Responses of soil carbon, nitrogen, and wheat and maize productivity to 10 years of decreased nitrogen fertilizer under contrasting tillage systems.

• 75% N in NT and CT increased SOC and STN compared to 100% N. • Soil quality, wheat and maize yields can be maintained by 75% N fertilizer. • The yield stability of the maize is greater than that of wheat. • CT increased yield stability and SOCS in 0–40 cm compared to NT. • NT increased STN concentration, STNS and NSR in 0–20 cm compared to CT. Excessive nitrogen (N) fertilizer application can cause resource waste and environmental pollution. Thus, whether the rate of N applied can be decreased under no-tillage, which usually increases soil carbon (C) and N stocks, has become an important topic. We hypothesized that a certain extent of N fertilizer application decrease under no-tillage can still maintain higher soil C and N stocks and yields of wheat and maize, however, the effects under different tillage systems may be different. To find the appropriate N fertilizer applications and tillage methods to keep higher soil C and N and crops yields, 10 treatments, including 2 tillage patterns (conventional tillage: CT and no-tillage: NT) and 5 fertilization rates (100%, 75%, 50%, 25% and 0 N of the common N fertilizer application), were tested in triplicate via a randomized block design on a Hapli-Udic Argosol during 2006–2016. The annual wheat and maize yields of 100% N, 75% N and 50% N under CT and NT treatments were significantly higher than those of 25% and 0 N on the studied period (P < 0.05). Higher yield stability of the wheat and maize were found under 75% and 50% N application compared to other N rates. However, the yield stability of wheat was lower than that of maize. The SOC concentration, SOCS and CSR of 75% N application were increased by 1.5, 2.2 and 20.6% than those of 100% N application respectively, in the 0–40 cm soil depth. The STN concentrations of NT-100 and NT-75 were significantly higher than those of other treatments (P < 0.05). The STNS and NSR in the NT-100 treatment were significantly higher than those of other treatments (P < 0.05). NT could lead to more accumulation of SOC and STN in the surface soil depth (0–20 cm) during 2007–2016. In conclusion, 75% of the common N application rate under NT and CT were better choices for sustainable agricultural development. [ABSTRACT FROM AUTHOR]