"Is there sufficient land to sustain the likely world population in the year 2000?" Previous estimates of the populations that can be supported by the arable lands in the world vary from 7.5 to 40 thousand million. However, these estimates have not taken account of some crucial aspects, namely: (a) Different quality of lands, their productive capacities and hence their varied potentials for supporting different levels of population on a degradation-free and sustained basis. (b) Different crops (with widely differing climatic and soil requirements). (c) Different levels of inputs and technology. (d) Different socio-economic factors.
Recognizing these aspects, FAO and UNFPA have initiated a project to compute the human supporting capacities of agricultural lands and to compare these with data on existing and projected populations. The project entitled "Land Resources for Populations of the Future" commenced on 1st September, 1976.
The Food and Agriculture Program at IIASA has participated in this project since September, 1978. IIASA's contribution in conjunction with the Land and Water Division, FAO, is concerned with the development and simulation of the overall methodology for the analysis of the FAO climate/soil data base to determine optimum crop mix and estimation of population supporting capacity.
The information generated in this approach is important in that it provides data which can form the basis of the planning of the food and agricultural sector. It is recognized that the analysis is carried out on the basis of the 1:5 million FAO-UNESCO soil map. Most developing countries have not had the resources to carry out detailed soil and climate surveys. Apart from being expensive in time and money, soil surveys are useful only if carried out with a view to assessing the agricultural potential. The methodology as developed in this project is particularly relevant since it considers the most important food crops as well as the degradation hazard in relation to the environment and management practice. At a country level, the data best generated here will certainly need to be supplemented by specific and in-depth surveys.
The present and future agricultural production in various countries depends on a wide variety of factors such as ecology, technology, environment, socio-economics, international trade, etc. All these aspects cannot be investigated at the global level but for particular country studies, the data base as generated in the AEZ project provides a starting point for the integration of the wide range of factors that are crucial to the development of the food and agricultural sector in various countries