3. literature survey - shodhganga : a reservoir of...
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3. LITERATURE SURVEY
Irrigation advancements within the last 3 decades have been
astounding. Microirrigation is one of the latest innovations for
applying water and it represents a definite advancement in irrigation
technology. It can be defined as frequent application of small quantity
of water directly, above or below the soil surface; usually as discrete
drops, continuous drops, tiny streams, or as miniature sprays
through mechanical devices called emitters or applicators, located at
selected points along water delivery line. Types of microirrigation
systems include surface drip, subsurface drip, spray irrigation and
bubbler irrigation. The surface drip includes both online drip system
and integral drip line system.
Many reports have cited and summarized potential impacts of
drip irrigation compared to other methods. (Annual report of NCPA,
1990 and Sivanappan, 1998). In this chapter an attempt has been
made to discuss the literature pertaining to the impact of adoption of
surface drip on crop yields, water, power and fertilizer savings; and
economics only, since most of the area covered under Andhra Pradesh
Microirrigation project (present study area) was under drip irrigation.
3.1 IMPACT OF SURFACE DRIP IRRIGATION ON CROP YIELDS
3.1.1 Fruit Crops
Improved crop yields with the adoption of drip irrigation were
reported by several researchers in fruit crops (Sivanappan, 1987;
Narayanamoorthy, 2004; Srinivas and Hedge, 1990).
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3.1.1.1 Banana
In banana adoption of surface drip irrigation increased the fruit
yield from 6 to 10% over flood irrigation (78.98 t/ha) in Bangalore
(Hedge and Srinivas, 1990). Likewise Bendale et al. (1998) reported
that the improvement in fruit yield of banana was 22% (89.10 t/ha)
with drip irrigation as compared to flood irrigation in Sangli region of
Maharastra. While others, notably reported 12% increase (Magar,
1985); 15% increase (Pawar et al., 2001); and (Narayanamoorthy,
2004) 23% increase in fruit yield of banana over conventional surface
method of irrigation.
Singh et al. (1993) found an increased yield of 52% with drip
irrigation (87.5t/ha) at Pantnagar. Likewise Taley et al. (1996)
reported an increased yield of 50% (75 t/ha) with drip irrigation over
flood irrigation at Akola.
From Coimbatore, Sivanappan (1994) reported increased yields
of 34% with drip irrigation (57.5t/ha) compared to flood irrigation. The
studies conducted by NCPA at various locations in India also revealed
similar increase in banana fruit yield (Annual report of NCPA, 1990).
The research studies conducted at Bhavanisagar, Tamil Nadu (Annual
report of WMS, 1997) revealed an increased banana yield of 27.3%
with drip irrigation over flood irrigation.
Microirrigation scheduling studies conducted by Salvin et al.
(2000) in banana registered highest yield of 44.0 tons/ha at 75%
evaporation replenishment, while the lowest yield of 26.12 tons/ha
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was observed with out any irrigation. Thus from the above review it
can be summarized that impact of adoption of drip irrigation in
banana proved to be positive in many agro-climatic zones of India and
varied from 6 to 52% in comparison to surface methods of irrigation.
3.1.1.2 Papaya
In Papaya the increase in yield with the adoption of drip varied
between 30 to 75% over surface methods of irrigation (Sivanappan,
1988). Padmakumari and Sivanappan (1983) found 43% increase in
fruit yield; Singh et al. (1993) found 75% increase in fruit yield;
Srinivas (1996) found 30% and Suresh and Saha (2004) found 37%
increase in fruit yield of papaya over surface methods. The work of
Sivanappan (1994) indicated that the increase in yield could be 45%
with drip irrigation over basin irrigation.
3.1.1.3 Mango
The studies conducted at Indian Institute of Horticultural
Research, Bangalore on mango by Srinivas (1999) revealed an
increased fruit yield of 14.7% to 23.2% over basin irrigation. Where
as, Shukla et al. (2000) found improvement in yield by 61% (21 t/ha)
under drip over basin irrigation at Pantnagar. Likewise Mane et al.
(2002) found 58.1% increased mango yields over basin irrigation in
Konkan region. Dixit et al. (2003) studied the performance of mango
under drip irrigation with mulching at Haryana Agriculture University,
Hissar and reported significantly higher yield of 28.9 t/ha. Likewise
Agarwal et al. (2005) reported that drip irrigation with plastic mulch
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registered highest yield of 29.80 tons/ha. Bhandarkar et al. (2005)
scheduled irrigations in mango based on climatological approach at
80% replenishment of evapo-transpiration and found higher yields
ranging from 31 to 32% over no irrigation. Similarly Sujatha et al.
(2005) reported that drip irrigation at 0.75 of pan evaporation rates
recorded significantly higher mango fruit yield of 44.9 kg/tree than no
irrigation (18.4 kg/tree). Patel et al. (2005) reported that in mango the
drip irrigation resulted in increased yield by 52% over surface
conventional basin irrigation.
Farre and Hermoso (1993) stated that in mango drip irrigation
with mulching resulted in increased yield of 12.9 Kg/plant compared
to 11.1 Kg/plant under flood irrigation.
3.1.1.4 Pomegranate
Reviews by Sivanappan (1994) and INCID (1994) indicated yield
increase in pomegranate to the tune of 50% by adoption of drip
irrigation as compared to conventional basin irrigation in Tamilnadu.
Where as Singh et al. (1993) found an increase of 98% at Pantnagar.
On the other hand Magar (1985) stated 43% improvement in yield
than conventional irrigation (11.3t/ha) in Maharastra. Chopade and
Gorantiwar (1998) reported that yield differed significantly between
drip and basin and potential yields of 65.53 q/ha were recorded with
drip irrigation. Similarly Behnia (1999) reported that drip irrigation in
pomegranate improved the yield by 21-24.5%. Studies of Firake and
Kumbhar (2002) suggested that about 36% increased yield was
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obtained with drip irrigation over surface basin irrigation. Prasad et
al. (2003) from Rajasthan stated that in pomegranate the yield
increase was 59.3% with drip irrigation (28.2 kg/plant) compared to
basin method. Similar observations were made by Sulochanamma et
al. (2005) from Andhra Pradesh. Prabhakar et al. (2006) reported that
in pomegranate drip fertigation with recommended dose recorded a
higher yield (14.89 kg/plant) with more number of fruits per plant.
3.1.1.5 Citrus Spp
Singh et al. (1993) reported that in sweet orange the adoption of
drip irrigation resulted in increased yield by 50% (150 t/ha) over
basin irrigation. Subhash and Satish Kumar (1996) reported 39%
highest yield over basin irrigation in Kagzi lime with drip irrigation.
Similar observations were made by Manjunatha et al. (2001) and
Rajbir Singh et al. (2001). Shirgure et al. (2003) found that in Nagpur,
mandarin fruit yield with different microirrigation systems was
significantly higher (48.23 to 58.93 kg per tree) than basin irrigation
(32.30 kg per tree).
3.1.1.6 Other Fruits
Singh et al. (1993) reported an increased yield of 23% in grapes
with the adoption of drip irrigation (32.5 t/ha) over conventional
irrigation. Similarly results of NCPA experiments, revealed a yield
increase ranging between 16 to 33% over conventional basin irrigation
(Magar, 1985; Shikhamany and Srinivas, 1999; Sivanappan, 1994;
and Narayanamoorthy, 2004).
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Palanichamy et al. (2002) stated that in coconut the yield
increase was 20-30% with the adoption of drip irrigation (90
nuts/tree) over basin irrigation. Similar results were recorded by
Muthuchamy et al. (1998) and Dhanpal et al. (1998).
In other fruits like guava, custard apple and water melon drip
irrigation was shown to increase yields ranging between 20 to 88%
(INCID, 1994 and Srinivas, 2001). Singh et al. (2005) stated that the
guava grown with drip irrigation increased yields by 28.5% over
normal basin irrigation.
3.1.2 Vegetables
3.1.2.1 Brinjal
Adoption of drip irrigation in brinjal resulted in increased yield
in comparison to flood irrigation method which varied from 4% to 39%
under different agro-climatic conditions (Annual report of NCPA,
1990). Padma Kumari and Sivanappan (1978) reported an increase of
4% yield over furrow irrigation. Similar increase in brinjal yields were
reported by several workers - up to 7% (Anonymous,1984) at Rahuri,
up to 30% (Tefera.,1987) at Pantnagar, Prabhakar and Hebber (1996)
up to 17% at UAS, Dharwad, Singh et al. (1993) up to 38% at
pantnagar, Magar (1985) up to 14% at Maharastra, Manjunatha et al.
(2001) up to 17% at Pantnagar, Raman et al. (2001) up to 17% at
Navsari, Pantnagar and Chauhan (2001) up to16% at Pantnagar.
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3.1.2.2 Tomato
Prabhakar et al. (1996) reported an increased yield of 7% with
drip over surface furrow irrigation (52.8 t/ha) in tomato at UAS,
Dharwad. Similarly Asokaraja (1998) reported 38% of increased
tomato fruit yields over surface irrigation in Tamilnadu. On the other
hand Sivanappan and Padmakumari (1980) found substantial
increase of 43 to 84 % yield over furrow irrigation in Coimbatore. The
results of Panda and Srivastava (1998) were in agreement with the
above observations.
Raina et al. (1998) reported that drip irrigation resulted
significantly higher fruit yield (16.6 tons/ha) 26% than surface furrow
irrigation. Similar increase in tomato yields were also reported by
Pratap singh (2001) up to 21% at Hissar, Manjunatha et al. (2001) up
to 23% at Pantnagar, at PDKV, Akola up to 22%, Annual report of
NCPA Pune up to 57%, Chauhan (2001) up to 22% at Pantnagar,
Raman et al. (2001) up to 41% at Navsari, Pantnagar, Singh et al.
(1993) up to 50% at Pantnagar, and Nageswara Rao et al. (2005) up
to 55%.
3.1.2.3 Chillies
The adoption of drip irrigation in chillies resulted in increased
yields which varied from 3 to 44% over surface furrow irrigation.
Veeranna et al. (2001) recorded an increase of 9% with the adoption of
drip irrigation over furrow method in Bangalore; where as Singh et al.
(1993) found an increase of 44% yield with drip irrigation over
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traditional flood method (4.2t/ha) in Pantnagar. Likewise the
increased yields in chillies were also reported by Raman et al. (2001)
up to 12% at Navsari, Manjunatha et al. (2001) up to 9% at
Pantnagar, Sivanappan and Padmakumari (1980) up to 30% at
Coimbatore, (Singh et al., 1999; Singh and Anurag Saxena , 2001) up
to 71% at Jodhpur, and NCPA (1990) up to 31%.
Swarajya Lakshmi et al. (2005) from Hyderabad reported that
drip irrigation in green chillies recorded an increase of 34% yield than
traditional flood method.
3.1.2.4 Other vegetables
Adoption of drip irrigation in several vegetables recorded
increased yields over flood irrigation. Sivanappan and Padmakumari
(1980) from Tamilnadu reported an increased yield of 13% in bhendi,
13% in radish, 33% in beetroot, and 28% in sweet potato with drip
irrigation over traditional irrigation method. Similarly Singh et al.
(1993) at Pantnagar reported increased yields in case of cabbage by
75%, radish by 13%, and in sweet potato by 39% over conventional
furrow irrigation.
3.1.3 Sugarcane
Adoption of drip irrigation in sugarcane resulted in increased
yield over flood irrigation (Sivanappan, 1998). Batta et al. (1998) from
Maharastra reported an increase of 12 to 25% yield of sugarcane with
drip irrigation over surface method of irrigation. On the other hand
Dhindwal et al. (1999) from Maharastra registered an increased yield
36
of 16-18% compared to flood irrigation. Shinde et al. (1998) from
Pune stated that, the pressure compensating and inline drip irrigation
systems were effective and increased cane yield by 17.42 to 20.32%
compared to furrow irrigation. Similarly Narayanamoorthy (2004a)
registered the increased yield of 20% - 25% over flood irrigation in
Maharastra. Similarly the increased yield of 17% was reported by
Anonymous (1984) at Rahuri and 24% increased yield was reported by
Selvaraj et al. (1997) at Bhavanisagar, Tamilnadu in sugarcane.
Mahendran et al. (2002) reported that the drip fertigation at
100% IW/CPE in two row planting system registered the highest cane
yield of 202 t/ha compared to a lowest cane yield of 144 t/ha with
surface flood irrigation.
3.2 IMPACT OF SURFACE DRIP IRRIGATION ON WATER SAVINGS
In traditional types of surface irrigation, huge amount of water
is lost through seepage and deep percolation while conveying water
from the source to field. Whereas in case of drip systems the water is
applied to the root zone of the crop in smaller droplets which results
in less losses of water and improved water use efficiency (Rajbir singh
et al., 2001). Narayanamoorthy (2004) in Maharastra registered a
water saving of 12 – 84% in vegetables, 45-81% in fruit crops and 40 –
60% in field crops like cotton and groundnut; and 65% in sugarcane
with the adoption of drip irrigation over conventional surface
irrigation.
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3.2.1 Fruits
Adoption of drip irrigation resulted in a substantial saving of
water which varied from 45 to 68% depending on crop and situation
over surface irrigation (NCPA, 1990).
3.2.1.1 Banana
Hedge and Srinivas (1990) registered a water saving of 25 % in
banana with drip irrigation over furrow irrigation (1600 mm). The
research studies conducted at Bhavanisagar, Tamil Nadu (WMS,
1997) revealed water saving of 41.6% in banana with drip irrigation.
Similar results of water savings ranging between 42-45% were
reported by Salvin et al. (2000) and Sivanappan (1994) in Tamilnadu.
Srinivas (1999) reported that the drip irrigation with water equivalent
to 80% of evaporation replenishment resulted in 42% water saving
with drip irrigation (1000 mm) in banana Robusta variety.
Narayanamoorthy (2004) reported water saving of 29% with drip
irrigation over flood irrigation in banana. Likewise Magar (1985)
reported water savings of 42% in Maharastra with drip irrigation over
furrow irrigation. On the other hand Pawar et al. (2001) found 23% of
water savings at MPKV Rahuri with drip irrigation over furrow
irrigation (347 mm).
Rajkumar et al. (2003) reported that for banana, water
consumption is less in case of drip irrigation (970 mm) as compared
with surface irrigation (1760 mm) resulting in 56% saving of water.
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3.2.1.2 Mango
Bangal (1987) reported a saving of 55% of water in mango with
drip irrigation compared to basin irrigation method. Similar
observations were made by Ravi Babu et al. (1996) and
Balasubrahmanyam et al. (1999, 2001) for mango. Shukla et al.
(2000) reported water saving of 58% at Pantnagar with drip irrigation
in mango compared to conventional basin irrigation (3720 mm).
Srinivas (1999) observed improvement in number and weight of
mango fruits with irrigation schedules at an evaporation
replenishment rate of 60% using drip irrigation.
3.2.1.3 Sweet orange
Rajbir Singh et al. (2001) recorded 35% of water saving in sweet
orange compared to basin irrigation (1260 mm) under Punjab agro-
climatic conditions. On the other hand Manjunatha et al. (2001)
registered 25% of water saving with local practice of ditch irrigation in
sweet lime. Similarly Shirgure et al. (2001, 2003) reported that in
Nagpur, mandarin crop consumed comparatively higher quantity of
irrigation water under basin irrigation (51-167 l/day/plant) than drip
irrigation (36-131 l/day/plant) during various stages of crop
development.
3.2.1.4 Papaya
Adoption of drip irrigation resulted in water savings of 25-45%
in papaya compared to surface basin irrigation (Padmakumari &
Sivanappan, 1983). Srinivas (1996) registered a 50-60 % of water
39
saving with drip method than furrow irrigation (3510 mm) in papaya
at Bangalore. Sivanappan (1998) found 68% savings in water at
Coimbatore with adoption of drip irrigation compared to basin
irrigation (2280 mm).
3.2.1.5 Pomegranate
Adoption of drip irrigation in pomegranate resulted in a water
saving of 45 to 94% at various locations in India over basin irrigation
method. Sivanappan (1994) reported 45 % of water saving in
pomegranate with drip than conventional basin irrigation at
Coimbatore (1440 mm). On the other hand the work of Singh et al.
(1993) registered 35-50% of water savings in pomegranate with drip
irrigation as compared to basin method at Pantnagar. Where as Magar
(1985) reported water savings of 62% in Maharastra with drip
irrigation than basin irrigation (1080 mm). At Bilaspur substantial
water savings of 94% were registered by adopting drip irrigation in
pomegranate compared to basin irrigation (WMS 1997).
3.2.1.6 Other crops
In grapes Umesh Chander et al. (1981) recorded a water savings
of 48% at UAS, Dharwad with drip irrigation compared to flood
irrigation (5320 mm). Alam (1987) reported water saving of 59 % in
grapes compared flood method of irrigation. Bendale et al. (1998)
stated that the water use with drip irrigation was 25% less compared
with furrow irrigation in Sangli region of Maharastra. On the other
40
hand Srinivas (2001) reported water saving of 32% in grapes with drip
irrigation over flood irrigation at Bangalore. Similarly
Narayanamoorthy (2004) reported a water saving of 37% in grapes
from Maharastra.
3.2.2 Vegetables
The adoption of drip irrigation resulted in a water savings which
varied from 6 to 84% in different vegetables under different agro-
climatic conditions of India. (Raman et al., 2001)
3.2.2.1 Tomato
Adoption of drip irrigation in tomato contributed to 6 to 79%
savings in water. The work of Sivanappan and Natarajan (1976) on
drip irrigated tomato revealed a water savings of 79% over flood
irrigation at Coimbatore. On the other hand Asokaraja (1998) reported
marginal water savings of only 6% in Tamilnadu compared to surface
furrow irrigation (421 mm).
Pandey and Vijay Mahajan (1998) studied the comparative
performance of drip and surface methods of irrigation in tomato (var.
Pusa early dwarf) and stated that there is a water savings of 20-52 %
over surface method of irrigation. Like wise Raina et al. (1998)
reported a water saving of 54% in tomato with drip irrigation. Similar
water savings with drip irrigation were reported by up to 30%, (297
mm) under furrow irrigation (Anonymous,1984) at Rahuri, 39% of
water savings by Singh et al. (1993) at Pantnagar, 35% water savings
at Gujarat by Raman et al. (2001), 14% water savings at Pantnagar by
41
Chauhan (2001), 21% of water savings in Maharastra by Magar
(1985) and 50% by Prabhakar and Hebber (1996) at UAS, Dharwad
over furrow irrigation.
3.2.2.2 Brinjal
Sivanappan and Natrajan (1976) conducted experiments in
brinjal and found a water saving of 65% than furrow irrigation method
(692 mm). Like wise Tefera (1987) reported a saving of 41.28% of
water with drip irrigation compared to surface furrow irrigation at
Pantnagar, while Singh et al. (1993) registered water savings of 56%
over surface furrow irrigation at Pantnagar.
Chauhan (2001) recorded water saving of 29 to 41.28% in
brinjal at Maharastra. Raman et al. (2001) found water savings of 64%
with drip irrigation in brinjal at Navsari, Pantnagar compared to
furrow irrigation (690 mm). The research studies conducted at PDKV,
Akola revealed water savings of 62% in brinjal over furrow irrigation
(1680 mm).
3.2.2.3 Chillies
Adoption of drip irrigation in chillies recorded water savings
varied from 23 to 62% at different agro-climatic conditions. The
research carried out at AICRP, Navsari revealed water saving of 23%
with drip irrigation compared to flood irrigation (1200 mm). (NCPA
1990). Singh et al. (1993) recorded 62% of water saving at Pantnagar,
while Manjunatha et al. (2001) reported 40% of water savings. On the
42
other hand Chauhan (2001) found 67% water saving at Pantnagar
with drip in chillies.
3.2.2.4 Other vegetables
Sivanappan and Padmakumari (1980) reported water saving of
83% in bhendi, 76% in radish, 79% in beet root, 60% in sweet potato
with drip irrigation compared to furrow irrigation.
Ravi Babu et al. (1995) estimated the water savings with
different microirrigation systems in bhendi and found drip irrigation
with single micro tube resulted in water savings of 47.71% over furrow
irrigation. The studies carried out by Bhatia et al. (2001) at CAZRI,
Jodhpur , revealed that the drip irrigation contributed to a water
saving of 35-50% in long gourd, round gourd, watermelon, potato,
cole crops, and maize.
3.2.3 Sugarcane
Adoption of drip irrigation resulted in water savings of 32 to
75% in sugarcane. Sivanappan and Padmakumari (1980) reported
32% of water savings in sugarcane at Coimbatore with drip irrigation
compared to flood irrigation (1360 mm). Shinde et al. (1998) recorded
50% of water savings with drip irrigation compared to furrow
irrigation (2206 mm) at Pune. On the other hand Narayanamoorthy
(2004) observed water saving of 40 to 47% in sugarcane cultivated
with drip irrigation compared to flood irrigation in Maharastra. Singh
et al. (1993) recorded water savings of 56% in drip irrigated sugarcane
at Pantnagar as compared to furrow irrigation (2150 mm).
43
3.3 IMPACT OF SURFACE DRIP IRRIGATION ON POWER
SAVINGS
Electricity savings is one of the important advantages of drip
method of irrigation. Drip irrigation substantially reduces the working
hours of pumpset by reducing the water consumption. As a result,
electricity required for irrigating unit area of land also reduces
significantly (Narayanamoorthy, 2004).
Narayanamoorthy, (1996, 1997 & 2001a) reported that the
adoption of drip irrigation resulted in a power savings of 44% in
sugarcane 37% in grapes and 29% in banana over flood irrigation in
Maharastra. Similarly the field survey conducted by
Narayanamoorthy, 2004 revealed a power saving of 41% in sugarcane
at Pune and 48% at Ahmednagar.
3.4 IMPACT OF SURFACE DRIP ON FERTILIZER SAVINGS
The right combination of water and nutrients is the key for high
yield and the quality of produce. Fertigation (application of fertilizer
solution with drip irrigation) has the potential to ensure that the right
combination of water and nutrients is available at the root zone,
satisfying the plants total and temporal requirement of these two
inputs (Neelam Patel and Rajput, 2001).
Fertigation in addition to saving of fertilizers also permits
applying fertilizer in small quantities according to the plants nutrient
requirements.( Veeranna et al., 2001 and Bhoi et al., 2001). It is also
44
considered eco-friendly as it avoids leaching of fertilizers.
(Shivashankar et al., 1998).
Adoption of drip fertigation resulted in savings of fertilizers over
surface broadcasting viz., 20% in banana, 50% in sugarcane, 40% in
bhendi, 40% in tomato, and 40% in onion. (Task Force Report, 2004).
Similarly Neelam Patel and Rajput (2001) reported fertilizer savings of
40% fertilizers as compared to the broadcasting method of fertilizer
application without affecting the crop yield in bhendi.
Anil kumar singh et al. (2001) reported 20-40% fertilizer savings
in Broccoli on sandy loam soil through fertigation compared to
traditional application.
Neelam Patel and Rajput, (2001) reported 60% fertilizer savings
in onion at IARI, New Delhi with fertigation compared to broadcasting.
3.5 IMPACT OF SURFACE DRIP IRRIGATION ON BENEFIT COST
ANALYSIS
Drip irrigation method requires fixed capital for installing the
drip system and the magnitude of the investment varied from crop to
crop. Wide spaced crops require relatively low fixed capital, while the
narrow spaced crops require higher fixed capital (NABARD, 1989).
Though the initial investment on drip system was high, due to its
results in increased yields, water savings and reduced cost of
cultivation result in a highest benefit cost ratio (Sivanappan, 1998);
Narayanamoorthy (1997 & 2004).
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3.5.1 Fruits
Sivanappan, (1998) reported a benefit cost ratio of 3.00 in
banana at Maharastra compared to 2.35 in flood irrigation. Tiwari
(1997) studied the response of banana under different irrigation
regimes of drip irrigation and found the highest gross benefit ratio of
4.56 with drip irrigation than basin irrigation, where as Pawar et al.
(2001) studied different irrigation and fertigation schedule and
reported that the benefit cost ratio was 2.72 under surface method
compared to 2.64 with drip irrigation at Rahuri in banana.
In sweet orange Rajbir singh et al. (2001) evaluated the
performance of drip irrigated Kinnow crop in Punjab and found a
benefit cost ratio of 2.36 with drip irrigation compared to 1.39 under
surface irrigation. Similarly Sivanappan (1988) reported a benefit cost
ratio of 1:2.60 with flood and drip irrigation in sweet orange at
Maharastra and Tamilnadu.
The studies conducted by Sivanappan (1988) revealed that a
benefit cost ratio of 1:1.52 in banana, 1:1.35 in mango, 1:1.54 in
papaya, 1:1.56 in pomegranate with the adoption of drip irrigation
over surface irrigation. Narayanamoorthy (1997) reported a benefit
cost ratio of 1:2.16 in banana and 1:1.76 in grape with drip irrigation
compared to flood irrigation.
3.5.2 Vegetables
Sivanappan, (1988) reported a benefit cost ratio of 1:2.80 in
chillies, 1:1.80 in tomato, 1:1.89 in brinjal at Tamilnadu with drip
46
irrigation compared to furrow irrigation. Likewise Manjunatha et al.
(2001) reported a benefit cost ratio of 1:11.91 in brinjal at ARS,
Gangavathi with drip irrigation over furrow irrigation.
3.5.3 Sugarcane
Sivanappan, (1988) reported a benefit cost ratio of 1:3.45 in
sugarcane in Tamilnadu. On the other hand Narayanamoorthy,
(2001 b) reported 1:2.02 with 10% discount rate with out subsidy with
the adoption of drip irrigation over flood irrigation in Pune and 1:1.87
in Ahmednagar in sugarcane.
3.6 IMPACT OF SURFACE DRIP ON SOIL SALINITY AND NO3
LEVELS
Drip fertigation provides an efficient method of fertilizer delivery
and allows precise timing and uniform distribution of applied
nutrients. Fertilizer application through drip irrigation (fertigation) can
reduce fertilizer usage and minimize groundwater pollution due to less
fertilizer leaching from irrigation. (Badr and Abou 2007).
Dariusz Swietlik (1995) reported that the nitrate leaching was
less with low volume irrigation compare to flood irrigation in grape
fruit orchard cv. 'Ray Ruby'.
Ramakrishna (2003) reported that properly designed trickle
irrigation system has the ability to minimize the salt concentration of
the soil water in the vicinity of plant roots, salt movement and hence
salt distribution in soils is directly related to water movement.
Adoption of drip irrigation resulted in concentration of salts at 0-50
47
cm depth and it reduces with the increase in depth. The fertilizer
application through fertigation device is restricted to the wetted
volume of soil where the active roots were concentrate and hence was
available to plants fully ( Neelam Patel and Rajput ,2001).
Mirjat et al. (2008) studied the nitrate movement in the soil
profile at Tanndojam, Pakistan and reported that the NO3- N
concentration was concentrated only in the top 0.6m depth under
trickle and sprinkler irrigation methods due to insignificant water
movement towards deeper depths, whereas under basin and furrow
irrigation methods the NO3 moved along with water deep into the
profile. Further the NO3 values were below threshold levels under drip
and sprinkler methods as compared to flood irrigation.
3.7 IMPACT OF SURFACE DRIP ON GROUND WATER NO3 LEVELS
Of all the fertilizers applied to the soil for increasing crop
production, nitrogenous ones are the most important. These are
rapidly converted in arable soils to NO3 form, which are readily
available to plants, but are highly soluble and hence easily leachable.
When quantity of nitrogen added to the soil exceeds the amount that
the plants can use, the excess NO3 does not get much adsorbed by soil
particles, but leaches out from the root zone by percolating water
through the soil profile and ultimately accumulates into the
groundwater. The magnitude of such leaching, however, depends
upon soil characteristics, types of crop grown, and management
practices followed. (Kundu et al., 2008).
48
Nitrate leaching is a global problem. Recently, there have been
many studies in India which point to the danger of nitrate leaching
and subsequent pollution of ground waters. Due to increased
agricultural activity which is necessary for enhanced food production
and also due to industrial activity, there is an increasing evidence of
nitrate pollution of ground waters. In agriculturally intensive areas of
Punjab, Delhi, Maharashtra and Andhra Pradesh where fertilizer
application levels are high, there is ample evidence of pollution of
ground waters by nitrate (Prakasa Rao & Puttanna, 2000).
Kundu et al. (2008) reported that the nitrate content was
significantly higher in samples collected during the post monsoon
season (0.87mg/l) than in those of premonsoon (0.58 mg/l) in
groundwater in Hooghly district where there is a usage of higher rate
of N-fertilizer.
Ritter and Manger (1985) concluded from the literature that
nitrate movement below the crop root zone can be minimized by
adopting proper water application methods. Linderman et al. (1976)
found that the quality of water percolating below a furrow irrigated
sandy soil varied from 25 to 30 mg/l NO3 depending on the nitrogen
application practices. Likewise Bouwer (1987) found that the nitrate
in the soil water solution moving below the crop root zone ranged from
15 to 50 mg/l. Keeney (1982) suggested that with the use of best
management practices the nitrate level in the soil water solution could
be reduced.
49
The work of Watts and Martin (1981) revealed that the content
of nitrate movement below the crop root zone is dependent on the
quantity of percolating water, thus the average NO3 – N losses were
19, 30, and 60 Kg/ha/year when deep percolation was 1.6, 2.9, and
7.3 cm/year, respectively (Smika et al.,1977).
50