Everything you need to learn about the cotton cultivation, harvest and growth.
Introduction to Cotton (Karpas, Kapas):
Cotton is the oldest and the most important commercial crop of the world. It has been grown in India in the Indus valley for more than 5,000 years. It is considered to be indigenous to south-east Asia and also to South and Central America. The crop is grown chiefly for fibre in many countries of the world, of which the principal ones are USSR, USA, China, India, Brazil, Pakistan, Turkey, Egypt, Mexico and Sudan.
These countries account for nearly 85 percent of the total world production. In acreage, India, which now grows nearly 7.5 million hectares, ranks first among the cotton-growing countries. With regard to production, however, it occupies the fourth position. The crop is grown in this country from the sub-Himalayan region in the north to the Cape Comorin in the south, the major cultivation being confined to the Peninsular or southern India.
A cotton fibre is a single-celled hair, a delicate tubular prolongation of the epidermis of the outer integument of seed. It may be of varying lengths, the maximum being about 51 mm. The fibre has characteristic twists and is commonly referred to as lint fibre. The lint hairs are mixed with some much shorter hairs known as fuzzy hairs, which do not exceed 10 mm in length and, unlike the former, lack the twists.
Cotton fibres are obtained on a commercial scale from the four cultivated species of the genus Gossypium, belonging to the family, Malvacear. Varieties of these four species of Gossypium, namely, arboreum and herbaceum of the Old Word and hircutum and barbadense of the New World, are grown in India.
Of these species, G. hirsutum occupies the largest area, roughly about 50 percent of the total cotton acreage in the country. This is followed by G. arboreum and G. herbaceum, with 29 percent and 21 percent respectively. G. barbadense occupies a few thousand hectares only.
Climate, Soil and Season Required for Cotton Cultivation:
Cotton is grown as a tropical and sub-tropical crop. A temperature range of 21° to 27°C is required for good vegetative growth and a lower temperature than 21°C is harmful to it. Warm days and cool nights during the period of fruiting are beneficial to boll and fibre development.
The crop requires sufficient rainfall during the early stages and a comparatively dry weather during flowering and fruiting. A minimum rainfall of 50 cm is required by the unirrigated cotton, which occupies about three-fourths of the total area under the crop in India. The distribution of rainfall is extremely important for obtaining good yields from the unirrigated cotton.
Cotton grows on different kinds of soils. While black cotton soils and medium black soils are suitable for the rain-fed crop, alluvial soils are suitable for the irrigated crop. Cotton is grown predominantly on alluvial soils in Punjab, Haryana, and Rajasthan and UP; on black cotton soils and red sandy loams to loams in Gujarat, Maharashtra, MP, AP, Karnataka and Tamil Nadu; and on lateritic soils found in parts of Tamil Nadu, Assam and Kerala. The crop cannot stand water – logging and hence the soil should be well-drained. Cotton can grow normally if the soil pH varies from 5.5 to 8.5.
Cotton is raised essentially as a kharif crop in most of the states in the country. The irrigated crop is sown in these areas from March to May and the rain-fed crop from June to July. In Tamil Nadu, a very large portion of both the irrigated and the rain-fed crops are sown in September – October. Sowing of the summer crop in the state is done during February – March.
Cotton is grown in rotation with a number of other crops. In the irrigated areas of Punjab, Haryana, UP and northern Rajasthan, cotton is rotated with wheat, jowar, or wheat and toria. A beneficial effect is produced on cotton if the preceding crop is berseem or guar. In the central and western parts of the country, jowar, bajra, wheat, gram or sesame is grown in rotation with cotton. In many parts of central India, cotton is grown in mixture with maize, jowar, sesame, pulses or vegetables. In the south, intercropping with ragi, other millets or groundnut is quite common.
Cultivation of Cotton:
In northern India, land for the irrigated cotton crop, which follows wheat, is prepared hurriedly since the time available after the harvest of wheat is quite short. The land is first irrigated heavily and then ploughed once or twice. Another light irrigation is given, which is followed by one or two ploughings and planking. These operations complete the preparation of the land.
In the areas with black cotton soil in central and southern India, land for the rain-fed cotton is prepared by harrowing the field with a blade harrow 3 or 4 times. A deep ploughing is necessary for the land, once in 4-5 years, for removing weeds. The red and lateritic soils of the south, in which little moisture is present, are given 2-3 light ploughings or harrowing for growing cotton as a rabi crop.
The seed is generally sown by broadcasting. It may also be sown in rows with a seed- drill or by hand. For the irrigated cotton, a seed rate of 15 to 25 kg per hectare and a spacing of 75 to 90 cm between rows are generally recommended, whereas for the rain-fed desi cotton, the seed rate is 12 to 16 kg per hectare and the spacing is 45-60 cm. In the case of the rain-fed American cotton, 12 to 16 kg seed is sown per hectare with spacing of 60 to 75 cm between the rows.
Manuring:
The cotton crop is not usually manured adequately in most areas. Since the cotton-growing soils are generally deficient in nitrogen and organic matter, but not in phosphate and potash, it is necessary to apply the first two in order to push up the yield.
A leguminous crop, raised for green manuring purposes or as a crop in rotation preceding cotton, increases the yield of the latter. Farmyard manure is now applied by certain progressive farmers at the rate of 6 to 12 tonnes per hectare to the rain-fed crop and 15 to 25 tonnes to the irrigated crop.
Of the chemical fertilizers, nitrogen is very important for increasing the yield of cotton. Application of 40 kg nitrogen per hectare to the irrigated crop and 20 kg per hectare to the rain-fed crop has been recommended. A higher dose of 60 to 100 kg is economical in north India. For the irrigated crop, it is economical to apply nitrogen in two equal split doses, first one as basal dressing at the time of sowing and the other one as top dressing during thinning or just before flowering.
Interculture:
The crop must be kept absolutely free from weeds. Regular inter- cultivation is, therefore, done with a blade-harrow, a three – tined hoe or a desi plough. Hand weeding is also sometimes done. Inter-cultivation checks the growth of weeds and also helps soil aeration. In some areas, weedicides like Diuron, Ansar – 529 and Toke E-25 have been used successfully for the control of weeds.
It is desirable to undertake thinning of plants for maintaining optimum plant- population. During this operation, which is specially done in the case of the irrigated crop sown on ridges in Peninsular India and in certain parts of Gujarat, weak seedlings are removed.
Irrigation:
Timely and optimum moisture supply to the irrigated cotton crop is extremely important. The most common method is surface irrigation by flooding the field. In certain areas, furrow irrigation is practised.
The irrigated cotton in northern India is sown after a heavy irrigation of the field. A light irrigation is then given, three or four weeks after germination. Further irrigations follow, depending on conditions of the soil and the weather. Special care has to be taken to provide adequate water to the plants during the flowering and boll-formation stages, otherwise heavy shedding of flower-buds and bolls takes place. Over-irrigation, which is injurious to the crop, should always be avoided.
Harvesting and Yield:
While cotton-picking is done in certain advanced countries with the help of machines, hand-picking is the only method followed in India. The harvesting of the entire crop cannot be done at a stretch and the opened bolls are picked at suitable intervals, the harvesting season covering several weeks. The picking of bolls usually starts in October and continues up to March – April. The seed cotton, which is commonly referred to as kapas, is removed from the bolls in the field.
The yield varies widely in different areas and different seasons. The average yields of seed cotton and lint per hectare in India are 400 – 600 kg and 150 – 200 kg respectively.
Uses of Cotton:
The cotton fibre is used chiefly, either alone or in combination with other fibres, in the manufacture of textiles of different types, namely, print cloth, yarn fabrics, sheeting, fine cotton goods, napped fabrics, duck, tyre fabrics and towels. Products, such as yarn and cord, including unwoven tyre cord, thread, cordage, twine, etc., are also made from cotton fibre.
Unspun cotton is extensively used for stuffing cushions, pillows, mattresses, etc. Cotton, which is pure cellulose, is used as raw material in cellulose industries, including plastics, rayon and explosives, Mercerized cotton, which is used in the production of very high grade textiles and also in combination with synthetic fibres, is made by treating the fibres with caustic soda.
Sterilized absorbent cotton is extensively used in medical and surgical practice. Cotton waste, obtained as a by-product in the spinning and weaving mills, consists mainly of short fibres and is often utilized in making cotton blankets, flannelettes, sheets, etc.
Varieties of Cotton:
Cotton research in India was started sometime in 1904 or soon after. The work was considerably accelerated during the First Five-Year Plan. During this plan-period, as many as 11 improved varieties were released for general cultivation in different states, notable among them being 320-F in Punjab, H.14 in Haryana, Deviraj and Digvijay in Gujarat and MCU-2 in Tamil Nadu.
Of the varieties released during the Second Plan period, Badnawar-1 in MP, Buri-147 in Maharashtra and MCU-3 in Tamil Nadu are important. During the Third Plan period, several varieties were released, which included Gujarat-47, V.797, J.34, MCU-4, AK.235, AK.277 and Buri-1007.
Research on the crop was intensified with the launching of the All India Coordinated Cotton Improvement Project in 1967 and a number of new varieties were released during 1968-72. Some of them are Krishna for the rice fallows of AP, MCU-5 and Sujata for the irrigated areas of Tamil Nadu, Khandwa-1 and Khandwa-2 for the unirrigated Nimar tract of MP, G-27 for the desi cotton tracts of Punjab and Haryana, Bharathi and K-8 for the rain-fed Karunganni area of Tamil Nadu, Mahalaxmi for the rain-fed tract of north AP, Hybrid-4 for different states, particularly Gujarat, Sujay for south Gujarat, MCU-7 for rice-fallows of medium duration in Tamil Nadu,RS-89 for Sriganganagar (Rajasthan) and Varalaxmi for the Tungabhadhra Project area in Karnataka. The release of the extra-long-staple variety, MCU-5 and that of Hybrid-4 and Varalaxmi, the two hybrid cottons, has been a significant achievement. Sujata is the first high-spinning Egyptian type of cotton released in India.
Besides the above, a number of other improved varieties have been bred and released in recent years for cultivation in different areas. Some of them are Bikaner Nerma, H 777, F 414, F 286, LH 900 and Ganganagar Ageti in the northern zone. G.Cot. 10, G.Cot 11, G. Cot. 12, G.Cot. 13, L 147 and LRA 5166 in the central zone and Jayadhar, Laxmi, Kanchana and Suvin in the southern Zone.
In addition to the two hybrids mentioned above, a few others have been developed and released, such as, JkHy, DCH 32, G.Cot. Hyb. 6, AHH 468 and NHH 44. The hybrids have helped in pushing up the yield to a great extent. Although they now occupy hardly 16 percent of the area, their contribution to the total production of the country is as much as 35 percent.
Diseases of Cotton:
The common diseases of cotton are:
(i) Anthracnose caused by Glomerella gossypii and Colletotrichum indicum, which can be controlled by treating the seed with any organo-mercurial (Agrosan GN or Ceresan) @ 2-2.5 g/kg or by spraying the crop with Bordeaux mixture.
(ii) Bacterial blight (black arm or angular leaf spot) caused by Xanthomonas malvacearum, which can be controlled by treating acid-delinted seed with an organo-mercurial (Agrosan GN or Ceresan) @ 2-2.5 g/kg or Agrimycin-100, spraying with 0.3% copper fungicide and by growing resistant varieties.
(iii) Dry root rot or sore shin caused by Macrophomina phaseoli, which can be controlled by practising crop rotation and by growing resistant varieties.
(iv) Wilt caused by Fusarium oxysporum f. vasinfectum, which can be controlled by growing resistant varieties.
(v) Verticillium wilt caused by Verticillium alboatrum, which can be controlled by growing resistant varieties and spot application of wet Ceresan 0.1%.
(vi) Leaf spots caused by Helminthoporium gossypii, Alternaria spp., Mycosphaerella gossypiana and Myrothecium roridum, which can be controlled by spraying the crop with 0.3% fixed copper or 0.2% Zineb.
(vii) Root rot caused by Rhizoctonia bataticola and R. solani, which can be controlled by sowing cotton early (1st week of April) or very late (1st week of June) or by practising mixed sowing with Phaseolus aconitifolius in infected areas.
(viii) Powdery mildew caused by Laveillula taurica and Oidium spp., which can be controlled by dusting the crop with finely powdered sulphur @ 15 kg/ha.
(ix) Stenosis (small leaf) caused by virus, which can be controlled by growing resistant varieties.
Insect Pests of Cotton:
The common insect pests of cotton are:
(i) Cotton jassid (Amrasca biguttula biguttula), which can be controlled by sowing resistant varieties and by spraying the crop fortnightly with 0.02% Phosphamidon, Methyl demeton, Monocrotophos or Dimethoate.
(ii) Spotted bollworms (Earias insulana, E. vitteulla), which can be controlled by avoiding growing lady’s-finger during the off-season in the vicinity of cotton fields, destroying attacked shoots and bolls, removing all stubbles after harvest and spraying 0.1% Carbaryl and 0.03% Monocrotophos alternately at fortnightly intervals 2-3 times.
(iii) Cotton stem- borer (Sphenoptera gossypii), which can be controlled by uprooting and burning withered plants.
(iv) Cotton stem weevil (Pempherulus affinis), which can be controlled by destroying all cotton plants after harvest in infested areas and by avoiding growing of alternative or collateral host plants during the off-season.
(v) Cotton whitefly (Bemisia tabaci), which can be controlled by the same methods as in the case of no. (i) above;
(vi) Pink bollworm (Pectinophora gossypiella), which can be controlled by clean cultivation, exposing the seed to sun’s heat for 2-3 days before sowing, destroying all fallen buds and bolls, and spraying 0.1% Carbaryl and 0.03% Monocrotophos alternately at fortnightly intervals.
(vii) Red cotton bug (Dysdercus koenigii).
(viii) Dusky cotton bug (Oxycarenus lactus), both of which can be controlled by dusting 5 – 10% BHC or spraying 0.04% Monocrotophos or Quinalphos.
(ix) Cotton leaf roller (Sylepta derogata), which can be controlled by destroying rolled leaves with larvae within, by spraying 0.1% Carbaryl or 0.04% Monocrotophos.
(x) Cotton aphid (Aphis gossypii), which can be controlled by the same methods as in the case of No. (i) above.