SOIL DEGRADATION: A THREAT TO INDIAN AGRICULTURE M. Dhakshinamoorthy, Professor, IMTI, Trichy
SOIL DEGRADATION: A THREAT TO INDIAN
AGRICULTURE
M. Dhakshinamoorthy, Professor, IMTI,
Trichy
India
is blessed with a wide array of soil types that would have developed in the
subcontinent as a direct consequence varying climatic conditions and
vegetations. According to the National Bureau of Soil Survey and Land Use
Planning (NBSS & LUP), taxonomically eight out of twelve Soil Orders in the
world exist in India . The
Inceptisols (alluvial soils) cover nearly one-third of the geographical area of
the country. The arable land available per head has been reduced by 50% in the
past fifty years from 0.34 ha (1950) to 0.16 ha (1998-99). The land available
for cultivation is shrinking at an alarming rate due to the exponential growth
of urbanization that commensurate with increasing proportion of lands
unsuitable for cultivation of crops (Yadav, ,2002). It is utmost essential to promote the soil
productivity in order to maintain the achievement already made in realizing
self-sufficiency in food grain production. India
has been exposed to a very high degree of soil degradation within the club of
developing countries. According to the latest estimate, 187.7 million hectares
(57.1%) of the total geographical area (329 million hectares) is degraded. The
degraded land encompasses water erosion (148.9 million ha), chemical hazard
(13.8 m ha) wind erosion (13.5 m ha), water logging (11.6 m ha), salinization
(10.1 m ha) and nutrient depletion (3.7 m ha). In this paper, various soil
degradation hazards and their impacts on agro-ecosystems and suggested policies
to be orchestrated in order to prevent further deterioration.
1. SOIL EROSION
Soil
erosion is the surface removal of productive soil by means of water, and wind
that is the prime environmental costs in agriculture. Soil erosion alone constitutes 86.5% of land
degradation that is considered the most serious hazard (Table 1). Approximately 5334 million tonnes of productive
soil is being carried away by erosion that accounts for 16.4 t/ha/year. The
eroded soils leaches out valuable plant nutrients to the tune of 5.0 to 8.4
million tonnes every year which accounts for Rs. 6,100 to 21, 600 crores of
estimated loss of money. The removed soil gets accumulated in the reservoirs
and thereby reducing their storage capacity by 1-2% every year. Erosion has
been accelerated in recent times by vegetation removal, over exploitation of
forest cover, excessive grazing and faulty agricultural practices.
Table
1: Soil degradation statistics (million hectares)
|
Types
|
1994
|
1997
|
|
Soil erosion
|
162.4
|
167.0
|
|
Salt affected soils
|
10.1
|
11.0
|
|
Water logging
|
11.6
|
13.0
|
|
Shifting cultivation
|
NA
|
9.0
|
|
Total
|
175.0
|
187.8
|
Sehgal
and Abrol (1994)
Government programmes introduced for
Soil Conservation
|
Year
|
Programme / Policies
|
Special features
|
|
1978
|
Desert Development Programme
|
Restoration of ecological balance by
harnessing, conserving and developing natural resources
|
|
1985
|
|
Policy planning for the scientific
management of the country's land resources
|
|
1985
|
|
Review
the implementation of ongoing schemes and programs connected with
conservation and development of land resources and soils
Formulate
a national policy and perspective plan for conservation, management and
development of land resources of the country
|
|
1985
|
National Wastelands Development Board
|
Formulate
a perspective plan for the management and development of wastelands in the
country
Identify
the waste land and assess the progress of programmes and schemes for the
development of wasteland
Create
a reliable data base and documentation centre .for waste land development
|
|
1988
|
|
To
devise an effective administrative procedures for regulating land use for
further deterioration
Allocation
of land for different uses based on land capability, productivity and goals
in order to restore the productivity of degraded lands
|
|
1989-90
|
Integrated Wastelands Development
Project
|
Adopt
soil and moisture conservation measures such as terracing, bunding etc.
Enhance
people's participation in wasteland development programmes
|
|
1992
|
Constitution(74th
Amendment ) Act, 1992
|
Regulation
of land use and urban planning brought under the domain of urban
self-governing bodies
|
|
1999
|
Department
of Land Resources
|
Formulation
of Integrated Land Resource Management Policies
Implementation
of land based development programs
|
Policy Suggestions to Prevent Soil
Erosion
The
erosion being the monstrous factor associated with soil degradation, it is
appropriate to develop holistic strategies to minimize the erosion hazard and
conserve soil productivity
·
Well-defined database and mapping of
various types of soil degradation hazard is very much required to develop
strategies that maybe widely adoptable. This task can be accomplished using
Geographical Information System (GIS) and Remote Sensing Techniques.
·
Encourage rural population and tribal
communities to utilize the non-conventional energy sources such as biogas
plants in order to prevent overexploitation of forest cover
·
Provision of incentives may be a cost
effective measure to encourage farmers to adopt soil conservation practices
·
Research should focus on the
sustainable farming practice "Integrated Crop Management " instead of
looking at the crop production system multi-dimensionally
·
Proposed land use policy should form a
basis for integrated approach comprising different components such as land,
soil and water
·
Despite huge sum of money has been
invested on watershed projects, the data generated from these programmes are
considered deficient and requires clarity.
A detailed database is required from each watersheds that enable the
policy makers to relate money invested and productivity gains.
2. NUTRIENT IMBALANCE IN INDIAN SOILS
In
the past fifty years, the fertilizer consumption has increased exponentially by
6 times from 3 (1950) to 18 million tonnes (2000) that commensurate with
four-fold increase in food grain output. It has been observed that the
indiscriminate use of nitrogenous fertilizers appears to affect the quality of
crops through nitrate pollution in the groundwater. A holistic approach is to
be adopted in order to maintain the balance between the crop removal and
addition of fertilizers. Balanced fertilizer application is imperative for
sustained productivity. In India ,
the problem is compounded by imbalanced fertilizer use, leading to widening of
NPK ratio from 5.9: 2.4: 1 in 1991-92 to 10: 2.9: 1 in 1996-97 as against the
optimum ratio of 4 : 2: 1 (Yadav, 2002). Most of Indian soils are deficient but
excessive use of N alone fails to produce sustainable yields over a long
period. Achieving balance between the nutrient requirements of crops and the
nutrient reserves in the soils is essential for maintaining high yields and
soil fertility, preventing environmental contaminations and sustaining
agricultural productions over the long-term.
The deterioration in soil health caused
by imbalanced fertilization has truly reflected on the annual yield growth rate
of several field crops that begin to stagnate over the past few years (Table
2). The data have shown that the decrease is annual yield growth rate of food grains
from 3.33 to 1.42%, from 2.47 to 1.28% in the case of non-food grains and from
2.99 to 1.34% in case of all crops. Cotton registered even a negative growth
rate. Despite the use of improved crop varieties and production technologies,
the declining trend is as a consequence of the deceleration in total factor
productivity. This is a serious concern in achieving targeted productions.
Table. 2: Average annual growth rate
(%) in yield of major crops of India
|
Crops
|
1980 - 1990
|
1991 - 1999
|
|
Cereals
|
3.43
|
1.63
|
|
Pulses
|
2.63
|
0.65
|
|
Oilseeds
|
2.73
|
1.62
|
|
Sugarcane
|
1.81
|
1.08
|
|
Cotton
|
3.56
|
-0.47
|
|
All Crops
|
2.99
|
1.34
|
(Swaminathan,
2000)
The
statistics on soil deterioration in conjunction with stagnation in crop yields
vividly suggest that there is an urgent need to bestow utmost importance to
balanced fertilization to enable sustainable farm productivity. Plausible
policies are to be orchestrated by both the Central and State governments to
reduce further deterioration in soil quality.
Suggested
Policies for the maintenance of soil nutrient balance
There
are new developments in the mission to maintain soil nutrient balance that
receive bountiful of appreciation from farmers, extension functionaries,
scientists and students. The following technologies are to be popularized both
by Central and State Governments.
·
Fertilizer subsidy to a specific
fertilizer may be avoided. Decontrol of nitrogenous fertilizers especially for
urea has triggered its excessive use in crop production with consequential
groundwater pollution.
·
The organic status of most Indian soils
has declined drastically due to continuous use of inorganic fertilizers. There
is an urgent need to integrate nutrient supply with organic sources to restore
the soil health. But the availability of organic manures (especially farm yard
manure) is scarce in many pockets of the nation that can be fulfilled by
alternate sources of organic manures such as vermicompost, composted coir
wastes and farm wastes may be encouraged.
·
Research on farm level nutrient balance
studies has to undertaken in order to assess the emerging trends in nutrient
deficiencies or toxicities in agro-ecosystems. The NUTMON tool box which is a
computer software that can generate nutrient balance to determine the nutrient
inflow and outflow in micro-level farming situations as well as regional and
national scale. The outcome of this research programme will be useful for
policy makers to plan for a sustainable nutrient management.
·
Appropriate computer-aided decision
support system can be lavishly used for scientific fertilizer prescription in
the mission of soil fertility management. The Tamil
Nadu Agricultural
University , Department of Soil Science
in Coimbatore , has developed a computer assisted
Decision Support System for Integrated Fertilizer Management (DSSIFER). The
DSSIFER is an effective tool to provide fertilizer prescription, ameliorative
measures for problem soil management and other improved agronomic practices for
cultivation of crops.
·
Suitable Government policies must be
evolved to distribute Soil Health Card (SHC) nation-wide to the farmers for
use. The SHC is similar to the ration card of a farm family who can make
entries of the nutrient management practices in the card on a regular basis to
enable them to identify the production constraints and take up suitable actions
for sustainable farming.
·
Encourage farmers to adopt Integrated
Nutrient Management (INM) practices to the maintain soil fertility and plant
nutrient supply to an optimum level for sustaining the desirable level of crop
productivity through the concomitant use of inorganic, organic and
biofertilizer inputs.
·
Biofertilizers offer an economically
attractive and ecologically sound means of reducing external inputs and
improving the quality and quantity of internal resources. These are bioinputs
that are mobilizing nutrients from non-usable to usable through biological
processes. The beneficial microbes include N fixers, P solubilizers and
mycorrhizas that could be able to save inorganic sources of nutrients by 25-30%
with an additional benefit of environmental safety.
·
Research priorities should include
developing recommendations and technologies for fertilizer and organic matter
management for specific soils, climate and crops as part of precision
agriculture.
.
3. MICRONUTRIENT STATUS OF INDIAN SOILS
In
India , the continuous
cultivation of crops with high analysis straight fertilizers has pronounced a
sharp decline in availability of micronutrients in soils and this associated
with a reduction in nutritional qualities of agricultural produce and crop
yields (Anon, 2003). It
has been reported that the occurrence of micronutrients deficiencies in Indian
soils to an extent of 46%, 9%, 5% and 4%, Zn, Fe, Cu and Mn, respectively
(Singh and Saha, 1995). Consequently, both the production and consumption of
micronutrients have increased by 30% in three years during 1999 - 2001.
Correction of micronutrient disorders is gaining importance and of utmost need
for sustainable farm production. Among the micronutrients, Zn appears to
be deficient in most soils in India
at varying intensities with the exception of acidic soil regions where the Zn
status is at the moderate level. The inherent ability of the soil to supply
boron and sulphur is at the declining trend and requires replenishment.
Augmentation or restoration of lost soil fertility and productivity can be
achieved only through addition of micronutrient fertilizers and mobilization of
their residual effect through proper nutrient cycling. The applied
micronutrient in the soil is often unavailable to the crop plants due heavy
fixation in soils. Consequently, the micronutrient use efficiency by plants is
extremely lower. To make the situation more complex, multiple micronutrient
deficiencies are more prevalent than as a single nutrient deficiency.
The response to soil application of
micronutrients is vividly indicated in field experiments conducted at the Tamil Nadu Agricultural University ,
Coimbatore Centre of the ICAR-Micronutrient Scheme in the past four decades. The
data have shown that Zn application has enhanced the yield of rice, pulses,
millets, oilseeds and turmeric to the tune of 25%, 20%, 16.7%, 17.3% and 14.4%,
respectively. The response to added Zn is often associated with deficiencies
below its critical levels in soils. Thus, addition of Zn is imperative in order
to maintain crop yields in various production systems. Next to the Zn, Fe
application appears to promote yields of millets and sugarcane by 30% and 40%
respectively. The deficiency of Fe is often associated with lime status. As
millets and sugarcane are quite sensitive to Fe, they exhibit interveinal
chlorosis as a consequence of calcium induced Fe deficiency. In addition to the
soil application, foliar sprays were found to correct nutrient disorders in
crop plants. The response was more pronounced for pulses than other crops. In
addition, pulses have responded favourably to foliar spray of Mn and Mo.
Suggested policies in micronutrient management
·
Delineation of micronutrient
deficiencies in India should
be done to create a database as a reference tool for policy making. The ICAR
has 15 micronutrient centres of which Tamil
Nadu Agricultural
University , Coimbatore ,
is one of the oldest Centres carrying out micronutrient research for the past
40 years. The data from various centres can be used to develop database on
micronutrient status of Indian soils. The GIS technology may be employed to map
the micronutrient deficient regions at the micro and macro levels.
·
Popularization of computer-assisted
software for the identification nutrient disorders in crop plants should be
taken up all levels. The Tamil Nadu Agricultural
University , Department of Soil
Science, Coimbatore , has developed an innovative
computer aided Visual Diagnostic Kit (VDK) that can be used for the
identification of nutrient deficiencies and to derive suitable remedial
measures. Besides it is a user-friendly tool for the farmers, students,
researchers and extension workers to precisely identify nutrient disorders in
crop plants.
·
Research on multi-micronutrient product
formulations including chelating compounds has to be carried out in various
cropping situations. This may be an effective technology to ameliorate
multi-micronutrient deficiencies and sustain farm production.
·
Studies on economizing micronutrient
use through seed pelleting and foliar sprays may be taken. As the utilization
of micronutrients by plants is relatively smaller these agro-techniques may be
useful in curtailing costs with an added benefit of highest rate of use
efficiency.
4. ORGANIC FARMING
In India ,
there are also efforts to return back to the organic agriculture in order to
improve the quality of food production and to promote nutritional security and
ensure sustainability. It’s the concept of “Merry Go Around”. Organic
production system largely excludes the use of synthetically compound
fertilizers, pesticides, growth regulators and livestock feed additives. To the
extent possible, organic farming rely on crop rotation, crop residues, animal
manures, biofertilizers, botanicals and biopesticides to maintain soil
productivity and tilth, to supply plant nutrients and to control weeds and
pests. The organic agricultural products fetched US $ 17 billion in the global
market in the year 2000 that is likely to double in five years reaching a
figure of US $ 31 billion in 2005. Over 50% of the global share comes from the USA India ’s share is meager 0.001%. India is ranking 75th position in the
global organic agriculture scenario. Why there is a vertical shift required
from inorganic to organic? The Indian agriculture is beginning to show a sign
of yield stabilization, imbalance in soil nutrient status, loss of nutritional
security and livelihood of people. India ’s
organic production has touched 14,000 tonnes in 2002, of which 11,000 tonnes
had been exported. The exported organic produce includes coffee, tea, rice,
wheat, pulses, oilseeds, fruits, vegetables, cotton and herbal extracts. India is a highly bidiversified country
producing a wide array of oriental vegetables and fruits that has greater
export market potential. Organic farming is essential to promote
export-oriented agriculture and stimulate livelihood of the farming
communities.
The organic farming in relation of
food security of India is
yet to be established. The primary concern for any Government is to meet the
food requirement of the people and to ensure hunger free situation in any
nation. To maintain current rate of food grain production in India without chemical fertilizer input,
additional area has to be brought under cultivation that is hardly possible to
achieve (Chhonkar, 2003). Almost all long-term fertilizer experiments conducted
by ICAR centres in the country have vividly demonstrated that the integration
of organics and inorganics can produce reasonably higher yields and maintain
soil fertility. Despite organics are indispensable in agricultural production
system, the realization of its fullest potential is yet to be seen in
sustainable grain productivity.
Suggested policies in organic farming
·
Policy initiatives are required to
demonstrate at the commercial scale that how best the organic agriculture can
minimize or eliminate usage of chemicals and costs involved in agricultural
production systems.
·
Efforts are to be geared up to enhance
the availability of non-conventional (coir waste compost and vermicompost) and
conventional (green manure) sources of organics.
·
Intense research is necessary to
unequivocally prove the nutrient utilization pattern and quality improvement in
organically grown agricultural produce.
·
Research on organic production package
for exportable crops such as sugarcane, fruits, vegetables and medicinal plants
is very much required
·
Organic certification centres have to
be established in various export zones with a complete set of administrative
and analytical facilities as is the one in Tamil
Nadu Agricultural
University , Coimbatore .
·
Laws and legislation should be in place
to monitor the organic production and marketing of agricultural produce
CONCLUSIONS
The soil degradation is increasing
at the alarming proportion and needs to be circumvented to sustain agricultural
production in India . Among
various factors responsible for soil degradation, erosion appears to be the
first and deserves governmental and non-governmental agencies to take immediate
steps to minimize the hazard. Currently, several policies are in place without
much impact at the large scale. Maintenance of soil nutrient status may be
possible by adopting recently developed innovative site-specific nutrient management
approaches. Micronutrient fertilization seems to contribute one-fifth of the
total agricultural output deserves much more significance in the years to come.
Timely identification and ameliorative measures are required to minimize the
loss in crop productivity. Organic movement is gaining momentum in India and its applicability is more rationale
and reasonable for export oriented agriculture. Sustainability in food security
in relation to organic farming is yet to be established.
REFERENCES
Chhonkar, P.K. (2003)
Organic farming : Science and belief. J. Indian Soc. Soil Sci. 51: 365-377.
Singh, M.V. and Saha, J.K. (1995)
Twenty sixth progress report of the All India
Co-ordinated
Scheme of Micro- and Secondary Nutrients and Polluted elements in the Soils and
Plants. Indian Institute of Soil Science, Bhopal .
Swaminathan, M.S. (2000)
Inaugural address at the International Conference on managing Natural Resources for Sustainable Agricultural
Production in the 21st Century, New
Delhi .
Yadav, J.S.P. (2002)
Agricultural resource management in India
- The challenges. J. Agric. Resource
Management. 1: 61-69.
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