FURTHER INVESTIGATIONS ABOUT THE COMPOSITION OF PEAT SUBSTRATE FOR YOUNG PLANTS
For each culture it is necessary to be able to define, in a rational way, the optimum proportion of nutritive elements and their most suitable concentration. It is therefore important to dispose of an adequate research method and we propose to use the method of "systematical variants" from HOMES. This method is based on the fact that, if one nutritive element is too much prevailing in the fertilization formula, it may have a baleful influence on the growth of the plants. The more this element causes damage to the plant, the less it should be present in the ideal fertilization formula.
In the method of systematical variants, HOMES makes a difference between the 3 main nutritive elements which are forming anions in solution (N, P, S are forming anions NO-3, PO---4, and SO--4) and the 3 main nutritive elements which are forming cations in solution (K, Ca and Mg, respectively K+, Ca++ and Mg++).
7 methods of fertilization have to be compared, 3 of which bear the names of the anion elements and contain the same proportion, expressed in equivalents, of the 6 main nutritive elements, except for the element which gave its name to the fertilizer and which is present 3 times more than in the 2 other fertilizers. The results obtained with these 3 formulas give the proportion of these 3 elements in the ideal composition of fertilization. This is also true for the 3 cation elements and the 3 fertilization formulas which bear their names. The 7th formula named M (after mixture) is a combination between an anion and a cation fertilizer and enables to define the ideal proportion of cation and anion elements.
When the ideal proportion for the 6 main nutritive elements is known, it is rather easy to define the optimum concentration. This is obtained from a test in which 3 or 4 different concentrations of the ideal fertilizationformula are compared. When putting these results on a diagram it is easy to find out where this curve reaches the maximum, which means the optimum concentration.
Last year, a small test was made with this method on Salvia Splendens and Tagetes patula. In each case a few seedlings or cuttings were placed