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Effects of Mulching Patterns on Spatio-temporal Variation of Soil Nitrate and Nitrogen Utilization Efficiency of Maize on Dry land The college of Materials science, Xi’an Univ. of Arch.Tech. ,Xi’an 710055 Zhang Xianmei 1205140117 Abstract: (A1)A field experiment in Lijiabu, Dingxi City of Gansu province, was carried out based on improving nitrogen use efficiency and reducing the pollution of nitrogen fertilizer.(A2) Four treatments, namely flat-planting with no mulching (NM), half-mulching and flat-planting (HM), complete-mulching and flat-planting (CM), completely mulched alternating narrow and wide ridges with furrow planting (CMRF).(A3)Experiment were designed to study accumulation of residual NO3--N and dynamic accumulation and distribution of dry matter and nitrogen use efficiency. (A4)The results showed that in the whole growth period of mulching treatments NO3--N content of 0-10cm soil layer was highest and were significantly higher than that of NM, indicating there existed NO3--N surface accumulation in mulching treatments. NO3--N content of all treatments under 140cm soil layer was accumulated. The average nitrogen accumulation in the whole growth period was: CMRF CM HM NM. Compared with CM and NM, grain nitrogen accumulation of CMRF was increased by 20.48% and 87.87%, (A5)showing that CMRF significantly enhanced plants nitrogen utilization from soil, as well as transport of nitrogen to grain Biomass yield of CMRF was37.60% higher than that of HM, maize yield was increased by 49.84%, and nitrogen harvest index was significantly increased by 22.55% compared with HM. During different treatments nitrogen use efficiency of maize was significantly different at 0.05 levels, CMRF was significantly increased by 53.98% than NM. Keywords: Mulching; Loess plateau; Nitrate; Nitrogen use efficiency; Maize Nitrogen is not only one of the important elements of life and indispensable nutrients in agricultural production, but also a growing environmental p