Ecological aspects of fertilisation with regard to subsoil
2001
Bujnovsky, R. (Soil Science and Conservation Research Institute, Bratislava (Slovak Republic))
Nutrient's content in subsoil represents interesting nutrient pool from view-point of plant requirements. Primary precondition for exploitation of this issue is the presence of root system that is able to adsorb nutrients, especially inorganic nitrogen, available potassium, and magnesium, respectively. As accessible soil parameters were used soil depth, salt content, soil texture and partly sloppiness that offers characteristics of main soil units (0 to 99) within soil ecological units system. Shallow soils up to 0.3 m, saline soil types, soil on excessive slopes (over 17 degree) and very heavy soils were excluded from suitable set of soils. The system of a seven-digit code of soil ecological units may be incorporated into algorithm of software for nutrient rates calculation because enables selecting soil types according categories of skeleton content (over 25%) and sloppiness as well as categories of soil texture more precisely. Depth of soil rooting as well as root system density are important parameters from view-point of selection of crops that are able to uptake the nutrients in the subsoil. Selection of crops was made on the base of available literary information. In the case of inorganic nitrogen there is possible directly update its content in topsoil layer by that one measured in subsoil (usually in layer 0 to 0.6 m) with occasional respecting the skeleton content. Introduced is especially valid at nitrogen rates actualisation in spring period. In the case of potassium is rather acceptable indirect way of topsoil-K updating because available K-content as well as other correction parameters (root system distribution or density, PBC and others) are not available
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