What unit of measure is commonly used to express the pressure of irrigation water?

The unit of measure commonly used to express the pressure of irrigation water is pounds per square inch (psi). This measurement is critical in irrigation systems as it indicates the force that water exerts within the system, which affects how efficiently water can be delivered to plants. Understanding this pressure is essential for selecting appropriate equipment, ensuring effective water distribution, and minimizing water waste.

While pascals are also a unit of pressure, they are less commonly used in the context of irrigation in the United States, where psi is more familiar to irrigators. Millimeters are typically associated with measuring precipitation or flow rates rather than pressure. Liters measure volume, which is not suitable for indicating the pressure of the water in an irrigation system. Therefore, pounds per square inch serves as the standard measure for pressure in irrigation contexts, making it the correct choice.