This document provides an overview of soil fertility and management in Bangladesh. It discusses the country's geography, soil types, fertility issues, and strategies for improving soil health. The key points are:
- Bangladesh soils generally have low organic matter, nitrogen, and phosphorus levels. Salinity is also an issue in coastal areas.
- Major causes of fertility degradation include intensive cultivation without balanced fertilizer use, removal of crop residues, and misuse of agricultural lands.
- To improve soil fertility, the document recommends soil testing, balanced fertilization, organic matter addition, crop rotation including green manures, and adopting integrated nutrient management.
Geography of Bangladesh
•Bangladesh is situated between 20º34′ and
26º38′ north latitude and 88º01′ and 92º41′ east
longitude. It is the fifth most populous
country in Asia and ranks eighteenth in the
global context.
• The topography is flat with elevation not
exceeding 10 meters above mean sea level. The
non-undulated topography is broken in the
southeast by the Chittagong Hill Tracts and
hills in the northeastern part of the country.
Floodplain and piedmont plains occupy
almost 80 percent of the land area. Slightly
uplifted fault blocks (terrace) occupy about
8 percent and hills occupy about 12 percent of
the land.
3.
Soil and LandResources of
Bangladesh
• Physiography: 15 (SRDI, 2013)
1. Tipam-Surma Hills (High Hills)
2. Dupitila- Dihing Hills (Low Hills)
3. Modhupur Clay Upland
4. Himalayan Piedmont Plain
5. Northern-Eastern Piedmont Plain
6. Tista River Floodplain
7. Brahmaputra-Jamuna River Floodplain
8. Surma-Kusiyara River Floodplain
9. Meghna River Floodplain
10. Ganges River Floodplain
11. Peat Basins
12. Ganges Tidal Floodplain
13. Meghna Estuarine Floodplain
14. Chittagong Coastal Plain
15. St. Martin’s Island
• High land:Above normal flood
level
• Medium High land: Inundated upto 3’
• Medium low land: Inundated upto 3-
6’
• Low land: Inundated upto 6-9’
• Very low land: Inundated >9’
Land type class: Based on inundation level
during monsoon
7.
Land type classin Bangladesh (%)
High land
20%
Medium
highland
36%
Medium
lowland
14%
Low
land
7%
Very
lowland
2%
Miscellaneo
us land type
21%
Drainage class ofBangladesh
(%)
Well
drained
14%
Moderately
well drained
2%
Imperfectly
drained
19%Poorly
drained
61%
Very poorly
drained
4%
10.
Water recession classof
Bangladesh
• Very early-Water recedes within Ashwin
from land surface
• Early- Water recedes after Ashwin but
within kartik from land surface
• Normal- Water recedes after kartik but
within Ogrohayon kartik from land
surface
• Late- Water recedes after Ogrohayon but
within 2nd week of Paush from land
surface
• Very late- Water recedes after 2nd week
of Paush from land surface
11.
Water recession classof
Bangladesh (%)
Very early
29%
Early
21%
Normal
18%
Late
10%
Very late
3%
Misc
19%
12.
Soil Fertility in
Bangladesh
•Soil Fertility capability or ability of soils to supply
elements essential for plant growth without a toxic
concentration of any element. It is the inherent capacity
of a SOIL to supply 14 of the 17 essential nutrient elements
to the growing crop.
• It is the quality of soil that enables it to provide
compounds or elements in adequate amounts and in
proper balance for the growth of specified plants when
other growth factors like light, moisture, TEMPERATURE and
the physical conditions of the soils are favourable.
• As such, a soil can be fertile for one plant and at the
same time be unfertile for another plant.
• On the other hand soil productivity is a measure of the
soils ability to produce a particular CROP or sequence of
crops under a specified management system. The major
constraints of BANGLADESH SOILs as regards general
fertility and health are briefly enunciated below.
13.
Causes of Fertility
degradation
•Intensive Crop Cultivation without
balanced inorganic and organic
fertilizer
• Adulterated Fertilizer
• Poor knowledge and resource base
of majority farmers’
• Removal of crop residues from
crop field (fuel purpose)
14.
SOIL REACTION
• SoilReaction The average pH of Bangladesh soils could be taken
on the acidic side of the pH scale, between 5.5 and 6.5.
• The Gangetic alluvium soils, particularly the calcareous
one, have pH greater than 7.0, reaching at times up to 8.5. These
contain free carbonates and bicarbonates. Soils in
plateaus, raised lands and hills are usually acidic in nature.
Because of pH variations, the nutrient availability, particularly
that of phosphorus (P) and some micronutrients, is affected.
Otherwise, lowland rice cultivation is not affected by original
soil reaction, as the pH tends to come to a value between 6.5
and 7.5 on submergence.
• LIMING is needed for crops other than tea in soils having pH less
than 4.5, which is more prominent in ACID SULPHATE SOILs and hill
soils.
• Upland crops are adapted to local SOIL pH. Soils are
categorized as (i) extremely acidic - having pH below 4.5; (ii)
strongly acidic - pH between 4.5 and 5.5; (iii) moderately acidic -
pH between 5.6 and 6.5; (iv) neutral - pH between 6.6 and 7.3; (v)
moderately alkaline - pH between 7.4 and 8.4; (vi) strongly
alkaline - pH between 8.5 and 9.0; and (vii) very strongly
alkaline - pH >9.0
16.
Organic Matter
• Organicmatter status Organic matter (OM) status of
Bangladesh soil is one of the lowest in the world. The average
OM content of Bangladesh soils is less than 1%, ranging between
0.05 and 0.9% in most cases.
• Soils of peat lands and some low-lying areas usually contain
OM higher than 2% on an average. Organic matter supply in soil is
one of the major constraints to the AGRICULTURE of the country.
Yet, the country has been producing good crops and cereal
production in 2000 exceeded 27 million ton, with a surplus of 9
million ton. This has been possible only due to the use of high
doses of synthetic fertilisers and improved varieties of seeds.
• Most of the Bangladesh soils show an improved response when
OM is incorporated along with inorganic fertilisers. The
recommended doses vary between 5 to 10 tons/ha of fresh or
partially decomposed cowdung. Use of green manuring plants
like Sesbenia rostrate is also encouraged. Use of compost is
absent or insignificant.
• The organic matter status has been classified as: very low (<1%);
low (1.1-1.7%); medium (1.7-3.4); high (3.4-5.5); and very high >5.5.
18.
Nitrogen status
• Nitrogenstatus Because of low level of OM
the nitrogen status of Bangladesh soils is
substantially low and most crops on all
soils respond to nitrogen applications.
• In fact, nitrogen (N) fertilizers are the most
commonly used FERTILISERs in the country. The
country has as many as 6 fertiliser factories
producing mostly UREA from NATURAL GAS.
Compared to production with no
fertilisers, a 2 to 3 fold increase is common
in most crops including RICE with N-fertilisers.
The N-fertiliser consumption during 1996-97
was more than 2 million metric ton.
19.
Phosphorus status
• Phosphorusstatus The available
phosphorus in Bangladesh soils could
be considered between low and
medium. Most soils respond to P-
fertilisation. Phosphorus availability
is pH dependent.
• The source of P supply in soils is
inorganic fertiliser. This again is not
proportionate to the supply of
inorganic N.
20.
Potassium status
• Potassiumstatus Bangladesh soils
are not deficient in potassium (K)
although many soils are found to
respond to K-fertilisation. These
are particularly non-alluvial soils
and the coastal saline soils.
• About 0.12 meq percent of NH4OAc
extractable K is considered the
critical limit for Bangladesh.
21.
Sulphur status
• Sulphurstatus Response to sulphur
(S) application is common in most
soils except in coastal saline
soils, acid sulphate soils and some
acidic soils. Irrigated crops in the
northern districts respond markedly
to S-application.
• About four million ha of land is
supposed to be S-responsive. Gypsum
is the principal source of sulphur.
22.
Zinc and Boron
•Zinc and Boron During the recent
past, soils, particularly those under constant
waterlogging and IRRIGATION have been found
to respond to zinc (Zn) and boron (B)
applications. The calcareous floodplain soils
are one of them. About 1.7 million ha of land
has been estimated to be deficient in Zn
supply.
23.
Other micronutrients
• Othermicronutrients Response to
micronutrients other than Zn and B has not
yet been reported in any soil for any particular
plant. However, it has been suggested that in
some peat land soils and other soils, Mn
application might have a positive response. It
has not yet been confirmed. Crop response to
Mo application is also found in some
AGROECOLOGICAL ZONE (AEZ).
24.
Cation exchange capacity
•Cation exchange capacity In Bangladesh soils
the organic matter content is low and the
majority of soils contain 1:1 clays and illites.
As such, the CEC of Bangladesh soils in general
is not appreciably high. Classification of
Bangladesh soils on the basis of CEC (meq%)
is: very high (>30); high (15-30); medium (7.5-
15.0); low (3.0-7.5); and very low (<3.0).
26.
Soil salinity
• Soilsalinity A vast area of land in
the coastal area is subjected to
seasonal salinity. The salinity is
mainly of Cl-SO4 type. As it is caused
by marine water intrusion, the
Ca:Mg ratio in the coastal saline
soils is less than 1.0, which creates
severe fertility problems. Most
lands in saline areas are under
single crop.
27.
Extent of soilsalinity during last 4
decades in Bangladesh
Salt affected
area (‘000 ha)
Salinity class and area (‘000 ha)
S1
(2.0-4.0 dS/m)
S2
(4.1-8.0 dS/m)
S3+S4
(8.1-16.0 dS/m)
S5
(>16.0 dS/m)
1973 2000 2009 1973 2000 2009 1973 2000 2009 1973 2000 2009 1973 2000 2009
833.45
1020.75
1056.26
287.37
289.76
328.43
426.43
307.20
274.22
79.75
336.58
351.69
39.90
87.14
101.92
* Source: SRDI, 2012
28.
Comparative Salt affectedarea
between 1973 and 2009 (SRDI, 2012)
Salt affected area (‘000 ha) Salt affected
area increased
during last 9
years (2000-
2009)
Salt affected
area increased
during last 36
years (1973-
2009)
1973 2000 2009
833.45 1020.75 1056.26 35.51 (3.5%) 222.81 (26.7%)
29.
Misuse and abuseof soils
• Misuse and abuse of soils It is high time for the planners
and policy makers to frame rules/laws to protect
arable soils from ruination. Many agricultural lands are
brought under urbanisation or industrialisation. One can
find numbers of brick kilns set up on fertile agricultural
lands along highways. As these lands are private
owned, the government has practically no control on
their use. Forestlands are also brought under
urbanisation and industrialisation.
• Only about 7% of the total land area is under forest
cover now. Overexploitation, ie using the soil for
intensive cultivation without replenishing it, is causing
nutrient mining to an extent that ultimately will make it
barren. Excessive greed, mingled with lack of
farsightedness, proper awareness and absence of punitive
laws, has aggravated the misuse and abuse of our limited
land and this is taking a heavy toll on our soils.
30.
Location
Dominant cropping
pattern
Total yield
(t/ha/yr)
Nutrientmining
(kg/ha/yr)
Palima, Tangail Mustard-Boro-T. Aman 13.0 -190
Polashbari, Gaibandha Mustard-Boro-T. Aman 10.2 -270
Narhatta, Bogra Mustard-Boro-T. Aman 9.5 -280
Palima, Tangail Wheat-Jute-T. Aman 7.0 -240
Paba, Rajshahi Potao-Jute-T. Aman 34.5 -350
Thakurgaon Sugarcane intercropping 60.0 -80
Joypurhat Sugarcane intercropping 107.0 -60
Rajshahi Sugarcane intercropping 90.0 -62
Bogra Boro-GM-T. Aman 11.0 -180
Bogra Wheat-GM-T. Aman 7.5 -170
Source: DANIDA/SFFP.
Soil nutrient mining status in Bangladesh (1998-99)
31.
Need for balancedfertilization in Bangladesh agriculture
• Imbalanced fertilizer use is both costly in terms of nutrient loss from soil
mining, decline in food supply and loss of soil fertility and land productivity and
the consequent decline in food production. Bangladesh adopted a strategy for
balanced fertilization to promote soil building to support sustainable land use
system and ensure stable supply of food grains from existing agricultural lands.
• Bangladesh is gradually moving away from the traditional and rather static
agriculture dependent on native soil fertility to a dynamic judicious fertilizer
dependent agriculture. In a judicious fertilizer-dependent agriculture, balanced
fertilization strategy has to be a cornerstone of all activities. Balanced fertilization
is aimed at:
Increasing crop yields;
Increasing crop quality;
Increasing farm income;
Correction of inherent soil nutrient deficiencies;
Improving soil fertility;
Avoiding damage to the environment; and
Restoring soil fertility and productivity of land that has been degraded by
wrong and exploitative activities in the past.
32.
Soil Fertility Managementin Bangladesh
• “The crops on a field diminish or increase in exact
proportion to the mineral substances conveyed to
them in manure (fertilizer).”---Justus Von Liebig, 1803-
1873
• Soil testing is needed for accurate and effective
fertilization of crops. Soil testing is essentially needed
to ascertain actual quantity of soil contents of different
plant nutrients already present in the soil. Needed
inorganic fertilizer for the crop in right quantity may be
computed after adjustment in consideration of the
nutrients present in the soil.
33.
Application of recommendedfertilizer to the soil will ensure
improvement of fertility and productivity status of the soil and the crop
under cultivation will have desired yield.
Addition of organic manures to the soil improves soil
structure, increases water holding capacity of the soil and improves
internal condition of the soil.
Inorganic fertilizers should be supplemented with organic manures.
Judicious crop rotation including a green manuring crop will add
appreciable amount of organic matter in the soil.
Crops like Dhaincha, mung-bean, mash-kalai, cow-pea may be cultivated
as green manuring crops. These crops at flowering stage may be
ploughed down and incorporated into the soil.
Most important step: Integrated nutrient management (INM) system
needs to be adopted.