By Prof. Junaid N. Khan

1. MICRO IRRIGATION SYSTEMS:
ADAPTABILITY and LIMITATIONS
Dr. Junaid N. KHAN
Professor

2. ARCHIMEDIAN SCREW

10. METHODS OF IRRIGATION

18. Comparative advantages of drip irrigation over conventional method
Variable Drip irrigation Conventional method
Water saving High 90-95% Less due to evaporation
run off, percolation.
Irrigation efficiency 80-90% 30-50%
Input cost Less in labour, fertilizer,
pesticides and tilling
Comparatively higher
Weed problem Almost nil High
Water quality Even saline water can
be used
Only normal water can
be used
Disease and pest problem Relatively less High
Water logging, run off Nil High
Water control Better and easy Less
Fertilizer use efficiency Very high and regulated
supply
Heavy loss due to
leaching
Range of applicability Wide range of soil Not suitable for sandy
and undulating soil
Yield 20-100% increase Less

24. Terminology
1. Wetting Circle
2. Radius of Throw
3. Uniformity of Water
Application
4. Overlapping of the
Precipitation
5. Water Pressure
6. Water Discharge
7. Precipitation Rate

29. Fertigation
 Application of fertilizers through an
irrigation system with the use of
drippers and sprinkler.
 Fertigation is a method of fertilizer
application in which fertilizer is
incorporated within the irrigation
water by the drip system. In this
system fertilizer solution is
distributed evenly in irrigation. The
availability of nutrients is very high
therefore the efficiency is more. In
this method liquid fertilizer as well
as water soluble fertilizers are used.
By this method, fertilizer use
efficiency is increased from 80 to 90
per cent. Sivanappan et al., 1996

32. Advantages of fertigation
 Most convenient, quick and economic means of supplying
nutrient materials.
 Ensures the direct application of fertilizers to root zone as
moving fertilizer into the root zone can be a problem in low
rainfall areas.
 Allows uniform and frequent application of fertilizers.
 Micronutrients application along with NPK is possible.
 Most useful in arid regions and annual crops.
 Lesser amount of fertilizers will be used.
 Leaching of nutrients will be less.
 Enhanced growth and yield.
 Offers increased flexibility of fertilization.
 Possibility of application in different grades to suit the stage of
the crop.
 Allows rapid movement of nutrients into root zone.
 Reduces groundwater pollution.

33. Disadvantages of fertigation
 Require expert design and installation
 High cost of water soluble fertilizers
 Lack of knowledge of fertiliser scheduling for difference crops.
 Uniformity of application depends upon uniform water
distribution.
 Only soluble forms of fertilizers can be used.
 Smaller root volume may cause uptake difficulties.
 Corrosion of metallic parts.
 Contamination of drinking water.
 In India, the required soluble fertilizers and grades are not freely
available (Kumar and Singh, 2003).
 Not suitable for closed growing crops
 Require higher investment & subsidy level is going down.

34. NUTRIENT and FERTILIZER MANAGEMENT
ESSENTIAL ELEMENTS
BASIC NUTRIENTS C,H,O
MAJOR NUTRIENTS N,P,K
SECONDARY NUTRIENTS Ca, Mg, S
Micro Nutrients B, Zn, Fe, Mo, Mn, Cu
Optimal Nutrients Na, Si, Ni, Co

35. Nutrient content of Fertilizer
Name of the fertilizer Nutrient Content (%)
N P2O5 K2O Others
UREA 46 0 0 -
Single super
phosphate(SSP)
0 16 0 S-11
Di- Ammonium
Phosphate(DAP)
18 46 0
Mono- Ammonium
Phosphate(MAP)
12 61 0 -
Muriate of Potash
(MOP)
0 0 60 Cl-47
Sulphate of Potash
(SOP)
0 0 50 S-18
Ammonium Sulphate 20.6 0 0 S-23

36. FERTILIZER SOLUBILITY
Fertilizer Solubility (g/L) at 20° C
Potassium Nitrate 310
Ammonium Nitrate 660
Ammonium Sulphate 1920
Calcium Nitrate 1290
Urea 510
SSP 150
MAP 374
Potassium Chloride 310
Magnesium Nitrate 710

37. FERTILIZER COMPATIBILITY
• When mixing fertilizers, it is important to check
fertilizer compatibility before application. If
incompatible fertilizers are mixed, they form
insoluble precipitations that can clog drip
emitters and damage sprayers used to apply
fertilizers.
• It is impossible to list all the incompatible
fertilizers. The best approach is to conduct a jar
test before mixing fertilizers. When doing a jar
test, the fertilizers should be mixed in the same
concentration as intended to be used. If you see
the mixed solution has a milky appearance, the
fertilizers should not be mixed and applied
together.

41. Method of application of fertilizer through drip
system
 Fertilizer tank
 Fertilizer pump
 Venturi type meters

42. VENTURI
• DESCRIPTION
• SELECTION CRITERIA
• INSTALLATION
• WHEN TO OPERATE
• APPLICATION
PRINCIPLE OF WORKING
• The working of the venturi
depends on the pressure
difference between inlet and the
outlet, and the motive flow.
Motive flow is the flow diverted
towards one venturi from
mainline by closing wall called
throttle valve and creating
pressure difference between inlet
and outlet. A vacuum is created
at the throat due to low pressure,
which causes the suction motion
to suck one fertilizer solution and
passes it to the mainline, As such
concentration of the solution
remains unaffected

43. FERTIGATION TANK
• DESCRIPTION
• SELECTION CRITERIA
• INSTALLATION
• WHEN TO OPERATE
• APPLICATION
PRINCIPLE OF WORKING
• It consists of air release valve,
non-return valve, inlet, outlet,
cap, drain plug and a cylinder.
Inlet and outlet are provided at
the top the tank. The inlet
extends to the bottom, fitted with
an elbow to release water
tangentially as such creating a
cyclonic effect(mixing). The water
entering from the inlet mixes
with the solution and the solution
level rises, causing it to flow out
through the outlet units into the
mainline. This is why the
concentration of fertilizer
solution decreases with time.

44. FERTILIZER INJECTION PUMP
• DESCRIPTION
• SELECTION CRITERIA
• INSTALLATION
• APPLICATION
PRINCIPLE OF WORKING
A 50-60% of water can be diverted in
one inlet of the pump. Water goes
into one inner cylinder of one pump
where an upper piston is provided.
At one head of piston assembly,
fulcurum and piston is provided.
When water is filled below one
piston, due to water pressure piston
moves upwards, so pivot touches
one upper body. A mixture of water
and fertilizer goes in the upward
direction and press one piston
downwards. Pivot touches one lower
body and fulcurum closes central
hole and the two sides open from
two holes fertigation and water
mixture.

45. FERTILIZER FREQUENCY
• Timing of fertilizer
application has a
significant effect on crop
yields. Proper timing of
the fertilizer application
increases yields, reduces
nutrient losses, increases
nutrient use efficiency
and prevents damage to
the environment
• CEC – Cation Exchange Capacity – this is a
parameter that measures the capacity of
the soil to hold and store positively-
charged elements, such as calcium,
magnesium and potassium. Soils with high
CEC require a lower frequency of fertilizer
application, and as a result, higher
fertilizer rates are applied with each
application. In soils with a low CEC
splitting the fertilizer application into
multiple applications is necessary to avoid
loss of nutrients
• Soil Texture – soil texture is strongly
related with CEC. Sandy soils usually have
a low CEC, while clayey soils have a higher
CEC. But while CEC gives an indication of
the capacity of the soil to hold nutrients,
soil texture refers to the particle size
distribution of the soil. Sandy soils can
hold less water than soils with a fine
texture. Irrigation frequency is usually
higher in sandy soils and, as a result,
leaching of nutrients is stronger.
Therefore, splitting fertilizer application in

46. NPK uptake distribution

49. Characteristics of water soluble fertilizers
 The WSF are completely soluble in water.
 The solution does not clog emitter tubes, pipes and other irrigation system.
 These are low in salt index.
 These are available in ionic form in water solutions.
 These are chloride free.
 They are free flowing and easy to handle.
 Split applications through irrigation system are possible without increasing
labour cost.
 WSF mixtures are used in low concentration.
 Fixation, leaching and evaporation losses are minimum.

50. Table Types of fertilizers which can be used through drip system
Sr. No.
Fertilizers Limitation on using
1 Liquid Ammonium nitrate None
2 Ammonium sulphate Should not be used in places
where calcium content of water
is higher than 70 mg/litre
3 Urea None
4 Crystalline potassium nitrate None
5 Liquid potassium nitrate None
6 Crystalline potassium chloride None
7 Liquid potassium chloride None
8 Compound fertilizers NPK e.g. 20: 20: 20
with or without microelements
Should be diluted at least 1:100.
9 Compound fertilizer N,K e.g. 24:24 with
or without micro elements
None
10 Compound fertilizers N,P (8:24) Should be diluted at least 1: 5000

51. Fertilizers not to be used in drip
 Aqueous ammonia (NH4OH)
 Potassium sulphate
 Calcium Ammonium nitrate
 Calcium nitrate
 Zinc nitrate
 Ferric sulphate
 Liquid ammonia

52. Precautions to be taken during fertigation
1.Perfect design of irrigation system. Every emitting point must deliver
the same volume of water.
2.The material used must be free from deposits or residues and must not
cause corrosion of system.
3.Constant operating pressure to facilitate uniform mixing of water and
fertilizers.
4.Selection of most appropriate fertilizer, injection system and crops for
fertigation.
5.Fertilzer injection should not begin until all lines are filled with water
and emitters are working.
6.Drip irrigation system should be allowed to its working pressure prior
to fertilizer injection.
7.Fertilizers/pesticides/chlorine should not be injected at the same time.

53. Table 12: Principle physical, chemical and biological components contributing to
clogging of drip system emitters:
Sr. No.
Physical (Suspended
solids)
Chemical precipitating
(Dissolved chemicals)
Biological
(Bacteria, algae)
1. Inorganic particles Calcium carbonate,
Magnesium
Slime filaments
i Sand Calcium sulphate Slimes, microbial
decompositions
ii Silt Heavy metals, Hydroxides
iii Clay Silicates and sulphides
2. Organic particles Oil or other lubricants
i Aquatic plants Fertilizers:
ii Aquatic insects Phosphate, liquid ammonia
iii Bacterial debris Iron, Copper, Zinc
Manganese

56. Table 13: Criteria of water for estimating emitter clogging hazard
Sr.
No.
Type of problem Minor Moderate Severe
1 Physical:
Total suspended solids
(mg/l)
<50 50-100 >100
2 Chemical (pH) <7.0 7.0-8.0 >8.0
- Dissolved solids (mg/l) <500 500-2000 >2000
- Manganese (mg/l) <0.1 0.1-1.5 >1.5
- Total iron (mg/l) <0.2 0.2-1.5 >1.5
- Hydrogen sulphide
(mg/l)
<0.2 0.2-2.0 >2.0
3 Biological: Bacterial
population (ml-1)
<1000 1000-
50000
>50000
Choudhary and Kadam,2006

57. Methods for Prevention of emitter
clogging
Chemical treatment:
 Continuous acidification for pH control to prevent carbonate formation
 A combination of 1mg/l or 10 mg/l chlorine and H2SO4 or HCl
treatment
Water filtration:
 When physical factors become severe
 Screen filter size ranges from 100-200 mesh should be used
Chemicals for water treatment:
 Sulphuric acids
 Hydrochloric acid
 Phosphoric acid
 Chlorination
Some alternative chemicals to control bacteria and algae are:
 Acrolein
 Copper salts
 Iodine

58. Reclamation procedure for clogging:
 Super chlorination at level 1000 mgl-1
 250 mg/l of sodium hypochlorite for atleast 12
hours
A 2% HCl treatment used for 15 minutes
remove slimes from operational emitters
Flushable emitter clogged with biological
slimes were reclaimed by treating the system
for about 24 hours with 100 mg/l of chlorine
and adding H2SO4 to lower the pH to 2

59. Prospects of drip irrigation and
fertigation
 Drip for waste land development
 Drip for hills and semi arid areas
 Drip for water scarce area
 Drip for coastal sandy areas
 Drip for community wells

63. L
300m
200m
50m
DESIGN OF DRIP IRRIGATION
Lateral
Main-Line
Submain

65. THANK YOU