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CHANGES IN DEMOGRAPHIC AND AGRICULTURAL FACTORS AND THEIR IMPACT ON CROPPING INTENSITY

AND NUTRIENT STATUS IN SOILS OF KALAPARA UPAZILA: A CASE STUDY

Course Title: Project Thesis

Course No. SS 5206

KHULNA UNIVERSITY

KHULNA

JULY, 2012

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CHANGES IN DEMOGRAPHIC AND AGRICULTURAL FACTORS AND THEIR IMPACT ON CROPPING INTENSITY

AND NUTRIENT STATUS IN SOILS OF KALAPARA UPAZILA: A CASE STUDY

This project thesis paper has been prepared and submitted to Soil

Science Discipline, Khulna University, Khulna, as partial fulfillment of

the requirements for the degree of Master of Science in Soil Science.

Submitted By

……………………………………..

Angshuman Sarker

Student ID. MS 111322

Session: 2010-11

KHULNA UNIVERSITY

KHULNA

JULY, 2012

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CHANGES IN DEMOGRAPHIC AND AGRICULTURAL FACTORS AND THEIR IMPACT ON CROPPING INTENSITY

AND NUTRIENT STATUS IN SOILS OF KALAPARA UPAZILA: A CASE STUDY

APPROVED AS TO STYLE AND CONTENT BY

……………………………………….

KhandokerQudrataKibria

Head and Associate Professor

Chairman of the Examination Committee

Soil Science Discipline

Khulna University, Khulna

KHULNA UNIVERSITY

KHULNA

JULY, 2012

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CHANGES IN DEMOGRAPHIC AND AGRICULTURAL FACTORS AND THEIR IMPACT ON CROPPING INTENSITY

AND NUTRIENT STATUS IN SOILS OF KALAPARA UPAZILA: A CASE STUDY

Supervisor

……………………………………….

Md. Sanaul Islam

Associate Professor

Soil Science Discipline

Khulna University, Khulna

KHULNA UNIVERSITY

KHULNA

JULY, 2012

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CHANGES IN DEMOGRAPHIC AND AGRICULTURAL FACTORS AND THEIR IMPACT ON CROPPING INTENSITY

AND NUTRIENT STATUS IN SOILS OF KALAPARA UPAZILA: A CASE STUDY

Co-Supervisor

……………………………………….

Md. ZaberHossain

Assistant Professor

Soil Science Discipline

Khulna University, Khulna

KHULNA UNIVERSITY

KHULNA

JULY, 2012

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Contents

Contents i-iv

List of Tables iii

List of Figures iv

CHAPTER: 1. INTRODUCTION 01

1.1. Objectives 03

CHAPTER: 2. LITERATURE REVIEW 04

2.1. Coastal Areas of Bangladesh 05

2.1.1. Population pressure in coastal areas 06 2.1.2. Cultivable land in coastal areas 07

2.2. Cropping Patterns and Cropping Intensity in Bangladesh 07

2.2.1.Cropping Pattern and Cropping Intensity in Kalapara upazila 13

2.3.Nutrient status in soils of Bangladesh 14 2.3.1. Nitrogen 15

2.3.2. Phosphorus 16

2.3.3. Potassium 16

2.3.4. Sulphur 17

2.3.5. Zinc 18 2.3.6. Calcium and Magnesium 18

2.3.7. Boron 18

2.3.8. Other Micronutrients 19

2.4. Nutrient Status of Kalapara Upazila 19

2.5. Cropping Intensity and Its Effect on Nutrient Status 20 2.6. Soil Salinity 25

2.6.1. Present Soil Salinity Status in Coastal Area 25

2.6.2. Effect of Salinity on Fertility Status of Soil 27

CHAPTER 3. MATERIALS AND METHODS 30 3.1.Conceptualization and Work plan prepation Materials 30 3.2. Study Area 30

3.2.1. Area and Geographical Location 30

3.2.2. Demography 31

3.2.3. Topography and Relief 32 3.2.4. General Geology of the Study Area 32

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3.2.5. Land Use Pattern 32

3.2.5.1. Cropland 33

3.2.5.2. Settlement 33 3.2.5.3. Fallow Land 34

3.2.6. Soil type 34

3.2.7. Climatic Condition 34

3.2.7.1. Rainfall 34

3.2.7.2. Temperature 34 3.2.7.3. Humidity 35

3.3. Selection of the Study Area 35

3.4. Data Collection 35

3.4.1. Cropping Intensity Determination 36 3.5. Data Interpretation 36

3.6. Data Processing and Analysis 36

CHAPTER 4. RESULTS AND DISCUSSION 37 4.1. Increase in population 37

4.2. Reduction of Cultivable land 38 4.3. Increase of Cropping Intensity 39

4.4. Increase of Salinity 39

4.5. Depletion of major Nutrient content 40

4.5.1. Nitrogen Depletion 40

4.5.2. Phosphorus Depletion 41 4.5.3. Potassium Depletion 42

4.5.4. Sulfur Depletion 43

4.5.5. Calcium Depletion 44

4.5.6. Zinc Depletion 45 4.5.7. Boron Depletion 45 CHAPTER 5. SUMMARY AND CONCLUSION 47

REFERENCES 48 - 60

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List of Tables

2.1 Population growth trend in the coastal area 06

2.2 Some dominant cropping patterns under variable crop production environments 10

2.3 Cropping intensity rating 11 2.4 Last 10 year cropping intensity of Bangladesh 12 2.5 Major cropping patterns and cropping intensity in Kalapara 14 2.6 Nutrient status of Ganges tidal floodplain 20 2.7 Nutrient status of Kalapara upazila 20 2.8 Emergence of new nutrient deficiency with time 24 2.9 Extent of soil salinity during about last four decades (1973-

2009) in coastal areas 26

2.10 Estimation of salt affected areas(in ‘000’ ha) in Patuakhali 27 2.11 Agro-chemical characteristics of soil in some of the coastal

and offshore areas (saline belt) of Bangladesh 28

3.1 Represents increase of population in Union of Kalapara upazila after 10 years

32

3.2 Represents the cropland use of Kalapara upazila 33 3.3 Cropping intensity of Kalapara upazila 36

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List of Figures

2.1 Land coverage status of major crops in Bangladesh 8

2.2 Acreage of different types of rice cultivated in Bangladesh 8

2.3 Land used under minor crops in Bangladesh 8

2.4 Nutrient input-output system 15

2.5 N+P+K input and output in Bangladesh 24

3.1 Location map of the study area 31

4.1 Population growth of five unions in Kalapara upazilla 37

4.2a Reduction of Cultivable land 38

4.2b Reduction of per capita land 38

4.3 Increase in Cropping Intensity 39

4.4 Increase in salinity 40

4.5 Depletion of Nitrogen 41

4.6 Depletion of Phosphorus 42

4.7 Depletion of Patassium 43

4.8 Depletion of Sulfer 43

4.9 Depletion of calcium 44

4.10 Depletion of Zink 45

4.11 Depletion of Boron 46

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CHAPTER 1

INTRODUCTION

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1. Introduction

Due to population increase, changes in the composition of the human diet and

increasing demand for bio-fuels, it is necessary to increase global crop production in

order to avoid a new era of malnutrition and hunger (Liu and Savenije,2008). The

food production increases in Arithmetic mean but population grows in Geometric

progression. So it is impossible to keep pace with the agricultural production and

increasing population. So far, the discussion on how to achieve the required increase

of crop production has been mainly restricted to the question of how many resources

(e.g. water, nutrients, energy, germplasm) are needed, and whether an extension of the

global cropland will be necessary or whether an increase of crop yields will be

sufficient (Neumann et al., 2010).

Cropping intensity is defined as the number of crops harvested per year and large

differences are reported in both space and time. Shifting cultivation is still practiced

by millions of farmers mainly in the tropics and subtropics and crop cultivation is

interrupted in these systems by fallow periods that may last decades (Hiernaux et al.,

2009). In contrast, up to four crops are harvested per year in very intensive land use

systems under similar climate conditions (Tanaka, 1995; Siebert et al., 2007). Crop

duration ratio is another indicator of land use intensity. Crop duration ratio is defined

as the fraction of the year in which the cropland is covered with crops (Siebert et al.,

2010).

According to the agricultural statistics database of the Food and agriculture

Organization of the united Nations FAO (2010), total cropland extent at the global

scale, computed as the sum of arable land and permanent crop area, is about 15.3

million km2. These statistics account for all cropland used at least once in a five-year

period, but neglect areas with longer fallow periods. The total harvested crop area

reported in the same database is 11.8 million km2 yr-1, indicating a global average

cropping intensity of 0.77 crop harvests per year. However, the extent of fallow land

is larger than the difference between global cropland extent and global harvested crop

areas because many areas are harvested more than once per year (Siebert et al., 2010).

With rising cropping intensities in South Asia, nutrient management is a major issue

being addressed by agricultural scientists for understanding any decline in yields.

Many long-term fertility experiments established in the region decades ago show no

evidence of yield decline at the farmers’ field level (Abrol et al., 1997).

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The intensive cropping systems introduced by the Green Revolution impose much

heavier demands on crop nutrients than traditional systems had; nutrient deficiencies,

therefore, are a common problem. Intensive agricultural practices can also result in

changes in soil physical and chemical properties. In irrigated rice, the formation of a

plowpan is a frequent problem, impeding root growth and limiting access to nutrients.

Irrigation can also cause salinization or water-logging. The yield declines observed in

the IRRI long-term cropping trials are thought to result from anaerobic conditions in

irrigated rice production leading to changes in soil physical and chemical properties

which make it less able to supply nutrients to growing crops (Dey and Haq, 2009).

Climate change is an important issue nowadays. Various human activities are making

the world hot to hotter. The ultimate result is global warming, i.e. climate change.

Rising temperature in the atmosphere causes sea level rise and affects low lying

coastal areas and deltas of the world. In 1990, Intergovermental panel on climate

change estimates that with business-as-usual scenario of greenhouse gas emission, the

world would be 3.3°C warmer by the end of the next country, with a range of

uncertainty of 2.2 to 4.9°C. With rise in Sea level rise will cause river bank erosion,

salinity intrusion, flood, damage to infrastructures, crop failure, fisheries destruction,

loss of biodiversity, etc. along this coast. Salinity intrusion due to sea level rise will

decrease agricultural production by unavailability of fresh water and soil degradation.

Salinity also decreases the terminative energy and germination rate of some plants

(Warrick et al., 1993). Salinity is an environmental stress that limits growth and

development in plants. The response of plants to excess NaCl is complex and involves

changes in their morphology, physiology and metabolism (Hilal et al., 1998). Salinity

is a very serious constraint to crop plant growth in about 100 countries of the world

(Munns, 2002; Sadiq, 2003). It can inhibit plant growth by a range of mechanisms,

including low external water potential, ion toxicity and interference with the uptake of

nutrients (Munns and Schachtman, 1995; Taffouo et al., 2009). Salinity toxicity is a

worldwide agricultural and eco-environmental problem. It is one of the most

important problems in crop growth and production (Ashraf, 2009). Approximately

one-third of the world land surface is arid and semi-arid, of which one half is affected

by salinity (Liang et al., 1996). It is estimated that about a third of the world’s

cultivated land is affected by salinity. The problem of salinity is of special importance

in Egypt for both the old cultivated area as well as for the newly reclaimed lands. The

major constraints for plant growth and productivity are ion toxicity with excessive

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uptake of mainly Cl- and Na+ as well as nutrients imbalance caused by disturbed

uptake or distribution of essential mineral nutrients (Hu and Schmidhalter, 2005).

Living with salinity is the only way of sustaining agricultural production in the salt

affected soil (Al-Rawahy et al., 2011). Salinity stress causes a number of effects on

plants such as osmotic effects, ion toxicity and nutrient imbalance. During a long time

in salinity, therefore, the sodium toxicity cause to reduce the yield. There are

antagonistic effects on nutrient uptake by plants that cause nutrient disorders

particularly of K and Ca under salinity conditions (Castillo et al., 2003).

The hypothesis therefore, is that fast population growth, rapid urbanization, increasing

food demand, high cropping intensity, intensive cultivation practices and salinity in

the study area may also entail negative impacts on soil fertility and nutrition and

finally may perish sustainability in agricultural use. In this research work the focus

mainly would be on impact of forgoing factors on some specific nutrient status in

soils of studied unions of Kalapara Upazila.

1.1. Objective

Objectives of this research work are –

To assess the rate of change of the triggering factors in the study areas

To estimate the impact of the change of the factors on nutrient status in the studied

unions of Kalapara Upazila. .

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CHAPTER 2

LITERATURE REVIEW

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2. Review of Literature

Bangladesh is an agro-based developing nation where majority of the people directly

or indirectly depend of agriculture. Crop agriculture in Bangladesh is constrained

every year by challenges, such as a) Loss of Arable Land, b) Population Growth, c)

Climate Changes, d) Inadequate Management Practices, e) Unfair Price of Produces,

and f) Insufficient Investment in Research. Bangladesh has lost about l million ha of

arable land from 1983 to 1996. Virtually, no step has been taken by the government to

arrest this loss. The landuse policy prepared by the government several years back has

not yet been implemented. Population growth poses another great threat to crop

productivity. Besides, crop agriculture in Bangladesh has become regularly vulnerable

to the hazards of climate change–flood, drought, and salinity in particular (Mondal,

2010). Bangladesh has one of the highest population densities in the world. The

population of Bangladesh followed an exponentially increasing trend during the past

century. Growth rate of population at present stands 1.42 % (BBS, 2011). Population

is increasing at the rate of 2 million per year and the total population would be around

233 million by 2050 if the current growth rate continues. Such a growth rate of a

country of 1,43,000 sq. km is viewed as a great challenge not only to different

economic development activities but also as crisis to accommodation, environment

and meeting other basic needs (food, education, and health). The rapid growth of

population and land loss impedes the agriculture development of this country. For this

reason the net cropped sown area of the country is decreasing but the cropping

intensity is increasing over times (Mondal, 2010).

Increased crop productivity from the shrinking land resources is the urgent need to

meet the increased food demand of the swelling population of Bangladesh. Food

requirement of the country is estimated to be doubled in the next 25 years. To feed the

teeming million the land resources in Bangladesh is intensively used for crop

production. Since land is a scarce resource in Bangladesh, the only choice is to

increase in cropping intensity. This resulted in increasing demand for nutrients, which

was reflected in more nutrient deficiencies exhibited by the crops (Islam and Haq,

1999).

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2.1. Coastal Areas of Bangladesh

The coastal areas of Bangladesh is different from rest of the country not only because

of its unique geo-physical characteristics but also for different sociopolitical

consequences that often limits people’s access to endowed resources and perpetuate

risk and vulnerabilities. Coastal areas include coastal plain islands, tidal flats,

estuaries, neretic and offshore waters. It extends to the edge of a wide (about 20 km)

continental self. A vast river network, a dynamic estuarine system and a drainage

basin intersect the coastal zone, which made coastal ecosystem as a potential source

of natural resources, diversified fauna and flora composition, though there also have

immense risk of natural disasters (Islam et al., 2006).

The coastal areas cover the nineteen districts in the south and south-east parts of

Bangladesh. It occupies 32% of the total area and 28% of the population of

Bangladesh (Islam, 2004). It covers an area from the shore of 37 to 195 km. whereas

the exposed coast is limited to a distance of 37 to 57 km (Islam et al., 2006). The

coastal belt of Bangladesh is divided into three distinct regions, that is, the western,

central and eastern regions. The western and central zones are very flat and low. The

land here is criss-crossed by numerous rivers and channels with a large number of

islands. The western zone of Satkhira, Khulna, Bagerhat, Perojpur is home to the

famous mangrove forest, the Sundarbans. A submarine canyon, Swatch of No Ground

runs NE-SW upto about 24 km. south of the western coast of the country. The central

region of Barguna, Patuakhali, Bhola, Barisal, Lakshmipur, Noakhali, Feni is

geomorphologically most active land formation process making a new shape of land

features. These areas are facing a lot of natural hazards that is salinity intrusion,

cyclones, and tidal surges, floods almost every year (Ahmed, 2011). People living in

different coastal areas have been suffering from lack of food security. There are many

reasons behind that such as lower crop productivity and less fertility in soil due to

increased salinity, increased cropping intensity, increased incidences of pests and

diseases, erratic rainfall, higher temperature, drought, tidal surges, cyclone,

submergence, large fallow lands/water bodies, land degradation, poor road network,

poor marketing facilities and unemployment with long-term cumulative effects of

soil-related constraints, climate risks and socio-economic problems (Miah, 2010).

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2.1.1. Population Pressure in Coastal Areas

This coastal area represents an area of 47,211 km2, 32 percent of the country’s

geographical area, wherein 35 million people i.e. 28 percent of the country’s total

population live at 6.85 million households (Population census in 2001). In terms of

administrative consideration, 19 districts out of 64 are considered as coastal district. A

study of IPPC reveals that 20 percent and 40 percent of the world population live

within 30 kilometers and 100 kilometers of the coast respectively, which is very true

in regards to Bangladesh’s perspective (Inter Governmental Panel of Climate Change,

2001). Again, population growth rate in the coastal areas is higher than the national

average. In between 1991- 2001 the average population growth rate was 1.29, if so

continued then by 2020 the coastal population will be 44 million, more people will be

landless, and more people will be city bounded for livelihood earning. Official

poverty indicators show a slightly higher percentage of the population living below

the absolute poverty line in the coastal zone compared to the country as a whole (52

percent vs. 49 percent), while the GDP per capita and the annual GDP growth rates in

the coastal zone are more or less similar to the national averages(Ahmad, 2005).

Urban population in Bangladesh has increased at an annual exponential rate of 6.1

percent during the inter-census period of last forty years (1961-2001). Urban

population growth has been slightly lower in the coastal zone with annual growth rate

of 5.9 percent. With the increasing population, land is being converted from

productive purposes, such as crop cultivation, to other uses. Bangladesh is losing

good quality agricultural land by approximately 80,000 ha annually to urbanization,

building of new infrastructure and implementation of other development projects

(World Bank, 2005).

Table 2.1. Population growth trend in the coastal area

Year Population(million) Urban

population

(%) Coastal

rural

Costal

urban

Total

2001 27 8 35 23

2010 25 14 39 36

2020 22 22 44 50

(Source: Coastal livelihoods, ICZM, 2003)

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2.1.2. Cultivable Land in Coastal Areas

The coastal area covers about 20% of the country and over thirty percent of the net

cultivable area. It extends inside up to 150 km from the coast. Out of 2.85 million

hectares of the coastal and offshore areas about 0.83 million hectares are arable lands,

which cover over 30% of the total cultivable lands of Bangladesh. A part of the

coastal area, the Sundarbans, is a reserve natural mangrove forest covering about

4,500 km2. The remaining part of the coastal area is used in agriculture. The

cultivable areas in coastal districts are affected with varying degrees of soil salinity.

The coastal and offshore area of Bangladesh includes tidal, estuaries and river

floodplains in the south along the Bay of Bengal. Agricultural land use in these areas

is very poor, which is roughly 50% of the country’s average (Petersen and Shireen,

2001). Observations in the recent past indicated that due to increasing degree of

salinity of some areas and expansion of salt affected area as a cause of further

intrusion of saline water, normal crop production becomes more restricted. In general,

soil salinity is believed to be mainly responsible for low land use as well as cropping

intensity in the area. Salinity in the country received very little attention in the past.

Increased pressure of growing population demand more food. Thus it has become

increasingly important to explore the possibilities of increasing the potential of these

(saline) lands for increased production of crops (Haque, 2006).

2.2. Cropping Pattern and Cropping Intensity in Bangladesh

Physiographically, Bangladesh has three categories of lands: floodplains (80%),

terraces (8%) and hills (12%). Crop cultivation is intense in floodplain soils. At

present, rice covers about 79.4 percent of cultivated land. Area coverage by other

crops is: pulses (4.64%), wheat (3.92%), oilseeds (3.77%), jute (3.71%), sugarcane

(1.23%), potato (1.11%), fruits (0.84%) and vegetables (1.39%) (Fig. 2.1) This

production system dominated by a single crop (i.e. rice) is neither scientific nor

acceptable from the economic point of view. It is therefore necessary to increase the

cultivation and production of other crops. However, considering the increasing

demand for food grains and with a view to ensuring food security (forecast for 2012),

production of rice will continue to have priority in the food grain production

programmes (Roy and Farid, 2011). Rice production systems make a vital

contribution to the reduction of hunger and poverty in Bangladesh. Total rice

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production in Bangladesh was 10.32 million tons in the year 1975-76 when the

country's population was only 79.90 millions and cultivated rice area was 10.32

million ha (DAE, 2007). However, the country is producing 34.28 million tons rice in

the year of 2008-09, where Boro rice contributed more than 55% (18.5 million tons).

From the analysis of the last few years’ data we found that its contribution in total rice

production follows an increasing trend.

Fig. 2.1. Land coverage status of major crops in Bangladesh

(Source: Roy and Farid, 2011)

Recently, the rate is increasing rapidly due to adoption of high yielding rice varieties,

including modern rice cultivation technologies, improvement irrigation facilities and

applications of fertilizer and pesticides. It has been broadly divided into three classes

viz, aman (transplanted and broadcast varieties), boro, and aush according to the

season in which they are harvested, namely, in December-January, March-May and

July-August respectively. Again, of these varieties transplanted aman is the most

important and covers about 46.30% of the paddy area, followed by boro (26.85%),

aus (17.59%) and broadcast aman (9.26%) (Fig 2.2) (Basak, 2010).

Fig. 2.2. Acreage of different types of rice cultivated in Bangladesh

(Source: BBS, 2008)

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Crops that are grown on less than one per cent of the gross cropped area (GCA) of a

country are considered minor crops. In Bangladesh gram, millets and maize, onion,

black gram, sweet potato, groundnut, green pea, sesame, linseed, garlic, pea and

barley, etc. are usually considered as minor crops (Fig. 2.3) In addition some crops,

including certain vegetables, spices, etc. occupy a very insignificant proportion of the

GCA (i.e., less than 0.10 per cent to each crop), and they account for 1.57 per cent

altogether (Mainuddin et al., 2011).

Fig. 2.3. Land used under minor crops in Bangladesh

(Source: BBS, 2008)

A spatial and temporal arrangement of crops within a cropping year is largely

determined by physical, biological, and socio-economic factors. There are three

cropping seasons (Rabi, Kharif-I or Pre-Kharif, and Kharif-II) during a year in

Bangladesh (Banglapedia, 2006a). The major cropping pattern in Bangladesh

agriculture mostly consists of rice based cereal crops. More than 60% of the total

cropped area covered by Boro-T. aman rice cropping patterns in Bangladesh (FRG,

1997). Rice is grown in three seasons. Aman, grown during July/August to

December/ January, is part rain-fed (during early part of growth) and part dry season

crop (during flowering and harvest time). This is followed by boro, grown at present

under irrigated conditions during the laargely dry period from February/March to

April/May. Aus are grown in rainfed conditions; it falls in between boro and aman

season but may overlap with both. This means that the longer-duration varieties of

rice do not allow for more than two rice crops per season on the same land, although

other crops may be grown, depending on duration of the crop and other agronomic

factors. The growth in rice output over the last quarter of a century has been

characterized by increasing reliance on irrigated boro cultivation, using fertilizer-

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intensive high-yielding varieties (HYVs). Boro rice now accounts for the bulk of rice

grown in the country (Asaduzzaman et al., 2010).

Table 2.2. Some dominant cropping patterns under variable crop production

environments

Rabi Kharif-I Kharif-II

Rainfed

condition

Wheat/Potato/Pulses/Oilseeds/Sugarcane Boro Aus/Jute Fallow

Irrigated

condition

Wheat/Boro/Wheat/Potato/ Tobacco/Vegetables Fallow T. Aus T.Aman

Fallow

(Source: Banglapedia, 2006a)

Depending on the land type, soil characteristics, and water availability, rice cropping

may be single, double, or triple. In general, double or triple rice cropping is practised

in high land areas. In medium lowlands, mixed cropping of Aus and broadcast Aman

is a common practice, while in deeply flooded lands, single cropping of broadcast

Aman (deepwater rice) in Kharif, or Boro in Rabi, is the common practice. Non-rice

crops are generally grown as a sequential or intercrop with rice. Most non-rice crops

are dryland crops, although some crops like jute (Deshi type), millets (Kaon), and

sugarcane can tolerate some degree of submergence at later stages of growth. Jute is

grown in the Kharif-I season, competes with Boro Aus for land, and is considered a

substitute crop for Boro Aus in cropping patterns. The dry (Rabi) season crops

included in cropping patterns may be early, middle, or late, depending upon land

types, recessions of floods, and dates of harvests of the preceding crops (Basak,

2010).

A change in cropping pattern thus implies a change in the proportion of area under

different crops. The cropping pattern in an area depends largely on agro-climatic,

technical and institutional factors (Vaidyanathan, 1987). The change of cropping

pattern is basically the results of the adoption of new crops and the intensification of

cultivation through multiple cropping. More precisely, changing in cropping pattern

over time are also function of changes in the extent and quality of irrigation and the

relative costs of and returns to competing crops and crop combinations (ghosh, 2011).

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Cropping intensity, defined as the ratio of gross temporary cropped area to net

temporary cropped area per annum. Intensity of cropping represents the ratio of the

gross cropped area to the net temporary cropped area expressed in terms of

percentage. It indicates the extent to which the same area is used for cropping

(Ahmed, 1992).

Cropping intensities were calculated by the following formula as suggested by Sing (2004).

Intensity of cropping = X 100

Calculating cropping intensity

• Step1. Assign a number to each crop in the rotation based on its

crop type.

0 = summer fallow

1 = cool season crops (wheat, canola, lentil)

1 = short season crops (millet, green fallow)

1 = full season crops (corn, sunflower, sorghum, soybean)

• Step 2. Add the intensity values for all crops in the rotation and

divide by the number of years in the rotation to obtain an intensity

rating (Table 2.2)

Table 2.3. Cropping intensity rating

Examples of Cropping Intensity Rating

Rotation Rating Wheat-fallow 0.5 Wheat-corn-fallow 1.0 Wheat-corn-millet-fallow 1.0 Wheat-corn-pea 1.33 Springwheat-winter wheat-corn-sunflower 1.5 Spring wheat-corn-soybean 1.67 Corn-soybean 2.0 Winter wheat-sorghum-corn-soybean 2.33

(Source: Beck et al., 1998).

Total cropped area

Net cultivated area

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Bangladesh faces formidable challenges to feed its population in the future from an

increasingly vanishing and degraded natural resource base for agriculture. The

agriculture is still an important segment of the country’s economy though the

contribution of broad agriculture sector in 2005-06 to GDP was 21.84%. Crops and

vegetables accounted for about 12% of GDP. About 52 percent of the total labor

forces of the country are engaged in agriculture (MOF, 2007). To feed the growing

population of Bangladesh (at the rate 1.59% per year) increased agriculture

production especially staple cereal rice is a must. In the year 2006-07, the staple

cereal rice was grown in 11.30 million hectare. HYV (High Yield Variety) rice was

produced on 8.50 million hectare. Of the total cropped area, 14.11 million hectares in

2004-05, the net cropped area was7.98 million hectare giving a cropping intensity of

1.77% (MOI, 2008). The Department of Agriculture Extension (DAE) claims that the

current cropping intensity is 195%.

Table 2.4. Last 10 years cropping intensity of Bangladesh

Year Total Land Area of the Country

Net Cultivable Land

% of Net Cultivable Land in Terms of Total Area

Net Area Sown

Total Cropped Area

Cropping Intensity (%)

2000-01 14.85 8.40 56.57 8.08 14.30 176.98

2001-02 14.84 8.48 57.14 8.08 14.30 176.98

2002-03 14.84 8.42 56.74 8.04 14.17 176.24

2003-04 14.84 8.40 56.60 8.03 14.23 177.21

2004-05 14.84 8.44 56.87 7.97 14.10 176.91

2005-06 14.85 8.29 55.82 8.03 14.20 180.00

2006-07 14.45 8.29 57.37 8.03 14.20 180.00

2007-08 14.85 9.09 61.21 8.23 16.50 179.00

2008-09 14.85 9.09 61.21 7.77 13.88 179.00

2009-10 14.85 9.23 62.15 7.69 13.91 180.88

(Source: BBS, 2010)

24

Bangladesh has made a remarkable progress in the last three decades towards

achieving self sufficiency in food grains due to substantial intensification of cropping,

introduction of high yielding crop varieties, and expansion of irrigated areas and

increased use of chemical fertilizers. Among the factors, contribution of fertilizers

leading to increased production is about 50 percent. But recently, declining or

stagnation of major crop yields have been recorded due to cumulative effects of many

soil-related constraints and climatic risks viz. depletion of soil organic matter,

imbalanced use of fertilizers, nutrient mining, degradation of soil physical and

chemical properties, erratic rainfall, temperature rise, droughts, floods, soil salinity,

water salinity, tidal surges, water-logging, cyclone, scanty use of bio and organic

fertilizers and poor management practices. The proportion of different nutrients used

in agriculture without soil testing in recent years is highly deleterious to soil

productivity. Nitrogen alone constitutes about 83 percent of total nutrient use in the

country, while the use of phosphorus and potassium is limited to only about 7.75 and

9.1 percent respectively (Miah, 2010).

2.2.1. Cropping Pattern and Cropping Intensity in Kalapara

Major crop cultivation in Kalapara is Transplant Aman (T- aman), Boro, potato and

vegetables. Sesame, linseed, sugarcane, kaon are extinct or nearly extinct crops of the

study area. Gher farming is done in some different land and also in some T-Aman

cropland. T-Aman is mainly the cultivated in the Kharif-2 season. At present, about

100% cropland is used for T- aman cultivation (Banglapedia, 2006).

The cropping pattern T. Aman – Fallow – Fallow has the highest coverage in the

Kalapara upazila. Some areas were cultivated for production of high yielding

varieties during Boro season, where the irrigation facilities were available either from

surface water or groundwater sources. The Boro area could be expanded by

introducing salt tolerant Boro Variety BRRI Dhan 47, where the water salinity ranges

upto 8 dS/m. Pulse followed by T. Aman pattern dominated in Kalapara upazila. The

highest cropping intensity of 199% was observed in Kalapara upazila followed by

other coastal upazilas (Bala and Hossain, 2009).

25

Table 2.5. Major cropping patterns and cropping intensity in of kalapara

upazila (2008)

Major cropping pattern % Coverage Cropping intensity (%)

T. Aman – Fallow – Fallow T. Aman – Khesari – Fallow/ T. Aus T. Aman – Mung – Fallow/ T. Aus T. Aman – Fallow – Aus T. Aman – Cowpea – Aus T. Aman – Cowpea – Fallow

27.7 18.9 6.8 13.0 12.7 11.0

199

(Source: Bala and Hossain, 2009)

2.3. Nutrient Status in Soils of Bangladesh

Soil Fertility capability 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. Fertility is the potential

nutrient status of a soil to produce crops. Soil productivity is a measure of the soils

ability to produce a particular crop or sequence of crops under a specified

management system (Banglapedia, 2006).

Nutrient status depends on nutrient balance of soil. Nutrient Balance is the sum of

nutrients inputs minus the sum of nutrients outputs; the balance may be positive or

negative. Positive balance indicates nutrient accumulation and negative balance shows

nutrient depletion (mining). To achieve sustainability, the quantity of nutrients inputs

and outputs could be equal. Nutrient mining may eventually cause soil degradation

and affect crop production. On the other hand, excess nutrient accumulation may lead

to soil and water pollution (BARC, 2005).

Input = Output: Sustainable system

Input > Output: Plant nutrient build-up/ Soil fertility increase. This may in Extreme

cases eventually lead to soil and water pollution.

Input < Output: Nutrient depletion or “nutrient mining”. May lead to serious soil

degradation.

In calculating nutrient balance, fertilizer, manure, BNF, deposition (rain),

sedimentation (flood) and irrigation water can be regarded as nutrients inputs, and the

crop produce, crop residues, leaching, gaseous losses (leaching and denitrification)

26

and soil erosion as nutrients outputs (Fig. 2.4 ) Hence, these major inputs and outputs

can be considered for calculating nutrient balance to understand partial or apparent

nutrient balance. Although the nutrient balance value tells us little about available

nutrient status of soils, it has important implications when considering the future long-

term total status of nutrients in soils. Nutrient balance values varied with locations,

cropping systems and nutrient management practices (BARC, 2005).

Fig. 2.4. Nutrient input-output system

(Source: FRG, 2005)

The role of macro and micronutrients is crucial in crop nutrition and thus important

for achieving higher yields. Nitrogen (N), phosphorus (P) and potassium (K), being

primary essential nutrient, have prime importance in crop nutrition (Raun and

Johnson, 1999). Bangladesh has wide variety and complexity of soils at short

distances due to a diverse nature of physiography, parent materials, lands, and

hydrology and drainage conditions. Due to intensive cropping to grow more food,

continuous changes are taking place in the soil fertility status due to organic matter

depletion, nutrient deficiencies, drainage impedance/water logging followed by

degradation of soil physical and chemical properties as well as soil salinity/acidity.

The fertility status of Bangladesh soils is extremely variable (Kafiluddin, 2008).

2.3.1. Nitrogen

Nitrogen is generally considered as the key nutrient in Bangladesh agriculture because

of its low supply in the soils. Portch and Islam (1984) reported that 100% of

27

Bangladesh soils studied contained available N below critical level. Most of the

agricultural soils are critically deficient in this nutrient.

The main reasons for such deficiency are due to:

- Intense decomposition of organic matter

- Rapid removal of mineralized products under high leaching conditions and

- crop removal.

Total nitrogen content of Bangladesh soils range from 0.032% in the Shallow Red-

Brown Terrace Soils to 0.20% in Peat Soils. For wetland rice, soil test values for

nitrogen interpreted as low, medium and optimum are 0.090-0.180, 0.181-0.271 and

0.271- 0.360%, respectively (Kafiluddin, 2008).

2.3.2. Phosphorus

Phosphorus is recognized as an important mineral element limiting crop growth and

production (Batten et al., 1984). It is generally considered as the second most limiting

nutrient after N for plant growth (Vance, 2001). The available P in Bangladesh soils

could be considered to be between low and medium. About 20.7% areas were

reported to be predominantly low in available P and 21.2% were medium in available

P which is limiting crop production. Therefore, one of the adverse effects in

agriculture practice in Bangladesh is phosphorus deficiency. Plants cannot live at

phosphate concentration below two parts per ten million in soil solution (Nautiyal et

al., 2000). For wetland rice, soil P contents of 6.0-12.0 μg g-1soil are considered as

low, 12.1-18.0 μg g-1 soil as medium and 18.0-24.0 μg g-1 soil as optimum. The

critical level of P by the Olsen method, which is extensively used for rice, has been

considered as 8.0 μg g-1soil in Bangladesh so long (Kafiluddin, 2008).

2.3.3. Potassium

Potassium is the seventh most common element in the Earth’s crust and is essential

for plant growth. Potassium, along with N and P, are the three major macronutrients

contributing to many functions in plants. The essentiality of this macronutrient was

known after Von Liebig’s published work in 1840 (Sparks, 2000). Potassium is one of

the major nutrients and absorbed in large quantities by crops. Intensive cropping with

modern rice varieties is responsible for increasing the K deficiency in soil (Tiwari,

28

1985). Most of the north-western parts of Bangladesh are deficient in potassium

(BARC, 2005). The critical levels of potassium for Bangladesh soils have been

determined 0.09-0.18 meq/100g soil as low, 0.18-0.27 meq/100g as medium, 0.27-

0.36 meq/100 g as optimum and above 0.36 meq/100 g high (Kafiluddin, 2008).

Regmi et al. 2002 reported that depletion of soil K and inadequate K fertilization

seem to be the primary reason of limiting and declining yield of the first rice and

wheat crop. Shah et al. 2008 reported that continuous omission of K in fertilizer

schedule for 23 yrs resulted in about 41% reduction of Boro rice yield over 100%

NPKSZn fertilization. The general recommended dose of K fertilizer for MV rice in

Bangladesh only around 35-40 kg K/ha (BARC, 1997), while an average rice yield

(4.0 t/ha) removes at least 70 kg K/ha from the soil. This level of K fertilization may

not be adequate for sustaining favorable K status of the soil in the long run.

2.3.4. Sulphur

Sulfur (S) deficiency has been recognized as a constraint on crop production all over

the world (Eriksen et al., 2004; Girma et al., 2005; Schonhof et al., 2007; Mascagni et

al., 2008) becoming a limiting factor to higher yields and fertilizer efficiency. Sulphur

has been recognized as the fourth major nutrient limiting crop production as early as

1980. In the past very little attention was paid to this nutrient until 1977 when sulphur

deficiency in wetland rice was first detected at the Bangladesh Rice Research Institute

(BRRI) farm and on nearby farmers’ fields (Kafiluddin, 2008). The main reasons are

the reduction of sulfur dioxide emission from power plants and various industrial

sources, the increasing use of high analysis low-S-containing fertilizers, the

decreasing use of S-containing fungicides and pesticides and high-yielding varieties

(Scherer, 2001; Eriksen et al., 2004). Until recently little attention has been given to

the problem of sulfur deficiency in soils. Intensive cropping has been resulting higher

removal of sulfur among the other nutrients rather its replenishment under natural

process (Balsa et al., 1996). In Bangladesh about 7 M ha (about 52%) of agricultural

lands are reported to consists of sulfur deficient soils in the Northern region of

Bangladesh (SRDI, 1999). The current intensive use of agricultural land for crop

production has extended the sulfur deficient areas to about 80% (Khan et al., 2007).

The critical level of sulphur for Bangladesh soils has been determined as 10 μg g-1

soil (Kafiluddin, 2008).

29

2.3.5. Zinc

The importance of zinc in crop nutrition has received considerable attention during

eighties in Bangladesh. This element deficiency has arisen in Bangladesh mainly due

to continuous mining of soil nutrients for increase cropping intensity (180% at

present). The availability of Zn in the soil varies widely depending on the soil

properties. The calcareous soils have low to medium extractable Zn content

(Jahiruddin and Islam, 1999). Zinc deficiency, together with sulphur deficiency, are

recognized as limiting factors in crop production in Bangladesh. About 1.75 Mha of

intensively cropped land are estimated to be affected by zinc deficiency, which

mainly affects rice and wheat (Ahsan and Beuter, 2000).

The incidence of zinc deficiency is widespread in most calcareous and alkaline soils.

The problem is more acute in wetland rice culture. The critical levels of available soil

zinc content as established by different extracting procedures are 1 ppm for light

textured soils and 2 ppm for heavy and calcareous soils. The critical level of Zn in

rice plant tissue is generally considered as 20 ppm. Yield responses of rice to zinc

fertilization have been well documented in different soils of Bangladesh where zinc

contents were below the critical level (Kafiluddin, 2008).

2.3.6. Calcium and Magnesium

The pH values of Bangladesh soils generally range between 5.8 and 7.0 with

exception observed in acid hill soils and calcareous soils. Thus, most of our soils have

adequate Ca and Mg saturation on the exchange surface. Recent investigations have

reflected that acid hill soils and Old Himalayan piedmont soils are extremely low in

exchangeable Ca and Mg. The critical levels for these two nutrients are as 2.00 and

0.5 meq100g -1 (Kafiluddin, 2008).

2.3.7. Boron

Although taken up in tiny quantities, boron deficiency may lead to serious

consequences regarding economic yield of various crops. Boron deficiency in

Bangladesh was first observed in reverine soils of Teesta on wheat causing sterility in

grains (Islam, 2006). Light textured soils of the country are deficient in available

boron where significant leaching loss of borate ions might have depleted soil boron

level. The available boron content of the major soils of Bangladesh varies between 0.1

and 1.9 ppm. But most of the light textured soils of Rangpur, Dinajpur and terrace

30

soils of Gazipur and hill soils of Srimangal contain low level of available B (0.1-0.3

ppm). The critical level of available soil boron used to interpret the soil test result is

0.2 ppm (Kafiluddin, 2008).

2.3.8. Other Micronutrients

Intensive cropping, imbalanced fertilization and no use of micronutrients, less or no

use of organic manures resulting the depletion of soil fertility in Bangladesh.

Consequently, micronutrients statuses have been decreasing day by day and finally

fertility status of Bangladesh soils have been declining. Micronutrients like Fe, Mn,

Cu, Mo and Cl have attracted less attention in Bangladesh agriculture. Generally they

are seldom needed to be applied in crop production in most soils. However, recently

Cu and Mn application in Calcareous Soils have appeared to be beneficial for higher

yield in some field trials. Recent studies have also indicated that Mo deficiency is

widespread in cabbage and legumes like groundnut acid soils. Appreciable yield

increases of these crops in presence of added molybdenum have also been recorded

(Kafiluddin, 2008).

2.4. Nutrient Status of Kalapara Upazila

This region occupies an extensive area of tidal floodplain land in the south-west of the

country. The greater part of this region has smooth relief having large areas of

salinity. There is a general pattern of grey, slightly calcareous, heavy soils on river

banks and grey to dark grey, non calcareous, heavy silty clays in the extensive basins.

Non calcareous Grey Floodplain soil is the major component of General Soil Types.

Acid sulphate soils also occupy significant part of the area where it is extremely

acidic during dry season. In general, most of the topsoils are acidic and subsoils are

neutral to mildly alkaline. Soils of the Sundarbans area are alkaline. General fertility

level is high with medium to high organic matter content and very high CEC and K

status but have limitations of high exchangeable Na and low Ca/Mg ratio. The Zn

status is low to medium and the B and S status is high (BARC, 2005).

31

Table 2.6. Nutrient status of ganges tidal floodplain

Major

Land

type

Soil

pH

Soil

OM

Nutrient status

N P K S Ca Mg Zn B Mo

Medium

Highland

(78%)

4.2-

8.1

L-M VL-

L

VL-L Opt-H Opt-

H

Opt-H Opt-

H

L-M Opt-

H

Opt

(Source: FRG, 2005)

Average Height of Kalapara upazila, in the northern edge is about 2m and in the

south is about lm high from mean sea level. But the maximum height is 6m. This area

lies in the southwestern part of Bangladesh and downstream of the well known

Ganges deltaic region. The area comprises a flat land with natural ground slopes are

found. Kalapara Upazila is a Ganges Floodplain (SRDI, 2001a). In Kalapara Upazila

most of the soil types are present deposits. In this region, pH varies from7.5-4.9. The

color of the soil is light grey, grey and black. The soil salinity varies from Moderate to

nil; (EC 0.37 to 15.2 dS m-1). The study areas are mainly located in Medium High

land. Here soil is rich in Calcium, Magnesium, Boron, Copper, and Sulphate and

moderately high in Manganese, Zinc and lower concentration of Phosphorus, Iron,

and Nitrogen (SRDI, 2001).

Table 2.7. Nutrient status of Kalapara Upazila

Depth Horizon pH Macro nutrient Micro nutrient

N% P S K Mg/100 Gm soil

Cu Fe B Mn Zn

Mg/L Mg/L 0-11 Ap1 5.6 0.09 1.90 67.0 0.07 5.82 180.0 0.92 12.1 0.68

0-17 Ap2 5.8 0.12 1.69 71.0 0.05 5.08 160.0 0.88 9.9 0.56

17-41 Ap3 7.9 0.09 0.96 24.0 0.17 1.72 11.0 1.44 2.3 0.16

41-79 Ap4 8.1 0.08 0.98 44.0 0.12 0.70 7.0 1.41 1.9 0.22

79-130

Ap5 8.3 0.06 0.75 38.0 0.11 0.64 8.0 1.46 1.6 0.22

(Source: SRDI, 2009)

2.5. Cropping Intensity and Its Effect on Nutrient Status Cropping intensity and sequencing have significant effects on soil structure or soil

tilth (Elliott, 1986). The intensive cropping systems introduced by the Green

32

Revolution impose much heavier demands on crop nutrients than traditional systems

had; nutrient deficiencies, therefore, a common problem. Intensive agricultural

practices can also result in changes in soil physical and chemical properties (Dey and

Haq, 2009). With rising cropping intensities in South Asia, nutrient management is a

major issue being addressed by agricultural scientists for understanding any decline in

yields. Many long-term fertility experiments established in the region decades ago

show no evidence of yield decline at the farmers’ field level (Abrol, et al., 1997).

Conventional tillage with intensive soil disturbance promotes rapid decrease of soil

organic matter and subsequent CO2 emission increase. A chemical, physical and

biological soil degradation process then develops, negatively affecting crop

productivity. Tillage is the principal agent producing soil disturbance and subsequent

soil structure modification, increasing potential soil organic matter loss by erosion and

biological decomposition (Langdale et al., 1992; Carter et al., 1994). Quantitatively,

the latter is thought to be the primary source of organic matter loss triggered by soil

tillage (Rasmussen et al., 1998).

Nitrogen, P, K, S and Zn, of which three major elements are most important both in

the terms of the extent of their deficiencies in the soils, and in terms of their potentials

for crop yield increases or losses. Nitrogen is the nutrient element limiting growth in

most of the rice soils (Savant and Datta, 1982), and there have been indications that

many rice soils of Bangladesh are becoming deficient in P, K, S and Zn (BARC,

2005). The decline in productivity of rice and wheat with continuous cropping was

related to deficiency of P, K, S, Zn and imbalanced nutrition (Kumar and Yadav,

2005).

Nitrogen is the most limiting nutrient in crop production all over the world. Nitrogen

deficiency occurs everywhere in Bangladesh. Understanding the behavior of N in soil

is essential for maximizing crop productivity and profitability on one hand and for

reducing the possible negative impact of N fertilization on the environment on the

other hand. The loss of N from the soil is mainly due to crop removal and leaching

(FRG, 2005). Phosphorus does not occur as abundantly in soils as N and K. Although

the total concentration of P in the soil varies between 0.02 and 0.10%, it has no

relationship with the availability of P to plants. The average concentration of P in soil

solution is about 0.05 ppm which varies widely among soils while the level of

organically bound P varies between a few ppm and 1000 ppm (FRG, 2005).

Phosphorus is removed or lost from the soil by: 1) crop uptake and removal; 2) runoff

33

and erosion and 3) leaching. Harvested crops remove phosphorus from the soil and

the farm. Phosphorus concentrations in plant tissues typically range from 0.1 to 0.5%

on a dry weight basis and most crops utilize or take up between 20 and 90 pounds of

P2O5 each year. Since soils are constantly subjected to changes due to the effects of

cropping practices, it is impossible to totally eliminate phosphorus losses from soil.

Water moving across the surface or through soils can remove both soluble (dissolved)

and particulate (eroded soil particles) forms of soil phosphorus. Phosphorus can also

loss by leaching (Mullin, 2009).

Potassium (K+) is an essential element for plant growth and development and is the

most abundant cation in plants, making up 3–5% of a plant’s total dry weight. Run-off

of drainage water and migration of elements and matter depends on the amount of

precipitation and cropping intensity. However, the results of a comparison of organic

and intensive cropping systems showed that cropping intensity had no influence on

potassium concentration in drainage and groundwater (Guzys, 2001). The balance of

potassium in both cropping systems was negative and the average amounts of K+

leached were 3.5-3.8 kg. Micronutrient S and Zn deficiencies in particular have an

adverse effect on yields, a common problem in intensive rice production, because

conditions in flooded paddies have a strong negative effect on their availability (Day

and Haq, 2009).

Rapid decline of Soil fertility is a problem of crop production in Bangladesh. Soil

fertility is a dynamic property which varies with crops, cropping intensity and input

use. More than 50% of our cultivated soil contains organic matter below the critical

level (1.5%). Annual depletion of plant nutrients in the intensively cropped area

ranges from 180 to more than 250 kg/ha. High and medium high land comprises 60%

of total cultivated land which is in most cases deficient in essential nutrients such as

nitrogen, phosphorus, potassium and Sulphur. The low organic matter content, higher

cropping intensity, improper cropping sequence and faulty management practices are

the major causes of depletion of soil fertility. Imbalance use of fertilizer is another

serious problem for the country. Nutrients present in soil, added as inorganic and

organic sources and the nutrient harvested by crops should be considered to develop a

cropping pattern based fertilizer recommendation. Available data indicate that the soil

fertility in Bangladesh is declining trend (Karim et al, 1994; Ali et al, 1997) which is

responsible for declining crop yields (Cassman et al, 1995).

34

About 60% of arable lands of Bangladesh are deficient in N, P, and K. Organic matter

content of soils is much below the critical level of 1.5%. Imbalance use of fertilizers,

unplanned cultivation and improper management of soil have already caused not only

stagnation but also declined in productivity of modern varieties. Intensive and

continuous rice-based crop culture, replacement of local rice varieties by modern

ones, decreasing jute cultivation, increasing adoption of power tillers for tillage

operations and increasing use of dung and organic waste as fuel have been negatively

affecting the status of soil organic matter. Increased cropping intensity and sustained

productivity of the soil are the important options to achieve self-sufficiency in food.

Sharp declining in soil fertility is a threat for sustainable crop production (Kashem et

al., 2007). In irrigated rice, the formation of a plowpan is a frequent problem,

impeding root growth and limiting access to nutrients. Irrigation can also cause

salinization or water-logging. The yield declines observed in the IRRI long-term

cropping trials are thought to result from anaerobic conditions in irrigated rice

production leading to changes in soil physical and chemical properties which make it

less able to supply nutrients to growing crops (Dey and Haq, 2009).

Depletion of soil fertility is mainly due to exploitation of land without proper

replenishment of plant nutrients. The problem is enhanced by intensive land use

without appropriate soil management. The situation is worse in areas where HYV

crops are being grown using low to unbalanced doses of mineral fertilizers, with little

or no organic recycling. Because of increasing cropping intensity (presently 198%)

and cultivation of modern varieties of crops, the net removal of plant nutrients is far

from the nutrient supply through fertilizers and manures. Nitrogen status in this

country’s soils resembles the results of SOM (Jahiriddin and Satter, 2010).

Ali et al. (1997) reported that the total carbon content on an average decreased by

11%, the total N by 12%, pH decreased by 4% and the exchangeable acidity increased

by 30%. The exchangeable K content in soil decreased by 31% and available P

showed a 9% decrease over 27 years (1967-1995). The annual removal of nutrients

from soil is higher compared to their addition. From an extensive review, Rijmpa and

Jahiruddin (2004) reported that the overall N balances of Bangladesh soil were

negative (-10 to –100 kg N ha-1

yr-1

depending on the nutrient management and

cropping systems), the P balances were near zero and the K balances were highly

negative (-100 to –225 kg ha-1

yr-1

) (Fig. 2.5).

35

Fig. 2.5. N + P + K inpute – outpute in Bangladesh

(Source: Jahiruddin and Satter, 2010)

Six mineral elements such as N, P, K, S, Zn and B are commonly deficient in

Bangladesh soils. Of them, nitrogen is the most limiting nutrient in Bangladesh

agriculture. Until 1980, deficiencies of three nutrients viz. N, P and K were identified

in Bangladesh soils. In early 1980s, S and Zn deficiencies in rice were observed. In

early 1990’s, the B deficiency of some crops was reported. There is sporadic

information of Cu, Mo and Mn deficiencies in crops. Deficiencies of Fe and Cl are

not yet reported in this country. Magnesium is reported to be deficient in Old

Himalayan Piedmont Plain and Tista Floodplain soils (Table 2.7) (Ferdoush et al.,

2003).

Table 2.8. Emergence of new nutrient deficiency with time

?

Mg Mg

B B B

Zn Zn Zn Zn

K K K K K K

P P P P P P P

N N N N N N N N

1951 1957 1960 1980 1982 1995 2000 2011

(Source: Jahiruddin and Satter, 2010)

36

2.6. Soil Salinity

Salinity is a major environmental constraint for crop production throughout the world

(Ashraf, 2004; Flowers, 2004; Munns et al., 2006). Salt-affected soils occupy more

than 7% of the earth land surface (Munns et al., 2006; FAO, 2008). Reduction in the

osmotic potential and toxic effect of excessive Na+ or Cl- on the plasma membrane

are the direct effects of salts on plant growth that reduce the availability of water to

plants. Now it is well known that salt stress causes a number of effects on plants such

as osmotic effects, ion toxicity, hormonal imbalance, generation of reactive oxygen

species and nutritional imbalance (Ashraf, 2004; Flowers and Flowers, 2005). Soil

salinity is a widespread problem, restricting plant growth and biomass production

especially in arid, semi-arid and tropical areas (Apse et al., 1999). On a global basis,

salt affected soils occupy an estimated 952.2 M ha of land, constituting nearly seven

per cent of total land area or nearly 33 per cent of the area of potential arable lands of

the world (Gupta and Abrol, 1990). Bangladesh covers more than 30% of the

cultivable lands of the country. About 53% of the coastal areas are affected by salinity

(Haque, 2006). Out of 2.86 Mha of coastal and offshore lands about 1.056 Mha of

lands are affected by different degrees of salinity. Out of 151 Upazilas (sub-districts)

in 19 districts coastal 93 Upazilas under 18 districts are affected by salinity. As the

cropping intensity and crop yields are well below the country average, the

contribution to agriculture sector is not proportional to its land mass. The reason

behind this is unfavourable agroecological conditions of the region. These include

coastal flooding in the monsoon, higher levels of soil salinity in the winter and higher

water salinity in winter reduces its potential for irrigation (Hussain, 2010).

2.6.1. Present Soil Salinity Status in Coastal Area

A direct consequence of sea level rise would be intrusion of salinity with tide through

the rivers and estuaries. It would be more acute in the dry season, especially when

freshwater flows from rivers would diminish. According to an estimate of the Master

Plan Organization, about 14,000km2 of coastal and offshore areas have saline soils

and are susceptible to tidal flooding. If some 16,000 sq km2 of coastal land is lost due

to a 45cm rise in sea level, the salinity front would be pushed further inland. The

present interface between freshwater and saline water lies around 120 to 160km

inland in the southwest, and this could well be pushed northward as far as central

Jessore region in the event of a sea level rise . Increase in salinity intrusion and

37

increase in soil salinity will have serious negative impacts on agriculture (Uddin et

al., 2011). In the winter months the areas suffer due to salinity related problems. In

absence of appreciable rainfall the soil in the coastal areas starts to desiccate, and

because of capillary actions salt comes up at the surface of the soil and accumulates in

the root zones of crops. Many of the crop varieties are not tolerant to salinity, and as a

result, a large area in the coastal districts becomes virtually unsuitable for a number of

crops, while the production of a few other crops is lesser under saline conditions.

Most of the land remains fallow in the dry season (January- May) because of soil

salinity, lack of good quality irrigation water and late draining condition. Farmers

cultivate mostly low yielding, traditional rice varieties during wet season. Only about

six percent of the land types in coastal area are highland and 13% medium low land.

The dominant land type in this region is medium highland, which is about 64%

(Hussain, 2010).

A comparative study of soil salinity maps of 1973, 2000 and 2009 shows the extents

of soil salinity intrusion in the coastal region. The map shows that about 0.223 million

ha (26.7%) new land is effected by various degrees of last four decades (Hussain,

2010).

Table 2.9. Extent of soil salinity during about last four decades (1973-2009) in

coastal areas

Yrar Total Salt affected area(‘000’

Salinity class S1 S2 S3 S4

1973 833.45 287.37 426.43 79.75 39.90

2000 1020.75 289.76 307.20 336.58 87.14

2009 1059.19 328.39 274.21 351.68 101.14

Percent increase (+) or decrease (-) during 2000-2009

+ 35.44 +38.63 -32.99 + 15.1 + 14.0

(Source: Ahsan and Sattar , 2010)

It was also found that about 0.0354 million hectares of new land is effected by various

degrees of salinity during last last 9 years only. Some of new land of Patuakhali,

Borguna, Barisal , Jhalakathi , pirojpur, Satkira, Jessore, Gopalgang and Madaripur

38

districts are affected by different degrees of salinity, which reduces agricultural

productivity remarkably (Hussain, 2010).

Table 2.10. Estimation of Salt affected areas (in ‘000’ ha) in Patuakhali

District

Year

Salinity Level* Salinity increase

over 4 decades

Remarks

patuakhali S 1 S2 S3* S4 Area (000’ha)

%

1973 68.50 46.60 0.00 0.00 43.28 37.60 Galachipa, Kalapara, Sadar,

Dashmina

2000 40.11 43.62 46.10 9.52

2009 57.73 39.90 44.98 15.77

(Souce: Miah, 2010)

2.6.2. Effect of Salinity on Fertility Status of Soil

Agriculture is a major sector of more than 30% of the cultivable land in Bangladesh is

in the coastal area. About 1.0 million ha of arable lands are affected by varying

degrees of salinity. Farmers grow mostly low-yielding, traditional rice varieties during

the wet season. Most of the lands remain fallow in the dry season (January–May)

because of soil salinity and the lack of good-quality irrigation water (Karim et al.,

1990; Mondal, 1997).

Nutrient uptake and accumulation by plants is often reduced under saline conditions

as a result of competitive process between the nutrient and a major salt species.

However, this depends on the type of nutrients and composition of soil solution

(Grattan and Grieve 1999, Maas and Grattan 1999, Homaee et al., 2002). Although

plants selectively absorb potassium over sodium, Na+-induced K+ deficiency can

develop on crops under salinity stress by Na+ salt (Maas and Grattan 1999). Research

revealed that salinity inhibits the growth of plants by affecting both water absorption

and biochemical processes such as N and CO2 assimilation and protein biosynthesis.

Under saline conditions plants fail to maintain the required balance of organic and

inorganic constituents leading to suppressed growth and yield (Gunes et al., 1996).

Plant performance, usually expressed as a crop yield, plant biomass or crop quality

(both of vegetative and reproductive organs), may be adversely affected by salinity

induced nutritional disorders. These disorders may be as a result of the effect of

39

salinity on nutrient availability, competitive uptake, transport or partitioning within

the plant (Grattan and Grieve, 1999; Zhu, 2003; Ali et al., 2006; Nasim et al., 2008).

Saline conditions drastically change the environment of root aeration, osmotic

potential of soil solution and normal equilibrium of the dissolved ions. The

availability of most micronutrients to crop plants mainly depend upon the pH of the

soil solution as well as the nature of binding sites on organic and inorganic particle

surfaces. In saline and sodic soils, the solubility of micronutrients (Cu, Mn, Fe, Zn

and Mo) is particularly low, and plants growing on such soils often experience

deficiencies in these elements (Page et al., 1990).

Soil fertility is an important factor for crop production. In general the coastal regions

of Bangladesh are quite low in soil fertility. Thus in addition to salinity, plant

nutrients in soils affect plant growth. Soil reaction values (pH) range from 6.0-8.4

with the exception of Chittagong and Patuakhali, where the pH values range from 5.0-

7.8. Most of the soils are moderate to strongly alkaline, the pH values of the surface

soils being lower than those of the subsurface soils. In places with higher pH values,

micronutrients’ deficiencies are expected (Haque, 2006). The total N contents of the

soils are generally low, mostly around 0.1%. The low N content may be attributed to

low organic matter contents of most of the soils. Available P status of the soils ranges

from 15-25 ppm. Some deficient P soils are also found in Patuakhali, Barguna,

Satkhira and Chttagong districts. Widespread Zn and Cu deficiencies have been

observed in the coastal regions (Karim et al., 1990).

Table 2.11. Agro-chemical characteristics of soils in some of the coastal and offshore

areas (saline belt) of Bangladesh

District pH OM Total

N (%)

CEC

m.e.%

Na

m.e%

K

m.e.%

Ca

m.e.%

Mg

m.e.%

P

ppm

Zn

ppm

Cu

ppm

Satkhira 6.2-8.4 1.8-2.2 0.9-0.3 14.2-25.5 0.5-0.6 0.2-1.2 6.3-16.2 2.8-11.4 12-24 0.1-0.8 0.08-0.30

Khulna 6.2-7.9 0.1-0.3 0.1-0.3 18.2-40.6 1.6-33.3 0.3-1.0 8.3-22.5 2.6-18.3 8-36 Tr-0.8 Tr-0.20

Bagerhat 6.0-7.8 0.3-2.8 0.1-0.2 15.9-37.0 0.6-7.0 0.2-1.0 9.4-24.2 4.2-17.7 6-26 Tr-1.6 Tr-0.40

Patuakali 5.0-7.8 0.1-1.0 - - - 0.2-0.6 2.7-7.5 1.6-6.6 10-28 0.2-0.8 0.06-0.39

Barguna 6.3-8.0 1.2-2.3 0.1-0.1 12.0-22 2.5-21.7 0.2-0.7 11.5-28 3.9-18.2 4-28 0.2-0.8 -

Bhola 6.3-8.0 0.4-7.1 0.1-0.2 11.8-26 0.6-3.4 0.1-0.4 7.2-20.8 2-9.5 4-14 Tr-3.0 Tr-0.70 Chittagong 5.0-7.4 1.0-2.9 - - - 0.2-0.8 2.7-7.1 2.9-11.3 8-30 0.1-0.9 0.3-1.0

Noakhali 6.0-7.5 0.8-3.1 0.1-0.3 9.4-19.5 0.4-39 0.1-0.5 5.3-12.4 2.3-9.5 4-11 Tr-1.8 Tr-0.70

Feni 6.0-7.5 0.9-2.9 0.1-0.2 11.8-16.2 0.8-3.8 0.4-0.5 7.8-8.0 5.0-6.8 8-24 0.9 -

(Source: BARI, 1989)

40

The adverse effects of saline water intrusion will be significant on coastal agriculture

and the availability of fresh water for public and industrial water supply will fall.

Bangladesh’s economy and the coastal area of Bangladesh is very fertile for growing

rice. Increase in salinity intrusion and increase in soil salinity will have serious

negative impacts on agriculture. Presently practiced rice varieties may not be able to

withstand increased salinity. The food production does not seem to have a better

future in the event of a climate change. In Bangladesh, rice production may fall by

10% and wheat by 30% by 2050 (IPCC, 2007). It is very likely that the soil salinity

would increase due to climate change and consequential effects. Increased salinity

would significantly decrease food grain production. Reduction in food grain

production would put additional pressure to the food security of the country

(Habibullah et al., 1999).

41

CHAPTER 3

MATERIALS AND METHODS

42

3. Materials and Methods

Methodology is the guiding framework for researcher, which will be used to contain

and harmonize the scientific investigation. According to the Dictionary of Social

Science, “methodology is the systematic and logical study of the principals guiding

scientific investigation”. For good accomplishment of the research work, a well

arranged methodology is extremely needed. Methodology shows the total procedure

and working plan of the research work. It is divided into three phases:

conceptualization, data collection, and analysis. Methods involve processes or

techniques in which various stages or steps are followed to conduct the research work.

It is a logical as well as systematic part of the study to guide researchers to acquire

necessary data or information and produce logical explanation to resolve the research

goal.

3.1. Conceptualization and Work Plan Preparation

The conception about the cultivable land reduction, cropping intensity and nutrient

depletion was built up through literature review related papers, journals, books,

dissertation papers etc. The work plan about the research that developed goals and

objectives was prepared after achieving clear ideas. It refers to the process that how

the study would be conducted or the steps required for conducting the study. In this

phase, all the possible activities were incorporated. It emphasizes on the sequence of

the activities that should be undertaken one after another.

3.2. Study Area

3.2.1. Area and Geographical Location

Kalapara (also known as Khepupara) is an Upazila of Patuakhali District in the

Division of Barisal. The upazila occupies an area of 492.102 Sq. km. The study area

is located between 21.9861° N and 90.2422° E. The area is bounded by Amtali

upazila on the north, the Bay of Bangla on the south, Rabnabad channel and

Galachipa upazila on the east, Amtali upazila on the west. Kalapara Upazila consists

of 9 Union Parishads, 57 mouzas and 247 villages with 4 property offices.

Administration Kalapara thana was established in 1906 and was turned into an upazila

in 1983. The average population of each union, mouza and village are 202078 (BBS,

2011).

43

Fig.3.1. Location map of the study area

(Source: Banglapedia, 2006)

3.2.2. Demography

The total population of Kalapara upazilla was 2, 20,074 in the year 2001. As of the

2011 Bangladesh census, Kalapara has a population of 2, 82,000. Males constitute are

52.85% of the population, and females 48.15%. Kalapara has an average literacy rate

of 51.04% (7+ years), and the national average of 57.53% literate. The religious

picture is Muslim 74.29%, Hindu 25.35%, others 0.36%; Density of population of the

study area is 861 per sq. km, the growth rate is 39.10. The decadal population growth

rate is 16.35% and annual compound growth rate is 2.53% (BBS, 2011).

44

Table 3.1. Represents increase of population in Kalapara Upazila after 10 years

Name of Union

Population 2001 2011

Chakamaya 14859 19021 Teakhali 11893 15225 Lalua 14139 18099 Mithagonj 23964 31952 Nilgonj 25553 34710 Khaprabhanga 28124 35847 Latachapli 27004 36102 Dankhali 22716 30078 Dulasor 15199 19456 Total 183451 240490

(Source: Upazila Statistics Office, Kalapara, Patuakhali, 2011)

3.2.3. Topography and Relief

Average height of Kalapara Upazila, in the northern edge is about 2m and in the south

is about lm high from mean sea level. But the maximum height is 6m. The study area

lies in the southwestern part of Bangladesh and downstream of the well known

Ganges deltaic region. The area comprises a flat land with natural ground slopes are

found the main rivers are the Andharmanik, Agunmukha, Payra, Lohalia, Patuakhali

and Tentulia (Banglapedia, 2006).

3.2.4. General Geology of the Study Area

The physiographic condition of Kalapara Upazila is broadly characterized by tidal

flood plains having lower relief and crisscrossed by innumerable river channels. The

study Area is located in the south-west part of the Bengal Basin, a long established

area of subsidence and deposition containing an almost complete sequence from the

Cretaceous to Recent alluvium. The surface topography of the quaternary deposits is

very gentle. The whole of the south-west area is below elevation 17 m and 75% is

below 5m. The surface geology consists mainly of quaternary sediments, although

there are some tertiary deposits in the eastern flood belt. Clay soils are prevalent in the

low laying areas, and medium textured soils at the higher grounds (SRDI, 2001).

45

3.2.5. Land Use Pattern

The land use pattern of an area depends upon the climate, geology, soil, surface and

ground water availability and quality. Among the lands in Kalapara , there are 40,000

ha of cropland , 28 ha of gher, 386.20 ha of settlements and 70 ha of fallow land

(Upazila Agriculture Office, 2011).

3.2.5.1. Cropland

Major crop cultivation in kalapara is Transplant Aman (T- aman), Boro, potato and

vegetables. Sesame, linseed, sugarcane, kaun are extinct or nearly extinct crops of the

study area (Banglapedia, 2006). Gher farming is done in some different land and also

in some T-Aman cropland. T-Aman is mainly the cultivated in the Kharif-2 season.

At present, about in 100% cropland is used for T- aman cultivation. Boro is cultivated

in the Kharif-l season, Rabi crops are cultivated in the Rabi seasons and gher farming

is done rest of the year (SRDI, 2001)

Table 3.2. Represents the cropland use of Kalapara Upazila

Cropland information of 9 unions of Kalapara Upazila.

Name of Union Crop land (ha)

2001 2011 Chakamaya 3438 3364 Teakhali 3289 2774 Lalua 5219 3615 Mithagonj 7385 6466 Nilgonj 6343 5313

Khapravanga 5273 5379

Latachapli 5720 4794

Dhankhali 5929 5551 Dulasor 3251 2743

Total 45818 40000

(Source: Upazila Agriculture Office, Kalapara, patuakhali, 2011)

3.2.5.2. Settlement

In Kalapara Upazila, about 19% land is used for settlements. There are about 56

markets, 243 education centers (7 Kindergartens, 8 community primary schools, 80

reg. primary schools, 78 govt. primary schools, 8 lower secondary schools, 29

secondary schools, 27 madrasas and 6 colleges ), 443 religious centers (387 mosques,

46

45 temples , 3 church , 4 buddhist vihara and 2 pagoda), 30 health centers (2 hospital,

6 family planning centers and 22 community clinics), 5 Launch ghat, 7 union

complexes, 1 upazila complex, 1 customs office, 27 post offices, 1 food storehouse

are in the study area (BBS, 2011).

3.2.5.3. Fallow Land

The fallow lands of the study area are about 51ha. Most of this type of land use is

seen in Nilgonj, Chakamaya, dhankhali and Mithagonj. In lalua most of the land

remains submerged due to high and low tide. So, the soil salinity of lalua union is the

most than others (Upazila Agriculture Office, 2011).

3.2.6. Soil type

KalaparaUpazila is a Ganges Floodplain. In Kalapara Upazila most of the soil types

are present deposits. In this region, pH varies from7.5-4.9. The color of the soil is

light grey, grey and black. The soil salinity varies from Moderate to nil; (EC 0.37 to

11.2 dS m-1). The study areas are mainly located in Medium High land. Here soil is

rich in Calcium, Magnesium, Boron, Copper, and Phosphorus and moderately high in

Manganese, Zinc and lower concentration of Sulphate, Iron, and Nitrogen. There are

rnainly three types of soil present in kalapara upazila. They are ramgoti, Jhalokathi

and Barisal (SRDI, 2001).

3.2.7. Climatic Condition

3.2.7.1. Rainfall

The rain fall pattern is quite similar with the other location of the South-West coastal

Belt. The rainfall pattern raises up to 350 mm in the rainy season and in the dry

season the average rain fall is below 52 mm. But a heavy rainfall is common in the

study area and that occurs four or five times in a year. In 2001, the maximum rainfall

was 397 mm in June and the minimum rainfall was 0 mm in December. In 2011, the

maximum rainfall was 344 in August and the minimum rainfall was 0 January (BMD,

2011).

3.2.7.2. Temperature

Kalapara Upazila is located in coastal region and it falls on South-western climatic

sub-zone of Bangladesh. In 2001, the average maximum temperature was 36.6oC in

the month of April and average minimum temperature of 15.2oC in the month of

47

December. In 2011the average maximum temperature was 36.7oC in the month of

April and average minimum temperature of 11.5oC in the month of January (BMD,

2011).

3.2.7.3. Humidity

Humidity of the study area is completely high. In 2000, the maximum humidity was

88% in the month of July and lowest humidity is 68 % in the month of March .In

2010, the maximum humidity was 85% in the month of September and lowest

humidity is 71% in the month of March (BMD, 2011).

3.3. Selection of the Study Area

The following criteria are being considered for selecting the Kalapara Upazila as the

study area:

Kalapara Upazila is mostly affected by salinity intrusion, tidal surge and

impact of sea level rise, because the people of Kalapara are living beside the

coast of Bay of Bengal.

This region is a well crop productive area of the southwestern coastal

Bangladesh.

Cropland condition have greatly hampered by increasing population and

cropping intensity in study area

Croplands are severely affected by salinity intrusion.

Kalapara is severely affected by the devastating cyclone induced storm surge

3.4. Data Collection All data were collected from the various sources. They are as follows –.

Soil Nutrient data (2011) collection from Soil Resource Development

Institute, Patuakhali.

Soil Nutrient data (2001) collection from Soil Resource Development

Institute, Barisal.

Cropland and Crop production data collection from Upazila Agriculture

Office, Kalapara, patuakhali.

Demographic and Settlement information from Bangladesh Bureau of

Statistics, Kalapara

48

Bangladesh Bureau of Statistics, community series, Patuakhali Zila

Bangladesh Meteorological Department, Kalapara.

Internet/journal

Published/Unpublished report

Upazila Agriculture Office and Upazila Parisad, Kalapara Upazila, Patuakhali.

3.5. Cropping Intensity Determination

Data on cropping pattern and the land coverage for Aman, Aus, Boro and Vegetable

crops were collected from Upazila Agricure Office. Cropping intensities of five

different study unions of Kalapara Upazila were calculated by the following formula

as suggested by Sing (2004).

Cropping Intensity =Total cropped areaNet cultivated area × 100

Table 3.3. Cropping intensity of Kalapara Upazila

Union Net cultivated

area

Aman Aus , Boro Robi crops Total cropped

area

Cropping

Intensity

2001 2011 2001 2011 2001 2011 2001 2011 2001 2011 2001 2011 2001 2011

Chakamoia 3438 3364 3435 3364 75 215 50 103 1607 2975 5167 6657 150% 186%

Nilgonj 6313 5313 6310 5313 101 301 75 200 3295 4290 9781 10095 155% 190%

Latachapli 5720 4794 5697 4794 53 101 30 80 1923 2875 7703 7850 135% 164%

Dhankhali 5929 5551 5925 5551 65 190 70 125 3071 4507 9131 10373 154% 187%

Mithagonj 7385 6466 7383 6466 105 295 45 105 3172 4972 10705 11838 145% 183%

(Source: Upazila Agriculture Office, Kalapara, Patuakhali, 2011)

3.6. Data Interpretation

All data were compiled, processed and interpreted for discussion and analysis. The collected

secondary data were grouped, categorized and interpreted according to the objectives as well

as the indicators. Some data contains numeric and some contains narrative facts. For

measurable and indicative answer data have been grouped in the tabular forms.

3.7. Data Processing and Analysis

Data were statistically processed, analyzed and interpreted by using computer

programs- MS WORD and MS EXCEL 2007.

49

CHAPTER 4

RESULTS AND DISCUSSION

50

4. Results and Discussion

This chapter contains the presentation of results (data and information that was

collected and that was generated) and their analysis. The study was conducted at five

unions of Kalapara Upazila in Potuakhali District. In a view to meet the objectives of

the research paper the results were tabulated, interpreted and analyzed in the

following ways:

4.1. Increasing in Population

Fig. 4.1 presents the population growth of the studied unions of Kalapara upazilla

during 2001- 2011. The growth rate in 10-year period is 35.8% in Nilgonj, 33.6% in

Latachabli, 33.3% in Mitagonj, 32.4% in Dhankhali and 28% in Chakamoia,

respectively.

Data presentation in fig. 4.1 shows that the highest population growth rate was found

in Nilgonj whereas the lowest growth rate was observed in Chakamoia union. The

highest population growth of Nilgonj union might be due to migration of the rural

people to town areas to enjoy the urban facilities as it is the nearest union of the

pourashava likewise Latachabli is the most distant and remotest union from

pourashava. So, people intended to dwell in Dhankhali.

The total population of Kalapara upazilla was 2,20,074 in the year 2001 and 2,83,000

in 2011(BBS, 2011). Rapid population increase is one of the major problems of

Bangladesh. The population growth rate is about 1.42 %, which translates into about

two million additional new mouths every year need to be fed (BBS, 2011).

0

10000

20000

30000

40000

14859

2555322716

2700423964

19021

3471030078

3610231952

Popu

latio

n

Fig.4.1. Population growth of five unions in Kalapara upazilla

2001

2011

51

4.2. Reduction of Cultivable Land

Fig. 4.2a presents the shrinkage of cultivable land and Fig. 4.2b represents the per

capita land reduction of the studied unions of Kalapara upazilla during 2001- 2011. In

2001, the cultivable land of Chakamoia, Nilgonj, Dhankhali, Latachabli and Mitagonj

were estimated to be 3438 ha, 6333 ha, 5929 ha, 5720 ha, and 7385 ha respectively

whereas in 2011 cultivable land reduced by (2.15 %), (16.23 %), (6.37 %), (16.18 %)

and (12.44 %) ha in the respective unions.

The order of cultivable land reduction was Nilgonj> Latachabli> Mitagonj>

Dhankhali> Chakamoia. Thus the increased pressure on the cultivable land entailed

per capita land reduction. Homestead and other settlements in Nilgonj and Latachabli

occupied much valuable cultivable land higher than other unions. The population

added by 10-year time is 63,000; the average per capita land therefore, reduced in a

10-year time from 0.21ha to 0.14 ha. The per capita land reduction was observed in all

the studied unions provided that highest reduction in Nilgonj and the lowest reduction

in Chakamoia unions.

The country has a land area of 148.4 million hectares (Mha), population of over

142.32 million with a density of about 1000 persons per km2, which is one of the

highest in the world (BBS, 2011). With the growing population, and their increasing

needs in various sectors, land use patterns are undergoing a qualitative change in

which the area under the net cropped land is gradually shrinking (BARC, 2011).

0

2000

4000

6000

8000

3438

6343 5929 57207385

3364

53135551

47946466

Lan

d in

hec

tare

Fig. 4.2a. Reduction of Cultivable land

2001

2011

0

0.1

0.2

0.30.23 0.25 0.26

0.21

0.3

0.180.15

0.180.13

0.21

Per c

apit

a la

nd (h

a)

Fig. 4.2b Reduction of per capita land

2001

2011

52

4.3. Increase in Cropping Intensity

Fig. 4.3 represents the increase of cropping intensity in 10-year period of the studied

unions of kalapara upazila. In 2001, the cropping intensity of Chakamoia, Nilgonj,

Dhankhali, Latachabli and Mitagonj was 150%, 154%, 155%, 135% and 145%

respectively while in 2011 it was increased to 186%, 190%, 187%, 164% and 183%

of those unions. The order of increase cropping intensity was Nilgonj> Dhankhali>

Chakamoia > Mitagonj> Latachabli. Increased population and land shrinkage might

be the cause of increasing cropping intensity to meet up the food demand.

Increased crop productivity from the shrinking land resources is the urgent need to

meet the increased food demand of the swelling population of Bangladesh. Food

requirement of the country is estimated to be doubled in the next 25 years. To feed the

teeming million the land resources in Bangladesh is intensively used for crop

production (Islam and Haq, 1999). Since land is a scarce resource in Bangladesh, the

only choice is to increase in cropping intensity (Ahmed et al., 2001).The net cropping

intensity of Bangladesh in 2009-10 was 180.88% (BBS, 2010) and the highest

cropping intensity of 199% was observed in Kalapara upazila followed by other

coastal upazilas (Bala and Hossain, 2009).

4.4. Increase in Salinity

Fig. 4.4 showed the increasing trend of salinity of the studied unions of kalapara

upazilla. In 2001, the salinity of Chakamoia, Nilgonj, Dhankhali, Latachabli and

Mitagonj was 4.48 dS/m, 3.79 dS/m, 3.21 dS/m, 6.67 dS/m and 3.48 dS/m

respectively but in 2011 it was increased to 7.60 dS/m, 5.88 dS/m, 7.26 dS/m, 8.87

0%

50%

100%

150%

200%150% 154% 155%

135% 145%

186% 190% 187%164%

183%

Cro

ppin

g In

tens

ity (%

)

Fig.4.3. Increase in Cropping Intensity

2001

2011

53

dS/m and 6.91dS/m. The order of increasing salinity was Dhankhali> Chakamoia>

Mitagonj> Latachabli> Nilgonj. Due to salt water intrusion from river in Dhankhali

and chakamoia unions, were found to be the highest increase in salinity.

A comparative study of soil salinity maps of 1973, 2000 and 2009 shows the extents

of soil salinity intrusion in the coastal region. It was also found that about 0.0354

million hectares of new land is affected by various degrees of salinity during last 9

years only. Some of new land of Patuakhali, Borguna, Barisal, Jhalakathi, pirojpur,

Satkira, Jessore, Gopalgang and Madaripur districts are affected by differerent

degrees of salinity, which reduces agricultural productivity remarkably (Hussain,

2010). The study area is not out of this effect.

4.5. Depletion of Major Nutrients

Intensive cultivation practice and mismanagement of cultivable land reducing the

nutrient content of Kalapara Upazilla. The trends of major nutrients depletion are

discussed in this section.

4.5.1. Nitrogen Depletion

Fig. 4.5 demonstrates the depletion of nitrogen percentages of soil of the studied

unions of Kalapara upazilla during 2001- 2011. In 2001, the nitrogen status of

Chakamoia, Nilgonj, Dhankhali, Latachabli and Mitagonj were 0.099 %, 0.097%,

0.125 %, 0.118 % and 0.093% and the maximum value (0.125%) was found in

Dhankhali union while in 2011 and the levels were 0.057 %, 0.081%, 0.086 %, 0.076

% and 0.062 %.

0

2

4

6

8

10

4.483.79 3.21

6.67

3.84

7.6

5.887.26

8.87

6.91

Salin

ity (d

S/m

)

Fig. 4.4. Increase in Salinity

2001

2011

54

The maximum reduction of nitrogen was observed in Chakamoia union and the lowest

change was found in Nilgonj union. Nitrogen was reduced in 10-year period by the

sequence of Chakamoia> Latachabli> Dhankhali> Mitagonj> Nilgonj. Cultivable land

shrinkage and increasing cropping intensity of five unions might be the cause of

Nitrogen depletion in soil of those unions. Though population growth rate and

cropping intensity of Nilgonj was higher than other unions but nitrogen depletion rate

was found the lowest. It might be caused by high input of organic manure and

inorganic nitrogen fertilizer to get higher crop production to meet up the food demand

of boosting population.

Nitrogen is generally considered as the key nutrient in Bangladesh agriculture because

of its low supply in the soils. Portch and Islam (1984) reported that 100% of

Bangladesh soils contained available N below critical level. Nitrogen is the most

limiting nutrient in crop production all over the world. Nitrogen deficiency occurs

everywhere in Bangladesh (Kumar and Yadav, 2005). They conclude that the

depletion of N from the soil is mainly due to crop removal and leaching for increase

cropping intensity.

4.5.2. Phosphorus Depletion

In 2001, the phosphorus levels of Chakamoia, Nilgonj, Dhankhali, Latachabli and

Mitagonj were 7.63 ppm, 4.86ppm, 8.64 ppm, 2.56 ppm and 6.74 ppm while in 2011

the levels were 6.6 ppm, 0.5 ppm, 6.2 ppm,1- and 5.1 ppm. However, in 2011

phosphorus was depleted by the order of Nilgonj> Dhankhali> Mitagonj> latachabli>

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.099 0.097

0.1250.118

0.093

0.0570.071

0.0860.076

0.062N

itrog

en (%

)

Fig.4.5. Depletion of Nitrogen

2001

2011

55

Chakamoia (Fig. 4.6). Cultivable land shrinkage and increasing cropping intensity of

Nilgonj might be the cause of higher phosphorus depletion in Nilgonj.

Phosphorus is recognized as an important mineral element limiting crop growth and

production (Batten et al., 1984). It is generally considered as the second most limiting

nutrient after N for plant growth (Vance, 2001). Phosphorus depletion in soil due to

the current intensive use of agricultural land for crop production (Nautiyal et al.,

2000).

4.5.3. Potassium Depletion

Fig. 4.7 represented the depletion of potassium concentration in soils Kalapara

upazilla. In 2001, the potassium levels of Chakamoia, Nilgonj, Dhankhali, Latachabli

and Mitagonj were 0.42ppm, 0.47ppm, 0.37ppm, 0.31ppm and 0.35 ppm while in

2011 and the phosphorus levels were 0.3 ppm, 0.27 ppm, 0.29 ppm, 0.19 ppm and

0.24 ppm. The maximum depletion of potassium was observed in Nilgonj union and

the lowest depletion was found in Dhankhali union. Potassium depletion in Nilgonj

was mainly caused by high cropping intensity. Although cropping intensity of other

unions were also high but potassium level didn’t change more due to salinity.

0

2

4

6

8

10

Chakamoia Nilgonj Dhankhali Latacabli Mitagonj

7.63

4.86

8.64

2.56

6.746.6

0.5

6.2

1

5.1

Phos

phor

us c

onc.

(ppm

)

Fig. 4.6. Depletion of Phosphorus

2001

2011

56

Tiwari (1985) concluded that Intensive cropping with modern rice varieties is

responsible for increasing the K Depletion in soil. Most of the north-western parts of

Bangladesh are deficient in potassium (BARC, 2005).

4.5.4. Sulfur Depletion

Fig. 4.8. represents the depletion of potassium levels of soils of the studied unions of

kalapara upazilla. In 2001 the sulfur contents of Chakamoia, Nilgonj, Dhankhali,

Latachabli and Mitagonj was 61.1ppm, 59.03 ppm, 51.85 ppm, 48.32 ppm, and 54.5

ppm respectively where as in 2011 it decreased to 23.7 ppm, 20.5 ppm, 23.9ppm, 21.5

ppm and 25.4 ppm and sulfur depletion trend was Nilgonj > Chakamoia> Mitagonj>

Dhankhali> Latachabli.

The maximum depletion of Sulfur was observed in Nilgonj union and the lowest

depletion was found in Latacabli union. Sulfur depletion in Nilgonj was mainly

0

0.1

0.2

0.3

0.4

0.5 0.420.47

0.370.31

0.350.3

0.27 0.29

0.190.24

Pota

ssiu

m co

nc .

(ppm

)

Fig. 4.7. Depletion of Pottassium

2001

2011

0

10

20

30

40

50

60

70

Chakamoia Nilgonj Dhankhali Latacabli Mitagonj

61.1 59.0351.85

48.3254.5

23.7 20.5 23.9 21.525.4

Sulfu

r co

nc. (

ppm

)

Fig. 4.8. Depletion of Sulfur

2001

2011

57

caused by high cropping intensity. Intensive cropping has been resulting higher

depletion of sulfur among the other nutrients rather its replenishment under natural

process (Balsa et al., 1996). The current intensive use of agricultural land for crop

production has extended the sulfur deficient areas to about 80% (Khan et al., 2007).

Bangladesh is not free from this threat. About 7 M ha (about 52%) of agricultural

lands are reported to consists of sulfur deficient soils in the Northern region of

Bangladesh (SRDI, 1999).

4.5.5. Calcium Depletion

Fig. 4.9 presents the depletion of Ca contents in soils of the studied unions of

Kalapara upazilla. The contents of Ca in Chakamoia, Nilgonj, Dhankhali, Latachabli

and Mitagonj unions were 6.3 ppm, 4.3 ppm, 5.1 ppm, 5.91ppm and 4.58 ppm in 2001

but it decreased sharply in 2011 and the Ca contents were observed 4.4 ppm, 2.9 ppm,

4.5 ppm, 4.7 ppm and 2.58 ppm. The maximum depletion was found in Chakamoia

union and the lowest depletion was found in Dhankhali. Due to lower cropping

intensity and higher rate of increasing salinity, Ca depletion rate was also found lower

in Dhankhali union. Jahiruddin and Islam (1999) reported that Zinc depletion in

Bangladesh is mainly due to continuous mining of soil nutrients for increase cropping

intensity (180% at present).

0

1

2

3

4

5

6

7

Chakamoia Nilgonj Dhankhali Latachabli Mitagonj

6.3

4.35.1

5.91

4.584.4

2.9

4.5 4.7

2.58

Cal

cium

con

c. (p

pm)

Fig.4.9. Depletion of Calcium

2001

2011

58

4.5.6. Zinc Depletion

Fig. 4.10 shows the depletion of Zn contents in soils of the studied unions of Kalapara

upazilla. The contents of Zn in Chakamoia, Nilgonj, Dhankhali, Latachabli and

Mitagonj unions were 0.74 ppm, 0.79 ppm, 0.64 ppm, 0.68 ppm and 0.91 ppm in

2001 while in 2011 it decreased dramatically and the Zn contents were observed 0.45

ppm, 0.28 ppm, 0.45 ppm, 0.39 ppm and 0.42 ppm. The order of depletion was

Nilgonj > Chakamoia > Mitagonj > Latachabli > Dhankhali. Intensive cultivation of

crops in Nilgonj might be the fact that reduced the Zn level.

Zinc deficiency, together with sulphur deficiency, are recognised as limiting factors in

crop production in Bangladesh. About 1.75 Mha of intensively cropped land are

estimated to be affected by zinc deficiency, which mainly affects rice and wheat

(Ahsan and Beuter, 2000). Jahiruddin and Islam (1999) reported that Zinc depletion in

Bangladesh is mainly due to continuous mining of soil nutrients for increase cropping

intensity (180% at present). They also said that availability of Zn in the soil varies

widely depending on the soil properties and the calcareous soils have low to medium

extractable Zn content.

4.5.7. Boron Depletion

Fig. 4.11 demonstrates the depletion of Zn contents in Kalapara upazilla. The contents

of Boron in Chakamoia, Nilgonj, Dhankhali, Latachabli and Mitagonj unions were

0.56 ppm, 0.49 ppm, 0.41 ppm, 0.45 ppm and 0.59 ppm in 2001 but after 10 years

Boron contents were observed 0.27 ppm, 0.19 ppm, 0.31 ppm, 0.23 ppm and 0.29

0

0.2

0.4

0.6

0.8 0.740.79

0.64 0.680.6

0.45

0.28

0.450.39 0.42

Zinc

con

c. (p

pm)

Fig. 4.10. Depletion of Zinc

2001

2011

59

ppm and the order of Boron depletion was Nilgonj, Mitagonj> Chakamoia>

Latachabli> Dhankhali.

This might be the effect of high cropping intensity in Nilgonj and Mitagonj. Although

taken up in tiny quantities, boron deficiency may lead to serious consequences

regarding economic yield of various crops. Boron deficiency in Bangladesh was first

observed in reverine soils of Teesta on wheat causing sterility in grains. Boron

depletion in Bangladesh is mainly due to continuous mining of soil nutrients for

increase cropping intensity (Islam, 2006).

0

0.1

0.2

0.3

0.4

0.5

0.6

Chakamoia Nilgonj Dhankhali Latachabli Mitagonj

0.560.49

0.410.45

0.59

0.27

0.19

0.31

0.230.29

Bor

on c

onc.

(ppm

)

Fig. 4.11. Deplition of Boron

2001

2011

60

CHAPTER 5

Summary and Conclusion

61

5. Summary and Conclusion

Rapid population increase has been the most persistent problem of Bangladesh since

last 50 years or more. All the triggering factors discussed in the scope of this research

paper are the outgrowth of the biggest trigger factor ‘swelling population’. Growing

population entails increase in food demand, migration and settlement in town areas,

land use, cropping intensity and many such other factors that trigger nutrient depletion

or imbalance leading to degradation. That may halt sustainability in agricultural use of

the land of Kalapara upazila as this might be projected that the picture of other unions

are similar to the studied unions.

However, from the study it can be summarized that -

Population increased in all the studied unions but the highest population

growth was found in Nilgonj.

Estimated cultivable land reduction and cropping intensity both were highest

in Nilgonj.

The highest per capita land reduction was found in Mitagonj and the lowest of

the same was observed in Chakamoia unions.

The maximum depletion of P, K, Zn and B was observed in Nilgonj.

The maximum depletion of N, S and Ca found in Chakamoia.

Salinity was increased in all the studied unions

Study showed that land use patterns are undergoing a qualitative change in

Kalapara upazila as cultivable land is gradually shrinking. This research paper

projects that much alike in the other areas in Bangladesh, increasing food and

shelter demand of Kalapara upazila would be met by increasing cropping intensity

from the ever shrinking land resources without considering the nutrient balance in

the soil that may soon lead to the degradation. That is the ultimate threat is

imminent.

It can also be concluded from the observed facts of the nutrient status that Nilgonj and

Chakamoia are the most vulnerable unions among the studied ones.

62

CHAPTER 6

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63

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