There are now watering devices that release water at soil level and do not allow any water to get on the leaves of the plants. These drip irrigation systems, as they are called, offer a number of important benefits to the yard and garden. First and foremost, they use much less water than the overhead sprinkler. You can assume that you will save at least 30 percent, and in some cases 50 percent, of your water over sprinklers or other methods of watering. Water delivered by a drip system has no chance to evaporate or run off, because it is completely absorbed by the soil and never touches the leaves of the plants.
Research has demonstrated that drip irrigation systems, especially those used in conjunction with mulch, increase the plant's performance. Plants show earlier blossoming, increased growth, and larger blooms. Because the water never touches plant leaves, they avoid many moisture-related diseases. Problems such as rust, mildew, and blossom damage are all reduced in gardens using a drip technique.
Another advantage is the cooling effect a drip system has on the soil. A properly managed drip irrigation system can be used to help keep down soil temperatures in the high heat of summer. This increases production, because plants grow more effectively in the cooler soil.
Finally, a drip irrigation system reduces the problem of soil compaction. When the soil is saturated with large amounts of water, its structure breaks down and compaction occurs. Drip irrigation reduces this problem because the water is introduced into the soil so slowly that the structure of the soil is not affected.
With no adjustments needed for evaporation and run off, you can plan your watering task around the need to get about 1 to 1-1/2 inch of water to your plants each week from rain or from your drip system. That is about a quart of water per square foot of garden per week. All you have to do is find out how much water per minute your particular drip system releases per square foot, and you can then calculate how long each day or every two or three days you need to run your system.
Pressure vs. Volume
Most drip systems require a reduction in the normal household water pressure to operate properly. In addition, some systems require a reduction in the volume of the water coming into the system. You must be sure, when buying your drip irrigation system to insure you have the proper pressure reduction device, and a volume reduction device if it is needed.
The trick is to keep water pressure high enough so that water drips out of the system at the same volume along the entire length of the hose. You do not want a lot of water near the house and very little water farthest away from the house.
Most drip lines irrigate a 2-foot-wide strip, about 12 inches on either side of the drip line. That means if you lay two lines 24 inches apart water will reach the roots of all the plants or shrubs in a 4 foot wide bed. Of course this estimate assumes you have normal, loamy soil. If your soil tends to be sandy and drains very quickly, place your lines just 18 to 20 inches apart to make sure all the plants are well irrigated. You can set up a drip system for a 200 square foot garden in an hour or two.
A drip irrigation system is not cheap. However, these systems will last for decades with very little maintenance. The only other weakness, besides price, of the drip system is that it is not practical or effective for watering lawn grass. Its advantages are found in the flower and vegetable garden or along lines of shrubs and trees.