Probability and logistic functions have proven quite useful in our work on
mathematical models of crop growth and yields over the last fifteen years.
Articles have been written in which the models have been applied to differe
nt crops on a variety of soils at various locations around the world, and f
or which model parameters have been evaluated. At first glance this work ap
pears to be an attempt to model the plant system. However, upon further exa
mination it becomes clear that what is being modeled is information about t
he system and not the physical system directly. In this article we examine
the models in the framework of Fisher information and identify the key para
meters for the probability and logistic models.