Equipment & Irrigation

Water wisdom I'm concerned that I waste a lot of water during irrigation. How can I be sure I'm watering my turf in an efficient manner?-Florida (via the internet)

Irrigation efficiency involves two determinants: Water loss and uniformity of application. Your system's design and your management of it influence these determinants. Management primarily affects water loss and system design affects uniformity. Efficiency is the ratio between how much water turf actually uses vs. how much water the system administers. Uniformity describes how evenly the system applies water over an area. Irrigation equipment and system design (such as sprinkler types, pressure, pipe and nozzle size) affect uniformity.

Distribution uniformity (DU) analyzes watered areas and irrigation auditors usually apply this calculation in landscape irrigation audits. You perform this test by distributing catch cans throughout the irrigated area and running your system. Then, you measure the amount of water in each can (use at least 15 to 20 cans). The DU formula is: Percent DU = average catch in the lowest fourth of the cans x 100 " average catch overall.

Instructions for specific tests for evaluating sprinkler irrigation and uniformity are available from California State University's Center for Irrigation Technology (Fresno, Calif.). For more information, visit

Marcell Marcelling I've noticed a wavy appearance in my turf after I mow it with a reel mower. Any ideas on what causes this?-Arizona (via the internet)

Wavy appearances indicate marcelling. Marcelling results when the clip of the reel (CR), which is the forward distance traveled between successive clips, exceeds the mowing height (MH). Thus, marcelling is more likely with faster mower speeds, lower MH, slower rotation of the reel and reels with fewer blades.

You can conclude from this that short-cut turf requires a lower CR to avoid marcelling. That's why greens-mower reels have more blades than other reel mowers. However, some people maintain residential lawns (especially bermudagrass turf) with a close cut and may find that their reel mower is not adequate to avoid marcelling at that low height.

Two primary ways to eliminate marcelling are: * Decrease CR. You can do this by using a reel with more blades or reducing the forward speed of your mower, if the mower allows it. * Increase MH. Depending on the turf, this may not be an option. However, if it is, it could be an easy solution to marcelling.

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