Abstract: A field experiment was conducted to study the effects of deep plowing at different time and of mulching with different materials in summer fallow period on the nitrogen absorption, translocation, and allocation, and on the water- and nitrogen use efficiency of dryland wheat. As compared with the deep plowing and mulching after 15 days of previous wheat harvest, the deep plowing and mulching after 45 days of previous wheat harvest improved the plant nitrogen content at elongation, booting, and mature stages, increased the plant nitrogen accumulation and nitrogen uptake at each growth stage, increased the nitrogen transfer amount and transfer rate in pre-anthesis, increased the contribution rate of nitrogen transfer to grain nitrogen in pre-anthesis under liquid film mulching and no-mulching, and increased the accumulation amount and rate of grain nitrogen while decreased the accumulation rate of nitrogen in leaf, steam, and glume + spike stem, with the better effects under seepage plastic mulching. Deep plowing and mulching after 45 days of previous wheat harvest, as compared with that after 15 days of previous wheat harvest, increased the yield and water use efficiency and the nitrogen uptake efficiency and production efficiency. In sum, deep plowing and mulching after rain in fallow period increased the plant nitrogen uptake and accumulation, and was conducive to the transfer of pre-anthesis stored nitrogen to grain, increased the accumulation of grain nitrogen, decreased the nitrogen accumulation of vegetative organ, and ultimately, improved the yield, water use efficiency, nitrogen uptake efficiency, and nitrogen production efficiency. Among the mulching measures, seepage plastic mulching had better effects.

Key words: rhizosphere, planting age, soil physicochemical characteristics., nematode community structure, Lycium barbarum