Why cotton is a problematic crop?
By Muhammad Amjad Ali & Dr Iftikhar Ahmad Khan
COTTON,
which is also known as ‘white gold’, is an important crop in
many developing countries. The yield of the crop is
dependent upon the environment in which it is grown and the
management practices of the cropping system.
Cotton yields are stagnant for the last several years.
Factors responsible for the stagnant cotton production
include: excessive rain at the time of sowing, high
temperature at flowering stage, late wheat harvesting
resulting in decline of area under the crop, leaf curl virus
incidence, soil system, weather adversaries, pest attack and
improper production technology in major cotton growing areas
of Punjab and Sindh. There are many social as well as
economic problems facing cotton production including,
illiterate farming community, high cost of inputs, small
landholdings, less adoptability of innovations by the
farmers, lack of guidance to farmers, high cost of
production and insecurity in the market, the cost of
production being the most significant among them.
In recent past two major factors had a significant impact on
the economics of cotton production. They are extensive use
of agrochemicals and yield stagnation. Among all
agrochemicals, fertilisers and insecticides are of utmost
importance. There are no efficient alternatives to synthetic
fertilisers and cotton production has to bear the use of
nutrient supplements in the form of inorganic fertilisers.
Among pesticides, insecticides are group of agrochemicals
which is extensively used on cotton.
Insects, being living organisms, have adjusted with the
injurious chemicals and learned to survive with
insecticides. Consequently, insecticide use kept increasing
causing a serious impact on the economics of cotton
production. Currently, there is a greater need for new
developments in production research but more and more
researchers are confronted with maintaining the current
status of yields in their countries. The cost of production
has increased to unacceptable levels in many countries that
threaten the economics of cotton production.
Cultural Problems: There are also many aspects which can
affect fibre quality and yield. Agronomic practices
affecting the yield include sowing time, low quality and
adulterated seed, timing of harvest, irrigation, use of
plant growth regulators, soil fertility, tillage, and
cultivar selection.
Currently cottonseed must be delinted to be used in modern
planting equipment. The two most common methods are wet acid
delinting using sulphuric acid and gas delinting using
hydrogen chloride. There are several possible problems
associated with acid delinting including damage to seed
quality by improper procedures during the acid delinting
process, damage to the seed by ammonia during the
neutralisation process, worker safety concerns, and disposal
issues.
Seed germination: Seed dormancy is a significant factor
involved in germination of cotton crop. Additionally, some
forms of cotton may produce ‘hard seeds’ that, upon drying,
become impermeable to water and suffer delayed germination.
Priming improved emergence and early growth of maize and
cotton in drying soils in the laboratory. On-farm seed
priming can partly compensate for the negative effects of
low soil water potential and large aggregate sizes on crop
establishment. Some studies have shown that
conservation-tillage systems can also decrease cotton yields
by increasing soil compaction and reducing water
availability.
Pests: Cotton is a pest-loving plant and due to this habit
it has become a problematic crop for the farmers. More than
1326 species of insects have been reported in commercial
cotton fields worldwide but only small proportions are
pests. Of the 30 pests of cultivated cotton the most
important are the caterpillars of pink, spotted and American
bollworms, aphids, whitefly, jassids, mealy bugs and the
spider mite.
The bollworm/budworm complex is a primary insect pest
problem with larvae attacking squares and bolls causing
significant yield losses if left uncontrolled. The cotton
whitefly is a pest of primary importance for fibre,
horticultural and ornamental crops worldwide. It can cause
extensive damage through direct feeding, honeydew production
and as a viral vector.
Pink hibiscus mealy bug is an emerging threat to the cotton
crop. Its host records extend to 76 families and over 200
genera, with some preference for Fabaceae, Malvaceae and
Moraceae. Growing points infested with cotton mealy bug
become stunted and swollen. This varies according to the
susceptibility of each host species. Plant protection
products are of limited effectiveness against the bug
because of its habit of hiding in crevices, and the waxy
covering of its body.
Poor spraying techniques and over-use of chemicals has led
to the pest becoming resistant to most of the available
insecticides. Seeing their crops devastated by bollworms,
and desperate to salvage something from their losses,
farmers have continued to buy more toxic (and expensive)
chemicals and to spray more frequently, but with decreasing
effectiveness.
Diseases: Never has a single pathogen or insect pest
threatened Pakistan's cotton culture, as has the cotton leaf
curl virus (CLCuV). In 1993-94, about 0.89 million hectares
were badly damaged resulting about two million bales loss in
production due to CLCuV. In economic term, the country had
suffered a loss of about 7.6 million bales, which costs to
the tune of Rs71 billion since 1988 due to the infestation
of CLCuV. Yield decreased from1.938 million metric tons in
1991 to 1.445 million metric ton in 1992 and fell further to
1.105 million metric ton in 1993.
Recently, cotton leaf curl virus has again emerged as a key
disease in the province of the Punjab in general and
Burewala area in particular. The re-emergence of virus
commonly called as Burewala Strain of Cotton Virus (BSCV)
has dangerous version and could develop into a serious
problem.
The continued use of CLCuV-susceptible varieties without any
programme of their replacement constitutes a major risk for
cotton production in Pakistan. So a premier focus should be
given to eliminate the CLCuV disease and a well-planned
programme of evolution and introduction of CLCuV-resistant
varieties of desired characteristics must be in place to
gradually replace the existing CLCuV-susceptible varieties.
This is only the sole and the most promising and least
expensive method of disease suppression.
Other important diseases are seedling diseases caused by the
fungi Pythium and Rhizoctonia, Black root rot, Fusarium wilt
and Verticillium wilt, Alternaria Leaf spots and Bacterial
blight.
Abiotic stresses: Water deficit, in conjunction with high
temperatures and incident radiation, poses the most
important constraint to plant survival and crop
productivity. Cotton crop was affected by drought and there
was yield reduction of 1.1per cent during the year 2003.
Drought stress causes severe shedding of small squares,
resulting in a decrease in flowering. An understanding of
the response of plants to water deficits is important in
efforts to model cotton growth, estimate irrigation needs,
and breed drought-resistant cultivars.
Although the cotton plant is a “sun-loving” plant, an
excessively higher temperature at reproductive phase (above
36oC) decreases its production significantly. According to
an estimate, cotton plant sheds about 65–70 per cent of its
fruiting points due to heat-induced sterility, spotted
bollworm attack and increased humidity during monsoon. High
temperature disrupts the movement of water, ion, and
inorganic solutes across the plant membrane, which
interferes with photosynthesis and respiration. Clearly, an
increase in high temperature at the reproductive phase is
the major factor of low productivity of cotton varieties
grown in the cotton belt of Pakistan.
Soil and fertility: Several soil conditions and farming
practices in Pakistan are perceived as being likely to
induce micronutrient deficiencies, including high soil pH,
calcareousness of soils, low soil organic matter and use of
fertilisers poor in micronutrients. Boron contents of soils
and plants from light and medium textured soils were less
than the critical levels. High soil pH, calcareousness and
low organic matter in such soils might be rendering the B
less available to the plants.
There may be less availability of phosphorus (P) in a
rapidly drying soil due to reduced P diffusion and poor
uptake by roots. This may result in inadequate P nutrition
for cotton plants.
Nutrient-poor, degraded, and often acidic, soils limit crop
production in many tropical regions. Limiting amounts of
phosphorous and excessive levels of aluminium are
characteristic problems of acidic soils.
Saline soils are found naturally in many locales and have
been created in others by poorly managed irrigation. Both
the timing and method of application of fertiliser are
important, though some evidence suggests that one method may
be better than the other under particular circumstances,
most of the literature suggests that timing of applications
of fertilizer is a much more important determinant of yield
response than method of application.
Salinity affects large areas of irrigated land, and is a
particular problem in NW India and in Pakistan, where it is
often combined with water-logging. The two stresses together
have far more severe effects than either alone: root ability
to screen out salt is much reduced, and lack of O2 leads to
metabolic problems.
In Pakistan, about 6.3 million hectare was affected by
salinity, and groundwater in most of these saline areas is
brackish and thus unfit for irrigation. So current cropping
intensities and groundwater usage in irrigated agriculture
are not sustainable due the problem of salinity.
Environmental and health hazards: During July-March,
2005-06, 17,900 and 36,000 tons of agricultural pesticides
were imported and locally formulated and most of them were
applied on cotton. Chemical pesticides affect human health
as well as biological diversity and surface and groundwater
quality. Some pesticides leave persistent residues in soil,
groundwater, and the food chain, thus exposing human
population to slow and cumulative poisoning (WTO).
Pesticides also affect wildlife, domestic animals, and
biological diversity. Pesticide poisoning remains a daily
reality among agricultural workers in developing countries,
where up to 14 per cent of all occupational injuries in the
agricultural sector and 10 per cent of all fatal injuries
can be attributed to pesticides.
Marketing: Between 1960–64 and 1999–2003 real cotton prices
fell by 55 per cent, quite similar to the 50 per cent
decline in the broad agriculture price index of 22
commodities. The grower-to-market links are usually absent,
and the research-extension-grower links essential to the
transfer of technology are often weak.
It is found that the incidence of poverty among cotton
growers could rise in the short run from 37 per cent to 59
per cent while the average incidence of rural poverty could
rise from 40 per cent to 48 per cent. So it appears that
cotton growers are heavily taxed both directly, through the
lower prices received by the state company which purchases
cotton and indirectly through the (likely misaligned)
exchange-rate regime. This assessment is shared by a recent
report which concluded that only one third of the world
price of cotton reaches the producers.
Strategies and prospects: Considering such a high importance
of the cotton crop in the national economy, the problems and
issues pertaining to this crop should be very carefully
evaluated and monitored.
The main objectives of government are overcoming the
scarcity of water through augmentation and conservation
means i.e. by construction of medium and large dams and by
efficient utilisation of irrigation water, restoring the
productivity of agricultural land through control of water
logging, salinity and floods.
The government should also provide farmers with the credit
facilities that they might be able to purchase good quality
inputs to raise high yielding stands of the crop.
Threshold-based sprays against the main pests, the use of a
cotton growth regulator, and earliness of cotton cultivar
and seed treatment are accountable for savings in pesticide
sprays. Bt cotton varieties should be locally developed and
distributed among the farmers to avoid the high incidence of
bollworms.
There are various management practices that should be
followed to help mitigate some of the environmental risks
associated with growing cotton. They include selection of
adapted cultivars, planting within the recommended range of
favourable planting dates and environmental conditions, use
of seed and seedling protectants to avoid stress or early
season diseases and insects, use of effective pest
management tactics to avoid competition and damage by weeds
and insects, management for optimal soil moisture, proper
fertility management, and management for maturity and
readiness for harvest at optimum times.
One of the tools used in reducing environmental risks and
increasing the possibilities of a profitable yield is
cultivar development through breeding and genetics. Breeding
for heat, salinity and water logging tolerance accompanied
with higher percentage of seedlings will emerge to produce
even and uniform plant stands. Grower-to-market and the
research-extension-grower links are essential to avoid
farmer against the clutches of middleman and to the transfer
of technology.
Courtesy: The DAWN
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