DRIP IRRIGATION SYSTEM

1.

Function

:

The system controls the supply of water to the plants by a network of tubes with water under pressure.

2.

Specifications

• The head unit consists of a pump or overhead tank

• Main line 50 mm, 63 mm and 75 mm HDPE or PVC pipes are used

• Sub-main 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 and 8 lph are more suitable

• Filter unit: Sand filter for coarse particle detention

• Mesh filter (120 micron) for fine particle detention

• Fertilizer unit: A fertilizer tank with ventury setup is used for applying liquid or dissolved fertilizers

• Pressure gauges 0.5 to 0.25 Ksc and gate valve depending on pipe size are also essential for the system to control and monitor the flow 

3.

Cost

The cost of the system varies with change in crop spacing.

Crops

Spacing (m)

Cost (Rs/ha)

Coconut

7.5x7.5

25,000

Grapes

3.0x3.0

40,000

Mango

10.0x10.0

24,000

Guava

5.0x5.0

34,000

Sapota

10.0x10.0

24,000

Pomegranate

5.0x5.0

34,000

Banana

2.0x2.0

50,000

Vegetables

0.3x0.6

70,000

Crop

Actual water used
(mm)

Water saving over surface irrigation
(%)

Water Use Efficiency Kg/ha/mm

Yield improvement

Tomato (Coimbatore)

200

68

44.36

-

Coconut

100lit/day/tree

66

1.5 nuts/m3/tree

15 nuts/tree/year

Grapes

29lit/day/vine

30

6t/ha/year

Tapioca

700

50

44.63

21t/ha/year

Among different types of emitters, micro sprinklers and tape systems are free from clogging. Maximum clogging occurs in bi-wall and typhoon systems; Pressure compensating drippers are also affected by clogging with improper irrigation management (25 % of surface irrigation) and the use of poor quality water.

• Prevented by injection of dilute HCl (1%) in the system.

• Running the system at least for 10 minutes even during rainy days increase the operation and lowering the clogging.

• Regular maintenance including checking and cleaning of emitters, filters and laterals at least once in a month.

• The drip system can be used for fertilizing crop through the system of fertigation

• Involves mixing the fertilizer in the irrigation water by suitable arrangement

• Experiment carried out on sugarcane / banana / turmeric at Tamil Nadu Agricultural University have revealed that urea can be fertigated which in turn advantage of reduction in dose and enhanced N use efficiency.

• Fertigating materials for P & K are also available (Prime solution) in the open market and these can be used with advantage

• Planting the sets in paired row technique at 30x30x30 / 150cm spacing

• 12mm lateral at 240cm spacing

• 8 lit/hour drippers preferred

• Basal dressing of  P @ 62.5Kg/ha

• Use of venturi arrangement for applying fertilizers at a ratio of 275:112.5Kg N & K in 10-12 equal splits from 15 to 180days of planting 

• Irrigation at an interval of 3 days (approximately) based upon evapotranspiration

• Saving in water to a tune of 25-50%

• Yield improvement to a level of 70-96t/ha compared to conventional method

• Additional income ranges from 15000-20000 Rs/ha

• Prevented by injection of dilute HCl (1%) in the system.

• Running the system at least for 10 minutes even during rainy days increase the operation and lowering the clogging.

• Regular maintenance including checking and cleaning of emitters, filters and laterals at least once in a month.

Element

Fertilizer

Nitrogen

Liquid Ammonium nitrate

None

Ammonium sulphate

To be avoided in uses of water having Ca > 70 ppm

Urea

None

Phosphorus

Super phosphate water

Colloidal particles well screened

pH of water regulated

Phosphoric acid

Very dilute solution

pH regulated

Avoid micronutrient deficiency in the soils

Potassium

Liquid potassium nitrate

None

Liquid potassium chloride

Avoid when water contain high chloride >300 ppm

Iron, Zinc

Chelated compound

none

Crop

Drip irrigation (litres/tree/day)

Surface irrigation (litres/tree/day)

Coconut

75-100

200-300

Grapes

25-45

90-100

Mango

30-50

90-150

Guava

20-30

70-100

Sapota

20-30

70-100

Pomegranate

20-40

60-130

Banana

12-16

30-40

Citrus

10-20

25-65

Papaya

5-8

18-26

Vegetables

1-2

4-8

Crop

Average water requirement (mm)

Interval (days)

Rice

1250

4

Maize

400

6-7

Groundnut

450

7-8

Sorghum

400

14-15

Bajra

400

6-7

Ragi

400

6-7

Sunflower

450

7-8

Soybean

670

6-7

Greengram

250

10-12

Blackgram

250

10-12

Gingelly

250

15-20

Sugarcane

2000

7-8

Banana

1800

6-7

Variety

:

Robusta

Type of planting

:

Normal planting

Spacing

:

2 m x 2 m  (pit size 0.3x0.3x0.3 m)

Cost of drip system with fertigation

:

Rs. 59,250 / ha (5 years life period)

  N     P     K  (g / plant)

Fertilizer level (under fertigation)

200 : 30 : 300

                      (under control)

200 : 30 : 300 (F0)

Water level     (under fertigation)

25 litres / plant / day (W1)

                      (under control)

Basin irrigation weekly once  (W0)

Scheduling (weeks)

N (g/sucker)

P (g/sucker)

K (g/sucker)

9 – 18^th

60

30

60

19 – 30^th

100

-

120

31– 42^nd

40

-

96

43 – 46^th

-

-

24

Total

200

30

300

Duration

N (g/sucker)

P (g/sucker)

K (g/sucker)

3^rd month

60

30

60

5^th month

100

-

120

7^th month

40

-

96

Before flowering stage

-

-

24

200

30

300

Method

Cost of production
(Rs.)

Yield (t/ha)

Gross income
(Rs.)

Net income
(Rs.)

B/C

Fertigation

1,41,606

111

3,89,655

2,48,048

1.75

Control

1,06,811

58.98

2,06,430

99,619

0.93

Fertigation

Control

Fixed cost (due to fertigation/year)

11,850

-

Field preparation and planting

32,995

32,995

Cultural operations

38,660

42,075

Plant protection

6,500

6,500

Fertilizer cost (F1)

49,101

10,716

Water cost (W1)

500

525

Fertilizer  and irrigation application

-

12,000

Harvesting

2,000

2,000

1,41,606

1,06,811