Spatial and temporal variability of rainfall makes
it a poor indicator of water availability for plants. An
option is to quantify the soil moisture dynamics at the
plant root zone by means of a water balance.
Following this goal, a simulation model to quantify
the available humidity for corn crop under rainfed
conditions was used. The model showed the best
fitness when soil water content kept lower than field
capacity. However, when soil moisture surpassed field
capacity, because of intensive or continuous rainfall,
the model overestimated soil moisture. A comparison
between observed and estimated data showed values
of r2 ranking from 0.654 to 0.903.