Tobacco
Despite increased health consciousness and antismoking campaigns, tobacco globally still represents an important economic crop. Tobacco is grown in more than 120 countries with large differences in intensities. China with a production of more than 2.2 million tonnes, produced on more than 1 million ha is by far the largest producer, followed by Brazil, India, and USA. Tobacco cultivativation in Europe has significantly declined in the last 20 years and today represents only 66,000ha with the main producers Italy, Spain, Poland, Greece, Croatia, France, Hungary, and Bulgaria, which account for 99% of the EU tobacco production. Depending on type and use of leaves, the tobacco plant requests particular conditions with respect to climate, soil and fertilizer management, shown in the following.
Tobacco quality – a matter of taste and combustibility
The preferred cultivation areas with yields of one to three t/ha are in the warmer regions of the temperate zone and in the subtropics. Among the numer types of tobacco, "Flue-cured" Virginia varieties account for 71% of output, "light-air-cured" Burley varieties 16%, "sun-cured" or oriental 7% and other varieties ("dark-air-cured" and "fire-cured") 6%. Independent of type, for smoking tobacco, cured leaves require a good combustibility. This is usually achieved by high potassium concentrations and low chloride concentrations in the harvested leaf. High chloride supply, i.e. by application of fertilizers has to be avoided.
- Management of tobacco (cultivation, harvesting and curing) of tobacco is relatively labour and cost intensive so that good fertilization based on yield and quality is a prerequesite for a economically viable production.
- The best tobacco qualities are achieved with optimum potassium fertilization based on low chloride sources, i.e. potassium sulfate (SOP) or potassium nitrate (NOP), as main sources.
- Fertilizing tobacco with SOP is especially rrecommended during top-dressing, when leaves are ready for ripening and the further supply of nitrogen should stop.
- As with other crops, sufficient supply of magnesium and sulfur guarantee reliable yields and healthy leaves.
Tobacco cultivation
Tobacco is one of the world's most important crops and is grown in around 120 countries. The preferred cultivation areas are in the warmer regions of the temperate zone and in the subtropics. Besides the traditional uses of smoking, chewing, and snuff, tobacco is also used in the production of perfume. The potential uses of tobacco could change considerably in the next few years, as the plant tobacco can be genetically modified very easily.
Scientists are therefore becoming increasingly interested in the tobacco plant with regard to "molecular pharming" (production of vaccines) and soil remediation (removal of TNT and heavy metal contamination).
The area under tobacco cultivation in Germany is about 4700ha, in Austria it is about 120ha. In Germany, mainly the tobacco varieties Virginia, Burley and dark varieties are cultivated. In recent years, the quality of the dark tobacco varieties in particular has improved considerably, so that they are now exported.
Tobacco has a high economic value; its production, however, is very cost-intensive. About 1000 hours of manual labor must be spent per hectare. For profitable production, plant growth must therefore be controlled by balanced fertilization based on yield and quality.
The growing season for tobacco is 60 to 150 days. During this period, the plants have a very high nutrient requirement to ensure their strong growth and leaf mass formation. One-sided high nitrogen fertilization has a detrimental effect on the maturity, burning properties and fragrance of the tobacco. In addition to nitrogen and calcium, the tobacco plant then needs potassium in particular. The potassium content in dried leaves should be between 3 and 6%; below 3%, deficiency symptoms occur.
Tobacco is regarded as chloride-sensitive crop, though the plant growth itself does not suffer from high chloride. A high supply of chloride leads to an accumulation in the leaves, which has a detrimental effect on the glowing properties of the end-product. Furthermore, it can also result in uneven leaf coloration; affect odor and aroma. The usually higher moisture content of Cl-fertilized tobacco also limits storage time and the fermentation. Therefore, fertilizers virtually free or low in chloride, e.g., potassium sulfate (SOP) should be used.
The most important nutrients for tobacco
Potassium – for best tobacco quality
Potassium has a significant influence not only on yield but also on the quality of the tobacco.
- In the course of vegetation, with a yield of 2t/ha, about 110kg/ha K2O are absorbed.
- Potassium promotes photosynthetic performance, which leads to increased substance and carbohydrate formation. In this way, yield (number of leaves per plant) and quality are positively influenced in the long term.
- Tobacco quality is determined by the sugar and nicotine content in the leaves, as well as by the sugar/nicotine ratio. As the potassium content in the leaves increases, the sugar content in the leaves also increases, while the nicotine content decreases. This results in an increase in the sugar/nicotine ratio, which is considered optimal at 10:1.
- Potassium strengthens the plant's resistance to diseases, pests, and frost.
- Due to negative effects of chloride on tobacco leaf quality, the crop has been characterized as chloride-sensitive. For good quality tobacco, i.e. burning characteristics of the end-product, potassium should be applied in sulfate form (K2SO4).
Magnesium and sulfur for ensured yields and healthy leaves
Magnesium
- As a central component of leafy greens, magnesium is essential for plant photosynthesis. An adequate Mg supply ensures biomass formation and guarantees maximum yields.
- Magnesium improves the coloration of tobacco leaves, resulting in optimum processing quality.
- Magnesium increases the plants' resistance to disease, especially viral diseases.
Sulfur
The sulfur content in tobacco leaves ranges between 0.15 and 0.65% of the dried leaf. Concentrations below that range should be avoided, as sulfur activates important enzymes in the energy and fatty acid metabolism. It is essential for the synthesis of sulfur-containing amino acids, influences overall protein synthesis and therefore has a positive effect on yield.
An optimal sulfur supply leads to efficient nitrogen utilization. If there is a lack of sulfur, the nitrogen taken up cannot be converted into proteins and a signal is sent to the roots to take up less nitrogen. Therefore, the plant's need for sulfur must be met for optimal nitrogen utilization. Optimal utilization of nitrogen in plant metabolism improves leaf quality in tobacco, including uniform maturity. Sulfur enables the plant to maintain its physiological processes optimally balanced, even under drought stress, avoiding or minimizing yield losses. Sulfur is a component of the metabolic product glutathione, which, as an antioxidant, renders oxygen radicals formed during drought stress harmless and therefore prevents necrosis of the leaves, important for quality.
Fertilizer recommendations for tobacco
Our fertilization recommendations are based on the variety of tobacco and the processing method.
Recommendation for soil fertilization
|
Flue-cured tobacco |
Potassium sulfate (kg/ha) 200-360 ESTA® Kieserit (kg/ha) 85-113 |
|
Air-cured Burley tobacco |
Potassium sulfate (kg/ha) 320-600 ESTA® Kieserit (kg/ha) 102-141 |
|
Dark tobacco varieties |
Potassium sulfate (kg/ha) 300-700 ESTA® Kieserit (kg/ha) 140-225 |
|
Oriental tobacco varieties |
Potassium sulfate (kg/ha) 80-150 ESTA® Kieserit (kg/ha) 7-10 |
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