Drip irrigation is probably the single most effective tool for water conservation at the dry climate gardener’s disposal. Unfortunately, many, perhaps most home gardeners do not know how to space and lay down the pipes, in order that the system provides adequate moisture to the plants, while saving water as much possible.
A Common Mistake
The worst error is to snake a dripper line in a long loop around the plants. There are three reasons why this is wrong.
*Firstly, a long, looping line will reduce the operating pressure of the system, causing the drippers at the end of the line to emit far less water than those at the beginning. Remember that the aim of efficient watering is to provide water as evenly as possible.
*Uneven coverage makes it impossible to calculate the volume of water necessary for any given watering, and then to use just that amount. For as quantities are determined by area, (i.e. 3 liters per square meter a month for established, drought tolerant trees and shrubs) it follows that each part of the irrigated area should be receiving the same amount of water.
*A looping, snaking dripper line is unsightly. Lines that are straight, taught, and parallel to each other, catch the eyeless, and give a more ordered look to the garden, until the plants cover them up.
Laying the Dripper Lines
The problems just outlined are avoided when the dripper lines are placed parallel to each other in short, straight lines, and where the drippers themselves are evenly spaced within any given line. But what is the optimal distance between the lines? The principle to follow is that they should be close enough to supply adequate coverage to the plants, but distant enough so that the amount of water emitted by the system per unit of time, is as low as possible. The purpose here is to allow the soil to absorb the water without run-off and wastage, or in technical terms, that the flow rate of the system is suited to the infiltration capacity of the soil. Here are some examples.
Shrubs and Bushes: For drought-tolerant bushes, choose a spacing of 1 meter (3ft) between the drippers and I meter between the lines. For less hardy landscape shrubs, 0.5*0.5 may be necessary. Add a circle of drippers around young trees at a distance of about 30cm (1ft) from the trunk.
Heavy Soil v Light Soil: Space the lines further apart in heavy, clay soil as opposed to light, sandy soil. For example, with flowers, a spacing of 30cm*30cm may be needed to supply moisture in light soil, whereas such spacing in heavy soil will cause puddles to form very quickly. As water moves horizontally in clay soil, a spacing of 30*50 would be more appropriate.
Integrated Dripper Pipes: Although more expensive, it is always better to buy pipes that are pre-inserted with drippers, as opposed to adding individual drippers to a blind line. These come in varying spacings such as 30cm. 50, 70, or 100cm. Choose the appropriate spacing according to the principles outlined above health Fitness Articles, and make sure the flow rate (given for each dripper) is the lowest available.