Garden Irrigation Update
In a post last month, I mentioned our experiments with drip irrigation in the garden. In a continuing effort to save water (and thereby save energy), we've continued to try different ideas. Our conclusion: drip doesn't work very well in the garden, where plants have wider, shallower root systems. The only way to really make it work would be to install a dripper for every plant. In an intensive agriculture garden, that's a lot of drippers!
Still, we've sought better ideas, since the typical center sprayer produces a lot of overspray in order to reach the corners of the raised beds. (Assuming equal distribution across the spray pattern, about a third of the water goes outside the bed.) Not only is a waste of water, but that water benefits nearby weeds, which really don't need the help.
Our latest experiment has been to install a 90-degree sprayer on each corner of the raised bed. The spray is directed into the box rather than out of it, and the 90-degree spray matches the edges of the bed, minimizing overspray. There's quite a bit of overlap at the center, but in theory, at least two sprayer hit every spot in the bed. (Reality is somewhat different due to variations in individual spray nozzles and fluctuations in water pressure.) We probably lose as much to evaporation as we did before, but at least the water we use is going where we want it, cutting our garden water usage by a third.
Instead of drip irrigation with individual drippers, wouldn't soaker hoses/pipes buried at about 4 inches do the trick? You'd have to experiment to get the flow right, alas, but once you did, you wouldn't have the expense and futility of the drip system or the evaporative waste of the sprinkler.
I assume you want to keep things in dirt instead of going the pure hydroponic route (no pun intended, though it could be inferred), which would probably be the most efficient water-wise, though requiring an appropriate investment in gravel, nutrient, bedding, and plumbing. I did hydroponics for a couple of years in a Wisconsin apartment with a west exposure and was able to get winter tomatoes, at least, and snow peas, thanks to the wonder of substituting q-tips for bees!
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I prefer to grow in real soil. As to soaker hoses, they would probably work too (if the voles didn't eat them)-- perhaos I'll experiment with them.
One advantage of the sprinklers over drippers seems to be that they add humidity to the air, which some garden plants like. The typical humidity here in summer is about 20%-- great for working outdoors when it's 100 degrees, but hard on agriculture.
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Getting sprinklers adjusted is like tuning a carberator: it takes a lot of repetitive practice! Good luck!
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Luck is indeed helpful. Actually, I've discovered that even though it looks like the new sprinklers throw less water than the old ones, perhaps because they do it more accurately, a lot more water gets on the garden faster. Instead of 20 minutes of watering, now 10 minutes is plenty. (They're adjustable from 0-30 GPH, so I have no idea in terms of flow whether it's really greater or less than what I had before.)
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