Micro-irrigation is a low pressure, low volume irrigation system suitable for vegetables, shrubs, flowers and trees.
Micro-irrigation has been gaining attention because of its potential to increase yields and decrease water use, fertilizer, and labor requirements if managed properly.
Micro-irrigation or low volume irrigation systems can be subdivided into three categories, according to uses:
Drip irrigation is the slow application of water directly to the plants' root zone in a predetermined pattern. Maintaining an optimum moisture level in the soil at all times results in less water lost to the sun and the wind. No water is wasted on non-growth areas, and the root zone is maintained at its ideal moisture level, combining the proper balance of water and air for a very efficient irrigation system.
Micro irrigation is designed for placement in both new and existing landscape and agriculture areas, and is ideal for installation on difficult terrain such as on slopes, in oddly shaped areas, and on windy sites.
Micro-sprinklers operate at low pressure and have a wide range of flow rates (5 to 50 GPH) and diameters (3 to 30'). Micro sprinklers have small droplets and a low flow application rate. Micro-sprinklers can prevent plant stress by maintaining low water tension in the soil, using a low flow application rate. New developments have made many more brands and spray patterns available. Application rates now vary widely, from 0.05 inches/hour up to 6 inches/hour. Because there is a direct relation between application rate and irrigation duration, there can also be a range in the duration to complete an irrigation cycle. For example, 8 minutes is required to apply 0.4 inch of water on the wetted area with an application rate of 3 inches/hour, while 8 hours is needed to apply the same amount at a rate of 0.05 inch/hour. This range of rates is readily available with micro-sprinklers today.
Drip Tape is a flat tape with drippers pre-inserted in a spacing of 12" to 18". The drip tape expands when filled with water and is ideal for use in vegetable gardens or for row crops or where total saturation of coverage is desired. Drip tape is used with special drip tape fittings. Drip tape fittings are different in design from those used with drip hose in that they work with a twisting lock device rather than with compression.
Drip tape: Has a flow rate of .35 to .85 GPH. It may be used above or below the ground. Maximum working pressure for drip tape is 25 PSI and it is highly recommend that it be used with a pressure regulator and a filter.
Fertilizer: Any water-soluble fertilizer may be injected through a micro-irrigation system.
System Layout and Equipment
Micro-irrigation systems consist of a head or head assembly and a distribution network. The head or head assembly consists of a controller, pump (if needed), backflow device, filter, pressure gauges, fertilizer injector and pressure regulator. The fertilizer injector is optional but highly recommended; the controller is necessary only if the system is to be automated.
|Figure 1: Head assembly on spigot||Figure 2: Inline head assembly|
Micro-irrigation distribution networks consist of mainline pipes, usually made of PVC, sub laterals made of polyethylene (PE), PVC fittings, drip fittings (barb, compression or spin-lock), drippers or emitters, micro-sprinklers and accessories such as hose end, goof-plugs, and punches.
|Figure 3: Typical layout of a micro irrigation system in a home garden or landscape area.|