Thank you Dustin Chabert, Jeremy Eubanks, Peter Plaehn, and Blake Leja for your input last week on Alsace's vineyard classification.
This week: Irrigation
What are some of the common irrigation techniques utilized in viticulture and what are their advantages/disadvantages?
There are several forms of irrigation. The most common are Furrow, Flood, and Drip. Furrow is used by digging a ditch between two rows of vines and redirecting a water source ( nearby river) into the channel and refilling your water resivoir. Flood irrigation is done by literally flodding your vineyard, and allowing the water to soak into the soil. Drip irrigation is most commonly done by running a hose along the roots of the vines and very slowly releasing water onto the vines when needed.
To add to Blake's answer, furrow is only possible if you have a nearby river or aquifer and one downside is that the parts of the vineyard furthest away from the water source tend to see less water, which can either be positive (limiting vigor) or negative (adds stress to the vine and can cause stomata to close if it's extreme). Flood irrigation is commonly found in flatlands with water restrictions, such a desert-like environment, but tends to be all-or-nothing in its approach. One upside, though, is that it can curb phylloxera progress by literally drowning the suckers. Lastly, drip irrigation is the most common and, while expensive to implement due to equipment, allows measured and specific irrigation block by block. However, regular drip irrigation tends to produce shallow root structures that suffer during hot weather or drought conditions/water restrictions (hello, California) and the other two forms don't, making stronger vineyards in general. Research has suggested that it's often better to irrigate large volumes at wide intervals, simulating natural random rainfall, rather than regular small amounts because it fosters a stronger root system more resistant to stresses. It's one of the reasons why minimally irrigated/dry-farmed vineyards didn't suffer as much during the CA drought; they were used to it and strong enough to survive.
While Peter referred to it, I would also include dry farming in this conversation, as it is often a choice employed in the vineyard in regards to irrigation management. Younger vines tend to be given some degree during their first couple of seasons in order to promote growth. With dry farming, there are a variety of advantages and disadvantages. On the plus side, the root systems are forced to dig deeper into the soil in research of moisture and nutrients. This makes them more resistant to drought conditions. Resulting yields from the vine tend to be smaller with smaller, more concentrated fruit, so the financial payoff for growers selling their fruit may often not be worth employing the technique. There is also a great deal of water savings, so there's an ecological advantage, especially in areas where water rationing is necessary for viticulture and human consumption. In order to employ dry farming, however, there needs to be enough annual rainfall in order for the soil to retain the moisture, so very arid areas are not suitable for this style of agriculture.
There are also overhead sprinklers, but that's a very bad idea.
Unless there’s a slip & slide involved.
For clarity sake, the hoses are usually positioned a few inches above the soil in drip systems.
If we're talking techniques, we should talk about the technique of scheduling in irrigation, too. Precise Timing and quantity decisions can alleviate some of the problems with root development mentioned, especially in more technologically advanced systems like drip and micro sprinkler.