SLOW-RELEASE FERTILISERS ON VEGETABLES

Kemira Agro Oy started production of methylene urea (MU), a slow-release nitrogen raw material in 1996. MU is mainly used as one nitrogen source when manufacturing NPKs, and on average the MU proportion of the total nitrogen content in the products is one third. Several trials on open field crops, including tomato, leek, onion and cabbage have been made with this type of NPK fertilisers in a number of European countries. In these trials, conventional fertilisation programmes were compared with slow-release fertiliser programmes at equivalent nutrient quantities/ha and with less application frequencies/ season. The results indicate that the slow-release fertiliser can give an equal or even a slightly higher yield of better quality than the conventional fertilisers. Slow-release fertilisers were also used with drip irrigation. The test NPK was added at planting time as a basic fertiliser, whereas the fertigation programme of equivalent amounts of nutrients were continuously applied. Based on the results, it can be suggested that the slow-release fertiliser gives better growth and provides at least the same yield level as fertigation.

In this paper, three selected trials on various crops and growing conditions are presented, one with onion in Hungary, one with tomato in Turkey, and one with drip-irrigated watermelon in Cyprus.

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