ABSTRACT An experiments to know the effect of urea fertilizer dose and time of application of urea fertilizer on yield of petsai (Brassica pekinensis L.) had been carried out since & February until 19 April 1998 at Ngargosoka village, Srumbung distrik, Magelang regency. The soil type is Regosol with pH 6,0 and altitude 580 meters. The method is factorial experiment (3x3) with randomized comple…