Agriculture Reference
In-Depth Information
Drip Irrigation
Drip irrigation was developed to save water by dripping it directly to the roots of plants,
rather than spraying the entire landscape. Note that I'm not talking about soaker hoses, or
microsprays. Drip irrigation is where tubing brings water to tiny nozzles that drip water dir-
ectly into pots or right onto the soil beside each plant in the garden. There are new systems
that can distribute the water further, but the classical approach is delivery just to the plants.
Drip irrigation was designed for farming in very dry climates where water is scarce. If
calibrated correctly and properly managed, it can work to save water in an agricultural
monoculture situation. In fact, some people think it was one of the most important techno-
logical developments for agriculture. It's useful for the above purpose, but it has made its
way into residential gardens where most of the time it's inappropriate because it waters a
tiny area right around the plant, ignoring the rest of the soil. This is problematic for two
reasons.
Roots look for moisture and stay away from areas that are dry. With the frequent, shal-
low watering of drip irrigation, the majority of the roots will tend to stay right by the plant
instead of reaching further into the soil for water and nutrients. This means most plants will
never reach a state of optimal health. Instead, there's a good chance they will be unstable
and unhealthy, covered in insects and disease and on their way to an early death. Many
times I have put a shovel into the soil 18 inches away from a drip emitter and found it to be
totally dry.
The rest of the soil needs water just as much as the plant because the microorganisms,
earthworms and insects need water, not only for their own health, but also in order to give
the plants nutrients, water, a healthy organic soil environment, and protection from plant-
feeding organisms. Remember, plants get all of these services from the organisms in the
soil. Drip irrigation may save water in the garden, but at the expense of the plants we're
trying to grow. Also once grown these plants would actually attract water into the land-
scape, sequester carbon, produce oxygen, feed bees, butterflies and other animals, and cool
our houses and cities.
That being said, enough people are successfully using drip irrigation to grow food for me
to mention that it's not only possible, but may become very important as our fresh water
sources continue to dwindle. These folks should be commended for finding these kinds of
solutions that may become necessary. One alternative method is to make the top three to six
inches of soil dry and not use mulch, thereby decreasing evaporation from the soil surface
and saving a lot of water. This method generally requires chemical salt fertilizer use, so as I
see it, there's a good chance of producing food that is substantially less nutritious in the
long run. My viewpoint is that if we're ultimately decreasing the organic content of the
