APSIh4 (Agricultural Production Systems Simulator) is a software system
which allows (a) models of crop and pasture production, residue
decomposition, soil water and nutrient flow, and erosion to be readily
re-con$gured to simulate various production systems and (b) soil and crop
management to be dynamically simulated using conditional rules. A key
innovation is change from a core concept of a crop responding to resource
supplies to that of a soil responding to weather, management and crops.
While this achieves a sound logical structure for improved simulation of
soil management and long-term change in the soil resource, it does so
without loss of sensitivity in simulating crop yields. This concept is implemented
using a program structure in which all modules (e.g. growth of
spectjic crops, soil water, soil N, erosion) communicate with each other
only by messages passed via a central ‘engine’. Using a standard interface
design this design enables easy removal, replacement, or exchange of
modules without disruption to the operation of the system. Simulation of
crop sequences and multiple crops are achieved by managing connection of
crop growth modules to the engine.