaction, erosion and acidification) is expressed in terms of soil quality indicators relating potential to actual production. Results are characteristically different for different soil units (genoforms), and the suggestion is made to present such differences in future soil databases for phenoforms that express effects of different forms of degradation or improvement, allowing better assessments for exploratory land use scenarios. Field studies should be initiated to describe realistic phenoforms for any given genoform