Nitrogen levels to be kept at optimum levels for good quality tobacco crop and yields.

Buhle Nkomo
Tobacco farmers are urged to maintain nitrogen levels at ideal levels from seedbed up to curing of tobacco to improve yields as excessive nitrogen may lead to brittle leaves and a reduction of plant population which in turn may increase the famers cost in doing gap filling.

Monitoring of a balanced supply of nitrogen should be well-thought-out from the seedbed stage because if not so, it might compromise the quality of the anticipated yield because nitrogen affects the growth of tobacco more than any other nutrient.

When tobacco seedlings are transplanted with excessive nitrogen it will result in transplanting shock therefore reducing plant population, which in turn will increase farmer’s cost of production as a result of gap filling.

Apart from the initial soil testing, to achieve a balanced supply of nitrogen in a plant, farmers are urged to apply the correct amount of fertilizer at the suitable times and by the time the plant has eight to twelve leaves one should be through with ammonium nitrate top dressing.

The amount of ammonium nitrate to be applied is dependent on soil type and variety of tobacco sown, for example on sandy soils early ploughed or second year requires 15-40 kg N/ha while late ploughed 35-70kg N/ha while sandy loams, early ploughed requires 10-30 N/ha while late ploughed 30-55 N/ha.

In sandy clay loams or heavier soils, 20-55 kg N/ha is required and noteworthy is that mineralization should occur when the soils are moist.

The amount of rain received has effect on the nitrogen in the soil as heavy rains result in leaching.

There are several effects of excessive nitrogen on a tobacco crop.

One can detect excess nitrogen in their crop by the outlook of the crop as the leaves turn very green, long and thin with chances of getting thicker as crop matures, however maturity can delay.

Sometimes nitrogen results in a bushy big plant with thin leaves, making the plant susceptible to diseases as the leaf would be easily attacked by pathogens.

Nitrogen excess may promote sucker growth and the process of removing suckers increase labour costs as well as reduce leaf size.

Excess nitrogen can make leaves brittle resulting in a lot of leaf damage during field operations resulting in reduced harvested leaves.

The plant may also delay maturity leading to difficult curing.

In the barn leaves with excess nitrogen turn black on every area concentrated with nitrogen and in certain instances it may cause leaf rotting.

It is therefore worth noting that the proportion of scrap and fines is higher than leaf in a crop with excess nitrogen, translating to a reduction in yield.

In addition farmers should also watch out for the deficiency of nitrogen on their tobacco crops as this can also compromise the quality of the yield.

Nitrogen deficiency may result in retarded growth, which means leaves will have a pale green colour.

Lower leaves may prematurely turn yellow while in some instances leaves will be small and dry up.

Reduced nitrogen affects the stem of the tobacco plant as it will be short and slender with pointed leaves.

Less nitrogen may also cause potassium firing which can be described as mottling and brownish –yellow spots which are usually confined to the leaf tips and may result in a ragged leaf.

The tobacco marketing season came to an end on Wednesday with 200 million kgs having been sold this season.

Farmers are encouraged to register for the 2016/2017 season, to attend training workshops offered by the Tobacco Industry and Marketing Board in the districts as well as to destroy stalks for those who may not have done so yet.

Written By Buhle Nkomo

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