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Objectives and targets of the scoping workshop and
overview of salinity intrusion in the region
Erandathie Lokupitiya
University of Colombo
Objectives
• Share information and experiences among the
regional countries in managing salinity
affected agricultural land
• Strengthen the collaborative ties among the
participating countries
• Improve and further develop the full proposal
Identification of the best agricultural
management practices with better
greenhouse gas benefits in salinity
affected areas of South Asia
Contribution of agriculture sector to GHG emissions
Agriculture sector contributes to about 10 – 12 %
of global anthropogenic emissions (IPCC, 2014)
• Impacts from climate change, especially the
increased occurrence of extreme events
(increased intensity of rainfall, storms, and
droughts) have affected the food security and
livelihoods in the region
• The sea level rise in coastal areas in Asia is 1-3
mm year-1 (Cruz et al., 2007)
Saline soils
• Excessive soluble salts in the soil solution
• Concentration of salts in the soil solution is
greater than salt concentration inside plant
roots-- wilting of plants due to osmosis
(chemical drought) even if the soil remains
moist
• Salts- NaCl, CaSO4 (gypsum)
• Soil salinity decreases soil fertility and overall
soil quality
Coastal area affected by tsunami in 2004
Coastal saline soils in South and South east Asia
(The extent is far greater now)
• In Bangladesh, ~30 percent of the arable land
is in the coastal zone, of which ~1.2 m ha soils
have become saline (Islam et al., 2011)
- Part of salinity intrusion has also been due to
conversion of croplands to shrimp farming
(and overexploitation of natural resources)
• India- coastal saline soil extent is >2 m ha
• Sri Lanka- Coastal salinity area ~0.1 m
(Akbar and Ponnamperuma, 1982)
Plant response to salinity
• Although salinity-affected plants appear normal,
they may show stunted growth and may have
darker green leaves, which could also be thicker
and more succulent
• nutrient-deficiency symptoms can be seen
sometimes
• Impact of salinity is reflected in the crop yield
Rice
• The staple food for majority of South Asian
population (~1.7 billion)
• ~37.5% of global rice area (60 million ha) and 32% of
the rice production is in South Asia
• Food security is threatened with increased impacts
from climate change
• Population increase continues, and South Asian
population is projected to be over 2 billion by 2030
• Rice is one of the most salt sensitive crops
South Asia has increased rice export over time
Salinity impacts on rice-2
• Salinity and sodicity (soils with high Na, CO3 , or
HCO3-1) cause problems for rice farmers in irrigated
and rain fed areas.
• In coastal areas, high tides bring sea water inland
• Projected sea level can impact large rice-grown areas in
India, Bangladesh, Maldives, and Sri Lanka
• Salinity can lead to
– nutritional imbalances or deficiencies and reduced
growth
– Reduced crop yields
• Rice threshold EC is ~3 dS/m, and an increase
of salinity by 1dS/m can reduce yield by 1012%
• Enhanced salt tolerance can increase the yield
• rice is also highly sensitive to salt stress in
early stages of growth
Relationship between soil salinity and yields of rice
varieties with different level of salinity tolerance
dS/m)
(Source: Nhan et al., 2012)
Coastal zone of Sri Lanka
Coastal zone is ~23% of the country’s land area, which is occupied by
about 25% of the population, including 65% of the total urban
population (CZMP, 2003)
• In Sri Lanka, agriculture accounts for ~10-13 % of
the coastal GDP
• Unsustainable, higher rates of water extraction in
coastal areas has led to saline water intrusion
into wells in areas where well water is extensively
used for irrigation purposes.
E.g. Puttalam, Mannar, Paranthan, Kilinochchi,
Mullativu
Some Remedial measures
Soil reclamation
• In most coastal areas, salinity is high in soil and water
during the dry season.
• Availability of a fresh water source (rain or irrigation)
is a determining factor in resilience, especially in arid
regions
• Land levelling (prior to surface flushing) and efficient
irrigation management is critical in the reclamation
of salt-affected soils
Water reclamation
• Contaminated wells can be reclaimed through
natural flushing during the next rainy season
or by pumping water
• An acceptable EC for agricultural and drinking
purposes would be <2 dS m-1.
• Adopting appropriate management strategies
along with salt-tolerant rice varieties is crucial
in managing the salinity impact on rice plants.
Potential sources of greenhouse gas emissions for
comparison of salinity-affected and remedied soils
• Organic amendments and increased soil
organic matter
• Flood water level
• Fertilizers – N2O emissions
• Other (Impact of other adaptive measures
including cultural practices)