In order to explore the effective measures that could improve the stable supply nitrogen in orchard soil

six-year-old ‘Yanfu3’/SH6/Malus hupehensis Rehd. and 15N isotope labelling technique were used to explore the effects of FSA (furrow applicator fertilizer)

FS+BC(half applicator and half bag-controlled release fertilizer)

BCRF(bag-controlled release fertilizer) on soil mineral nitrogen and 15N-urea absorption

utilization and loss of Fuji apple. The main results were as follows: Soil mineral nitrogen content provided by BCRF treatment stably throughout the growing season

soil mineral nitrogen content provided by FSA treatment increased rapidly in the short term

and then decreased sharply. At the fruit maturity stage

nitrogen content in the plant of the BCRF treatment (121.64 g) was higher than that in the FSA treatment (79.01 g)

and slightly higher than that in the FS+BC treatment (95.92 g). Ndff in different organs was significantly affected by different fertilizer treatments

and the Ndff of fruits was the highest. Ndff in different organs was the highest in the BCRF treatment

followed by the FS+BC treatment

and the lowest in the FSA treatment. The BCRF treatment increased N use efficiency significantly

which was 1.82 and 1.32 times as high as of the FSA treatment and FS+BC treatment. 15N loss rate in the BCRF treatment was 36.23%

which was obviously lower than that in the FSA treatment (57.44%) and FS+BC treatment (51.16%). 15N residue in soil of BCRF treatment mainly concentrated in the upper soil layer (0—40 cm)

deep soil leaching and losses decreased. The results suggested that the BCRF treatment was beneficial to ensure a stable supply of soil nitrogen

improved nitrogen use efficiency and reduced nitrogen loss.