SLOw – RELEASE FERTILIZERS AND POSSIBILITIES OF THEIR UTILIZING IN NURSERY

SALA�, P.: Slow-release fertilizers and possibilities of their utilizing in nursery. Acta univ. agric. et silvic. Mendel. Brun., 2004, LII, No. 2, pp. 155-164 Reserve, slow-release fertilizers (SRF) enable to simplify the whole system of plant nutrition and fertilisation. Tabletted fertilizers of the Silvamix series represent a prospective product of Czech provenience. At our university, these fertilizers have been tested and used since the year 1991. Ornamental woody species grown in containers were investigated in two stages. Experiments with ornamental plants were established using one-year-old cuttings and seedlings of the following deciduous and evergreen woody species: Cotoneaster dammeri Skogholm, Berberis thunbergii, Potentilla fruticosa Snowflake, Ligustrum vulgare Atrovirens and Picea omorika. After planting into containers, fertilizers in the dose of 1 tablet (i.e. 10 g) per litre of substrate were applied either to roots level or on the soil surface in the container. Silvamix in the dose of 5 g.l-1 was used as the tested fertilizer in the second stage. It was applied during the planting in the form of tablets and/or a powder. Control plants were fertilized in the course of growing season using a common agricultural fertilizer Cererit Z. The annual plants increments were measured. These experiments demonstrated a long-term optimum effect of this product on woody species and an equal quality and efficiency of its tabletted and powdered forms. fertilizers, nursery production, growing technologies, ornamental plants Ročník LII 18 Číslo 2, 2004 155 Reserve, slow-release fertilizers (SRF) enable to simplify the whole system of plant nutrition and fertilisation. The period of efficiency is dependent on the type and dose of fertilizer, soil properties and climatic conditions. There are two basic issues concerning basic and supplemental fertilization of forest stands. The first one concerns nutrition of nursery seedlings in and/or outside containers while the second one stock fertilization of seedlings after their replantation to target locality and supplemental fertilizing of young trees (Kučera, 1995). A lot of various types of stock fertilizers with an extended period of efficiency have been developed for this purpose. The slow and gradual release of nutrients from these special fertilisers is accomplished by different mechanisms, which also cause different results. Perhaps the best known of them is the pelleted fertilizer Osmocote which is used throughout Europe, first of all in ornamental plant nurseries. Application of such fertilizers seems to be important especially in the field of establishment of permanent stands because it provides a continuous supply of nutrients to plants throughout the most critical period of their existence, i.e. after replanting, during the period of rooting and in the first stage of their growth and development. This critical period may last either for several months (e.g. for herbs) or even for several years (in case of woody species) and depends above all on climatic factors occurring in the given period of time. It is also obvious that after their replantation in the target locality it is mostly impossible to provide the plants with a similar care as in the period of pre-planting. The slow-release fertilizers can be divided into two basic groups: fertilisers with low water solubi-