Production of container-grown nursery plants on capillary sand beds

This study investigated the effect of growth medium on the growth of nursery plants in a capillary irrigation system, the use and amount of slow-release fertilizer for the fertilization of container-grown nursery plants, and the need fora base dressing with a slow release fertilizer. Also investigated were the effect of different concentrations of alkyl aryl trimethyl ammonium chloride solution (Gloquat C) in preventing rooting through, and the use of a watering control device based on measuring radiation energy in field conditions. The experiments on growth medium revealed that all the growth media included in the experiment, i.e. sphagnum peat, peat/rock wool mixture (1 : 1),or peat/sand mixture (3 : 1), can be used for container-grown nursery plants if a base dressing is used with Nutricote(70), a slow-release fertilizer. The effect of slow-release fertilizer was better in peat mixtures, and this effect was especially clear when no base dressing was used. The use of slow-release fertilizer proved to be a good fertilization method in a capillary irrigation system. The fertilizing effect of Nutricote (70) given in the spring lasted until early June of the following year. Nutricote(70) was found to need a base fertilizer dressing. Abase dressing of 1.2 kg/m3 of a compound fertilizer (Turpeen Y-lannos; N 11 % P 10.5 %, K 18.3 %) with 1.5 kg/m3 of slow release fertilizer proved to be a suitable fertilization method for ornamental woody nursery plants in a capillary irrigation system. The tallest plants were obtained with a base dressing that was mixed with 3 kg/m3 of the slow-release fertilizer. Plants thus fertilized were, however, considered to be too large for transport and handling. The problem of a secondary root ball under the pot in sand beds was prevented by spreading 15 ml/m2 of Gloquat C on the sand surface. The capillary irrigation system and the automatic irrigation control worked well in experiments carried out under practical conditions. The potted nursery plants were kept evenly moist, and the plants grew to market size in one growing season