Nitrous oxide emissions from an intensively cultivated maize-wheat rotation soil in the North China Plain [An article from: Science of the Total Environment, The]

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Description:
N"2O emissions from a maize-wheat rotation field were monitored in the Fengqiu State Key Agro-Ecological Experimental Station (Fengqiu County, Henan Province, China) from June 2004 to June 2005. The experiment included four treatments: a bare (crop-absent) soil treated with 150 kg N ha^-^1 (WN150) and soils fertilized with 0 (N0), 150 (N150), and 250 (N250) kg N ha^-^1 and cropped with maize or wheat. The bulk of the N"2O emissions occurred in pulses following the application of fertilizer N at soil temperatures of 15^oC or more. The application of fertilizer N significantly increased the N"2O emission, from 636 g N"2O-N ha^-^1 year^-^1 in the N0 treatment to 4480 g N"2O-N ha^-^1 year^-^1 in the N250 treatment. However, this increase primarily occurred during the maize growing season. The emission factor of applied fertilizer N as N"2O was 1.05-1.34% and 0.24-0.26% during the 105-day maize and 241-day wheat growing seasons, respectively, and was on average 0.61-0.77%. Increasing the rate of fertilizer application increased the emission factor during the maize growing season. The presence of maize appears to increase N"2O emission by 45% versus bare soil during the maize growing season. And, N"2O emission during the maize season were significantly related to CO"2 production (R=0.43-0.81, n=30, P