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: ecological intensification (EI) treatment with application of 170 kg N, 75 kg P₂O₅ and 70 kg K₂O/ha in winter wheat and 182 kg N, 67 kg P₂O₅ and 65 kg K₂O/ha in summer maize; and farmer’s practice (FP) treatment with application of 225 kg N, 120 kg P₂O₅ and 50 kg/ha in winter wheat and 255 kg N, 80 kg P₂O₅ and 20 kg K₂O/ha in summer maize. Three subplots included: N applied in all three years (N all yr), N applied in 2 of every 3 years (N 2/3 yr), and no N applied (N 0 yr). Winter wheat (the sixth successive crop) was planted on October 19, 2011 and harvested on June 18, 2012, while summer maize (the seventh successive crop) was planted in the same plots on August 20, 2012 and harvested on October 12, 2012.

No significant difference in grain yields was found between EI and FP treatments for winter wheat, although more 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 (6.6 kg/kg) than in the FP treatment (5.1 kg/kg). Similarly, partial factor productivity of N (kg grain yield per kg N applied) was considerably higher in the EI treatment (41.5 kg/kg) than in the FP treatment (29.5 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