College Papers

Land policy makers and agricultural scientists of the

Land
degradation: Situation in South Asia

Asia, the most thickly
populated area in the world has been influenced by desertification. With the
rapid economic development in Asian countries, the rapidly growing population
is placing ever-increasing demands on the land, clearing natural vegetation and
tilling soil without fallow or inadequate nutrient replenishment. With
increasing use of unsustainable resources, land degradation further degraded,
which leads to increased poverty and many people have to face deteriorating
living conditions. About 35% of the arable land in Asia has been influenced by
desertification. Nearly 1.3 billion people or 39% of the total population in
Asian region are exposed to desertification and arid conditions.

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The food demand and
internal supply situations in most SAARC countries have not been satisfactory
as the scope of horizontal expansion of agriculture has almost exhausted and
crop yields began to stagnate or even decline in many cases. The recent food
price hikes and limited availability of food in the international market have
further complicated the issues related to achieving food security in the SAARC
countries and at the same time maintaining the pace of their socio-economic
development. The implication is that, countries must produce enough food for
their present populations and check population growth rates to ensure that food
shortage do not occur in the future, virtually all of the food increase will
have to come from land. The population growth rate was high, around 2% per annum
in the impoverished, developing nations of Asia. For example in the SARC
countries, the total population was 1418.5 million in 2004 which is estimated
to be about 1800 million by the year 2020 (SAARC Statistical Data Book,
2006-2007), about 22 percent of the world’s population live in the eight SAARC
countries.

There are limited data on
the latest information and statistics about the nature and extent of the
different land degradation components in the SAARC countries varying in content
and precision from country to country. However, what is known to date may be
largely qualitative and not always precise but these do provide food for
thought for policy makers and agricultural scientists of the region for future
action plans to protect the region from the bad effect of land degradation. For
the practical purpose of assessment of land degradation in SAARC countries and
determination of the needs for technological and policy interventions, the
following list showing the causes of land degradation, natural or human
induced, should suffice:

·        
Natural hazards e.g., flood, drought,
tidal surge, snow melt, etc. (some or the other in all SAARC countries – e.g.,
floods and tidal surges in Bangladesh, drought in Pakistan and India, snow melt
and landslides in Nepal and Bhutan)

·        
Erosion by water and wind (e.g., serious
land erosion from river water currents in Bangladesh during recurrent floods,
wind erosion in the semi-arid regions of India and Pakistan)

·        
Salinization and acidification (natural
and anthropogenic e.g., tidal flooding, shrimp culture in crop land in
Bangladesh, faulty irrigation and drainage in India and Pakistan, arid and
semi-arid conditions in India and Pakistan, draining and drying of potentially
acid sulphate soils, etc.)

·        
Formation of hardpan, compaction and water
logging (mostly human induced in all SAARC countries)

·        
Deforestation, shrinkage of vegetation
cover on land, overgrazing (natural and / or human induced in India and
Pakistan, for example)

·        
Inappropriate management in cultivation of
land on steep slopes (human induced – e.g., in Nepal)

·        
Nutrient mining and inadequate nutrient
replenishment (human induced – all SAARC countries)

·        
Soil organic matter depletion (mostly
human induced – e.g., serious problem in Bangladesh)

·        
Over-exploitation of ground water in
excess of natural recharge capacity (faulty irrigation practice, human induced)

·        
Use of poor quality irrigation water (e.g.
use of groundwater containing high arsenic concentrations for irrigation in
Bangladesh and West Bengal of India, risk of toxic levels arsenic accumulation
in soils and foodstuff)

·        
Pollution of soil and surface water bodies
(rivers, ponds) by urban industrial waste, excessive use of agrochemicals, oil
spills etc. (human induced – e.g., in India, the most industrialized SAARC
country)

·        
• Global warming and consequent sea level
rise, an impending calamity (mostly human induced, mainly responsible are the
industrialized countries of North America and Europe, but the SAARC countries
are under the influence of severe consequences).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DISCUSSION

Factors
affecting Land Degradation

A big difficulty in
studying these components of land degradation and their impacts on agricultural
production separately is that, these are caused by both natural factors and
human interventions mostly in overlapping ways. For example, soil degradation
may occur due to fertility decline caused by loss of nutrients through erosion
(natural cause) and simultaneously, intensive cropping without appropriate
fertilization (human factor) and it has some adverse effect which result a huge
crop loss. The crop loss could be measured, it would be almost impossible to
determine exactly which factor contributed how much in causing yield loss. Some
statistics gleaned from various countries (SAARC Statistical Data Book,
2006-2007) are given below as references:

·        
Water erosion and chemical degradation are
the most devastating land degradation pathways in the SAARC region. Erosion
risk is the highest (53% of the total area) in Bhutan, followed by 42% in Sri
Lanka, 31% in Nepal, 29% in India, 15% in Bangladesh and 13% in Pakistan

·        
Soil salinity/sodicity is a problem in
Pakistan (20% of the total area), India (8%) and Bangladesh (6%)

·        
Land with shallow soils (poor fertility
and physical properties): 24% in Pakistan, 21% in Nepal, 13% in Bhutan, 10% in
Sri Lanka, 9% in India and 1% in Bangladesh.

·        
Soil fertility decline due to organic
matter depletion is a growing problem in all countries. In Bangladesh about 60%
of the soils have low organic matter content, often less than 1%.

·        
In India 41% of the land area is under
major soil constraints, the figures for Sri Lanka, Bangladesh, Nepal, Bhutan
and Pakistan are 37%, 29%, 26%, 22% and 9%, respectively.

·        
On a SAARC regional basis, only 24% of the
total land area in without major soil constraints.

Land degradation through
human activities is progressing at a fast pace in all South Asian countries.
Human induced land degradation in India is the highest (58% of the total
degraded area) followed by Sri Lanka 54%, Bangladesh 27%, Nepal 27% and
Pakistan 24%. It is in this aspect of land degradation, i.e., human induced
land degradation, where there is the greatest scope and necessity to intervene
with national and regional policy measures and technological innovations. This
is the time to give emphasis to initiate research work extensively to solve the
problems of soils of Bangladesh that occupies 60% area of which 0.88 m ha in
salinity, 35 m ha in drought, 26 m ha in water-logging, 0.83 m ha in char land
and 1.2 m ha in high temperature zone.

There are some examples
of the present and potential impacts from one SAARC country only (Bangladesh).
Land degradation in almost all its known forms is going on in all other SAARC
countries. The extent and intensity of the various land degradation processes
would differ, however, from country to country. For example, arsenic
contamination of the irrigation water-soil-crop systems is known to be quite a
serious water quality/soil degradation problem in Bangladesh and West Bengal of
India, but this is not much of a problem in Pakistan, other parts of India and
other SAARC countries. Again, sea level rise due to global warming could be a
very serious threat to Bangladesh and Maldives, but Nepal and Bhutan are not
supposed to be directly affected. Since no generalization can be made regarding
the causes and effects of land degradation, it is imperative that dependable
data for each country be available so that scientist, policy makers and farmers
can take appropriate measures to face the problem nationally and regionally.

 

 

 

 

 

 

 

 

 

 

Impacts
of Land Degradation

Estimating the impact of
land degradation is a very difficult task as this would involve not only the
biophysical and agro-ecological issues but also socio-economic and development
issues. However, this is very important since policy makers, donor agencies and
international development partners would be more interested in quantitative
estimates of the impacts of land degradation than just qualitative statements
about what could happen. A concerted effort by agricultural and social
scientists is very much needed. A study of the effect of land degradation in
south Asia concluded that land degradation was costing countries in the region
and economic loss of the order no less than US$ 10 billion, equivalent to 7% of
their combined agricultural GDP (FAO, 1994). The current figures could be much
higher.

Over the last 2-3
decades, enormous pressure has been exerted on the land resources of the
country. The rapid population growth and the concurrent increase in demand for
agricultural land, food, water and shelter has put pressure on the land and
water resources. This is resulting in environmental degradation in the region
and the trend is intensifying unceasingly. In Bangladesh, roughly 220 hectares
of land goes out of cultivation per day which means, nearly 1 percent of the
cultivable land is being lost every year (BBS, 1997). This has serious
implication on the sustainability of agricultural development potential, food
supply and food security of the country.

Due to decline in natural
vegetation and unsustainable agriculture, the capacity of soil and water
resources to support life has been steadily reduced. According to the data from
UNEP in 1997, of the 1.96 billion ha of soil resources in the world, that have
been degraded, Asia ranked the highest rate with approximately 38% percent of
total declination. Due to overgrazing and deforestation, natural vegetative
cover continues to decline, which created negative impact on the biodiversity.
There are a number of interrelated land degradation components, as follows, all
of which may contribute to a decline in agricultural production (FAO, 2000):

·        
Soil degradation : Decline in the
productive capacity of the soil

·        
Vegetation degradation: Decline in the
quantity and quality of the natural biomass and loss of vegetative cover (For
example, the supper cyclone “Sidr” in Bangladesh caused at least 5% loss of the
Sundarbans, the largest mangrove forest of the world, As a result the “green
wall” against cyclone has been seriously lost in Bangladesh)

·        
Water degradation: Serious increase of
pollution of ground water due to arsenic, industrial effluents. Decline in the
quantity and /or quality of the surface and groundwater resources

·        
Climate deterioration: Changes in climatic
conditions that increase the risk of crop failure. This components caused yield
reduction in wheat and mustard

 

Major
types of land degradation in Bangladesh:

Major types of land
degradation that occur in Bangladesh constitute:

i) soil erosion, ii)
water erosion, iii) river bank erosion, iv) salinization, iv) sedimentation, v)
acid sulphate soil, vi) Acidification, vii) water logging and viii) soil
fertility depletion.

Table 1: Different
types/areas of land degradation and their extent in Bangladesh

A)
Soil erosion

Soil
erosion has been remarkably encountered in the hilly regions of the country
which occupy about 1.7 million hectares and the areas which are susceptible to
different degrees of erosion in the hilly areas of Bangladesh is shown in Table
3 (SRDI, 2005). Sheet erosion is a general phenomenon occurring throughout the
country. It poses a serious problem locally in parts of level to gently
undulating high terraces of the Madhupur, Barind and Akhaura tracts in terms of
considerable amount of topsoil and nutrient loss. There is also visible
evidence of fertile topsoil loss in the flood plain, but a quantitative
estimate of soil loss has not yet been scientifically made.

B)
Water erosion

Water
erosion is a serious problem in Bangladesh. Because of high seasonal rainfall,
low organic matter content, poor soil structure, poor soil management and rapid
destruction of vegetative covers in different slopes of the hills, the surface
soils are being continuously washed away. Water erosion covers all forms of soil
erosion by water including sheet and rill erosion and gullying. Human induced
enhancement of landslides, caused by clearing of vegetation, earth removal,
road construction, etc., are also included. Water erosion is the most
widespread form of degradation affecting 25% of agricultural land. Accelerated
soil erosion has been remarkably encountered in the hilly regions of the
country which occupy about 1.7 million hectares and the areas which are
susceptible to different degrees of erosion in the hilly areas of Bangladesh is
shown in Table 3 (SRDI, 2005). The data reflects that about 75% of the hilly
areas have very susceptibility to erosion while about 20% have high
susceptibility and 5% have moderate susceptibility to erosion.

Table 2: Land susceptible
to different degree of soil erosion in the hill areas of Bangladesh (in Km)

Rill and gully erosions
in severe forms occur in the hill areas due to rapid removal of the vegetable
cover. Over 17% of the growing stock was depleted between 1964 and 1985 in the inaccessible
state forest of the Chittagong Hill Tracts (SRDI, 2005), while there is no data
available for the unclassed state forests occupying 10,085 km2 . They are open
to shifting cultivation, pineapple plantation and many other forms of
disturbances. A study shows that sediment loss from well stocked slopes ranged
from 2.7 to 7.2 t-1ha1 year-1, while that from the clean field slope was 102
t-1ha-1year-1 (SRDI, 2005). More severe forms of soil erosion are occurring in
different parts of the hills due to nontraditional practices of the pineapple
and rubber plantations (Layzell, 1982). It was estimated that the annual soil
loss under pineapple was in excess of 200 t-1ha-1year-1. Landslide occurs in
Bangladesh in the hills with 70% slope or steeper during heavy depressional
rainfalls. These are observed in the forms of landslip, mud flow, flow side,
slump and occasional rock fall. The area and extent increase with the increase
of rapid destruction of vegetable covers in the hills.

About 10,000 hectares of
forest land, including reserve forest, have been brought under jhum cultivation
in the current season at eight upazilas in Khagrachari. Jhum is a traditional
method of cultivation of indigenous people in the Chittagong Hill Tracts.
Continuous tilling of hill slopes is also appears as a major concern of massive
soil erosion as forests and shrubs are cleared off damaging biodiversity that
may cause environmental disaster. It was observed that soil loss from Jhum on
steep slope, moderate slope and gentle slope were 40.0, 35.0 and 32.0
t-1ha-1year-1, respectively (Khan et al., 2008). On the other hand Jhum with
vegetative barrier resulted soil loss of 9.0, 10.0 and 17.0 t-1ha-1year-1 in
gentle slope, moderate slope and steep slope, respectively.

Table 3: Soil loss from
Agricultural land use at different slopes due to Jhum Cultivation

C) River Bank Erosion

River bank erosion is
rampant in areas along the active river channels of the Ganges, the Jamuna, the
Meghna and the Tista and in the coastal and off-shore areas of Bangladesh. In
Bangladesh, bank erosion is caused mainly due to strong river current enhanced
by mechanized river traffic and/or channel diversion during the rainy season.
Bank erosion causes extensive loss of land, crops and hose holds and urban migration
of the landless and uprooted rural populace. This has created an unchangeable
chronic socio-economic problem in Bangladesh. About 1.7 million hectares of
floodplain areas are prone to river bank erosion.

 

 

D) Wind erosion

In Bangladesh, some areas
are affected by wind erosion mainly in the districts of Rajshahi and Dinajpur
during the drier months of the year. Sand dunes in the young alluvial lands
(charlands) of Kustia and sandy beaches along the seashore are some of the
visual evidence of wind erosion in Bangladesh. Droughty situation leading to
wind erosion and its impact on agricultural production has been documented by
Karim et al. (1990), but quantitative data has not yet been estimated.

E) Salinization

In Bangladesh,
salinization is one of the major natural hazards contributing towards land
degradation. Soil salinity is a seasonal problem that goes, among the three
seasons, in rabi season salinity affects crop production severely in the saline
belt whereas in kharif-1 salinity reaches about to neutral and does not affect
crop production which is unusual to rabi season. Maximum salinity occurs in the
month of March and April, the peak dry season and minimum salinity occurs in
the month of July and August after the onset of monsoon rains (Mondol, 1997).
The coastal area of Bangladesh is about 710 km long. Out of 2.85 million
hectares of coastal and off-shore area (30 % of net cultivable area) about 0.85
hectare of arable land were affected by varying degrees of soil salinity.
Recently, salinity both in terms of severity and extent has increased much due
to the intrusion of saline sea water because of the diversion of the Ganges
water in the dry season. Impact of salinization is more apparent than other
forms of land degradation. This is partly because, its effects are substantial
and visibly apparent, partly because the degradation can be readily quantified.
In Bangladesh, mainly rabi season crops (wheat, barley, maize, boro, mustard
and vegetables) are affected due to different degrees of salinity. Production
loss is estimated here for wheat considering an average yield of 2.0 t ha-

 

Table 4: Loss of
production due to Salinization at different degrees of land degradation.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CONCLUSION

Land degradation is a
threat to natural resources with consequences on food security, poverty and
environment stability. The increase in temperature will create an impact on
land degradation processes, including floods, mass movements, soil erosion,
salinization, water logging and carbon sequestration in all parts of the globe.
It is essential to improve the monitoring of land degradation as well as
climate change. Innovative and adaptive land management responses to inherent
climatic variability and natural hazards must be identified for sustainable land
management. Land degradation typically occurs because of land management
practices or intervention that is not sustainable over a period of time. An
increase of CO2 will cause an increase in temperature and increased land
degradation due to increase in frequency and intensity of severe weather and
extreme climatic events (floods & droughts). Global warming and climate
change have detrimental impact on soil fertility and crop productivity. Soil
organic matter is decreasing due to rise of soil temperature.

Extent and severity of
natural disaster like flood, drought, cyclone and tidal surges will be more in
the coming years. Increased drought and salinity, prolonged inundation and
excessive soil erosion will reduce the crop area and yield. Appropriate crop management
practices should be followed in the affected areas. Selection of appropriate
crop species/variety should be chosen for specific area. Increased land
degradation will lead to reduced retention of soil moisture and increased soil
erosion, and hence desert encroachment. The information on land degradation
must be applied in developing sustainable practices to land degradation. Many
things are common in South Asian countries. There should be some joint program
to combat land degradation. All the countries will be mutually benefited if
sharing of knowledge, joint pilot program, information and exchange visit of
scientist of South Asian countries are made possible. It is the high time to
exchange views and share ideas with the SAARC countries and work together to
save the man kind from the devastating effect of land degradation and its
consequences.

 

 

 

Appendix

                                                             

Reference

 

1.      Land
degradation and desertification. (n.d.). Retrieved January 15, 2018, from http://www.who.int/globalchange/ecosystems/desert/en/

2.      Land
Degradation. (n.d.). Retrieved January 15, 2018, from http://en.banglapedia.org/index.php?title=Land_Degradation

3.      Causes,
Effects and Solutions of Soil Degradation. (2016, December 24). Retrieved
January 15, 2018, from https://www.conserve-energy-future.com/causes-effects-solutions-soil-degradation.php

4.      Water
Air and Soil Pollution | RG Impact & Description … (n.d.). Retrieved
January 15, 2018, from https://www.bing.com/cr?IG=76311F0F88BC4EBBB50D56E11F6F400E=087230E7B6CB627F3DA33B9FB7646352=1=b91b5sw93DGSfE4s8Uccsm3VXjnhisIjmmlQq-6QnaU=1=https%3a%2f%2fwww.researchgate.net%2fjournal%2f0049-6979_Water_Air_and_Soil_Pollution=DevEx,5068.1

5.      Ahammad,
S. U. (2017, January 22). The Dynamics of Agricultural Land Management System
in Bangladesh: The Challenges for Sustainable Development. Retrieved January
15, 2018, from http://pubs.sciepub.com/ajrd/5/1/2/index.html