The maximum length and the area covered by the pivot are determined by the daily water requirement of the crop and the intake rate of the soil.

The maximum length and the area covered by the pivot are determined by the daily water requirement of the crop and the intake rate of the soil.
Irrigation systems which apply water frequently to crops (drip, center Pivot, and solid set sprinkler irrigation systems) can mantain relatively constant, high soil moisture levels in the soil. Therefore they contribute to higher transpiration rates.
The root zone of the plant determines how big a soil reservoir there is for the plant from which to draw water. Early in the season the crops have shallow root zones that require light frequent irrigations. As the plant grows the roots go deeper into the soil with a corresponding increase in water requirements….