Sri Lankan Soil Health: Issues, Challenges, Initiatives and Priority Areas by Asiri Weerasinghe

1. Sugarcane Research Institute, Sri Lanka
Asiri Weerasinghe
Soil Scientist
Sugarcane Research Institute, Sri Lanka.
Invited through,
Sri Lanka Council for Agriculture Research Policy (SLCARP)
Colombo, Sri Lanka.
Regional Conference on Role of Soil and Plant Health
Towards Achieving Sustainable Development Goals in Asia-
Pacific
21-23 November 2018
Bangkok, Thailand.
Sri Lankan Soil Health: Issues,
Challenges, Initiatives and Priority
Areas

2. Sugarcane Research Institute, Sri Lanka
Sri Lanka: Brief Introduction
Area - 65610 km2
Population - 20.9 m
P Density - 334 per km2
Arable land – 46 %
Agricultural land - 42 %
Agri to GDP – 7.7 % (2017)
Area - 65610 km2
Population - 20.9 m
P Density - 334 per km2
Arable land – 46 %
Agricultural land - 42 %
Agri to GDP – 7.7 % (2017)
Rainfall
>2500 mm - WZ
1750-2500 mm - IZ
<1750 mm - DZ
Rainfall
>2500 mm - WZ
1750-2500 mm - IZ
<1750 mm - DZ

3. Sugarcane Research Institute, Sri Lanka
Soil map of Sri Lanka
Dominant soil
orders
ALFISOLS
ULTISOLS
ENTISOLS

4. Sugarcane Research Institute, Sri Lanka
Sri Lankan Soil Health: Issues
Physical
Soil erosion – changes
in soil texture and
moisture
One third of the land
subjected to soil erosion.
Onsite cost
LoP - Rs 3529/ha/yr
LoN – Rs 5068/ha/yr
Offsite cost
LoP – Rs 3952/ha/yr
LoN – Rs 5481/ha/yr
Soil erosion – changes
in soil texture and
moisture
One third of the land
subjected to soil erosion.
Onsite cost
LoP - Rs 3529/ha/yr
LoN – Rs 5068/ha/yr
Offsite cost
LoP – Rs 3952/ha/yr
LoN – Rs 5481/ha/yr
Use of
machinery
during land
preparation
and harvesting
Soil becomes
compact
Use of
machinery
during land
preparation
and harvesting
Soil becomes
compact
Land slides – damage
of soil structure
12,500 sq. miles in the
central and southwestern
parts are vulnerable to
landslides
Land slides – damage
of soil structure
12,500 sq. miles in the
central and southwestern
parts are vulnerable to
landslides
Threat in rain-fed
farming areas in
dry zone
Threat in rain-fed
farming areas in
dry zone
Severe in hill
country on
sloping lands with
vegetables,
poorly managed
seedling Tea and
chena cultivation
Severe in hill
country on
sloping lands with
vegetables,
poorly managed
seedling Tea and
chena cultivation
Changes in
•Soil structure
•Soil texture
•Soil moisture
•Soil compactness
1
2
3
4

5. Sugarcane Research Institute, Sri Lanka
Sri Lankan Soil Health: Issues
Chemical
• Build up of P, K
and chemical
residues in soil
• Changes in soil
pH
• Low CEC and
OC in soil
• Heavy metals ?
Soil pH increases
in the low country
(basic >8)
Soil pH increases
in the low country
(basic >8)
Soil pH reduces in
hill country (acidic
< 4)
Soil pH reduces in
hill country (acidic
< 4)
Low Organic Carbon
(OC) - Changes in soil
pH and CEC
Soil erosion is the main
factor affecting in low OC
(< 0.8) thus low CEC (< 8
cmol+/kg of soil).
Low Organic Carbon
(OC) - Changes in soil
pH and CEC
Soil erosion is the main
factor affecting in low OC
(< 0.8) thus low CEC (< 8
cmol+/kg of soil).
1
2 3
Build up of P, K and
chemical residues in
soil
Mainly in the upcountry
vegetable fields (due to
excess application of
fertilizer and pesticides)
Build up of P, K and
chemical residues in
soil
Mainly in the upcountry
vegetable fields (due to
excess application of
fertilizer and pesticides)
Soil P accumulation
300-400 ppm
(Acceptable level
40 ppm)
Soil P accumulation
300-400 ppm
(Acceptable level
40 ppm)
Build up of
internal salinity
under rain-fed
cultivation in
the Dry zone
Build up of
internal salinity
under rain-fed
cultivation in
the Dry zone
4
Heavy metals ?Heavy metals ?

6. Sugarcane Research Institute, Sri Lanka
Sri Lankan Soil Health: Issues
• Low diversity
and density of
micro and
macro
organisms.
Increase in Nematode
population
The nematode population
has increased in the wet
zone affecting Tea, Rice
and vegetables
Increase in Nematode
population
The nematode population
has increased in the wet
zone affecting Tea, Rice
and vegetables
Macro and micro
organisms are affected
due to low OC in soil,
excess fertilizer and
pesticide
affects throughout the
country
Dry zone rain-fed
conditions - severe
Macro and micro
organisms are affected
due to low OC in soil,
excess fertilizer and
pesticide
affects throughout the
country
Dry zone rain-fed
conditions - severe
Biological
1
2

7. Sugarcane Research Institute, Sri Lanka
•Low response to
fertilizer
•Loss of biodiversity
(micro-flora)
•Increasing soil
erosion
•P build up
•Increasing coastal
salinity
•Acidification
•Nematodes build
up
•Salinity build up
•Desertification
•Land slides
Acidification,
Nematodes build up,
Marginalization of Tea
lands
(30 % tea lands
unproductive or on limited
use)
Acidification,
Nematodes build up,
Marginalization of Tea
lands
(30 % tea lands
unproductive or on limited
use)
Through out the
country
Through out the
country
Salinity build up
Desertification (hotter parts
of the dry zone)
Marginalization of DZ
agricultural lands (1.2 m ha
unproductive or on limited use)
Salinity build up
Desertification (hotter parts
of the dry zone)
Marginalization of DZ
agricultural lands (1.2 m ha
unproductive or on limited use)
Sri Lankan Soil Health: Challenges
Coastal salinity
Salt water intrusion
Coastal salinity
Salt water intrusion
1
2
3 4

8. Sugarcane Research Institute, Sri Lanka
•Low response to
fertilizer
•Loss of biodiversity
(micro-flora)
•Increasing soil
erosion
•P build up
•Increasing coastal
salinity
•Acidification
•Nematodes build
up
•Salinity build up
•Desertification
•Land slides
CapacityCapacity
Challenges in dealing with the previous Issues
(Capacity, Infrastructure for research, extension and policy)
Infrastructure for researchInfrastructure for research
ExtensionExtension
PolicyPolicy
Knowledge and Human resourceKnowledge and Human resource
Basic infrastructureBasic infrastructure
Advance infrastructure
and research
Advance infrastructure
and research
Good and can improve furtherGood and can improve further
Poor implementation of policiesPoor implementation of policies

9. Sugarcane Research Institute, Sri Lanka
Site specific fertilizer recommendations
• Soil testing carried out.
• Accordingly recommend the
required straight fertilizer only.
• Soil quality index is used for
replanting Tea lands.
Integrated plant nutrition systems
(IPNS)
Policy level encouragements for usage
of organic fertilizer
• Provide balance fertilizer with both
inorganic and organic sources
Sri Lankan Soil Health: Initiatives
Rehabilitation of degraded
agricultural lands in Kandy,
Badulla and Nuwaraeliya
districts – FAO and GEF
funded project

10. Sugarcane Research Institute, Sri Lanka
Improving / maintaining soil quality in dry and wet
zones of the country under changing climatic conditions
Addressing salinity problems inland (dry zone) and
close to the coastal areas
Priority areas to be addressed in Sri
Lanka
Quantification of accumulated chemical residues in soil
(nutrients and heavy metals) and its impact on plants
and environment (detail studies)
Rehabilitation of marginal lands

11. Sugarcane Research Institute, Sri Lanka
1. Anon. 2000. National report on desertification/land degradation in Sri Lanka.
2. CBSL. 2017. Annual report. Central bank of Sri Lanka.
3. ESSL, 2018. Economics statistics of Sri Lanka. Department of census and statistics.
Ministry of National Policies and Economics affairs.
4. FAOSTAT. 2014. Statistical database, Rome, FAO (available at:
http://faostat3.fao.org/download/T/TP/E)
5. Jahan, F.N. and Gurung, T.R. 2017. Best practices of integrated plant nutrition systems
in SAARC countries.
6. World bank: CIAT. 2015. Climate smart agriculture in Sri Lanka, CSA country profiles
for Africa, Asia, Latin America and Caribbean series. Washinton D.C.: The world bank
group.
7. Integrated plant nutrition systems, training manual for Sri Lanka
8. Mapa, R. B., Kumaragamage, D., Gunarathna, W.D.L. and Dassanayaka, A. 2002.
Land Use in Sri Lanka. Past, Present and Future. Paper No 974. 17th World Congress
of Soil Science, Thailand.
9. AgStat, 2015. Pocket Book of Agricultural Statistics. vol XXI, Social economic and
Planning Centre, Department of Agriculture, Sri Lanka. 67 p
10. PCRS. 2012, 2014, 2016. Proceedings of Plantation Crop Research Symposiums, Sri
Lanka …..
References

12. 5th
Symposium on Plantation Crop Research, BMICH, Colombo, Sri Lanka
Acknowledgements
•APAARI for providing us the facility to come over
•Ministry of Public Enterprise and Plantation Industries
•Chairman and Secretary of SLCARP
•Director Sugarcane Research Institute

13. Sugarcane Research Institute, Sri Lanka