About the Irrigation Scheduler

The irrigation scheduling model uses a number of variables to determine an estimate of the optimum amount of water to be applied to the crop. Field specific variables (crop type, crop stage, soil type, and recent irrigation amounts) are considered as well as actual rain, temperature and solar radiation data.

When the form information is submitted, the outcome is a total water deficit or surplus. The total deficit represents the amount of water your specific field requires based on the information provided. A negative number indicates the amount of moisture your field requires, while a positive number indicates that the field is sufficiently moist.

Definitions

The crop stage is the current development stage of your crop. This variable is dependent on the crop type.

The crop type is simply the kind of crop that has been planted. The crop stage choices are decided based on the crop type chosen.

The deficit is the amount of moisture your crop requires. This is based on the details you provided in the form, as well as the amount of rain and the ETo values accumulated during this period. A negative number represents the amount of water to apply, while a positive number indicates that the field is sufficiently wet.

ETc, short for evapotranspiration is the sum of evaporation and plant transpiration. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, and waterbodies. Transpiration accounts for the movement of water within a plant and the subsequent loss of water as vapour through stomata in its leaves.
For this model, we acquire ETo values from weather stations near your location. Where this information is unavailable, historical averages are used.

ETo is a representation of the environmental demand for evapotranspiration. This represents the evapotranspiration rate of a short green crop (of uniform height and with adequate water status in the soil profile) completely shading the ground. It is a reflection of the energy available to evaporate water, and of the wind available to transport the water vapour from the ground, up into the lower atmosphere.

In the case of this model, the irrigation amount input should represent the total amount of water applied to your crop between your chosen start date and today. Any rain should not be included in this amount as the model uses actual rain data collected at weather stations. The unit selection determines both how you would like to input your irrigation amount and what measurement units the water deficit will be displayed in.

The location should be the nearest possible place to your own field location as it determines what rain and ETo data will be used for your calculations.

In the case of this model, rain is the actual recorded rain amounts at weather stations near your location.

The soil type is used in the model to determine water absorption rates in your field.

The start date determines the day from which the calculations for water deficit will begin. The end date is automatically set to today.