1. No category

Productivity improvement of saline paddy
fields in Sri Lanka. A case study in Puttalam
district
DN Sirisena
Deputy Director (Rice Research and Development)
Rice Research and Development Institute
Batalagoda, Ibbagamuwa
Sri Lanka
Sri Lanka
Population 20.2 m
Total Land area 6.5 m ha
Cultivated area 2.2 m ha
Elevation 0- 2000 m MSL
Temperature 15° C – 30° C
Rain fall 600 – 2500 mm
Rice as a food crop
Per capita consumption
110 - 116 kg / year
major source of energy (40%) and protein (40%).
Area under rice
0.7 million hectares
33 % of the total cultivated extent
Rice growing seasons
Dry season: March - August (Yala)
Wet season: September - February (Maha)
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B a al e
t ti e
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A m loa
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Sow n extent (000 ha)
Rice growing districts in Sri Lanka
120,000
100,000
80,000
60,000
40,000
20,000
0
Districts
Percentage distribution of rice varietal
categories in Sri Lanka 1950 – 2009
Percentage Distribution of Rice Varietal Categories in Sri Lanka,
1950 - 2009
100
New Improved Variety
Traditional Variety
80
70
Old Improved Variety
60
50
40
30
20
10
0
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
00
01
02
03
04
05
06
07
08
09
Percentage (%)
90
YEAR
Trend in asweddamized extent, annual
cultivated extent, production and average
yield of rice in Sri Lanka 1950 -2010
4.50
4.5
Average Yield
4.00
4.0
3.50
3.5
3.0
2.50
2.5
2.00
2.0
1.50
1.5
Annual Cultivated Extent
1.00
1.0
Paddy Land Extent
0.50
0.00
YEAR
0.5
0.0
Average Yield (t/ha)
Annual Production
3.00
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
00
01
02
03
04
05
06
07
08
09
Asweddumized Ext. & Cultivated Ext. (mill. ha),
Production (mill. t)
Trend in Asweddumized Extent, Annual Cultivated Extent, Production and Average
Yield of Rice in Sri Lanka ( 1950 - 2009 )
Rice for future Sri Lankans
To meet rice demand – 1 % per year
To reduce wheat flour consumption – 25 kg /person/year
(All wheat flour requirement is met by importation)
Best Practices and Procedures
are needed to improve and sustain productivity of paddy fields
in Sri Lanka
Major constrains in rice production
Biotic stresses
Insects, diseases and weeds
Controlled by introducing resistant varieties and
agrochemicals
Abiotic stresses - ??????
Biotic stresses
Controlled by introducing resistant varieties and agrochemicals
Major abiotic stresses in rice cultivation ..
Salinity
Floods
Drought
Iron Toxicity
Salinity, an island wide problem
affecting rice production
• Sri Lanka is surrounded by
Indian Ocean – Vulnerable to
Coastal Salinity
………. Salinity an island wide problem
affecting rice production
75% of the paddy fields situated in the drier part of country
and cultivated by supplementary irrigation
- vulnerable to inland salinity
Irrigation of upland paddy fields
Approximately 67% of agro-wells wells
have moderately saline water and 33%
have high and very high saline water
Distribution of saline paddy lands in
Sri Lanka
Estimated extent of saline paddy fields
• De Alwis and Panabokke (1972), The area affected by
coastal salinity - 0.112 million ha.
• Sikurajapathy et al. (1983), 4.96% of the paddy fields in
Mahaweli H area in the Anuradhapura district are affected
by salinity
• Amarasekara (1992), Approximately 13% of the total
irrigated extent in Sri Lanka is affected by salinity
• Abeysiriwardena et al. (2000), 30% of poorly drained soils
in newly developed paddy lands in Kirindi Oya project is
affected by salinity
…….Estimation of extent of saline paddy
fields
• Wickramasinghe et al. (2005) - 4000 ha of costal
rice soils in Sri Lanka were flooded with salt
water in 2004 due to Tsunami incident taken
place in Sri Lanka
Non-uniform plant population
Complete crop losses
Sea water intrusion to paddy fields
Abandoned Paddy fields
Salt accumulation on soil surface due to
higher evaporation than rainfall
Salt deposition in the soil profile
Salt containing irrigation water
Current status of soil salinity in paddy
fields
Farmers do not have any idea about salinity
conditions in their paddy fields
• Nothing is being done to overcome the ill effect of
soil salinity
• Return to investment is very low in saline areas.
• Average rice yield is well below 4 t ha-1 (Potential
yield is 10 t ha-1 )
Identification of saline areas in
Puttalam district
Puttalam district has the
most salt affected paddy
fields in Sri Lanka
Due to
Inland salinity
Salt containing irrigation water
Halide minerals in soil
Coastal salinity
Due to intrusion of sea-water
Study Area: Puttalam district
Paddy extent:
26,412 ha
Sown extent : maha
13,994 ha
Sown extent : yala
11,533 ha
Total extent: 315,209 ha
Map of the soil conductivity
Paddy land extent affected by salinity
EC levels dS m -1
% paddy land extent
< 1.0
34.4
1.01 – 2.0
42.4
2.01 – 3.0
14.8
3.01 – 4.0
4.1
> 4.0
4.4
More than 20% of the lands are affected by salinity
Soil Chemical properties of saline areas in the
Puttalam district
Location number
EC
pH
-1
Na
Ca
-1
(dS m )
Mg
-1
-1
(mg kg )
(mg kg )
(mg kg )
1
9.01
6.92
799
3452
780
2
6.48
6.69
800
774
411
3
12.12
6.39
1419
957
520
4
10
6.48
878
3341
726
5
17.31
6.52
1129
1891
593
6
6.51
6.42
1355
1873
744
Average
10.2
6.57
1063
2048
629
Land Suitability
Land Suitability classes
Suitable
Moderately suitable
Marginally Suitable
Unsuitable
Percent land extent
63.1
14.1
18.8
04.0
Effect of soil salinity on soil reactions
Exchangeable sites are filled with prominent cations,
viz. Ca, Na and Mg .
Accumulation of Na ions in the exchangeable sites
causes soil particle dispersion.
Water movement through soil profile declines
Higher run off due to low porosity.
Soil pH increased and nutrient availability reduced (eg.
Zn deficiency).
Applied nitrogen fertilizer evaporated as NH3 due to
high soil pH.
Productivity improvement technical package
introduced to saline areas in Puttalam district
Systematic land preparation
(Deep ploughing and leveling)
Drained canal preparation
Organic matter addition
Old seedling transplanting
Maintaining water levels at 2-3 cm until
maturity
Introduction of salinity tolerant rice varieties
Bg 310
Bg 5-110
Bg 369
At 354
Na, Ca and Mg contents in the soil after
implementation of BPP’s
Na (mg kg-1)
Ca (mg kg-1)
Mg (mg kg-1)
Before
After
Before After
Before
After
1
799
427
1873
1022
744
289
2
800
428
774
751
411
380
3
1419
977
957
1030
520
470
4
878
511
3341
2150
726
523
5
1355
815
3452
1132
780
627
6
1129
887
1891
1728
593
568
Average
1063
674
2048
1302
629
476
Location
Location
Location
Location
Location
Location
Location
9th WAP
Time
7th WAP
5th WAP
3rd WAP
1st WAP
18
16
14
12
10
8
6
4
2
0
Initial(September
2008)
Electrical Conductivity (dS/m)
Change of Electrical conductivity after
introducing of BPP’s
1
2
3
4
5
6
Reltive yield
Relationship between soil salinity and rice
yield
100
90
80
70
60
50
40
30
20
10
0
Tolerant to salinity
Susceptible to salinity
2
4
6
Salinity (dS/m)
8
10
Yield performance of rice varieties grown
in saline areas
Yield (t/ha)
8
6
4
2
0
Bg 352 (Salinity Bg 369 (Salinity Bg 310 (Salinity At 354(Salinity
Susceptible)
tolerant)
tolerant)
tolerant)
Rice Variety
All salt tolerant rice varieties performed well under saline conditions
. Farmers preference to salinity tolerant rice varieties
Farmers Preference (%)
100
80
60
40
20
0
At 354
Bg 369
Bg 310
Variety
Bg 310 (Bg 4-91) is the most suitable and highly adaptable rice varieties
because of the short age (3m)
Availability of salt tolerant rice
Seed materails
Seed production farms were set
up in Puttalam district
Temporal variation of soil salinity in
Puttalam district
Relationship between rainfall and soil
salinity
Out come of the study
Saline areas in Puttalam district identified
Temporal variation of soil salinity in these areas understood
Best practices, procedures to alleviate soil salinity tested
Seed materials of saline tolerant rice varieties available
Productivity improvement of saline area
in Puttalam district is possible
Conclusion
Soil salinity is a problem in most of the paddy fields in the
coastal areas as well as in the irrigated inland areas of Sri
Lanka
Identification of these saline areas, understanding
temporal variation and introduction of best practices and
procedures are needed to alleviate soil salinity in these
soils in long run.
Introduction of salt-tolerant rice varieties along with best
practices and procedures allow salt-affected paddy lands
in Sri Lanka to attain their full potential.
Structures should be constructed, man made activities
should be stopped and soil salinity should be regular
monitored to prevent salt accumulation in Sri Lankan
paddy fields in the future
Rice productivity in salt accumulated areas
can be improved and sustained to meet the
future rice demand in Sri Lanka
THANK YOU !