2. Crop water need
The crop water need (ET crop) is defined as the depth
(or amount) of water needed to meet the water loss
through evapotranspiration. In other words, it is the
amount of water needed by the various crops to grow
Consumptive use (CU): Sum of ET and quantity of
water used for metabolic activities.(ET and CU often
used interchangeably because only 1% water is used
for metabolic activities).
3. Evapotranspiration (ET) process
The combination of two separate processes where by
water is lost from the soil surface by evaporation and
from the crop by transpiration is referred to as ET.
The ET rate is normally expressed in millimetres (mm)
per unit time.
The rate expresses the amount of water lost from a
cropped surface in units of water depth.
The time unit can be an hour, day, decade, month or
even an entire growing period or year.
+ = evapotranspiration (ET )
the plants extract
water from the
soil; this water
leaves the plant
during the day
through the stem
and the leaves
• an open water
• the soil
• the leaves and the
stem of the plant
During the day water
ecapes as vapour to
The atmosphere from:
5. Factors affecting ET
Weather parameters: The principal weather
parameters are radiation, air temperature, humidity
and wind speed.
Crop factors: The crop type, variety and
development stage should be considered from crops
grown in large, well-managed fields.
Management and environmental conditions:
Factors such as soil salinity, poor land fertility, limited
application of fertilizers, the presence of hard or
impenetrable soil horizons, the absence of control of
diseases & pests and poor soil management may limit
the crop development and reduce the ET.
6. Evapotranspiration concepts
Reference crop evapotranspiration (ETo): ETo is a
climatic parameters expressing the evaporation power of
Crop evapotranspiration under standard conditions
(ETc):ETc refers to the ET from excellently managed,
large, well-watered fields that achieve full production
under the given climatic conditions.
Crop evapotranspiration under non-standard conditions
(ETc adj):Due to sub-optimal crop management and
environmental constraints that affect crop growth and
limit ET, ETc under non-standard conditions generally
requires a correction.
8. Crop ET
Crop coefficient approach: Crop ET (ETc) is
calculated by multiplying the reference crop ET
(ETo) by a crop coefficient (Kc):
ETc = Kc ETo
ETc crop evapotranspiration [mm d-1],
Kc crop coefficient [dimensionless],
ETo reference crop evapotranspiration [mm d-1].
9. Types of Watering Systems
1. Manual/Hand Watering
2. Overhead Irrigation System
2.1 Sprinkler Irrigation
2.2 Boom Irrigation
3. Surface Irrigation System
3.1 Drip irrigation
3.2 Perimeter watering system
3.3 Tube water system
4. Subsurface Irrigation System
4.1 Ebb and Flow System
4.2 Capillary Mat Watering System
4.3 Floor Flood Irrigation System
4.4 Water Trays and Saucers
11. It is most common but most uneconomical and expensive system of
watering but still is followed where labour is cheap and scale of
operation is rather small and automation is not practiced.
It requires considerable time and it is not pleasant work. But still it is
followed where crops is at high density like nursery production, seed
flats or pots.
Where it is practiced care should be taken that force of water should
be broken either by using fine rose spray or breaker at the end of
pipe so that it does not result in washing of root medium out of pots
and disturb structure of root medium surface.
1. Manual/Hand watering
14. GH crops are most easily and cheaply irrigated from
In this system pipes are hanged 60 cm to 180 cm above
Nozzles are fitted in the pipes at 360° pattern.
Care should be taken so that the water should be of
good quality and properly filtered so that these nozzles
are not clogged.
2.1 Sprinkler Irrigation
16. A boom system consists of one or more pipes containing nozzles
that apply water as the system moves over the plants. It may be
suspended from an overhead rail system or from a cart that moves
down the aisle. Water is supplied by a trailing hose and powered by
a battery pack or electric supply cable.
The advantages to a boom system are greater uniformity of water
application, less water required and less aisle space is needed for
Because of the large number of options, careful selection of a boom
system is required. Factors affecting selection are type & style of
GH, cropping system, water quantity & quality and the amount of
2.2 Boom Irrigation
19. • It is a controlled, slow application of water to
soil over a long period of time.
•The water flows under low pressure through
plastic pipe/tubing laid along each row of plants.
3.1 Drip Irrigation
20. Comparison of Drip, Sprinkler and flood irrigation methods
Fig. 1: Availability of moisture in different irrigation methods
21. 1. Surface drip irrigation
1.1 Online Drip Irrigation
1.2 Inline drip irrigation
2. Sub surface drip irrigation
Types of Drip Irrigation Systems
23. Water Source
There are basically two main types of water sources: groundwater
and surface water. Many existing and potential water supply
sources for irrigation systems are derived from surface water,
which does not tend to have high levels of salts (with the
exception of some coastal areas), and thus systems are usually less
prone to formation of precipitates in drippers when using a surface
Surface water: It can pond, open canal, river stream, well etc. It,
however, tends to introduce biological hazards. If wastewater is
being considered as a source, quality and clogging potential will
vary depending upon the extent of treatment.
Groundwater: Groundwater is generally of higher quality than
surface water. However, iron and manganese levels should be
measured, as high levels may lead to dripper clogging, and
treatment may be required.
24. Pumps and pumping stations
Unless the water at the source is supplied at an
adequate flow rate and pressure (by municipal or
other entity supply, a pre-existing pump upstream
from the irrigation system or gravitational pressure),
a pump will be needed to push water from the source
through the pipes and drippers.
Most irrigation systems include pumps as an integral
part of the drip irrigation system.
Power source for the pump: The power source for
the pump will depend on the availability and
accessibility of the energy resource in the local area.
Electricity is good source, if electricity is not
available, alternative power sources such as diesel,
gasoline, or solar may be used.
25. It play key roles in controlling pressure, flow and
distribution under different conditions to optimize
performance, facilitate management, and reduce
The water flow rate and pressure throughout the
irrigation system should be precisely controlled to
ensure efficient and timely water application;
therefore proper selection and placement of valves is
26. These valves may be installed at any point where
possibility exists for excessively high pressures,
either static or surge pressure.
A bye pass arrangement is simplest and cost
effective means to avoid problems of high pressures
instead of using costly pressure relief valves.
Pressure relief valves, regulators or bye pass arrangement
27. ukWu fjVuZ okYo
(Non Return Valve)
Check valves (non-return
valves/on-way valve): These valves
are used to prevent unwanted flow
reversal. They are used to prevent
damaging back flow from the system
to avoid return flow of chemicals and
fertilizers from the system into the
water source itself to avoid
contamination of water source.
Control valves (ball valves):
Generally, they are installed on
filtration system, mainline and on all
submains. They are made up of gun
metal, PVC, cast iron and their size
ranges from 20 mm to more than 140
Rotating the lever turns the ball so
that when the port is in line with the
pipe, flow will occur, and when
perpendicular to the pipe, flow is
blocked. It is designed to be fully
opened or closed
28. Air release cum
It is provided at the highest point
in the main line to release the
entrapped air during the start of
system and to break the vacuum
during shut off. It is also
provided on submain if submain
length is more.
Pressure gauges are essential
components in a drip irrigation
information concerning the
irrigation system, they help in
the detection of leaks and
clogging and in the management
of filters, chemical injectors and
in keeping the system in its
It is critical component in any drip irrigation system.
Effective filtration is essential for proper irrigation system
operation and long-term performance, as it prevents the
irrigation water from clogging the drippers.
Water quality will dictate filtration requirements, fertigation
requirements and management of the irrigation systems to
prevent dripper clogging.
Causes of dripper clogging in systems may be chemical
(precipitates or scale), physical (grit or particulates such as
sand and sediment) or biological (such as algae or bacteria).
The type of filtration to be used is carefully selected at the
planning stage according to the general quality of the
irrigation water, and the presence of various substances in
it, with respect to the specific requirements of the irrigation
31. WHY FERTIGATION
Application of Nutrients
Plants get a larger dosage of fertilizer than
they require at the time it is applied. Losses
Fertilizers are applied according the need
for nutrients, following the uptake rate of
32. Fertilizer Use Efficiencies Under Various
Fertilizer Use Efficiency (%)
Soil application Fertigation
Nitrogen 30-50 95
Phosphorous 20 45
Potassium 50 80
34. Water Distribution Network
The water distribution network constitutes main line, submains
line and laterals with drippers and other accessories.
Main line: It transports water within the field and distribute to
submains. It is made of rigid PVC or High Density Polyethylene
(HDPE). Pipelines of 65 mm diameter and above with a pressure
rating 4 to 6 kg/cm2 are used.
Submains: It distribute water evenly to a number of lateral lines.
For sub main pipes, rigid PVC,HDPE or LDPE (Low Density
Polyethylene) of diameter ranging from 32 mm to 75 mm having
pressure rating of 2.5 kg/cm2 are used.
Laterals: It distribute the water uniformly along their length by
means of drippers or emitters. These are normally manufactured
from LDPE and LLDPE. Generally pipes having 10, 12 and 16
mm internal diameter with wall thickness varying from 1 to 3 mm
36. ,UM dSi
They are used to
close the lateral
It is provided to
flush out the
water and dirt
the end of
37. Water saving
Fertilizer saving and increased fertilizer use
Energy and labour saving
Reduced weed growth
Marginal land & undulated land can be irrigated
Use of saline water is possible for irrigation
Less problem of disease and pest
Makes intercultural operations easy
38. In this system, pipes run around the perimeters of a bench with a
nozzle that sprays water in root medium below the foliage. Thus
this system is most pertinent for production of fresh flowers.
The pipes may be of galvanized iron or PVC.
Rubber pipes if are used they can be rolled if it is not in use. In
these pipes, nozzles are fitted at an angle of 45, 90 or 180
Normally pipes of 19 mm diameters are used. Depending upon
the length of beds, valve may be provided accordingly.
3.2 Perimeter Watering System
40. This system is mostly used for watering the pots. Water
is carried to each pot by the polyethylene micro tube.
These micro tubes are available in different inner
diameter varying from 0.9, 1.1, 1.3, 1.5, 1.9 mm and
The number of pots that can be watered from a single
19 mm main water pipe will depend upon inner
diameter of micro tube being used e.g., 0.9, 1.1, 1.3,
1.5 mm micro tube will be able to handle 900, 700, 600
and 400 pots, respectively.
These micro tubes should be provided with a weight at
the end of it so that speed of water can be broken
otherwise there is a danger that pipe being thrown out
of the pot and will dig a small pit in medium.
3.3 Tube Watering System
43. It a sub irrigation system for potted and bedding plants. Pot or flats
are grown in a leveled bench made of plastic or fiber glass
available in various widths and length.
These benches are glued together to make a bench of desired length
and width. These benches can move over a stand. These have
channels to drain out irrigation water.
There is a water tank below the bench. This tank is covered to
avoid dust or algal growth. The area of watering and size of pump
should be matched.
To ensure watering of pot, water remains on the bench for 10
minutes and collected in tank and reused. Fertilizer may also be
applied through this system of watering. Pot with bottom hole is
better than side holes.
4.1 Ebb and Flow System
45. Capillary mats are a subsurface way of providing a steady, adequate supply
of water to the plants. A capillary mat is made of absorbent materials upon
which potted seedlings sit. The mat absorbs water from a reservoir and the
pots are able to draw a steady supply of water from it, absorbing the exact
amount they need, when they need it.
Essentially, it is a wicking process, whereby the mat wicks water and then
the soil in the pot wicks the water from the mat. It is traditionally used in
GH or with hydroponic systems, but they are now widely used by home
gardeners as well.
Benefits of capillary mats are numerous. The obvious benefit is
convenience - all you have to do is fill the water reservoir once or twice a
week and the plants get exactly what they need, when they need it. The
researchers also found that some plant species using capillary mats grew
more robustly, producing a bigger canopy. Using capillary mats tends to
make plants grow deeper roots, because they have to reach to absorb water
from down below.
4.2 Capillary mat watering system
47. 4.3 Floor flood irrigation system
The flood irrigation on tables or on flood floors is applied in the ornamental
plant production and more recently in transplants production of tomato and
cucumber cultivated in cubes of rockwool. Cubes of rockwool or pots filled
with substrate with growing plants are placed on the tables or flood floors.
The plants are flooded depending on water and nutrient needs. Cubes and
pots are flooded with nutrient solution having a height of 3- 5 cm for 10 to
15 minutes. In flood fertigation pots whose bottom does not adhere closely
to the surface but with intermittent beads on the perimeter are used. In
addition, the pots and the pallets must have large holes on the bottom and
The nutrient solution is absorbed by the substrate, and the excess of
nutrient solution is drained to the tank. Due to the uniform watering and
fertilization, the plant material is normally of very good quality and grows
Its advantages include: low labor intensity, full automation of irrigation and
fertilization, water and fertilizer savings, quickly and even growth, the
possibility to keep leaves clean and dry (and consequently less problems
related to fungal diseases development) and reduced environmental
49. In this system, water is applied to the surface and is collected
under the container through collection trays or saucers Water
trays and saucers, depending on their shape and spacing on the
bench, can greatly reduce runoff and leaching by containing the
water draining from pots and holding the water which misses the
pot during overhead watering.
They are inexpensive and reusable. Water which collects in them
should be given adequate time to evaporate or be absorbed by the
plant before further irrigation.
Avoid closed plant spacing and poor ventilation to prevent
disease problems when using this technique.
4.4 Water Trays and Saucers