Learn Commercial Crops with Rahul

Plant Nutrient management

  • The efficient use of nutrients, including those in the soil naturally or as a result of previous fertilization and management practices, can help reduce the cost and environmental concerns of fertilizers without reducing the yield and quality.
  • Tobacco yield of 1000 kg leaves per ha removes 90 kg N, 22 kg P2O5, 120 kg K2O, 78 kg Ca, 11 kg Mg and 4.5 kg S from the soil.
  • Economic benefit in case of tobacco is realized not only in terms of yield but also in terms of its quality. And quality, particularly in the smoking types, depends on the balance of the nutrients in the leaf.
  • A high-quality tobacco usually is high in soluble carbohydrates and potash, but relatively low in crude fiber, nicotine, nitrogen, calcium, ash, and acids.
  • Nitrogen is necessary not only for good growth and high yield but also because it forms 13% of nicotine.
  • Moreover, nitrate form of N is good as it gives good smell and better taste of tobacco.
  • Nitrogen deficit results in lower yield and slick cured leaf while excess N delays ripening and induce sucker growth and high nicotine content.
  • With excess N supply, C:N ratio gets reduced that reduces the tobacco quality.
  • However, in case of chewing, hookah and bidi tobacco, yield is an important factor and abundant supply of N is essential.
  • In tobacco, the normal ripening process is caused by partial starvation that should begin with the time of topping. Partial starvation means that the N in the soil is near to depletion by that period of time.
  • Nitrogen is usually applied @ 10-40 kg/ha for flue-cured, up to 100 kg/ha for air-cured and fire-cured and 10-20 kg/ha for Turkish tobacco.
  • Phosphorus accelerates the root growth and ripening of the plant. It is not very leachable and its uptake by the tobacco plant is also very low in comparison to other nutrients.
  • P deficit leads to dark green color of the leaves and low-quality produce while it’s excess shortens the leaf growth duration by hastening ripening.
  • Depending on the availability of phosphorus in the soil, the rate of application may vary from 40-120 kg/ha. In case of flue-cured tobacco, the plants require about 50-75 kg P2O5/ha.
  • Potassium is important for healthy growth of the plant. It is leachable, especially in deep sandy soils.
  • Its role in osmoregulation is a virtue to better leaf turgidity and final yield.
  • Optimum amount of potash in tobacco leaves is essential for good burning quality and ash quality.
  • The tobacco burning quality is a function of the coefficient K/(Ca-Mg). Chlorine is detrimental to quality of cured tobacco. Thus, potassium fluoride is recommended to be used in tobacco rather than potassium chloride.
  • Depending on the soil requirements and the type of tobacco, the rate of potassium application may be increased up to 100-150 kg/ha.
  • The blanket recommendation for fertilizers in Nepal are 10 t compost/ha along with 35:23:60 kg N, P2O5 and K2O /ha.
  • When higher rates of organic manures are used, care should be taken that FYM from dairy cattle are not used @ > 10 t/ha because of chlorine and soluble salts uptake in the tobacco leaves.
  • However, specific recommendations are made for different types of tobacco. Virginia type (Flue-cured) tobacco is fertilized at the rate of 40-60 kg N, 60-80 kg P2O5 and 60-80 kg K2O per ha and Natu and Belachhapi-1 tobacco are fertilized at the rate of 40-50 kg N, 60-65 kg P2O5 and 60 kg K2O per ha.
  • All the doses of Phosphors and Potash and 1/3rd of Nitrogen is applied as basal dose before transplanting and 2/3rd of the remaining Nitrogen is top dressed after 1 month of transplanting in 2-3 splits.
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