Drip irrigation
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An Emitter or dripper in action
Drip irrigation, also known astrickle irrigationormicro
irrigationorlocalized irrigation, is anirrigationmethod that saves
water and fertilizer by allowingwaterto drip slowly to therootsof
plants, either onto thesoilsurface or directly onto theroot zone,
through a network ofvalves,pipes,tubing, andemitters. It is done
through narrow tubes that deliver water directly to the base of the
plant.
Contents
[hide] 1History 2Components and operation 3Advantages and
disadvantages 4Uses 5See also 6References 7Further
readingHistory[edit]
Drip irrigation in New Mexico vineyard, 2002
Primitive drip irrigation has been used since ancient times. Fan
Sheng-Chih Shu, written inChinaduring the first centuryBCE,
describes the use of buried, unglazed clay pots filled with water
as a means of irrigation.[1]Modern drip irrigation began its
development inGermanyin 1860 when researchers began experimenting
with subsurface irrigation using clay pipe to create combination
irrigation and drainage systems.[2]Research was later expanded in
the 1920s to include the application of perforated pipe
systems.[3]The usage of plastic to hold and distribute water in
drip irrigation was later developed inAustraliaby Hannis
Thill.[4]Usage of a plastic emitter in drip irrigation was
developed inIsraelbySimcha Blassand his son Yeshayahu.[5]Instead of
releasing water through tiny holes, that are blocked easily by tiny
particles, water was released through larger and longer passageways
by using velocity to slow water inside a plastic emitter. The first
experimental system of this type was established in 1959 by Blass
who partnered later (1964) withKibbutz Hatzerimto create an
irrigation company calledNetafim. Together they developed and
patented the first practical surface drip irrigation
emitter.[2]
HYPERLINK "http://en.wikipedia.org/wiki/Drip_irrigation" \l
"cite_note-6"[6]In the United States, the first drip tape,
calledDew Hose, was developed by Richard Chapin of Chapin
Watermatics in the early 1960s.[7]Beginning in 1989,Jain Irrigation
Systemshelped pioneer effective water-management through drip
irrigation in India.
Modern drip irrigation has arguably become the world's most
valued innovation inagriculturesince the invention of theimpact
sprinklerin the 1930s, which offered the first practical
alternative tosurface 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 (SDI) uses permanently or temporarily buried dripperline
ordrip tapelocated at or below the plant roots. It is becoming
popular for row crop irrigation, especially in areas
wherewatersupplies are limited or recycled 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.
Components and operation[edit]
Drip irrigation system layout and its parts
Water distribution in subsurface drip irrigation
Nursery flowers watered with drip irrigation inIsrael
Horticulturedrip emitter in a pot
Components used in drip irrigation (listed in order from water
source) include:
Pumpor pressurized water source
Water filter(s) or filtration systems: sand separator such as
Hydro-Cyclone,screen filters,media filters,disk filters Fertigation
systems (Venturi injector) and chemigation equipment (optional)
Backwash controller (Backflow prevention device)
Pressure Control Valve (pressure regulator)
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 (emitter or dripper, micro spray
head, inline dripper or inline driptube)
In drip irrigation systems, pump andvalvesmay be manually or
automatically operated by acontroller.
Most large drip irrigation systems employ some type offilterto
prevent clogging of the small emitter flow path by small waterborne
particles. 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. Last line filters just
before the final delivery pipe are strongly recommended in addition
to any other filtration system due to fine particle settlement and
accidental insertion of particles in the intermediate lines.
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-releasefertilizerare
sometimes ineffective, so drip systems often mix liquid fertilizer
with the irrigation water. This is calledfertigation; fertigation
and chemigation (application ofpesticidesand other chemicals to
periodically clean out the system, such aschlorineorsulfuric acid)
use chemical injectors such asdiaphragm pumps,piston pumps,
oraspirators. 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.
Properly designed, installed, and managed, drip irrigation may
help achievewater conservationby reducingevaporationanddeep
drainagewhen 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 veryarid
regionsor onsandy soils, the preferred method is to apply the
irrigation water as slowly as possible.
Pulsed irrigationis 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.
An emitting pipe is a type of drip irrigation tubing with
emitters pre-installed at the factory with specific distance and
flow per hour as per crop distance.
An emitter is also called a dripper and is used to transfer
water from a pipe or tube to the area that is to be irrigated.
Typical emitter flow rates are from 0.16 to 4.0 U.S. gallons per
hour (0.6 to 16 L/h). In many emitters, flow will vary with
pressure, while some emitters arepressure compensating.
Advantages and disadvantages[edit]This articlecontains apro and
con list, which is sometimes inappropriate.Please helpimprove itby
integrating both sides into a moreneutralpresentation, or remove
this template if you feel that such a list is appropriate for this
article.(November 2012)
Banana plants with drip irrigation in Maharashtra, India
The advantages of drip irrigation are:
Fertilizer and nutrient loss is minimized due to localized
application and reduced leaching.
Water application efficiency is high.
Field levelling is not necessary.
Fields with irregular shapes are easily accommodated.
Recycled non-potable water can be safely used.
Moisture within the root zone can be maintained at field
capacity.
Soil type plays less important role in frequency of
irrigation.
Soil erosion is lessened.
Weed growth is lessened.
Water distribution is highly uniform, controlled by output of
each nozzle.
Labour cost is less than other irrigation methods.
Variation in supply can be regulated by regulating the valves
and drippers.
Fertigationcan easily be included with minimal waste of
fertilizers.
Foliage remains dry, reducing the risk of disease.
Usually operated at lower pressure than other types of
pressurised irrigation, reducing energy costs.
The disadvantages of drip irrigation are:
Expense: initial cost can be more than overhead systems.
Waste: the sun can affect the tubes used for drip irrigation,
shortening their usable life.
Clogging: if the water is not properly filtered and the
equipment not properly maintained, it can result in clogging.
Drip irrigation might be unsatisfactory if herbicides or top
dressed fertilizers need sprinkler irrigation for activation.
Drip tape causes extra cleanup costs after harvest. Users need
to plan for drip tape winding, disposal, recycling or reuse.
Waste of water, time and harvest, if not installed properly.
These systems require 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.
Germination problems: in lighter soils subsurface drip may be
unable to wet the soil surface for germination. Requires careful
consideration of the installation depth.
The main purpose of drip irrigation is to reduce the water
consumption by reducing theleaching factor. However when the
available water is of highsalinityoralkalinity, the field soil
becomes gradually unsuitable for cultivation due to high salinity
or poor infiltration of the soil. Thus drip irrigation converts
fields in to fallow lands when natural leaching by rain water is
not adequate insemi aridandarid regions.
Salinity: most drip systems are designed for high efficiency,
meaning little or no leaching fraction. Without sufficient
leaching, salts applied with the irrigation water may build up in
the root zone, usually at the edge of the wetting pattern. On the
other hand, drip irrigation avoids the high capillary potential of
traditional surface-applied irrigation, which can draw salt
deposits up from deposits below.
Rodents: the PVC pipes often suffer from rodent damage,
requiring replacement of the entire tube and increasing
expenses.
drip irrigation systems cannot be used for damage control by
night frosts (like in the case of sprinkler irrigation systems)
Uses[edit]
Irrigation dripper
Drip irrigation is used byfarms, commercialgreenhouses, and
residentialgardeners. Drip irrigation is adopted extensively in
areas of acute water scarcity and especially for crops and trees
such ascoconuts, containerized landscape
trees,grapes,bananas,ber,eggplant,citrus,strawberries,sugarcane,cotton,maize,
andtomatoes.
Drip irrigation for garden available in drip kits are
increasingly popular for the homeowner and consist of
atimer,hoseand emitter. Hoses that are 4mm in diameter are used to
irrigate flower pots.
Rainmaking
From Wikipedia, the free encyclopedia
(Redirected fromArtificial rain)
For rituals intended to invoke rain, seeRainmaking (ritual).
For Weather modification includingcloud seeding, seeWeather
modification.
This articleneeds additional citations forverification.Please
helpimprove this articlebyadding citations to reliable sources.
Unsourced material may be challenged and removed.(October 2008)
Rainmaking, also known asartificial precipitation, is the act of
attempting to artificially induce or increaseprecipitation, usually
to stave offdrought. According to the clouds' different physical
properties, this can be done using airplanes or rockets to sow to
the clouds with catalysts such asdry ice,silver iodideand salt
powder, to make clouds rain or increase precipitation, to remove or
mitigate farmlanddrought, to increase reservoir irrigation water or
water supply capacity, or to increase water levels for power
generation.
In the US, rainmaking was attempted by traveling showmen. It was
practiced in theold westbut may have reached a peak during thedust
bowldrought of the American West and Midwest in the 1930s. The
practice was depicted in the 1956 filmThe Rainmaker. Attempts to
bring rain directly have waned with development of the science
ofmeteorology, the advent of laws against fraud and increased
communication technology, with some exceptions such ascloud
seedingandrain dancesor other forms ofprayer, which are still
practiced today. Prayer for more rain is also a cross cultural
practice in Christian and Muslim Ethiopia as well as in areas where
people keep "traditional" non-scriptural religions.[citation
needed]In the Christian areas the Defteras (learned clerics of the
Orthodox Christian Church) believed to have the wisdom to arrest
the rain, to bring hail to farms of individuals who refuse to
comply with religious rules as well as to bring more rains when the
rainy season fell short of giving the usual amount of rain needed
for growing cereals.[citation needed]The term is also used
metaphorically to describe the process of bringing new clients into
a professional practice, such as law, architecture, consulting,
advertising, or investment banking in general, processes that
bringmoneyinto acompany.
Cloud seeding[edit]Since the 1940s, cloud seeding has been used
to change the structure of clouds by dispersing substances into the
air, potentially increasing or altering rainfall. In spite of
experiments dating back to at least the start of the 20th century,
however, there is much controversy surrounding the efficacy of
cloud seeding, and evidence that cloud seeding leads to increased
precipitation on the ground is highly equivocal. One difficulty is
knowing how much precipitation might have fallen had any particular
cloud not been seeded.Operation Popeyewas a US military rainmaking
operation to increase rains overVietnamduring theVietnam Warin
order to slow Vietnamese military truck activity in the region.
Rainmaking is notgeoengineering, which seeks to alter climate, but
a form ofweather modification, as it seeks only to change local
weather.
William Reich's Cloudbuster[edit]Austrian-American
psychoanalystWilliam Reichdesigned a "cloudbuster" in theUnited
Stateswith which he said he could manipulate streams of orgone
energy (which he claimed was a primordial cosmic energy) in the
atmosphere to induce rain by forcing clouds to form and disperse.
It was a set of hollow metal pipes and cables inserted into water,
which Reich argued created a stronger orgone energy field than was
in the atmosphere, the water drawing the atmospheric orgone through
the pipes. Reich called his research "Cosmic Orgone
Engineering".
Rain dances and prayer[edit]In many societies around the
world,rain dancesand other rituals have been used to attempt to
increase rainfall. SomeNative Americansused rain dances
extensively. European examples include theRomanianceremonies known
aspaparudaandcaloian. SomeUnited Statesfarmersalso attempt to bring
rain during droughts through prayer. These rituals differ greatly
in their specifics, but share a common concern with bringing rain
through ritual and/or spiritual means. Typical of these ceremonies
was then-governor of GeorgiaSonny Perdue's public prayer service
for rain, in 2007.
Design
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Center Pivot
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Drip
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Surface
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Subirrigation
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Flood
Irrigation sprinkler
Animpact sprinklerhead in action
Irrigation sprinklersare sprinklers providingirrigationto
vegetation, or for recreation, as a cooling system, or for the
control of airborne dust.The sprinkler system irrigates the field
drop by drop and thus it is widely used in sandy areas as it checks
the wastage of water through seepage and evaporation.Sprinkler
irrigation is a method of applying irrigation water which is
similar to natural rainfall. Water is distributed through a system
of pipes usually by pumping. It is then sprayed into the air
through sprinklers so that it breaks up into small water drops
which fall to the ground. The pump supply system, sprinklers and
operating conditions must be designed to enable a uniform
application of water.
Types[edit]Industrial[edit]Sprinklers that spray in a fixed
pattern are generally called sprays or spray heads. Sprays are not
usually designed to operate at pressures above 30lbf/in (200 kPa)
(30psi "Pounds per square inch"), due to misting problems that may
develop.
Higher pressure sprinklers that themselves move in a circle are
driven by a ball drive, gear drive, or impact mechanism (impact
sprinklers). These can be designed to rotate in a full or partial
circle.
Rainguns are similar to impact sprinkler, except that they
generally operate at very high pressures of 40 to 130lbf/in (275 to
900 kPa) and flows of 50 to 1200 US gal/min (3 to 76 L/s), usually
with nozzle diameters in the range of 0.5 to 1.9inches (10 to
50mm). In addition to irrigation, guns are used for industrial
applications such asdustsuppression andlogging.
Many irrigation sprinklers are buried in the ground along with
their supporting plumbing, although above ground and moving
sprinklers are also common. Most irrigation sprinklers operate
through electric and hydraulic technology and are grouped together
in zones that can be collectively turned on and off by actuating
asolenoid-controlled valve.
Residential[edit]
This section requiresexpansion.(June 2008)
Home lawn sprinklers vary widely in their size, cost, and
complexity. They includeimpact sprinklers,oscillating
sprinklers,drip sprinklers, andunderground sprinklersystems. Small
sprinklers are available at home and garden stores or hardware
stores for small costs. These are often attached to an outdoor
water faucet and are placed only temporarily. Other systems may be
professionally installed permanently in the ground and are attached
permanently to a home'splumbingsystem. An ingenious domestic
sprinkler made by Nomad called a 'set-and-forget tractor sprinkler'
was used in Australia in the 1950s. Water pressure ensured that the
sprinkler slowly moved across a lawn.[1]Permanently installed
systems may often operate on timers or other automated processes.
They are occasionally installed with retractable heads for
aesthetic and practical reasons (making damage duringlawn mowingor
other maintenance less likely). These often are programed to
operate at certain times of day or on some other schedule.
Underground[edit]Underground sprinklers function through means
of basic electronic and hydraulic technology. This valve and all of
the sprinklers that will be activated by this valve are known as a
zone. Upon activation, the solenoid, which sits on top of the valve
is magnetized lifting a small stainless steel plunger in its
center. By doing this, the activated (or raised) plunger allows air
to escape from the top of a rubber diaphragm located in the center
of the valve. Water that has been charged and waiting on the bottom
of this same diaphragm now has the higher pressure and lifts the
diaphragm. This pressurized water is then allowed to escape down
stream of the valve through a series of pipes, usually made of PVC
(higher pressure commercial systems) or polyethylene pipe (for
typically lower pressure residential systems). At the end of these
pipes and flush to ground level (typically) are pre measured and
spaced out sprinklers. These sprinklers can be fixed spray heads
that have a set pattern and generally spray between 1.52m (715ft.),
full rotating sprinklers that can spray a broken stream of water
from 612m (2040ft.), or small drip emitters that release a slow,
steady drip of water on more delicate plants such as flowers and
shrubs. use of indigenous materials also
recommended.[2]Agricultural[edit]Center pivot irrigationsprinkler
nozzles, used incropirrigation
Rotator style pivot applicator sprinkler
End Gun style pivot applicator sprinkler
The first use of sprinklers by farmers was some form of home and
golf course type sprinklers. These ad hoc systems, while doing the
job of the buried pipes and fixed sprinkler heads, interfered with
cultivation and were expensive to maintain. In the 1950s a firm
based in Portland, OregonStout-Wyss Irrigation System, developed
the rolling pipe type irrigation system for farms that has become
the most popular type for farmers irrigating large fields. With
this system large wheels attached to the large pipes with sprinkler
heads move slowly across the field.[3]Use[edit]Most irrigation
sprinklers are used as part of a sprinkler system, consisting of
various plumbing parts, piping and control equipment. Outdoor
sprinkler systems are sometimes used as a deterrent againsthomeless
people. This sprinkler system was programmed to drench unsuspecting
sleepers at random times during the night. Local businessmen soon
copied this system in an effort to drive homeless people away from
public sidewalks adjacent to their businesses.
