Use of Sewage in Agriculture: Some Experiences

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Use of Sewage in Agriculture Some Experiences
P.S. Minhas Central Soil Salinity Research
Institute, Karnal-132001
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SCINARIO ON WATER RESOURCES
Irrigated area 71 M ha or 40
gross cultivated area 80 of water resources
Projected population 1.40 billion by
2025 Urban population 550 M (39) Share of
agriculture 73 of 1050 km3 Consumptive Use
20-30 vs. 60-70 in agriculture
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Current Status and Mode of Disposal CPCB(2000)
Population covered 88 in Class-I cities Out
of 299 cities 77 100 158 gt 75
43 gt 50 10 lt 50 water supply Per capita
water supply 9-550 lpd (Mean 183 lpd)
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Basinwise wastewater generation, collection and
treatment
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Basin-wise disposal modes of wastewater in
class-I cities
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Average characteristics of sewage waters of
Haryana
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Average characteristics of sewage waters of
Haryana
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Advantages ? Irrigation potential (0.4-1.2
Mha) ? Nutrients potential (0.36 M ton) ?
Independent of electricity ? Continuous and thus
more reliable than rain/canal water
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Case Study-1 Domestic sewage from Kurukshetra
district
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Changes in properties of soils irrigated
with sewage and tubewell water Distance
(m) O.M. Available (kg ha-1) Total (kg ha-1)
DTPA ext.(ppm) Along Longt.
to () ---------------------- --------------------
--- ---------------------- the channel
N P K N P K Zn Pb Cd 50
25 1.73 91.6 24.6 268 2891 1771 4236 2.6 1.7 0.01
250 50 1.78 95.1 58.2 239 2908 2015 3788 2.
5 1.9 0.01 500 500 0.97 66.9 25.4 238 1348
471 3696 0.9 0.8 ND 1000 75 1.68 89.6 64.4 305
2688 1866 4712 2.8 1.6 ND 2000 100 1.18 71.7 36
.9 249 1623 1072 3996 1.0 1.0 ND
2000 125 1.24 74.6 34.0 235 1608 1171 3673 1.0 1.
0 ND
ND-Not detected Tubewell water
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Characteristics of sewage (SW) and tubewell
(TW) waters
ND-Not detected
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Case Study-2 Domestic sewage mixed with effluent
from textile industry in Panipat district
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Composition of waters drawn from tube
wells(T) and hand pumps(H) in Binjhole, Panipat


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Contamination as related to depth of aquifer
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TR - Transplaing TL - Tillering FL -
Flowering MR Milk ripe M - Maturation
BOD tolerance of paddy
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Response of wheat to applied-N under sewage and
tubewell water irrigation
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Effect of time of application of reduced dose of
N (50) on wheat yields (t/ha)
Organic matter content () CRI Crown root
initiation stage
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Effect of sewage irrigation on yield and quality
of cabbage
PLW10 denoted physiological weight loss after 10
days of storage
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PROFILE II DTPA - extractable micronutrients
and heavy metals in soil profiles irrigated with
effluent waters (EICL)
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Contents of heavy metals (mg/kg) in different
parts of vegetable plants
Mean of 10 samples Tr-Traces Source
Gupta (2002)
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Langmuir adsorption parameters for sewage
irrigated soils
Xmax 233.5 60.4 OM() 5.2 Clay ()
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Microbiological quality guidelines for wastewater
used crop irrigation1
Source WHO (1989)
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Effect of cutting management of sorghum fodder on
coliform count
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23-26 l/d 19-22 15-20
Transpiration as determined through sap flow
gauges from a 2-year old Eucalyptus plantation
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Conclusion Excessive contents of toxic ions like
Cd, Ni, Cr etc and those of pathogenic bacteria
in sewage pose serious health risks. Except for
reductions in BOD, treatment through STP is
ineffective to reduce the levels of dissolved
ions and pathogens. Case studies show that
sewage from domestic origin is being used as
source of irrigation as well as plant nutrients
allowing the farmers to reduce or even eliminate
chemical fertilisers. Mostly the land in
peri-urban areas receiving sewage is put under
labour-intensive vegetable cultivation thus
creating lot more employment opportunities for
the rural poor but the present sewage farming
practices are crude and need better planning to
minimise risks to ground water contamination
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Enhanced organic matter in sewage-irrigated soils
reduces bio-availability of toxic ions through
enhanced adsorption capacity of soils. Analysis
of different plant parts show that in the most of
crops/vegetable, the edible parts are lesser
contaminated those reduce health risks from their
use Further research information is needed on
loading rates, irrigation application techniques,
adsorption capacity of soils and quality of
produce to develop appropriate control measures.