Quality of Irrigation water and brackish water Management

1. Banda University of Agriculture & Technology, Banda
College of Agriculture
Subject: SOIL 511 (2+1) Management of Problems Soils and Water
Assignment on: Quality of irrigation water; Management of brackish water for irrigation; Salt balance under
irrigation; characterization of brackish waters, Area and extent; Relationship in water use and
Quality
Presented by –
Saurabh Upadhyay 3115
Neetika Nigam 3116
Vipul Kumar (3121)
Presented to –
Dr. Dev Kumar
Assistant Professor
Dep. of SS&AC

2. Quality of irrigation water
INTRODUCTION
• The suitability of irrigation water is mainly depends on the amounts and type
of salts present in water.
• The main soluble constituents are calcium, magnesium, sodium as cations and
chloride, sulphate, biocarbonates as anions.
• The other ions are present in minute quantities are boron, selenium,
molybdenum and fluorine which are harmful to animals fed on plants grown
with excess concentration of these ions.
• Irrigation water contains 10 – 100 times more salts than rain water.

3. Irrigation Water Quality Criteria
Water quality is determined according to the purpose for which it will be used. For irrigation
water, the usual criteria include salinity, sodicity, and ion toxicities.
Various criteria are considered in evaluating the quality of irrigation water namely:
➤ Salinity hazard
➤ Sodium hazard
➤ Salt index
➤ Alkalinity hazard
➤ Permeability hazard
➤ Specific ion toxicity hazards

4. Salinity Hazard
Accumulation of soluble salts in the soil is directly related to the salt content of the
irrigation water. Salinity problem due to irrigation water occurs when the total quantity of
soluble salt is high enough to accumulate in the root zone. Problem-Osmatic nature. It is
measured by EC term.
Water class EC (dS m-1) Remarks
C1 - Low salinity 0-0.25 Can be used safely
C2 - Medium
salinity
0.25-0.75 Can be used with
moderate leaching
C3 - High salinity 0.75-2.25 Can be used for
irrigation purposes with
management practices
C4 - Very high 2.25-5.00 Can not be used for
irrigation purposes

5. Sodicity Hazard
High concentrations of sodium are undesirable in water
because sodium adsorbs on to the soil cation exchange sites,
causing soil aggregates to break down (deflocculation), sealing
the pores of the soil and making it impermeable to water flow.
The sodicity hazard of irrigation water is usually evaluated by
Sodium adsorption ratio (SAR)
United States Salinity Laboratory (USSL) staff introduced the
concept of sodium adsorption ratio (SAR) to predict sodium
hazard. It is calculated as
Water
class
SAR Remarks
S1 low
sodium
hazard
0-10 Little or no
hazard
S2
medium
sodium
hazard
10-18 can be used
with
appropriate
management
S3 High
sodium
hazard
18-26 Unsatisfactor
y for most of
the crops
S4 Very
high
sodium
hazard
>26 Unsatisfactor
y for most of
the crops

6. Sodium to Calcium Activity Ratio (SCAR)
The application of SAR to the group of water, which have EC > 5 dS m-1 and Mg/Ca ratio > 1
is obviously questionable. For the ground water having EC > 5 dS m-1 and dominance of
magnesium over calcium, the SAR value should be calculated as Na+ / .
The classification of SAR/ SCAR ratio was given by Gupta (1986) by following 6 classes of
sodicity.
1. Non-sodic water (< 5)
2. Normal water (5-10)
3. Low sodicity water (10-20)
4. Medium sodicity water (20-30)
5. High sodicity water (30-40)
6. Very high sodicity water (>40)

7. Alkalinity hazard
• Residual Sodium Carbonate (RSC)
• Residual Sodium Bicarbonate (RSBC)
• Bicarbonates (HCO3-) occur in low salinity water and its
concentration usually decreases with an increase in EC. The
proportion of bicarbonate ion is higher than calcium ions are
considered undesirable, because after evaporation of
irrigation water bicarbonate ions tend to precipitate calcium
ions. Hence, the effect of bicarbonate together with
carbonates evaluated through RSC.
• RSC = (CO3-- + HCO3-) - (Ca2+ + Mg2+), all ions
expressed as me L-1.
RSC (me l-1
) Water quality
< 1.25 Water can be
used safely
1.25 - 2.5 Water can be
used with
certain
management
> 2.5 Unsuitable for
irrigation
purposes

8. Chlorides
The occurrence of chloride ions in irrigation water increases
with increase in EC and sodium ions. Therefore, these ions are
most dominant in very high salinity water. Unlike sodium ions,
the chloride ions neither affect on the physical properties of the
soil, nor are adsorbed by the soil. Therefore, it has generally
not been included in modern classification system. However, it
is used as a factor in some regional water classification.
Chloride
concentration
Water quality
4 Excellent water
4-7 Good Water
7-12 Slightly usable
12-20 Not suitable
>20 Not suitable

9. Nitrate
• Very frequently ground water contain high amount of nitrate. When such type of irrigation
water is applied on soils continuously, various properties of soils are affected.
NO3 me l-1
Remarks
<5 No problem
5-30 Intensity of problem is moderate
>30 Intensity of problem is severe

10. Management of brackish water
Sustainable management of brackish water
 Crop Management
Water Management
Chemical Management
Cultural Practices

11. 1. Crop management
i) Selection of crops
for successful use of saline water crops that are semitolerant to tolerant (wheat, mustard,
cotton) as well as low requirement of water should be grown.
Crops like rice, sugarcane and forages requiring liberal use of water should be avoided.
ii) Growth stages
In most crops, germination and early seedling is most critical stages.
Therefore, to increase the plant stand, strategies for minimizing the salinity of the seedling
zone should be followed.
iii) Crop cultivar:
Cultivar like “HD- 2560 of wheat, CS- 52 mustard and MESR-16 of cotton suggest that it is
possible to breed cultivars both high yield potential and as well as higher salt tolerance.

12. 2. Water management
Farm irrigation management :
 Irrigation interval
under saline condition, Irrigation should meet both the water requirement of crops and the leaching requirements to
maintain a favorable salt balance in the root zone.
During the interventing periods between the irrigation cycles, evapotranspiration by crops reduces the soil water
content, which is turn decreases the solute potential.
 Pre irrigation
Crops like mung bean, sorghum and mustard could tolerate higher salinity once the non saline water was substituted
for presowing irrigation to leach out the salts of the seedling zone
 Method of irrigation
High energy pressurized irrigation methods such as sprinkler and drip are typically more efficient.
application of highly saline water through sprinkler to pearl millet and cotton is detrimental, wheras it can be safely
used for wheat and paddy.
The application of irrigation water through drip system has revolutionized the production of some high – value crops
and orchards in countries like israel and elsewhere, especially when using saline waters.

13. 3. Chemical management
i) Fertilizer use
For alleviating salinity stress through enhanced fertility reveals that such a strategy of
additional application
of fertilizer N to reduce the adverse effect of salts .
ii) organic/ green manure
Incorporation of organic manure may have advantages in saline and alkali soil environment.
iii) Use of amendments
The adverse effect of high Na on physical and chemical properties of soil can be mitigated by
the use of amendments which contain ca (gypsum).

14. 4. Cultural practices
• Planting procedures and tillage practices
Furrow irrigation and bed planting system has been compared with conventional planting for
cotton/ pearl millet- wheat rotations for 3 years and showed an improvement in yield.
Wheat crop responds to deep tillage, and the average yield increase .
• Row spacing / plant density
Studies with wheat at Agra ( AICRP- Saline waters 1993) have been shown 10-15% improvement
in grain yield when 25% extra seeds were planted and plants later thinned to a uniform population.

15. How is brackish ground water treated?
There are two commonly used desalination methods
1. Reverse osmosis
2. Nano- filtration
3. Electrodialysis
4. Ion exchange
1. Reverse osmosis
The motivation to use RO for desalination comes from the slogan “ making the desert green”
initiated in the united states.
The first RO plant for brackish water desalination was built in 1979 with a capacity of 20-
21metre cube/hour for a range between 4-15g/L
RO technology much more economic than distillation.
RO treatment plants use semi- permeable membranes and pressure to separate salts from water.

16. 2. Electrodialysis
• Electrodialysis is a membrane separation process in which ions are separated through ion
exchange membranes driven by potential gradient.
• In electrodialysis systems, the cation and anion are transferred via a direct current field through an
ion selective membranes.
• By applying a potential gradient across the electrodes, cationic species (Na ion , K ion , NH4 ion
migrate to the cathode while anion species (Cl–, SO42–, PO43–) move towards the anode.
• To enhance the selective removal process, cation exchange (CEM) and anion exchange
membranes (AEM)were embedded into the electrolytic system to allow only positive or negative
charges to pass through and reject ions to provide purified water .

17. 3. Nano- filtration
• Nano-filtration (NF) is an effective pressure-driven membrane process using material with a
pore size of between 0.5 and 1.5 nm. Unlike RO and ultra-filtration processes, NF operates not
only under lower operation pressures, higher water fluxe.
• Recently, NF membranes have mostly been used for the softening and removal of organic
compounds from surface and brackish water.
4. ION EXCHANGE RESINS
• Ion exchange (IX) is used for the purification, separation, and decontamination of aqueous and
other ion-containing solutions with solid ion exchange resins. They are either cation exchangers
or anion exchangers and can be regenerated by acid or alkali, respectively.

18. CHALLENGES OF DESALINATION TECHNOLOGIES IN
AGRICULTURE
• Operation cost
• Feed water quality
• Brine disposal
process Investment
cost ($/m2)
Operation
cost($/m2)
Life
time(years)
Water
recovery(%
)
reference
Reverse osmosis 1,627-2,543 0.5-1.0 5-7 65-75 Ghaffour&Amy
,Valero et al.
(2011)
electrodialysis 580-3307 1.01-2.85 7-10 80-90 Burn et al.
(2015), Valero
et al.(2011)
Ion exchange
resins
1718-5643 0.92-1.22 2 90 Burn et al.
(2015)
Electrochemical
process
436-2487 0.76-2.14 8-10 90 Dao(2011)

19. State – wise details in brackish water area available and
production-2015
States /union territories Total brackish water
area(ha)
Area under culture (ha) Productivity(kg/ha/annum)
Andhra Pradesh 60,000 846 680
Goa Neg 576 2000
Gujarat 1,000,000 968 1276
Karnataka 10,000 3022 1826
Kerala 2,40,000 4568 1700
Maharashtra 10,000 1539 600
Odisha 4,30,000 14670 1300
Tamil Nadu 60,000 7548 2000
West Bengal 2,10,000 5994 1106
Puducherry Neg Not available Not available
Andman &Nicobar island 1,20,000 Not available Not available
Total 12,40,000 39750 12488
Source- handbook of
Fisheries statistics ,2014

20. Relationship in water use and Quality
Water is one of the most important natural resources essential for life.
Agriculture, industry, and domestic activities are highly dependent on water.
Water use affects soil health, crop productivity, and ecosystem stability.
Water quality determines its suitability for irrigation, drinking, and industrial
purposes.
Ensuring sustainable water use is crucial for food security and environmental
protection.

21.  Agriculture is the largest consumer of freshwater globally (~70%).
Water is used for :
• Irrigation of crop
• Livestock watering
• Aquaculture
 Efficient water use methods:
• Drip irrigation – supplies water directly to plant roots, reduces losses.
• Sprinkler irrigation – mimics rainfall, suitable for uneven lands.
• Surface irrigation – traditional method, but can cause waterlogging.
• Proper water use reduces wastage, soil degradation, and salinity problems.
Water Use in Agriculture

22.  Water quality affects both soil and crop health.
 Important parameters:
• Physical: Temperature, color, turbidity, suspended solids.
• Chemical: pH, electrical conductivity (salinity), dissolved oxygen, nitrates,
phosphates, heavy metals.
• Biological: Bacteria, algae, pathogens.
 Poor water quality can lead to:
• Reduced soil fertility
• Accumulation of toxic elements in crops
• Health risks to humans and livestock
Water Quality Parameters

23.  Excessive irrigation may cause nutrient leaching, reducing soil fertility.
 Runoff from fields can carry fertilizers and pesticides into water bodies,
affecting water quality.
 Poor water quality can reduce crop growth, yield, and soil productivity.
 Integrated water management balances water use and maintains quality.
Sustainable practices include:
• Efficient irrigation Proper drainage
• Monitoring chemical inputs
Relationship Between Water Use and Water Quality

24. Soil degradation due to salinity and sodicity
Reduced crop productivity and poor quality produce
Contamination of groundwater and rivers with nitrates, phosphates, and heavy
metals
Increased cost of water treatment for irrigation and domestic use
Long-term effects include loss of biodiversity and ecosystem imbalance
Impact of Poor Water Quality on Agriculture and
Environment

25.  Efficient irrigation: Drip and sprinkler irrigation minimize wastage
 Integrated nutrient management: Reduces chemical leaching and protects
water quality
 Rainwater harvesting: Captures and stores rainwater for irrigation and
domestic use
 Water recycling and reuse: Treated wastewater can be used safely in
agriculture
 Monitoring water quality: Regular testing for pH, salinity, and pollutants
 Buffer zones: Planting vegetation near water bodies prevents runoff pollution
Sustainable Practices for Water Use and Quality

26. References
 www.agriinfo.in
 ecourses.iasri.res.in
 Panda SC. 2003. Principles and Practices of Water Management.
Agrobios.
 Michael AM. 1978. Irrigation Theory and Practice. Vikas Publ.
 Paliwal KV. 1972. Irrigation with Saline Water. IARI Monograph,
New Delhi.
 Lenka D. 1999. Irrigation and Drainage. Kalyani
 Deelip Kumar Das, Introductory Soil Science, 2021
 Reddy, Water Management in Agriculture, 2019