|Authors: ||M. Prasad, P.A. Gallagher|
Due to increasing use of peat substrates for vegetable production and their susceptibility to leaching (Prasad and Woods, 1971), the need for slow release fertilizers is evident.
The need for increasing amounts of nitrogen at the 3rd and 4th truss in glasshouse tomato production has been recognised (Winsor, 1968). By using an N-fertilizer or a combination of N-fertilizer which shows increasing releases at this stage and using the standard liquid feed programme, the thinning and paleing of the tops could be avoided.
Obviously this is more convenient than adding dried blood which is sometimes done at this stage.
Increasing the amount of liquid feed would be dangerous because it may increase the salt concentration levels or may affect the water regime and consequently leaching.
In addition, often the liquid fertilizer programme added every day has been found to be not as effective as a slow release fertilizer (Furuta et al. 1967, Lunt and Clark, 1969).
Sulphur coated urea (SCU) when produced commercially would be only slightly more expensive than conventional fertilizers (Rindt et al., 1968). Rennet Casein, a by product of the creamery industry was freely available in 1969 when there was a butter surplus in Europe and was evaluated as a cheap source of nitrogen.
This experiment reports the release characteristics of these fertilizers and their performance for tomatoes under glass using different methods of application.
Certain other slow release fertilizers were included for comparative purposes.
An earlier paper (Prasad, 1971) deals with some of these fertilizers for tomato propagation.
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