Drip irrigation
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Drip irrigation, also known as trickle irrigation or microirrigation is an irrigation method that applies water slowly to the roots of plants, by depositing the water either on the soil surface or directly to the root zone, through a network of valves, pipes, tubing, and emitters, with the goal of minimizing water and fertilizer usage. Modern drip irrigation has arguably become the most important innovation in agriculture since the invention of the impact sprinkler in the 1930s, which replaced wasteful flood irrigation. Drip irrigation may also use devices called micro-spray heads, which spray water in a small area, instead of dripping emitters. These are generally used on tree and vine crops with wider root zones. Subsurface drip irrigation or SDI uses permanently or temporarily buried dripperline or drip tapelocated at or below the plant roots. It is becoming more widely used for row crop irrigation especially in areas where water supplies are limited or recylced water is used for irrigation. Careful study of all the relevant factors like land topography, soil, water, crop and agro-climatic conditions, are needed to determine the most suitable drip irrigation system and components to be used in a specific installation.
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[edit] History
Drip irrigation has been used since ancient times when buried clay pots were filled with water and the water gradually seeped into the soil. Modern drip irrigation began its development in Germany in 1860 when researchers began experimenting with subirrigation using clay pipe to create combination irrigation and drainage systems. In 1913, E.B. House at Colorado State University succeeded in applying water to the root zone of plants without raising the water table. Perforated pipe was introduced in Germany in the 1920s and in 1934, O.E. Robey experimented with irrigating through porous canvas hose at Michigan State University.
With the advent of modern plastics during and after World War II, major improvements in drip irrigation became possible. Plastic microtubing and various types of emitters began to be used in the greenhouses of Europe and the United States. A new technology of drip irrigation was then introduced in Israel by Simcha Blass and his son Yeshayahu. Instead of releasing water through tiny holes, blocked easily by tiny particles, water was released through larger and longer passageways by using friction to slow water inside a plastic emitter. The first experimental system of this type was established in 1959 when Blass partnered with Kibbutz Hatzerim to create an irrigation company called Netafim. Together they developed and patented the first practical surface drip irrigation emitter. This method was very successful and subsequently spread to Australia, North America, and South America by the late 1960s. Netafim and many others continue to produce drip irrigation systems today. In the United States, in the early 1960s, the first drip tape, called Dew Hose, was developed by Richard Chapin of Chapin Watermatics (first system established during 1964). [1] Beginning in 1989, Jain irrigation helped pioneer effective water-management through Drip Irrigation in India. Jain irrigation also introduced some drip irrigation marketing approaches to Indian agriculture such as `Integrated System Approach’, One-Stop-Shop for Farmers, `Infrastructure Status to Drip Irrigation & Farm as Industry.’ The latest developments in the field involve even further reduction in drip rates being delivered and less tendency to clog.
[edit] Components and Operation
Components (listed in order from water source)
- Pump or pressurized water source
- Water Filter(s) - Filtration Systems: Sand Separator, Cyclone, Screen Filter, Media Filters
- Fertigation Systems (Venturi injector) and Chemigation Equipment (optional)
- Backwash Controller
- Main Line (larger diameter Pipe and Pipe Fittings)
- Hand-operated, electronic, or hydraulic Control Valves and Safety Valves
- Smaller diameter polytube (often referred to as "laterals")
- Poly fittings and Accessories (to make connections)
- Emitting Devices at plants (ex. Emitter or Drippers, micro spray heads, inline drippers)
- Note that in Drip irrigation systems Pump and valves may be manually or automatically operated by a controller.
Most large drip irrigation systems employ some type of filter to prevent clogging of the small emitter flow path by small waterborn particals. New technologies are now being offered that minimize clogging. Some residential systems are installed without additional filters since potable water is already filtered at the water treatment plant. Virtually all drip irrigation equipment manufacturers recommend that filters be employed and generally will not honor warranties unless this is done.
Drip and subsurface drip irrigation is used almost exclusively when using recycled municipal waste water. Regulations typically do not permit spraying water through the air that has not been fully treated to potable water standards.
Because of the way the water is applied in a drip system, traditional surface applications of timed-release fertilizer are sometimes ineffective, so drip systems often mix liquid fertilizer with the irrigation water. This is called fertigation; fertigation and chemigation (application of pesticides and other chemicals to periodically clean out the system, such as chlorine or sulfuric acid) use chemical injector such as diaphragm pumps, piston pumps, or venturi pumps. The chemicals may be added constantly whenever the system is irrigating or at intervals. Fertilizer savings of up to 95% are being reported from recent university field tests using drip fertigation and slow water delivery as compared to timed-release and irrigation by micro spray heads.
If properly designed, installed, and managed, drip irrigation may help achieve water conservation by reducing evaporation and deep drainage when compared to other types of irrigation such as flood or overhead sprinklers since water can be more precisely applied to the plant roots. In addition, drip can eliminate many diseases that are spread through water contact with the foliage. Finally, in regions where water supplies are severely limited, there may be no actual water savings, but rather simply an increase in production while using the same amount of water as before. In very arid regions or on sandy soils, the trick is to apply the irrigation water as slowly as possible.
Pulsed irrigation is sometimes used to decrease the amount of water delivered to the plant at any one time, thus reducing runoff or deep percolation. Pulsed systems are typically expensive and require extensive maintenance. Therefore, the latest efforts by emitter manufacturers are focused toward developing new technologies that deliver irrigation water at ultra-low flow rates, i.e. less than 1.0 liter per hour. Slow and even delivery further improves water use efficiency without incurring the expense and complexity of pulsed delivery equipment.
Drip irrigation is used by farms, commercial greenhouses, and residential gardeners. Drip irrigation is adopted extensively in areas of acute water scarcity and especially for crops such as coconuts, containerized landscape trees, grapes, bananas, ber, brinjal, citrus, strawberries, sugarcane, cotton, maize, and tomatoes.
Garden drip irrigation kits are increasingly popular for the homeowner and consist of a timer, hose and emitter.
[edit] Advantage / Disadvantages of Drip Irrigation
The advantages of drip irrigation are:
- Minimized fertilizer/nutrient loss due to localized application and reduced leaching.
- High water distribution efficiency.
- Leveling of the field not necessary.
- Allows safe use of recycled water.
- Moisture within the root zone can be maintained at field capacity.
- Soil type plays less important role in frequency of irrigation.
- Minimized soil erosion.
- Highly uniform distribution of water i.e., controlled by output of each nozzle.
- Lower labour cost.
- Variation in supply can be regulated by regulating the valves and drippers.
- Fertigation can easily be included with minimal waste of fertilizers.
- Early maturity and a bountiful harvest (season after season, year after year)
The disadvantages of drip irrigation are:
- Expense. Initial cost can be more than overhead systems.
- Waste. The plastic tubing and "tapes" generally last 1-3 seasons before being replaced.
- Clogging, if the water is not properly filtered and the equipment not properly maintained.
- Drip irrigation might be unsatisfactory if herbicides or top dressed fertilizers need sprinkler irrigation for activation.
- Drip tape causes extra cleanup costs after harvest. You'll need to plan for drip tape winding, disposal, recycling or reuse.
- Waste of water, time & harvest, if not installed properly. These systems requires careful study of all the relevant factors like land topography, soil, water, crop and agro-climatic conditions, and suitability of drip irrigation system and its components.
[edit] Drip manufacturers
- Agrifim
- Antelco
- Aquarius
- Chapin Watermatics
- DIG Corp.
- Eurodrip
- Jain Irrigation Systems Ltd.
- NDS
- Netafim
- Orbit
- Plasgot
- Rain Bird Corporation
- Raindrip
- T-Systems
[edit] See also
- irrigation
- Center for Irrigation Technology Fresno California
[edit] References
- Irrigation, 5th Edition, Claude H. Pair, editor, published by the Irrigation Association, 1983
- Trickle Irrigation for Crop Production, F.S. Nakayama and D.A. Bucks, editors, published by Elsevier, 1986, ISBN 0-444-42615-9
- S. Blass, Water in Strife and Action (Hebrew), published by Massada limited, Israel, 1973
- Maintenance Manual, published by Jain Irrigation, 1989
