Plant available soil water is modelled using the Ritchie two-layer fallow evaporation model described in Ritchie, J.T. 1972, Model for predicting evaporation from a row crop with incomplete cover.
While plant available soil water graphs can help create a narrative for the progress of a crop and aid key in-season decision-making, other key factors also need to be considered for any given crop to arrive at an accurate picture. These include:
- Soil status and characteristics including stored soil moisture, soil water-holding capacity and any barriers to infiltration.
- Stored nitrogen and other nutrient availabilities.
- Factors such as non-wetting, water-logging through topography or impermeable layers, leaching or dispersible clays in the soil.
The timing and event intensity of rain during the growing season can also greatly influence the conversion of rainfall to biomass and yield.
To use the tool, select a weather station, a soil type and whether the model is for a fallow or cropped situation from the drop-down lists below. Graphs can be downloaded and saved by clicking on the three horizontal lines to the right of the graph title.
Maps of plant available soil water, updated monthly in the early part of the growing season, can be viewed and downloaded from our Seasonal climate information page.
There is a problem with the crop model used in the soil water tool, please use only the fallow model and note that it will not give accurate results when there is a crop cover. The bug will be fixed as soon as possible.