SOIL, WATER AND CLIMATE RELATED CONSTRAINTS FOR CROP PRODUCTION
M. S. Khan, R. Sen, S. Noor, H. M. Naser and M. K. Alam
Soil Science Division, BARI, Gazipur-1701
Crop production situation in Bangladesh becomes worsen due to various soil, water and climate related constraints. Global warming and climate change phenomena exacerbate this situation.
CH4 (ppb)
1750 1500 1250 1000 750 310
1.5
Carbon Dioxide
1.0 0.5 0.0
Methane
0.50 0.25 0.00
Nitrous Oxide
0.15 0.10
290
0.05
270
0.00
250 1000
1200
1400
1600
Year Source: IPCC 2001
1800
2000
Radiative forcing (Wm-2)
CO2 (ppm)
360 340 320 300 280 260
N2O (ppb)
Atmospheric concentration
Indicators of the human influence on the atmosphere during the industrial era
The contribution from each of the human-made greenhouse gas to the change in radiative forcing
CO2 60%
CH4 20% N2O 6%
Others 1 %
Source: IPCC 2001
CFCs & HCFCs 13%
Temperature Anomaly (ºC)
0.6
Global Temperatures 0.4
Five year average
0.2 0.0 - 0.2 - 0.4 - 0.6 1860
1880
(Source: www.globalwarmingart.com)
1900
1920
1940 1960
Year
1980
2000
Global warming: Causes and effects Causes Large-scale use of fuels, factories, & deforestation
Global warming: Causes and effects Causes Large-scale use of fuels, factories, & deforestation
ts c fe f E
Damaging storms, drought and related weather phenomena
Ef
fe ct s
Warmer weather provides breeding grounds for insects
Global warming: Causes and effects Causes Large-scale use of fuels, factories, & deforestation
ts c fe f E
During the past 100 years global sea levels have risen 4 to 8 inches
Ef
fe ct s
Increasing hot summers & intense thunderstorms
What causes the sea level to change? Terrestrial water storage, extraction of groundwater building of reservoirs, changes in runoff, and seepage into aquifers
Surface and deep ocean circulation changes, storm surges
Subsidence in river delta region, land movements, and tectonic displacements
As the ocean warms, the water expands
Exchange of the water stored on land by glaciers and ice sheets with ocean water
Asia's largest rivers, the Ganges and the Bramaputra, join in the world's most extensive delta and flow into the Bay of Bengal. (Source: IPCC 2001)
utra p a m h a r Origin-B
Ga ng es
Possible Climate Change due to Global Warming Variables of Climate Change and possible change of climate Variables
Climate Change Slow
Extreme
Average temperature increases (°C)
+ 02
+ 04
Sea level rise (cm)
+ 30
+ 100
Rain fall (%) Rainy season Dry season
+ 18 - 12
+ 33 - 22
Evaporation (%) Rainy season Dry season
+ 08 + 10
+ 15 + 20
River Water flow (%) Maximum flow Minimum flow
+ 06 - 12
+ 13 - 22
Storm Intensity (%)
+ 10
+ 25
Climatic risks for Bangladesh Environmental Impacts
Socio-economic Resources & Sector affected
• Changes in rainfall patterns
Water resources
• Increased frequency and severity of :
Agriculture and forestry
Floods
Food security
Droughts
Human health
Storms
Infrastructure (e. g. transport)
Heat waves
Settlements : displacement of inhabitants and loss of livelihood
• Changes in growing seasons and regions Coastal management • Changes in water quality and quantity
Industry and energy
• Sea level rise
Disaster response & recovery plans
Major constraints to crop productivity in Bangladesh
¾ Soil Fertility Decline ¾ Soil Erosion and land loss ¾ Soil Salinity ¾ Loss of water/Inefficient Use of Water ¾ Climatic stresses
Soil Fertility Decline
In Bangladesh, major food crops remove about 2.98 m tons nutrients annually against a total addition of 0.72 m ton. According to an appraisal report on Bangladesh’s soil resources, soil of about 6.10 m ha contain very low (less than 1%) organic matter, 2.15 m ha contain low (1-2%) organic matter and the remaining 0.90 m ha contain high (more than 2%) organic matter.
Changes of organic matter with time in Major AEZs. % Organic Matter (Mean) Name of AEZ
Land type
1969-1970
1989-1990
Depletion of OM (%) 1999-2000 (1970-2000)
Madhupur Tract
HL
1.78
1.20
1.02
42.7
Barind Tract
HL & MHL
1.45
1.15
0.76
47.6
Old Himalayan Piedmont Plain
HL
1.32
1.2
1.04
21.2
Tista Meander Floodplain
HL & MHL
1.55
1.23
0.97
37.4
Northern & Eastern HL Hills
2.04
1.32
1.05
48.5
Old Meghna HL Estuarine Floodplain
2.16
1.17
0.91
57.9
High Ganges River Floodplain
HL
1.21
0.98
0.83
62.4
Old Brahmaputra Floodplain
MHL
1.56
1.23
1.15
26.3
H, high. M, medium. L, land
Source: Karim et al., 2004.
The state of decline is also reflected in deficiency of N in almost all soil types, deficiency in P, Zn, S, B, etc. Five m ha of land suffer from S deficiency and 2 m ha from Zn deficiency.
Different types of land degradation and their extent in Bangladesh Types of land degradation
Areas (in m ha) affected by different degrees of degradation
Total area (m ha)
Light
Moderate
Strong
1. Water Erosion -Bank erosion
0.1 -
0.3 1.7
1.3 -
1.7 1.7
2. Wind Erosion
-
-
-
-
3. Soil Fertility Decline - P deficient (for HYV rice) - P deficient (for Upland crops) - K deficient (for HYV rice) - K deficient (for Upland crops) - S deficient (for HYV rice) - S deficient (for Upland crops) Soil Organic Matter depletion
3.8 5.3 3.1 4.0 2.1 4.4 4.1 1.94
4.2 3.2 2.5 3.4 5.4 3.3 4.6 1.56
4.05
8.0 8.5 5.6 7.4 7.5 7.7 8.7 7.55
4. Water logging
0.69
0.008
-
0.7
5. Salinization
0.29
0.43
0.12
0.84
6. Pan formation
-
2.82
-
2.82
7. Acidification
-
0.06
-
0.06
8. Active floodplain
-
-
-
1.53
9. Deforestation
-
0.3
-
0.3
-
-
-
0.773
10. Barind
Source: BARC, 1999.
Soil Erosion and Land loss High seasonal rainfall, low organic matter content in soils, poor soil management and steep slopes particularly in hilly areas contribute to soil erosion. It is reported that about 1.74 m ha land is prone to soil erosion. Land degradation result in part from deforestation both in hills and plains, occurring now at 5-6% annually.
Shifting cultivation Soil erosion Soil fertility degradation Environment degradation
Month wise soil loss at different hill slope (average of 1998-2000)
Months
Soil loss (t ha-1) at different hill slopes
April
10% 0.30
20% 0.46
30% 0.60
May June
1.64 6.02
2.10 8.18
2.56 10.0
July August
4.18 3.06
7.06 5.12
9.11 6.33
September October
1.28 0.92
2.05 1.36
2.82 1.68
Source: Khan, 2001.
Soil Salinity Of the 2.85 m ha of coastal areas (some 30% of the total arable land of the country), about 0.87 m ha are affected by different degrees of soil salinity. The problem has exacerbated in recent years, specially in Khulna-Jessore region as a result of reduced dry season water flow below the Farakka Barrage in India. Water conductivity of 750 mmhos is damaging to human health while a rating of 2,000 mmhos affects yields of irrigated rice and many other crops.
Effect on saline water on rice and wheat Yield decrease
EC on Rice (m mhos cm-1)
EC on Wheat (m mhos cm-1)
0% 10% 25% 50%
2,000 2,600 3,400 4,800
4,000 4,900 6,400 8,700
Source : FAP, 1993.
Inefficient Use of Water The water use efficiency in Bangladesh will hardly exceed 30%. It may be worthwhile to mention that irrigation water worth about Tk. 12 m is wasted annually in Bangladesh because of poor management practices and wrong setting of tubewells for irrigation.
Climate Stresses Climate remains as the most determining factor for crop productivity although the impact of climate on productivity is not often appreciated by scientists. Changes in climate have profound effect in crops specially grain crops.
i) Rainfall : Crop production in Bangladesh is predominantly rainfed. Hence the onset, duration, amount and the periodic aberrations of rainfall dictate the nature and type of crops to be grown and the activities of crop production. The annual average rainfall of the country ranges from 1194 mm to 3454 mm.
Early monsoon flood (Early June – Mid July)
Source: BARC
Late monsoon flood (Early Aug. – Mid Sept.)
Source: BARC
1998 Flood Extent Damages of 1998 Flood 32 districts affected 100,000 sq km (66% area) affected 575,000 ha of crops destroyed 1,050 deaths reported 30 million people affected 25 million people left affected 26,000 livestock lost 20,000 schools and other edu. facilities damaged 300,000 tube wells damaged 16,000 km of roads flooded 4,500 km of river embankments damaged Source: ActionAid, 1999
Natural hazards and affected area Hazards Floods (flash, rain water, river water and tidal floods)
Area affected 1.32 mha of net cultivated area (NCA) severely affected 5.05 mha of NCA moderately affected
Droughts
2.32 mha of crop affected in kharif season 1.20 mha affected in rabi season
Salinity and coastal 0.87 mha is affected surges 2.80 mha of coastal area are subjected Cyclones and wind to damaging cyclones
iii) Drought : Drought of different intensities occur in our country, which severely affects annually about 2.3 million ha in the Kharif season and 1.2 million ha in the dry (Rabi and pre Kharif) seasons.
Extent of Drought
Drought prone areas (Kharif season)
Source: BARC/UNDP/FAO
Intensity of Rabi and Pre kharif droughts and yield reduction of crops
Drought Classes
Area (ha) Percent of yield reduction of crops Wheat Potato Mustard B. Aus
Very Severe Severe
363855 864063
60-70 50-60
>70 60-70
>50 40-50
>40 30-40
Moderate Less Moderate
3284698 1457740
40-50 30-40
50-60 40-50
30-40 20-30
20-30 10-20
Slight
4352410
36oC
Potato
Temperature>20oC depress initiation and bulking
Soybean
It has great ability to recover from Shibles et al., 1975 temperature stress
Source : Acock and Acock (1993)
lose
viability
at Decker et al., 1986
tuber Prange et al. 1990
v) Cyclone and tidal surges: Cyclone and tidal surges are also common in the coastal area and they cause severe loss to the crops and lives. Salinity and tidal submergence tolerant rice varieties and appropriate cropping pattern with proven soil reclamation methods need to be developed to increase the cropping intensity of the coastal saline area.
Bangladesh Cyclone path INDIA
INDIA
MYANMAR
INDIA
SIDR 15 Nov. 2007
Cyclone ‘SIDR’ inflicted losses
SIDR 15 Nov. 2007
Loss of lives
3363
Monetary losses
6100 crores (Tk.)
Affected people
1 crore
Damages of crops
13 lacs m tons
Household’s affected (fully damaged 5.64 lacs)
15 lacs
Affected roads & highways
8000 km
Untraced people
871
Injured
55 thousands
Affected educational institute 8000 (4489 pri. Sch., 3750 H. sch. & coll.) Affected sanitary systems Sources: The Dainik Ittefaq, 18 December 2007.
70%
vi) Hailstorms : Hailstorms are thunderstorms.
usually
associated
with
violent
In Bangladesh, it mainly occurs during March to May and causes severe damage to standing crops like boro rice, wheat, jute, mungbean, summer vegetables, fruits etc.
Opportunities to Adaptation the Constraints We have to face the challenges of the coming years by developing and applying technologies that can help increase yield to feed the growing population and this is to be achieved in ways that are economically viable and environmentally sustainable.
• Crop Management • Nutrient/Fertilizer Management • Water Management • Climate
Conclusion Global warming and climate change have detrimental impact on soil fertility and crop productivity. Soil organic matter is decreasing due to rise of soil temperature. Extent and severity of natural disaster like flood, drought, cyclone and tidal surges will be more in the coming years. Increased drought and salinity, prolonged inundation and excessive soil erosion will reduce the crop area & yield. Appropriate crop management practices should be followed in the climate change affected areas. Selection of appropriate crop species/variety should be chosen for specific area
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