INFLUENCE OF DIFFERENT NITROGEN DOSES ON WOLSKA AND RAWSKA ONION YIELDS AND HARVEST-TIME
On an average the nitrogen luxury nutrition was reached at nitrogen doses 140-210 kg N/ha. Nevertheless, on some soils the highest yields were not reached even at 350 kg N/ha and on other soils the lowest dose 70 kg N/ha already diminished the yields. The nitrate nitrogen content in lower parts of external leaves in the end of May - beginning of June seems to be the index of nitrogen nutrition status of onion.
In 15 experiments the drying of the leaves and harvest maturity were retarded in proportion to applied nitrogen level, ranging from about six days at insufficient nitrogen fertilization to 13 days at luxury and excessive fertilization.
The share of thick necked bulbs in total yield was mostly dependent on weather conditions and only in little extend on nitrogen fertilization.