Agricultural Production Systems Simulator (APSIM)

Most detailed crop growth models operate on a daily time step, requiring daily inputs of radiation, temperature, and rainfall at the minimum. The Agricultural Production Systems Simulator (APSIM) model is a highly advanced simulator of agricultural systems that contains a suite of modules which enable the simulation of plant growth, nutrient dynamics and management interactions.

The weather stations that have been installed in Malawi will enable the research team to build simulations that capture soil water and nutrient dynamics across at least three agroecologies in Central and southern Malawi. Our expanded research sites and activities will enable us to investigate better technologies that can be deployed to mitigate the effects of frequent droughts and building of resilience.

A typical met file that drives APSIM simulations looks like this:

Year day radiation Max T Min T rainfall
MJ/m2 (oC) (oC) (mm)
2017 1 26.3 28.1 13 0
2017 2 23.0 28.5 26 0
2017 3 26.5 26 18 0
2017 4 22.5 23 19 17
2017 5 22.8 24 18 29
2017 6 24.7 25 17 3
2017 7 26.0 27 19 0
2017 8 28.2 30 22 1
2017 9 28.6 29 19 0
2017 10 27.7 25 18 22

 

For each day of the year, daily radiation, maximum and minimum temperature, and rainfall are required. Radiation intercepted by crops is core to crop growth. The daily maximum and minimum temperatures are required for computation of daily heat units that feed into the crop growth physiology. Rainfall feeds into the soil water module, which is a cascading water balance model, which is also interfaced with other modules that influence nutrient dynamics and rainfall partitioning into infiltration and runoff.

Learn more about APSIM