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.

260280300320340360

CO

2(p

pm) 1.5

1.00.50.0

CH

4(p

pb)

7501000

15001750

1250

0.50

0.25

0.00

1000 1200 1400 1600 1800 2000

0.15

0.050.00

0.10

250

270

310

290

N2O

(ppb

)Atm

osph

eric

con

cent

ratio

n

Rad

iativ

efo

rcin

g (W

m-2

)

Year

Indicators of the human influence on the atmosphere during the industrial era

Source: IPCC 2001

Carbon Dioxide

Methane

Nitrous Oxide

Source: IPCC 2001

The contribution from each of the human-made greenhouse gas to the change in radiative forcing

CO2 60% CH4 20%

N2O 6%

CFCs & HCFCs 13%Others 1 %

1860 1880 1900 1920 1940 1960 1980 2000

Tem

pera

ture

Ano

mal

y (º

C)

0.6

0.4

0.2

- 0.2

- 0.4

- 0.6

0.0

Global TemperaturesFive year average

Year(Source: www.globalwarmingart.com)

Global warming: Causes and effectsCauses

Large-scale use of fuels, factories, & deforestation

Global warming: Causes and effects

Effects Effects

Causes

Large-scale use of fuels, factories, & deforestation

Warmer weather provides breeding grounds for insects

Damaging storms, drought and related weather phenomena

Global warming: Causes and effects

Effects Effects

Causes

Large-scale use of fuels, factories, & deforestation

During the past 100 years global sea levels have risen 4 to 8 inches

Increasing hot summers & intense thunderstorms

Terrestrial water storage,extraction of groundwaterbuilding of reservoirs,changes in runoff, andseepage into aquifers

Subsidence in riverdelta region,land movements, andtectonic displacements

Surface and deep oceancirculation changes, storm surges

As the ocean warms,the water expands

Exchange of the waterstored on land byglaciers and ice sheetswith ocean water

What causes the sea level to change?

(Source: IPCC 2001)

Asia's largest rivers, the Ganges and the Bramaputra, join in the world's most extensive delta and flow into the Bay of Bengal. Asia's largest rivers, the Ganges and the Bramaputra, join in the world's most extensive delta and flow into the Bay of Bengal.

Origin-Brahmaputra

GangesGanges

Possible Climate Change due to Global Warming

Variables of Climate Change and possible change of climateVariables Climate Change

Slow ExtremeAverage temperature increases (°C) + 02 + 04Sea level rise (cm) + 30 + 100 Rain fall (%)

Rainy seasonDry season

+ 18- 12

+ 33- 22

Evaporation (%)Rainy seasonDry season

+ 08+ 10

+ 15+ 20

River Water flow (%)Maximum flowMinimum flow

+ 06- 12

+ 13- 22

Storm Intensity (%) + 10 + 25

Climatic risks for BangladeshEnvironmental 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

Soil Fertility Decline Soil Erosion and land lossSoil Salinity Loss of water/Inefficient Use of Water Climatic stresses

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.

Soil Fertility Decline

Name of AEZ Land type% Organic Matter (Mean) Depletion

of OM (%)(1970-2000)1969-1970 1989-1990 1999-2000

Madhupur Tract HL 1.78 1.20 1.02 42.7Barind Tract HL & MHL 1.45 1.15 0.76 47.6Old 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 Hills

HL 2.04 1.32 1.05 48.5

Old MeghnaEstuarine Floodplain

HL 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

Changes of organic matter with time in Major AEZs.

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 BangladeshTypes of land degradation Areas (in m ha) affected by different

degrees of degradationTotal area

(m ha)

Light Moderate Strong

1. Water Erosion-Bank erosion

0.1-

0.31.7

1.3-

1.71.7

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

3.85.33.14.02.14.44.11.94

4.23.22.53.45.43.34.6

1.56

-------

4.05

8.08.55.67.47.57.78.7

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

10. Barind - - - 0.773Source: BARC, 1999.

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.

Soil Erosion and Land loss

Shifting cultivationSoil erosionSoil fertility degradationEnvironment degradation

Months Soil loss (t ha-1) at different hill slopes10% 20% 30%

April 0.30 0.46 0.60May 1.64 2.10 2.56June 6.02 8.18 10.0July 4.18 7.06 9.11August 3.06 5.12 6.33September 1.28 2.05 2.82October 0.92 1.36 1.68

Month wise soil loss at different hill slope (average of 1998-2000)

Source: Khan, 2001.

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.

Soil Salinity

Yield decrease EC on Rice(m mhos cm-1)

EC on Wheat (m mhos cm-1)

0 %10%25%50%

2,0002,6003,4004,800

4,0004,9006,4008,700

Source : FAP, 1993.

Effect on saline water on rice and wheat

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 StressesClimate 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.

Source: BARC

Early monsoon flood(Early June – Mid July)

Source: BARC

Late monsoon flood(Early Aug. – Mid Sept.)

1998 Flood ExtentDamages of 1998 Flood

32 districts affected100,000 sq km (66% area) affected575,000 ha of crops destroyed1,050 deaths reported30 million people affected25 million people left affected26,000 livestock lost20,000 schools and other edu. facilities damaged300,000 tube wells damaged16,000 km of roads flooded4,500 km of river embankments damagedSource: ActionAid, 1999

Natural hazards and affected area

Hazards Area affectedFloods (flash, rain water, river water and tidal floods)

1.32 mha of net cultivated area (NCA) severely affected5.05 mha of NCA moderately affected

Droughts 2.32 mha of crop affected in kharifseason1.20 mha affected in rabi season

Salinity and coastal surges

0.87 mha is affected

Cyclones and wind 2.80 mha of coastal area are subjected to damaging cyclones

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.

iii) Drought :

Extent of Drought

Source: BARC/UNDP/FAO

Drought prone areas(Kharif season)

Drought Classes

Area (ha) Percent of yield reduction of cropsWheat Potato Mustard B. Aus

Very Severe 363855 60-70 >70 >50 >40Severe 864063 50-60 60-70 40-50 30-40Moderate 3284698 40-50 50-60 30-40 20-30Less Moderate

1457740 30-40 40-50 20-30 10-20

Slight 4352410 <40 30-40 <20 <10

Intensity of Rabi and Pre kharif droughts and yield reduction of crops

Source: Karim et al., 1990.

High temperature effect on key development stage of major agricultural crops

Crops Effect ReferencesWheat Temperature>30oC for more than 8

hours can reverse verbalizationEvans et al. 1975

Rice Temperature>35oC for more than 1 hour at anthesis causes high percentage spikelets sterility

Yoshida, 1981

Maize Pollen begins to lose viability at temperatures>36oC

Decker et al., 1986

Potato Temperature>20oC depress tuber initiation and bulking

Prange et al. 1990

Soybean It has great ability to recover from temperature stress

Shibles et al., 1975

Source : Acock and Acock (1993)

iv) Temperature:

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.

Cyclone pathBangladesh

INDIA

INDIA

INDIA

MY

AN

MA

R

SIDR15 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 15 lacs(fully damaged 5.64 lacs)

Affected roads & highways 8000 km

Untraced people 871

Injured 55 thousandsAffected educational institute 8000 (4489 pri. Sch., 3750 H. sch. & coll.)

Affected sanitary systems 70%

Cyclone ‘SIDR’ inflicted losses

Sources: The Dainik Ittefaq, 18 December 2007.

SIDR15 Nov. 2007

vi) Hailstorms :

Hailstorms are usually associated with violent thunderstorms.

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

ConclusionGlobal 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

Thanks