Video by K.Mohanraj and S.Suresh
PG Students, Agricultural Extension, TNAU , Coimbatore.
a. FUNCTION
The system controls the supply of water to the plants by a network of tubes with water under pressure.
b. EQUIPMENTS / COMPONENTS
The Head unit consists of a pump or over head tank.
Mainline 50 mm, 63 mm and 75 mm HDPE or PVC pipes are used
Submain 45 mm, 50 mm HDPE pipes are used.
Laterals 12 mm and 16 mm LLDPE pipes are used.
Drippers - pressure compensating type 2 lph, 4 lph, 8 lph are more suitable
Filter unit : Sand filter for coarse particle detention. Mesh filter (120 micron) for fine particle detention.
Fertiliser unit: A fertiliser tank with ventury setup is used for applying liquid or dissolved fertilisers. Pressure gauges 0.5 to 2.5 Ksc and gate valve depending on pipe size are also essential for the system to control and monitor the flow.
Fertilizer Tank – cost Rs 3500
Ventury Rs 1250
Fertilizer pump Rs. 12,000
c. SALIENT FEATURES
50 to 65% water saving compared to control method.
Crop attains early maturity.
Crop quality and yield increased.
Requires least land levelling.
Poor quality water can be used.
Advantages of drip irrigation system (after sailent features)
High quality and increased fruit size
Suitable for all types of soil
Easy method of fertigation and chemigation
Saving in labour and field preparation cost
Disadvantage of drip irrigation system
High initial investment
Clogging of emitters
Possible damage of system components due to animals, etc.,
Investment cost mostly differs based on spacing of the crops
Generally, the reasons for clogging are solid particles (sand, rust), soft dirt (organic matter, algae, micro organism, salt), sediments (salt in the fertilizers).
Filtration is the main key factor to the success or failure of the system. The main of filtration is to stop dirt particles which damage any components of the system.
To remove salt encrustation, 30 per cent commercial hydrochloric acid can been used at the rate of one liter per one m3 area. (One part HCl mixed with 5 parts of water)
To remove algae and fungal clogging 5 to 500 ppm sodium hydrochloride (10 per cent chlorine) can be used.
Maintenance of drip system
Back washing and sand filters has to be cleaned
Frequent cleaning of emitters and drippers
Flushing at every irrigation
Cleaning of sub main and main pipes
Cleaning of PVC pipes and laterals and acid or chlorine may be used to remove clogging.
Water used and yield of crops in micro and conventional irrigation methods
Crop
Methods of irrigation
Water requirement (cm)
% water saving
Yield kg ha-1
% increase in yield
Water use efficiency (kg ha mm-1)
Banana
Drip
97.00
45.00
87500
52.00
90.20
Surface
176.00
-
57500
-
32.67
Sugarcane
Drip
94.00
56.00
170000
33.00
180.85
Furrow
215.00
-
128000
-
59.53
Grapes
Drip
27.80
48.00
32500
23.00
116.90
Surface
53.20
-
26400
-
49.62
Aerobic
rice
Conventional aerobic rice
74.30
38.10
4747
-
6.39
Surface drip
61.90
48.40
5940
14.20
9.60
Sub-surfacedrip
61.90
48.40
6227
19.80
9.74
Conventional
transplanted
120.00
-
5200
-
4.33
Cotton
Drip
28.00
66.27
3250
25.00
116.10
Furrow
83.00
-
2600
-
31.33
Beetroot
Drip
17.70
79.34
887
55.34
50.11
Surface
85.70
-
571
-
6.66
Radish
Drip
10.80
75.72
1186
13.49
109.80
Surface
46.40
-
1045
-
22.52
Papaya
Drip
73.88
67.89
23490
69.47
0.32
Surface
225.80
-
13860
-
0.06
Mulberry
Drip
20.00
60.00
71400
3.03
3570
Surface
50.00
-
69300
-
1386
Tomato
Drip
18.40
39.00
48000
50.00
260.86
Surface
30.00
-
32000
-
106.66
(WTC Annual Reports 1985-2003)
d. COST
Water requirement (lit/day), increase in yield, water saving (percent), lateral spacing and cost are given in Table (1).
Table 1. Water Saving, Yield Benefits, Lateral spacing and Cost in drip system