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

This long-term experiment was initiated in June 2009 in Hebei province. Summer maize was the first crop grown at this site, where winter wheat-summer maize rotation system is common. The main plot had two treatments: a) ecological intensification (EI) treatment with 120-60-80 kg N-P₂O₅-K₂O/ha fertilizer application in winter wheat and 150-40-50 kg N-P₂O₅-K₂O/ha in summer maize; and b) farmer’s practice (FP) treatment with 225-120-50 kg N-P₂O₅-K₂O/ha fertilizer application in winter wheat and 300-135-0 kg N-P₂O₅-K₂O/ha in summer maize. Three subplots included: a) N applied in all 3 years (N all yr), b) N applied in 2 of every 3 years (N 2/3 yr), and c) no N applied (N 0 yr). Winter wheat was planted on October 19, 2010 and harvested on June 18, 2011, while summer maize (storage maize) was planted in the same plots on August 20, 2011 and harvested on October 12, 2011.

No significant difference in grain yields was found between EI and FP treatments for winter wheat, although higher N and P were applied in FP. However, agronomic N efficiency (kg grain yield increase per kg N applied) was higher in the EI treatment (13.3 kg/kg) than in the FP treatment (9.4 kg/kg). Similarly, partial factor productivity of N (kg grain yield per kg N applied) was considerably higher in the EI treatment (67.3 kg/kg) than in the FP treatment (37.7 kg/kg). Similar trends for grain yield and N use efficiencies were found in summer maize. N 2/3 yr treatment produced yields similar to N all yr treatment. This demonstrated that skipping N application in two seasons did not affect the grain yield during the third maize growing season. IPNI-21