Which of the following systems of irrigation is classified as a closed system?

Ebb and flow is classified as a closed system of irrigation because it utilizes a cycle of flooding and draining the growing area, which is typically contained within a tray or bed. Water is pumped into the growing area to saturate the medium and then allowed to drain back into a reservoir for reuse. This method minimizes water waste and allows for better control over nutrient delivery, as the same water can be recirculated.

In contrast, perimeter watering, tube watering, and hand watering are all considered open systems. These methods rely on delivering water directly to the plants and do not typically return excess water back to a reservoir for reuse. As such, they don’t offer the same water conservation and efficiency benefits associated with a closed irrigation system like ebb and flow.