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DISTINGUISHING NITRIFICATION AND DENITRIFICATION SOURCES OF N 2 O IN A MEXICAN WHEAT SYSTEM USING 15 N
Author(s) -
Panek J. A.,
Matson P. A.,
Ortíz-Monasterio I.,
Brooks P.
Publication year - 2000
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/1051-0761(2000)010[0506:dnadso]2.0.co;2
Subject(s) - denitrification , nitrification , nitrogen cycle , environmental science , irrigation , soil water , agronomy , nitrogen , flux (metallurgy) , simultaneous nitrification denitrification , ecology , chemistry , soil science , biology , organic chemistry
Irrigated wheat systems in the Yaqui Valley of Sonora, Mexico, receive high nitrogen inputs and large discrete inputs of irrigation water, with extended drying periods between irrigation events. We used this system to determine the contribution of the separate processes of nitrification and denitrification to the total N 2 O flux from the soil and to link each process with important driving variables. At the beginning of the wheat cycle, in an experimental wheat field, we established and maintained replicated, paired soil plots labeled with 25% atom excess (a.e.) K 15 NO 3 and ( 15 NH 4 ) 2 SO 4 at a rate of 7% of the existing pool of NO 3 − and NH 4 + , respectively, and measured the evolution of 15 N 2 O in each over the course of an irrigation/fertilization cycle. Denitrification losses of N 2 O predominated over nitrification in the two days following irrigation, and continued for six days. The duration of denitrification was corroborated by measures of 15 N 2 flux. Nitrification became increasingly important as soils drained. Each process contributed equally to total N 2 O losses over the 4‐wk period after the wheat cycle began.