Simulation of Soil-Plant Nitrogen Interactions for Educational Purposes.

A computer model characterizing the balance of soil-plant N is described, which is coded in a language that provides a graphic interface for use by students and others with minimal programming experience. Equations representing simultaneous water, C, and N balance reactions in a soil-plant system are solved over time. Both qualitative and quantitative relationships between various interacting system components are presented in graphic form to facilitate an intuitive understanding of the dynamic interactions between system functions. By manipulat­ ing various combinations of input functions, the student can see the likely consequences of different biological and weather related parameters upon the N cycle. Three uses for the model are proposed: (i) orienting beginning students toward an un­ derstanding of fundamental components of the soil N cycle, (ii) providing in-depth information for advanced students in­ cluding access to the defining equations and citations of rele­ vant journal articles, and (iii) supplying source-equations for scientists who may wish to extend the model or explore the dy­ namic consequences of using alternate formulations.