The nitrogen (N) use status and soil fertility and wheat yield were studied under the condition of reduced urea N input and combined with organic matter

to provide a theoretical basis for winter wheat cultivation in the North China Plain

in terms of improving the N use and fertilizer efficiencies. Field trials were carried out with five treatments:no N application (CK)

farmer N application (FN)

20% reduction N application (80% FN)

20% reduction N application with bio-organic manure (80% FN+OM)

and 20% reduction N application with biochar (80% FN+BC). In the study

the responses of soil bulk density

organic matter

NO3--N

microbial diversity

yield

and N utilization of wheat were measured under winter wheat-maize rotation systematically. The results showed that soil capacity was significantly influenced by the application of organic matter. Compared with 80% FN

the soil bulk density in 80% FN+OM and 80% FN+BC were decreased by 3.83%~4.58% and 2.96%~5.07% in 0-20 and 20-40 cm at maturity stage

respectively. Soil organic matter content of 80% FN+OM was higher than other treatments

and greater by 2.13%~18.81% with 80% FN+OM than N fertilizer treatments in 0-40 cm at maturity stage. Soil NO3--N was significantly affected by the application of N fertilizer. Soil NO3--N was higher in 80% FN+OM and 80% FN+BC than other treatments in 0-40 cm at flag raising stage. Soil NO3--N content with 80% FN+BC was higher than other treatments in 0-80 cm at grouting stage. The soil NO3--N residues of FN treatment was higher than other treatments at maturity. Combined application of organic matter could improve soil microbial diversity

increase the number of bacteria OTU

balance the relative abundance of bacteria

and stabilize the soil micro ecological environment. The wheat yield and N agronomic efficiency with 80% FN+OM were 1.09%~7.34% and 2.78%~41.49% higher than other N application treatments

respectively. In the perspective of soil physical and chemical properties

N reduction combined with bio-organic manure rather than with biochar could promote soil quality through increasing soil physical and chemical properties

soil microbial diversity

and wheat production. It is recommended that scientific application of N fertilizer combined with organic matter could improve the sustainable utilization of soil.