Effects of integrated agronomic management practices on yield and nitrogen efficiency of summer maize in North China

Excessive nitrogen (N) fertilizer application, outdated fertilization techniques, and non-optimal planting patterns are current cultivation problems with summer maize (Zea mays L.) among smallholders in North China. To try to solve those problems, this study examined four integrated agronomic management treatments-MT (FP: traditional farming practices; OPT-1: an optimized combination of cropping systems and fertilizer treatment; HY: treatment based on high-yield studies; and OPT-2: further optimized combination of cropping systems and fertilizer treatment) and four N application rate treatments-NT (0, 129.0, 184.5, and 300.0 kg ha(-1)). Maize grain yield and N efficiency were determined under each treatment. Grain yield, yield components, individual/population dry matter weight, N partial factor productivity (PFPN), N use efficiency (NUE), and agronomic efficiency of N (AEN) were measured. Results from the NT revealed no significant increase in grain yield in response to N applied above 184.5 kg ha(-1) and increased yield was achieved by the MT. In MT. the change in sowing method from relay intercropping to direct seeding was effective in avoiding maize rough dwarf virus and in encouraging mechanized production; individual and population dry matter accumulation from the tasseling stage (VT) to physiological maturity stage (R6) increased in response to delayed sowing date and harvesting time; grain yield increased significantly from more ears per hectare due to increased planting density; and high N efficiency was achieved after optimizing fertilization patterns. In this study, OPT-2 obtained 67.0%, 104.0%, and 53.5% higher grain yield, PFPN, and NUE, respectively, compared to FP, achieving high yield and high N efficiency. Furthermore, the low AEN value suggests that further reduction in the N application rate of OPT-2 may be possible. (C) 2012 Elsevier B.V. All rights reserved.