Tuesday, March 30, 2010

Get to Know Your Wet Spots

To test your soil and to understand how emitters work, buy a single emitter, use an emitter punch (which cuts a tiny circular hole) to pierce a hole near the bottom of an empty plastic one-gallon milk jug, and insert the emitter's barb. Fill the jug with water and place it on a dry spot in the garden. After the milk jug is empty (which may take 24 hours or more because it's not under pressure), dig a small trench next to the emitter to see the shape of the wet spot in your soil. This is the most graphic way to understand how the water from each emitter you install will move in your soil. (The shape of the wet spot will change, usually both wider and deeper, when the emitter is used under pressure.) The shape of the moist area is affected differently by each type of garden soil and ranges from long and carrot-like to squat and beet-shaped. Emitters with a higher rating, such as 2 or 4 gph, will cause the wet spot to be wider than 1/2 or 1 gph emitters.

A moist-but-not-too-wet spot that is the key to drip irrigation's superiority over all other forms of irrigation. With proper timing, a drip irrigation system provides moisture to the soil without overly saturating the pore spaces in the soil. The labyrinth of minute pore spaces helps the soil breathe. When a more aerobic condition in the soil is maintained by drip irrigation, the roots don't drown, the soil's beneficial bacteria can continue to release valuable nutrients, and harmful anaerobic fungi don't easily proliferate—thus, better growth and greater yields

The lower chart (From Drip Irrigation for Every Landscape and All Climates) and shows how the water can move in a theoretical soil. The darker the wet spot, the more it is anaerobic.


Let me know what you think.Visit my web site to learn about my new book on drip irrigation and other gardening books. Thanks, Robert

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