ISHS Acta Horticulturae 26: III Symposium on Peat in Horticulture
THE USE OF FRITTED TRACE ELEMENTS IN PEAT-SAND SUBSTRATES |
| Author: | A.C. Bunt |
| Abstract:
It is common experience that plants grown in peat or peat-sand substrates are liable to suffer from a deficiency of one or more minor elements. During the course of studies at the Glasshouse Crops Research Institute on the nutrition of plants grown in peat-sand substrates, deficiencies of boron, copper and iron have been of fairly common occurrence with molybdenum deficiency occurring less frequently. These deficiencies can be corrected by the inclusion of the appropriate inorganic salt with the base fertiliser; the quantity required is, however, rather small, and problems may occur in achieving a uniform distribution. Furthermore, in some cases the difference between the amount of salt necessary to correct a deficiency and the quantity which can cause phytotoxity is very little. Bunt (2) found that whilst 7 g m-3 of sodium borate was sufficient to correct boron deficiency in pot-grown chrysanthemums, phytotoxicity occurred at three times that rate. Problems encountered during minor element studies by the release of minerals from the walls of clay pots are well known, and Badger and Bray (1) suggested the use of glass of low solubility to give a controlled supply of minor elements. The desired minor elements are mixed with silicates, fused by heating to 1, 000°C, quenched in cold water and then ground to a fine powder. The product is known as a fritted trace element mixture, and in this form has a much lower solubility than the original inorganic salts, thereby giving a release over a long period and at the same time providing a greater margin of safety against phytotoxicity. Preliminary work had shown that the use of a general purpose frit containing boron, copper, iron, manganese, molybdenum and zinc corrected boron deficiency in pot chrysanthemums (Bunt, 2), but subsequent work indicated that it might be desirable to vary the rate of frit with the form of nitrogen used. Further work was, therefore, undertaken to investigate those factors which could interact with the use of fritted trace elements in pot plant substrates. | |
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