Download Organic Cultivation of Cotton

Organic Cultivation of Cotton
Cotton, the most important fibre crop of India plays a dominant role in its agrarian
and industrial economy. It is the backbone of our textile industry, accounting for 70%
of total fibre consumption in textile sector, and 38% of the country's export, fetching
over Rs. 42,000 crores. Area under cotton cultivation in India (8.9 million ha) is the
highest in the world, i.e., 25% of the world area and employs seven million people for
their living.
Merits of Organic Cotton Cultivation
(A) Environmentally Friendly Technology
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Due to excessive use of fertilisers and insecticides, all the elements of the agroeco system gets polluted by the conventional method. Organic cotton
production relies on non-chemical inputs and will decrease pollution hazards.
Pesticides residues in fibre may cause carcinogenic damage to users. The use of
bio-rational products and biocontrol agents for pest management in organic
farming will cause no such effects.
Large scale discharge of untreated and unprocessed effluents by textile industry
and dyeing units has not only caused health problems to man, cattle and fish
in the rivers and canals, but yields of cotton are reported to be affected due to
polluted water that is used for irrigation.
Destruction of beneficial soil organisms may cause damage to soil health
creating imbalance in the natural population of predators/parasitoids of cotton
pests. Organic farming helps to restore or preserve the natural equilibrium
between different components of the ecosystem.
(B) Reduction in Cost of Cultivation
Modern production technology has lowered the cost-benefit ratio of cotton production.
Farmers in Andhra Pradesh, Punjab, Maharashtra etc. are reported to have committed
suicide due to escalation of production cost without occurring commensurate profit
from cotton cultivation. On the other hand, organic farming creates rural
employments and uses of on-farm resources to make it more cost-effective.
(C) Management of Insecticide Resistance
Due to indiscriminate use of hazardous insecticides for controlling cotton pests, the
resistance of insects against the insecticide hiked up and in turn compelled the use of
more number of sprays, and thus a vicious cycle is created, escalating cost of
cultivation. Organic farming will help in reversing this trend. Evidences on poorer
choice of multiplication rate of pests on organically grown cotton are encouraging
factors to pursue this protocol.
Approaches for Farming of Organic Cotton
Since organic cotton production warrants the cultivation in the absence of agrochemicals, it involves a careful selection of components of farming system keeping the
local resources, agro-climatic features and socio-economic structure for the formation
of a suitable package as follows:
1] Selection of site
Fields with high degree of soil erosion and heavily infested with perennial weeds
should not be put under organic farming. Organic farming is not a farming by neglect
or arm-chair cultivation and so, fertility levels of less fertile soils should be improved
through organic means before opting for this type of cultivation.
2] Varietal selection
High yielding varieties, which respond well to chemical inputs, may not always be
suitable for organic farming. Instead, varieties which are hardy and capable of giving
acceptable farming especially in the early phase of conversion are ideal. Varieties,
which are jassid-tolerant, can be preferred over susceptible ones. Early maturing
varieties are less exhaustive and will also help the crop to escape heavy bollworm
damage.
3] Seed rate and sowing
Acid delinted seeds cannot be used according to international norms (e.g. IFOAM) for
organic cultivation for the purpose of certification of the fibre. However, those farmers
who pursue organic farming for reducing the cost of cultivation and to increase the
profitability could use acid-delinted seeds in order to avoid seed borne pathogenic
infections and achieve optimum plant stand. If fuzzy seeds are used, however, higher
seed rate is to be used in order to achieve the same goal. About 25 kg/ha of seeds at
75x15 cm spacing ensures a final plant population of 85-90 thousand plants/ha. One
row of fodder cowpea (Vigna unguiculata) should be drilled between two rows of cotton.
This crop could be ploughed down and buried in soil just before its flowering.
4] Manuring
To realise economical production, soil fertility has to be maintained and gradually
improved. Improvement and maintenance of organic matter of the soil is important in
organic cotton production, as this would increase physical parameters of soil, improve
soil structure and enhance nutrient supply. Since huge amounts of FYM to meet
nutrient requirement of the cotton crop is not generally available, a combination of
sources with different biological properties should be preferably used. Organic
manures (FYM, compost, Vermicompost), in situ green manuring, cowpea and
Biofertilizers along with fertility restoring crop rotations form the components for
maintaining soil fertility.
a] Farm yard manuring (FYM)
FYM @ 15 t/ha must be added before preparatory tillage and mixed thoroughly. FYM
should be well decomposed and should be preferably treated with composting
organisms such as Trichoderma viride. The rate may gradually be brought down 5-10
t/ha, once the farm yield stabilises over a few years.
b] Fodder cowpea
In situ green manuring with fodder cowpea and its burying at 40 days after sowing
[DAS] will ensure a steady N supply during the grand-growth phase and flowering
period, when the N demand peaks up in the crop. It hastens microbial activity in soil,
reduces weed growth and enhances natural enemy build up. This provides around
400-500 kg dry matter per hectare with 2.5% N and contributes 10-12 kg N/ha during
squaring. Its additional benefits include smothering of weeds, controlling seasonal soil
erosion and nurturing natural enemies of cotton pests.
c] Dhaincha (Sesbania aculeata)
Dense stand of this legume can be raised around cotton field at a width of 2 m; its
lopping cut and spread between cotton rows at 65-70 DAS. Its fast decomposing leaves
provide N during early boll development period and stalks act as temporary mulch,
preventing soil moisture evaporation.
d] Vermicompost
Vermicompost @ 1-2 t/ha should be added supplementing FYM on the furrow lines on
which sowing is done. Its nutrient composition varies with substrate that is
verrmicomposted, but generally contains several diverse microflora that aid in good
plant growth. It offers good scope for recycling of farm waste.
e] Biofertilisers
Seed inoculation of Azatobactor or Azospirillum @ 200 g/seed required for sowing one
acre is recommended.
5) Technology for Composting
(i) Vermicompost
Reliance on green biomass and farmyard manure is a sure method of increasing soil
organic content. However, under the existing conditions, these requirements are not
fully met with. Enormous quantity of farm wastes and organic residues are simply
burnt. In order to utilise farm wastes and organic residue for being recycled into
compost, the modern thoughts are for utilising earthworms and fungus that are
habituated to such conversion. Promising Indian species, Eisenia foetida can convert
organic wastes into vermicompost in about one month's time and convert anything
except plastic into compost.
Since preparation of vermicompost utilising any of the above species can be a very
promising endeavour in rural areas, in addition to meeting the compost requirement of
one's own farm, it is desirable to take this up as part of organic farming. The brief
details regarding vermicomposting techniques is as follows.
Vermicompost can be made in raised beds of 15-25 cm height. The length and width
can vary according to the quantum of wastes available for composing. Beds of 6x2 m
are ideal. These beds should be made slightly raised at the centre and sloping towards
the sides (to facilitate effective drainage), preferably under shade. As earthworms do
not relish light, it is advisable to keep the pits covered. Darkness also reduces the
composting time.
A soft bedding material with wheat/soybean straw is added as the first layer. This
should be followed by a thin layer of cow dung slurry. Earthworm culture @ 1 kg/10m
length of bed (2m wide) is then added. Earthworm cocoons or starter inoculant worms
from vermi compost can also be used. Weeds, leaves chopping, farm wastes,
household wastes and other degradable materials can be continuously added on the
top. Water should be sprinkled periodically to keep the beds slightly moist, but never
wet. Under ideal moist and temperature conditions (27-33° C) the composting time
would be 40-50 days. Earthworm castings contain approximately 2.0-2.5% N, 2.5-2.9
per cent P2O5 and 1.2- 1.4% K2O, the exact composition varies according to the
substrate and composting conditions. The excreta of organisms contain more N
content over their level of consumption of N as in vermi castings too.
(ii) Composting of cotton stalks through Trichoderma viride
Cotton stalks are burnt as fuel after picking of seed cotton is over. This residue
together with farm wastes from other crops and weeds can effectively be utilised for
preparing compost, through the use of beneficial fungi like Trichoderma viride. The
technique, as developed at CICR, Nagpur is briefly described.
In a pit of 10 x 2 x 1m in size, dried cotton stalks from 2 hectare area are filled in four
layers interspersed with other soft farm waste, such as sorghum stubble, linseed
straw and soybean pod-haulms (to fill the gaps in between cotton stalks) and 50 kg of
cow dung (to provide a soft substrate for initial multiplication of the fungus). Each
layer was sprinkle inoculated with 2.5 kg T.viride wettable powder in 60 litre water
mixed with half-kilogram jaggery and 15 g yeast. The pit is finally covered with one
foot layer of sunhemp stalks for checking water loss. Periodic watering is made to
maintain sufficient moisture in the pit and turning of the top layer at least once during
the decomposition process.
In the span of four months, most of the cotton stalks are converted into compost, the
rest (20%) being black, brittle, semi-decomposed stalks. This compost is comparable to
well-decomposed vermicompost. It could be used for nutrient recycling, antagonistic
fungus against certain soil-borne pathogens, viz., Fusarium spp., Rhizoctonia spp. etc.
6) Weed Management
Fields not infested with perennial weeds such as Cyperus sp. (Motha), Cyanodon
dactylon (Doob) and Sachharum sp. (Kans) are preferred for organic farming as these
are difficult to control. However, if such weeds occur in patches, their underground
propagatory structures (stolons, rhizomes etc.) must be exposed by summer
cultivation and manually removed. Mechanical/manual weeding as per existing
practice may be adopted. Composting can recycle the weeds removed. It must be
ensured that the FYM, compost added is completely decomposed, otherwise many
seeds of annual weeds, introduced through FYM, will germinate and aggravate the
weed problem. Growing a crop of cowpea between 2 rows of cotton will also suppress
the early emerging weeds.
7) Selection of rotations
Crop rotations play a very important role in restoring soil fertility and minimizing
damage due to insect pests and weeds. High nutrient-exhaustive rotations must be
avoided and instead rotations with a legume that is recommended for the locality may
be adopted.
8) IPM strategies for crop protection
The crop protection to reduce the damage due to insect pests to organically cultivated
cotton revolves around the use of bioagents such as predators such as Chrysoperla sp.
or Apertochrysa spp., egg parasitoids such as Trichogramma, larval parasitoids such
as Habrobracon spp. or insect pathogens such as Helicoverpa armigera Nuclear
Polyhydrosis Virus [NPV] and a bacterium, Bacillus thuringuiensis var. kurstaki (B.t.k.)
formulations along with utilisation of bird perches and botanical insecticides like
neem products.
Avoidance of pesticide application by introducing biocontrol agents, either by natural
augmentation processes or by artificial releases increased the stability of cotton
cultivation. The basic concept of conserving natural mortality agents of pests can be
achieved in organic cotton cultivation, primarily by reducing insecticide application.
These toxicants destroy both, pests and their natural enemies, and so, are not
desirable for common use. To sum up, the following pest suppression strategies are
recommended for organic cotton cultivation.
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Select a reasonably jassid tolerant cultivator.
Release of Chrysoperla spp. @ 500-1000/ha according to the intensity of jassid
damage between 20-25 days of crop growth once. For jassid susceptible
cultivator, this may be released after 35 days.
Release Trichocards @ 5/ha once at 45-50 days and then after 10-12 days,
twice more in order to kill bollworm eggs.
Spray H-NPV @ 250 larval equivalent (LE) [1LE= 200 crore (109 ) Poly Inclusion
Bodies [PIBs] or Poly Occlusion Bodies [POBs] when very young larvae of
American bollworm are spotted. This could be repeated after every 15 days for
retaining good inoculum of the pathogen. This could be alternated with any
commercial B.t. formulation @ 1.5 l/ha.
Release of Habrobracon hebator is also useful for controlling growing bollworm
larvae and other caterpillars damaging leaves and flowers.
Placement of bird perches @ 5-6/ha would help in increasing the predatory bird
visit in cotton fields.
The need-based botanical insecticides, seed kernel extract is used at 5% v/v or
1-% oil are very useful to deter pest activity in the crop.
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Monitoring of bollworm using the respective pheromone traps would give a clue
regarding their first occurrence in a season in order to initiate adequate and
suitable crop protection measures.
One of the important cultural practices that is desirable is to depot the crop
that has grown beyond 80 days. This would reduce the egg laying of H.armigera.