Effects of controlled-release nitrogen fertilizer and bag-controlled release fertilizer on utilization of 15N-urea in ' Orin' apple and its accumulation in soil. - SHA Jian-chuan; WANG Fen; TIAN Ge; YU Bo; GE Shun-feng; JIANG Yuan-mao (Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao, 2018)