2.2.3 Micro-Irrigation: Raised Beds

Raised Bed

Shrubs planted on raised beds are watered using rowcrop trickle tubing laid on top of the beds, or buried just under the surface of the bed. For coarse soils a spacing of about 12 to 15 in. between tubings should be adequate. For fine soils a tubing spacing of up to 24 in. may be allowed. The soil type and row spacing of the crop are factors in tubing spacing.

Water will move laterally by capillary action further in fine soils. Space Tubing should be spaced to adequately wet the root zone. (see Raised Bed Trickle diagram)

Rowcrop tubing is also referred to as "tape". It is available in 4 mil (0.004 in.) to 25 mil wall thickness. An emitter water distribution system is built into the tubing and discharges water at intervals of 2 inches to 36 inches. Water discharge from rowcrop tubing is typically 0.5 gpm per 100 feet of tubing.

Depending on the product selected, the rate can be from 0.25 to 1.5 gpm per 100 feet of length. The water infiltrates into the soil and moves laterally and vertically through the soil. Little wetting is seen on the surface. Underground the water wets an onion shaped zone in the soil.