Yield and nitrate content of carrots (Daucus carota L.) as affected by nitrogen supply

In order to derive recommendations for the nitrogen (N) fertilization of ca rrots with high yield and low nitrate content, the effect of different leve ls of nitrogen fertilization was tested for the cultivars Ingot (medium ear ly harvest, fresh market) and Karotan (late harvest, processing). Data was taken from field experiments carried out in 1992 and 1993 on a sandy soil w here 0, 50, 100 and 150 kg N ha had been applied. In both cultivars, all fe rtilizer treatments led to nitrate contents of carrot roots lower than the German nitrate threshold value for baby food (250 mg NO3 kg(-1) on a fresh weight basis). Treatments had no significant effect on either yield or nitr ate content. From the experimental data and from results found in the literature, it was concluded that no nitrogen fertilizer should be applied for medium early c arrot cultivars (total yield approximately 80 t ha(-1)) in sandy soils with average nitrogen mineralization rates and that for late cultivars with hig her yield (approximately 110 t ha(-1)) a soil mineral N target value of 75 kg N ha(-1) is appropriate.