Maybe the season following a dry winter is not he optimal time to do it, but as my vines get bigger, I wanted to change my irrigation by raising the lines and moving out my drippres.
This consisted of raising the lines 18 inches off the ground, adding emitters (18″ from the trunk – one on each side) and digging small wells under each dripper.
First, I ran 16 gauge wire along the t-posts, again 18 inches above the ground. Normally, the polyethylene tubing is clipped to the wires with plastic (or poly) spirals clips. I used sort lengths of 19 gauge wire spaced about 3 feet apart (see video, below).
Finally, I dug small troughs/wells under each dripper. The idea here is to let the water fall and collect at the same level as the vine’s trunks come out of the ground. I don’t want to be saturating 20 inches of soil above the roots.
By the end of the season, these wells will fill in. I am considering filling them with some crushed aggregate, crushed granite or crushed lava and then covering with soil. This way, I hope to get more water to the roots and reduce waste on top soil as well as evaporative loss.
While on the subject of evaporative loss, I wanted to mention two other techniques described in the Summer 2012 issue of the California Sustainable Winegrowing Alliance’s newsletter, “Highlights”:
The “Big Drink” method consists of less frequent, but larger volume watering. This is said to allow water to seep deeper into soil, taking the roots with it, strengthening the vine in the process. Additionally, by applications of large volumes, evaporative loss can be reduced. This approach can, however create a cycle of alternating water abundance and water stress. Drought-tolerant root stocks and other soil cultivation techniques are also recommended.
Another way to reduce evaporative loss, highlighted in the newsletter, is by burying irrigation lines underground. Lines are placed between the rows, at the depth of the root zone (about 18″). High burrowing rodent activity presents some obvious risks to this approach.
Some additional resources additional resources can be found here:
The one remaining thing to do is put in stakes at the ends of the rows to support the ends of the irrigation lines.