October 1, 2007	Monday	Ramazan 18, 1428

COTTON is the lifeline of our economy which provides a lot of foreign exchange besides employing millions in rural and urban areas. There are many cotton producing countries which have a crop life span of 120-130 days rather than 200 or even more as in our country.

It is believed that cotton can be successfully grown in July without any loss in yield and quality, instead of May or June. The July sowing may have 1.5 to two hundred thousand plants per hectare by controlling plant height with growth regulators.
If on an average 7-10 bolls are set on each plant in September, it will produce a good quality of 3,000-5,000kg or even more of seed cotton per hectare at lesser cost. If such cotton crop is harvested by mid-November, wheat can be sown at an ideal time to obtain maximum yield.

The average yield of cotton has been erratic in Punjab achieving an all time high of 2,550kg of seed cotton per hectare in 1991-92, which unfortunately fell as low as 1,480kg per hectare in a short span of two years, owing both to heavy onslaught of insects and cotton leaves curl virus (CLCV).

Conversely there has been steady increase in cotton yield in Sindh. It was around 1,000kg seed cotton per hectare in 1989-90, which jumped to 2,425kg in 2004-05, as compared to Punjab which stood at 2,260kg seed cotton per hectare in the same period.

It is presumed that insects and CLCV had not affected the cotton crop in Sindh. The growers in Punjab are using higher dosage of insecticides than used by farmers in Sindh. In fact higher use of insecticide has ruined the balance amongst friendly and harmful insects besides polluting the environment and destroying flora and fauna. Most of the countries either do not use any insecticide or use it sparingly to obtain substantial results.

The following technology may be adopted to obtain higher yield of cotton with lesser inputs and lower costs:
Varieties: Only cotton varieties approved for the particular zone should be cultivated as they have been bred keeping in mind the climatic and eco systems of the zone. As regards transgenic varieties, such as Bacillus thuringiensis (B.T), there are conflicting views about its effectiveness against American bollworm.

The varieties developed under our environmental conditions may perform better than imported ones as they may be prone to sucking insects and CLCV.

Plant population: Majority of cotton growers have 2.5 to three hundred thousand plants per hectare, which is quite below as compared to recommended population. It is assumed that 20 per cent yield can be enhanced if the plant density is increased to the desired number of 40,000 as recommended by the department. It is possible that in such cases the seed rate is low with poor germination thus leading to poor stand of crop. Hence the seed rate may be increased to improve plant population. In order to obtain 1.5 hundred thousand plants per hectare 15kg robust seed must be used.

Nutrient requirement: Amongst major nutrients potash is available in abundance in the soil here, except in rare cases. As regards phosphorus, if 45-70kg of P2O5 is used at the time of sowing wheat, it will not only meet the requirement of the crop, but the residual phosphorus will also meet the needs of the coming cotton crop. Care must be exercised in N&P use. Usually nitrogenous fertiliser is broadcast or drilled in dry soil of standing cotton crop many hours before irrigation. Since the day temperature is very high, nitrogen is lost due to volatilisation.

Best results have been obtained when urea or other nitrogen fertiliser is broadcast or drilled in “tar wattar” conditions in the morning or preferably in the evening. The phosphatic element is most immobile hence it must be drilled in bands along with seed row. If per chance phosphatic fertiliser is not available at sowing time its application can be deferred till first irrigation without any significant loss in yield. It is just possible that some micro nutrients may be deficient in soil, which may limit its yield. Extensive soil analysis may be carried out to determine the nutrient level of the soil.

Use of green manure: The soil is deficient in many nutrients and organic matters, which needs replenishment through green manure. The growers, therefore, must use green manure after every four or five years.

Weed Control: There are three ways to control weed i.e., through rotation of crops, removal manually or through mechanical means and chemical control. The two earlier methods are preferable. If weed is uprooted then it should not be left on the field or fed to animals. It should rather be collected and burnt to destroy its seed.

Insect control: Chemical control is not the only solution to control cotton insect especially the chewing types. Many cotton growing countries having higher yield do not use chemical to control insects.

Since insect situation is not as pathetic in Sindh as in Punjab, hence extra care should be taken while using chemical sprays and try to minimise its use gradually. Meanwhile predators and parasites may be encouraged to control insects.

To compete in international market, there is need of drastic reduction in the cost of production along with substantial increase in yield, which is possible by reducing life span of crop as well as expenses on pesticide use.

For successful control of sucking insects detergent and cooking oil mixed in water can be effectively used to control insects provided the emulsion is sprayed on the target insects. These insects always reside underneath the leaves. It is non- toxic and not harmful to environment.

Relative resistance trial: An assistant entomologist of the Regional Agriculture Research Institute, Bahawalpur, conducted trials on relative resistance of cotton varieties for the past many years. The results are very fascinating which unfortunately have not been applied by the growers at all. Such trials may be conducted on large blocks at various locations in Punjab on standard varieties and promising strains to determine their relative resistance against insect complex. The following treatments may be included:

No spray. Control of sucking insects through chemicals. Control of only bollworms. Control of all insects. Release of predators for control of insects. Use of detergents and cooking oil for control of sucking insects.

Alternates of cotton crop: If due to shortage of irrigation water or sufficient rains, target area of cotton is not achieved, then alternative crops like guar, moong beans, mash and corn may be grown and the farmers advised accordingly before hand. These crops shall vacate land at proper time for sowing of wheat with possibility to have yields as high as 6,000kg per hectare. Except maize other crops will also enrich the soil by fixing nitrogen in its root. If the cotton picking is late and wheat sowing is delayed its seed can be broadcast in the standing cotton crop provided the weeds are under control.