Global Maize Project in China: Dahe, Shijiazhuang, Hebei Province

This long-term Global Maize ecological intensification (EI) experiment was initiated in 2009 in Dahe Station, Shijiazhuang city, Hebei Province. The main cropping system in Hebei is summer maize rotated with winter wheat. Winter wheat (the 12^th successive crop) was planted on October 2014 and was harvested on June 12, 2015. Summer maize (the 13^th successive crop) was planted on June 14, 2015 and harvested on October 6, 2015.

The two main fertilizer treatments were EI with 182-73-70 kg N-P₂O₅-K₂O/ha in summer maize and 182-107-86 kg/ha in winter wheat. Farmers’ practice (FP) included 225-120-50 kg/ha in summer maize and 225-120-50 kg/ha in winter wheat. The study also had three subplots that created three different N application regimes: (1) N applied in all three years, (2) N applied in two of every three years, and no N applied in any year.

The EI treatment produced a much lower maize grain yield average (5.0 t/ha) compared to FP (6.7 t/ha). This gap was primarily due to a severe lodging problem under EI, which had a higher plant density of 82,500 plant/ha compared to 67,500 plant/ha under FP. The agronomic efficiency (AE) of N (kg grain yield increase per kg N applied) was 9.5 kg/kg under EI, which was much higher than under FP (6.1 kg/kg). No significant difference in partial factor productivity (PFP) of N (kg grain yield per kg N applied) was found between EI (27.2 kg/kg) and FP (29.6 kg/kg).

In winter wheat, no significant difference in grain yields were found between EI (7.9 t/ha) and FP (8.2 t/ha). A much higher AE value was found under EI (23.0 kg/kg) versus FP (18.2 kg/kg). Significantly higher PFP (43.6 kg/kg) was found for EI compared to FP (36.3 kg/kg). Higher N use efficiency parameters under EI were possibly a result of less N fertilizer application.

After seven crops of summer maize and six crops of winter wheat treated with EI and FP management, it was concluded that though no significant grain yield difference between the two treatments were recorded, although the reduced input of N and P, and increased K, significantly increased N efficiencies. We anticipate that further adoption of reduced N and P rates will positively impact on ecological and sustainable management practices.