THE TOTAL SOLUBLE SALTS CONTENT AND THE PHOSPHORUS MOBILITY DEPENDENT ON APPLIED FERTILIZER AND OF pH VARIATION IN SUBSTRATE

Substrate reaction is one of the most important agrochemical indices which affect the plants by their different requirements from this point of view. Substrate reaction or pH is determinate by the presence in the liquid phase of H ions, as result of the ionic equilibrium between liquid phase and solid phase. Some species prefer an acid pH and other accept a large scale of pH, so it is important to know this fact because the commercial fertilizers have great limits of variation for pH (3.5–8). These fertilizers can modify the substrate pH in time. Salinity expressed as the content of salts dissolved (mg/l or ppm) or electrical conductivity (mS/cm or dS/m) is an agrochemical indicator which can influence the plant growth and development. Salts accumulation into the substrate can occur by: the presence of high salts concentrations into the constituents of the substrate; the excessive fertilization; the irrigation with improper water; the uncontrolled mineralization of some organic materials. In order to avoid the negative effects of salinity, the periodically measurement of electrical conductivity in the substrate, the pH control and the correlation of fertilizations with these agrochemical indices are recommended. The paper presents the results of the total salts content depended of applied fertilizer and of ornamental cultivated specie. The culture substrate was composing by following compounds: leaves compost +forestry compost +peat + marc compost in ratio of 1:1:1:0.5. In year II of culture was followed the growing and development of four ornamental species Tamarix tetrandra, Ligustrum ovalifolium Aureum, Chamaecyparis pisifera Boulevard and Chamaecyparis lawsoniana Stardust. Under the effect of fertilizers the substrate pH was modified and the nutritive element release was different in substrate. The content of mobile phosphorus varies with the modification of the substrate pH.