Effect of water-fertilizer and theoretical analysis of deep plough-deep fertilization at one earlier time in winter wheat-growing regions of Weibei rainfed croplands

The aim of this study was to explore the effect of deep plough-deep fertilization at one early time before sowing to winter wheat growth and development in Weibei tableland of Shaanxi Province, China. The results show that both nitrogen fertilizer use efficiency and water use efficiency are obviously increased by using the approach of deep plough-deep fertilization at one earlier time before sowing, as well as the NO3--N storage and water storage in the soil profile after the crop harvesting. The distribution of NO3--N in soil profile is the logarithmic distribution which can indicated as y=a-blogx, where y is amount of NO3--N at a given depth, x is soil depth. This might be the characteristic pattern of the NO3--N distribution in rainfed farming soil. The NO3--N leakage does not occur during the period of experiment. The theoretical meanings of the earlier deep plough-deep fertilization at one time can be explained as “Autumn rainfall-Winter storage-Spring use” and “Autumn fertilization-Winter storage-Spring use”.