Soil and climate- 1.Conservative behavior in the response of crops to water and light; 2. Atmospheric CO2, global carbon fluxes and the biosphere; 3. Nitrogen influence on the physiology of crop yield; 4. On scale problems in modeling; an example from soc

Biology of the cereal aphid system; The model; Results; General discussion.

Verification in the field is done by comparing simulation results with population measurements in several orchards. The correspondence in general pattern of population fluctuations of prey and predator and the good correspondence between simulated and measured colour values of the predators enables the model to be used for sensitivity analysis and management.

Theory of modelling and systems management; Basic techniques of dynamic simulation; Population development in time and space; Coupling of crop growth and pests, diseases and weeds; Decision making and management.

This paper describes the political changes that will be needed to incorporate the principles outlined in the World Food Summit which were the need to increase food production and to strengthen the political will and commitment to achieve food security and access to food for all. The paper indicates what steps are needed to achieve the goals and the technical feasibility of those steps.