N sub(2)O emission from conventional and minimum-tilled soils

• Published in: Biology and fertility of soils Vol. 44; no. 6; pp. 863 - 873
• Main Authors: Beheydt, Daan, Boeckx, Pascal, Ahmed, Hasan Pervej, Cleemput, Oswald
• Format: Journal Article
• Language: English
• Published: 01-07-2008
• Subjects: Zea mays
• ISSN: 0178-2762; 1432-0789
• DOI: 10.1007/s00374-008-0271-9

In this study, we investigated N sub(2)O emissions from two fields under minimum tillage, cropped with maize (MT maize) and summer oats (MT oats), and a conventionally tilled field cropped with maize (CT maize). Nitrous oxide losses from the MT maize and MT oats fields (5.27 and 3.64kg N sub(2)O-N ha super(-1), respectively) were significantly higher than those from the CT maize field (0.27kg N sub(2)O-N ha super(-1)) over a period of 1year. The lower moisture content in CT maize (43% water-filled pore space [WFPS] compared to 60-65%) probably caused the difference in total N sub(2)O emissions. Denitrification was found to be the major source of N sub(2)O loss. Emission factors calculated from the MT field data were high (0.04) compared to the CT field (0.001). All data were simulated with the denitrification decomposition model (DNDC). For the CT field, N sub(2)O and N sub(2)O+N sub(2) emissions were largely overestimated. For the MT fields, there was a better agreement with the total N sub(2)O and N sub(2)O+N sub(2) emissions, although the N sub(2)O emissions from the MT maize field were underestimated. The simulated N sub(2)O emissions were particularly influenced by fertilization, but several other measured N sub(2)O emission peaks associated with other management practices at higher WFPS were not captured by the model. Several mismatches between simulated and measured $${\text{NH}}_4 + $$, $${\text{NO}}_3 - $$ and WFPS for all fields were observed. These mismatches together with the insensitivity of the DNDC model for increased N sub(2)O emissions at the management practices different from fertilizer application explain the limited similarity between the simulated and measured N sub(2)O emissions pattern from the MT fields.