Abstract: In order to clarify the effect of soil surface mulching during summer fallow period on soil water, N absorption and translocation, yield, and water and N utilization affected by N application, an experiment was carried out in a wheat field in Wenxi, Shanxi Province. Three N fertilization levels (75, 150 and 225 kg·hm^-2) were included under mulch and no mulch conditions in fallow period. The results showed that after mulching in fallow period, soil water storage in the depth of 0-300 cm (each 20 cm as a soil layer) at sowing stage was increased by 70-80 mm, especially below the depth of 80 cm. Soil water storage in the depth of 0-300 cm was lower at mature stage than at sowing stage, especially in the depth of 0-160 cm being 20-30 mm lower. Mulching increased the population’s tiller number and panicle number, and there was a significant difference between the low and high N fertilization treatments. Mulching also increased wheat’s total water consumption by 5.68-31.30 mm, yield by 1.43%-7.16%, and water use efficiency by 1.27%-4.23%. N accumulation at different growth periods, N translocation before anthesis (NTBA) and N accumulation after anthesis (NAAA) were increased, and the N accumulation at different growth periods significantly differed among the different N fertilization treatments. Mulching improved the N agronomic efficiency and N recovery rate. The results also showed that after mulching in fallow period, the N application level of 150 kg·hm^-2 was the best among the three levels in terms of yield and water use efficiency, and 75 kg·hm^-2 was the lowest. Meanwhile, the 150 kg N·hm^-2 treatment had the highest N accumulation at different growth periods, NTBA and contribution of NTBA to N in grains, and the highest N agronomic efficiency and N recovery rate. In addition, among the yield components, the correlation with the yield was greatest for panicle number, moderate for grain number per panicle, and the lowest for 1000grain weight. In a word, mulching in fallow period in dryland wheat could store and conserve rainfall in fallow period, improving soil water conservation. A synchronous N application of 150 kg·hm^-2 is more beneficial to promote the interaction between water and N, enhancing N absorption, accumulation and translocation, and achieving the purpose of increasing yield and fertilizer utilization efficiency.

Key words: phosphorus addition, organic carbon mineralization, priming effect., paddy soil,  ,