Nutrition Intensity in Ternary Diagrams Interpretation for Some Ornamental Species Cultivated on Organic Substrate with Increased Biological Activity

Abstract

Nowadays, many biodegradable organic wastes no longer need to represent an environmental hazard and as a consequence, they could be recycled to obtain horticultural substrates. An experiment was conducted on two deciduous (Tamarix tetrandra, Ligustrum ovalifolium ‘Aureum’) and two coniferous species (Chamaecyparis pisifera ‘Boulevard’, Chamaecyparis lawsoniana ‘Stardust’) grown on a soil mixture of forestry compost, leaves compost, peat and grape marc compost. The aim of the research was to investigate the response to fertilization and to obtain valuable information regarding absorption rate of nutritive elements during vegetation. Nitrogen data show a lowering of its nutritive equilibrium point towards autumn in the leaves of deciduous shrubs species. Resorption of nutrients before leaves fall occurs due to conservation process in woody plants with deciduous leaves. In the case of coniferous species, the lowering of nitrogen content is less intense. The monthly fertilization with Coïc solution indicates no influence on nitrogen metabolism of this species. The exception was on Ligustrum with differences between nitrogen content in fertilized and unfertilized plants. The phosphorus nutritive equilibrium point reveals a decrease during the summer months (July - August), the species presenting the lowest values in this period and the cause of this behaviour was the plants adaptation to high temperature and low humidity. Potassium nutritive equilibrium data indicates small differences in the unfertilized plants in comparison with those fertilized in all species. The novelty of the research is represented by the ternary diagrams N-P-K that were constructed, interpreted and reported for dendrologic species.