Low-flow irrigation systems
Low-flow irrigation systems, called low volume irrigation or microirrigation, is an irrigation method that operates under a lower water pressure than standard service systems, with a "lower-flow" resulting when combined with water delivery components manufactured for this application. Low volume irrigation is used in agriculture for row crops and orchards; in the horticulture industry at wholesale nursery growing grounds; in the landscape industry for civic, commercial, and private landscapes and gardens; and in the restoration ecology and environmental remediation sciences and professional methods.
Use of Low volume irrigation and Microirrigation systems on green building candidate projects can help them to "accumulate points" for LEED - (Leadership in Energy and Environmental Design) certification rating and awards.
- 1 Description
- 2 System components - all uses
- 3 Landscape and gardens
- 4 Agriculture
- 5 Ecological restoration and phytoremediation projects
- 6 Water conservation and regulations
- 7 See also
- 8 References
- 9 External links
'Low-flow irrigation systems can use drip emitters, trickle-"spider spray", micro spray-sprinklers, and-or mist emitters; to distribute irrigation water slowly in small volumes and targeting it to plants' root zones with less-no runoff or "overshooting" or landscape and garden "regular flow" conventional spray and rotary sprinklers. The low volume allows the water to penetrate and be absorbed into slow-percolation soils, such as clay, and those with a 'packed dirt' hard surface, minimizing water runoff.
System components - all uses
With any application finer gauge and flush-able inline filtration, pressure regulation for reduced static and dynamic GPM (gallons per minute), and manual shutoff valves for repair, additions, and adjustment is required. Since water conservation is a frequent reason for choosing Low-flow irrigation systems, also installing moisture sensors, rain shutoffs, wind shutoffs, and the new computerized ET Controllers significantly enhance water expense reductions, resource conservation, and sustainable agriculture and sustainable landscaping.
Landscape and gardens
Low-flow irrigation systems in gardens using drip apply water through two methods:
- pre installed small holes in small diameter tubes placed on or below the surface or
- self cleaning emitters, in different precipitation rates, pre installed or contractor installed for different rate emitters on same supply line (i.e. trees-higher, perennials-lower). The Flexible supply pipe can be buried either underground or pinned on the surface and buried under
Trickle emitters, also called 'spider sprays,' come in fixed or adjustable radius shapes and diameters, and are installed directly on the flexible supply pipe or on tubing connected to it, and mounted on small stakes. Trickle emitter-'Spider sprays' work well for plants with more fibrous root systems, tree and large shrub basins, and in pots and container gardens - allowing automated watering of plants on decks and patios. Mist emitters can also be used in pot, both on the ground and hanging, with humidity-fog watering for epiphytes and ferns replicating habitats.
Low volume spray - small
Low volume spray head micro sprinklers can be attached to conventional 'hard plumbed' PVC supply systems on stationary or pop-up risers, when pressure regulators are set low to specifications and the pop-ups are specified for lower GPM pressure operation. Low volume spray heads can also be installed in a similar manner as Trickle emitters above, mounted on stakes and attached to small diameter tubing connected to flexible supply pipe.
Low volume spray - large
A different low volume landscape irrigation system is more similar in installation, durability, and a long spray radius; the current most prominent one under the Hunter Industries trade name "MP Rotator"; - but with water delivery at Low-flow rates.  It has the same slow application rate, deep penetration-absorption, and reduced-eliminated runoff benefits as the micro-sprinklers, but serves large civic, commercial, and private landscape installations. Low flow- spray heads are used to retro-fit existing conventional spray heads on standard-flow systems, utilizing pressure reduction devices. Some cities, such as Santa Monica, California, and water districts such as the Los Angeles Department of Water and Power, have offered rebates and specified "this product or equal" clauses for building permits requiring landscape plan-water use calculation submittal.  
Low-flow irrigation systems often use the two delivery components of drip or trickle systems to apply water through small holes in small diameter tubes placed on or below the surface of the field. This is done instead of agricultural surface irrigation and furrow irrigation for vegetables, fruits and berries, and other high-value crops.
Another type of delivery components, micro sprinklers and "spider sprays", supply water from low-volume sprinkler heads located above the surface. This is often used for fruit and nut orchards and vineyards. Low flow systems are expensive for large-scale agricultural use and are predominantly used for high-value crops.
In the Horticulture industry, wholesale growers and plant nurseries often use the trickle emitters for 5-US-gallon (19 L) and larger container stock, to automate watering. Attached to longer supply tubing on short stakes, they are easily movable to new containers when stock is moved or sold. Mist emitters are used for propagation, epiphytes, and other plants needing higher humidity.
Ecological restoration and phytoremediation projects
Low-flow irrigation systems are used on some native plant habitat restoration and environmental remediation projects. The lower operating pressure can be the only choice for remote locations with wells or small storage tank water sources. It is used in temporary installations during initial establishment periods, and being on the soil surface easily removable with minimal damage to the recovering plant community. An example is its use in riparian zone restoration, and environmental remediation projects using Phytoremediation and Bioremediation techniques.
Water conservation and regulations
As municipal and agricultural water supplies become more limited; through increased population demands, droughts, and climate change; city, water district, and state-province level regulations and codes are beginning to encourage, offer rebates with use, or mandate significantly reduced water allowances, at higher costs, that are bringing many water conservation products and techniques both to the forefront and more competitively matched to traditional irrigation system costs.
- This article incorporates public domain material from the Congressional Research Service document "Report for Congress: Agriculture: A Glossary of Terms, Programs, and Laws, 2005 Edition" by Jasper Womach.