Spatial variation of nitrous oxide emission between interrow soil and interrow plus row soil in a long-term maize cultivated sandy loam soil

There is a high spatial variation in N2O emission from agricultural fields and N2O emissions from fields cultivated with stalk-crops was generally measured in the interrow area. The aim of this study was to evaluate the difference in seasonal N2O emissions between interrow soil and interrow + row soil, and to understand the effect of different fertilizers on N2O emissions in a maize-cultivated sandy loam soil in the North China Plain. The experiment included five treatments: organic manure (OM), half-organic manure N plus half fertilizer N (HOM), fertilizer NPK (NPK), fertilizer NK (NK) and control (CK). Cumulative N2O emission from interrow + row soil during the maize growth season was 0.84-1.22 kg N ha− 1 with an average of 0.98 kg N ha− 1 in the N-fertilized treatments, significantly higher than the 0.30-0.49 kg N ha− 1 from interrow soil. However, no significant difference was observed in the CK treatment. The measurement in interrow soil underestimated N2O emissions by 44-67%. This difference mainly occurred at the two peak emission periods following fertilizer application probably due to discrepancy in soil denitrification potential. Manure application more efficiently increased difference in N2O emission between interrow soil and interrow + row soil than inorganic N fertilizer application. The higher NO3− concentration did not induce larger N2O emission from interrow soil in the NK treatment than in the NPK treatment, but did from interrow + row soil, resulting in greater difference in N2O emission between interrow soil and interrow + row soil. It is suggested that measuring N2O emission solely from interrow soil could underestimate seasonal N2O emissions, and partly mask the effect of N fertilizer application rates on N2O emission in a maize-cultivated soil in the North China Plain.

► Cumulative N2O emissions in interrow + row significantly higher than in interrow. ► Manure resulted in greater spatial variation in N2O flux than inorganic fertilizer. ► Measurement in interrow soils underestimated field N2O emissions by 44-67%. ► Measurement in interrow may mask the effect of applied N rates on N2O emissions.