Abstract: On the basis of long-term experiment at Changwu station on the Loess Plateau, winter wheat yield, nitrogen fertilizer use efficiency, and soil water cycle under continuous wheat cropping system were investigated. For the average of wheat yield over 17 years, CK, M, N, NP, NM, and NPM treatments were 1.5, 2.6, 2.0, 3.3, 3.4, and 4.0 t·ha-1, respectively. For total N uptake by wheat after 17 years, CK, M, N, NP, NM, and NPM treatments were 509.0, 854.6, 781.9, 1 199.8, 1 067.5, and 1 430.9 kg·ha-1, respectively. For NO3--N level in 0-300 cm in 2001, CK, M, N, NP, NM, and NPM treatments were 52.2, 113.1, 1064.8, 254.5, 535.4, and 512.1 kg·ha-1, respectively. Fertilizer N use efficiency ranged from 15% to 36% among fertilizer N treatments. For NO3--N accumulation, N treatment was high in depth of 0-300 cm, NP, NM, and NPM treatments were high in 0-180 cm. Soil water content at harvest follows this order: CK＞N＞M＞NP＞NPM. For NP, NPM treatments, subsoil water deficit produced at planting. Fertilization significantly (P＜0.05) enhanced crop yield, increased soil productivity led to subsoil water deficit, the soil-water deficit retarded NO3--N movement down and accumulated in the soil profiles. Fertilization is a common drive to increase crop yield, subsoil water deficit and nitrate accumulation in the soil profiles of continuous wheat cropping system on the Loess Plateau.

Key words: Semi-arid, Wheat, Yield, Fertilization, Soil water, NO3--N accumulation