EFFECT OF NITROGEN FERTILIZATION ON YIELD, NH4+ AND NO3- CONTENT OF WHITE CABBAGE

Abstract. The results of three year investigations with ‘Galaxy ’ F1 cabbage grown under field conditions are presented. The effect of the rate of ammonium sulphate and RSM (so-lution of ammonium nitrate + urea), the method of application (placement and broadcast technique) and foliar fertilization (urea and Supervit K) on the yield and nitrate accumula-tion was studied. The form of N fertilizer significantly increased the cabbage yield only in 2007. In this year the better nitrogen source was ammonium sulphate in comparison with RSM. In the other years no differences between the kind of N fertilizer were observed. The method of application did not affect cabbage yield any year. However, slightly better cropping was noted for following treatments 75 % N broadcasted at planting + 25 % N dur-ing growth season, 75 % N broadcasted at planting + foliar fertilization, and after place-ment fertilization with reduced rate (75 % N) as compared to control (100 % N broadcasted at planting), in every year of the experiment. In 2006 and 2007 fertilization at the rate of 75 % N and supplemented with addition 25 % N during the growth or foliar sprays signifi-cantly increased nitrate content in cabbage as compared to control treatment. Key words: white cabbage, foliar, placement fertilization, nitrate and ammonium conten