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CORESTA Congress, Shanghai, 2008, AP 35

Cropping tobacco in a high fertilizer price context: how to maximize nutrient efficiency

MIELE S.; BARGIACCHI E.
University of Pisa, Dpt of Agronomy and Agroecosystem Management (DAGA), Pisa, Italy

Over the past two years increasing costs of energy and raw materials have seen fertilizer prices rocketing. Although fertilization is not retained a major cost in tobacco production, however it is a key factor for leaf quality and hygiene, in terms of low TSNA and heavy metal concentrations. Problems arising from exploiting marginal phosphate rock ores and using recovered sulphuric / phosphate acids are mainly related to carrying significant traces of Cd, Pb, and radionuclides to crops and soils. To contain fertilization costs, growers should implement their strategy by an action plan which considers: (i) frequent soil / plant / water tests, also to maintain soils in the correct pH range; (ii) full fertilizer tests, including also some selected trace elements; (iii) green manuring, wherever required, e.g. by a plowed-down Trifolium squarrosum L. crop, which helps also contain Orobanche sp. infestation; (iv) reduced fertilizer rates, applied as directed, more efficient fertilizer formulations. For this latter point, a striking example is the use of microgranulated starter fertilizers, which are distributed in Italy and other European countries. Their application to tobacco increases earliness, yield and quality under most conditions. In a short perspective, research will consider also co-products of the bioenergy production plants, which are spreading in Europe. In particular, some wise reuse of ammonium-rich waters and digested phase from anaerobic digestion plants, and ashes from burning poplar wood crops (short rotation forestry) and cereal straw in cogeneration plants. Application of compost and other byproducts from agricultural processes requires more attention, as their quality may vary quite a lot according to their production cycles.