ISHS Acta Horticulturae 198: Symposium on the Timing of Field Production of Vegetables
EFFECT OF N- AND P-FERTILIZATION ON YIELD AND HARVEST TIME IN BULB ONIONS (ALLIUM CEPA L.) |
| Author: | K. Henriksen |
| Abstract:
Experiments on sandy loam has shown that in the earliest period of growth, when soil temperature is below optimum, supply of P to the onion plants is very important in order to promote rapid growth, high yield and full mature bulb in time. The most effective method of P-supply regardless of the soil nutrient level has shown to be placement of P-fertilizers in the soil near to the plant at the same time and in connection with sowing/planting the crop. Combination of P and N in a fertilizer like monoammoniumphosphate has shown to give the best utilization of P applied. This method of fertilization has compared to broadcasting increased the yield with up to 8–10% and at the same time maturity was advanced one week. Application of the optimum amount of N-fertilizer at the right time is at least as important to yield and quality of the bulb onions as optimum P-supply. In experiments on sandy loam concerning increasing amounts of N as calcium nitrate the yield of marketable bulbs increased with N-application up to a total of 120 kg N per ha. Further on there was a clear correlation between time of top fall-over and N-supply demonstrated by earlier maturing onions as the N-amount increased. On average bulb onions supplied with 120 kg N per ha matured 9 days earlier than the O N treatment. Plant analysis of N concentration in onion plants show a clear response of the N-amount applied. Therefore also a correlation between percentage of N in plants at early growth might exist. Further work may find methods to evaluate and predict the yield level and maturity time from plant analysis in onions. | |
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