Nitrous oxide fluxes from corn fields: on‐farm assessment of the amount and timing of nitrogen fertilizer

Abstract

Nitrogen fertilization is considered as an important source of atmospheric N 2 O emission. A seven site-year on-farm field experiment was conducted at Ottawa and Guelph, ON and Saint-Valentin, QC, Canada to characterize the affect of the amount and timing of N fertilizer on N 2 O emission in corn (Zea mays L.) production. Using the static chamber method, gas samples were collected for 28-days after preplant and 28-days after sidedress fertilization at the seven site-year, resulting in 14 monitoring periods. For both methods of fertilization, peak N 2 O flux and cumulative emission increased with the amount of N applied, with rates ranging from 30 to 900 lg N m À2 h À1 . Depending on N amount and time of application, cumulative emission varied from 0.05 to 2.42 kg N ha À1 , equivalent to 0.03% to 1.45% of the N fertilizer applied. Differences in N 2 O emission peaks among fertilizer treatments were clearly separated in 13 out of 14 monitoring periods. Total N 2 O emissions may have been underestimated compared with annual monitoring in 10 out of the 49 cases because the monitoring period ended before N 2 O efflux returned to the baseline level. The flux of N 2 O was negligible when soil mineral N in the 0-15 cm layer was o20 mg N kg À1 . While rainfall stimulated emission, soil temperature 415 1C was likely the driving force responsible for the higher levels of N 2 O found for sidedress than preplant application methods. However, caution must be taken when interpreting these later results as preplant fertilization may have continuously stimulated N 2 O emissions after the 28-days monitoring period, especially in situations where N 2 O effluxes have not fallen back to their baseline levels. Increasing fertilizer rates from 90 to 150 kg N ha À1 resulted in slight increases in yields, but doubled cumulative N 2 O emissions.

Nitrogen fertilizer management for nitrous oxide (N2O) mitigation in intensive corn (Maize) production: an emissions reduction protocol for US Midwest agriculture

“…1). Non-linear relationships have also been found in corn and wheat systems in Ontario and Alberta, (Grant et al 2006;Ma et al 2009). Emissions of N 2 O may therefore exhibit a threshold response related to crop N requirement and the magnitude of N input (Erickson et al 2001).…”

Non-linear response of soil N2O emissions to nitrogen fertiliser in a cotton–fallow rotation in sub-tropical Australia

“…There was no significant difference in cumulative N 2 O emissions between the 0N and 90N treatments, indicating that soil microbes responsible for N 2 O production had limited access to N. The N 2 O fluxes in the 180N and 270N treatments increased by 60 and 184% respectively, compared with the 90N treatment. Previous studies reported both linear and nonlinear responses of cumulative N 2 O emissions to N fertiliser rates (Hoben et al 2011;Lebender et al 2014;Liu et al 2012;Ma et al 2010;McSwiney and Robertson 2005). However, recent metadata analyses suggest a non-linear response of direct N 2 O emissions to increased N additions (Kim et al 2013;Shcherbak et al 2014).…”

Nitrous oxide emissions from a maize field during two consecutive growing seasons in the North China Plain

“…However, the design of control treatments in the literature did not have uniform rule. For instance, Dusenbury et al (2008) established uncultivated grass system as their control plot (no fertilizer, crop and irrigation) for deriving EFs of fertilizer crop fields in a wheat field, while others only mentioned unfertilized or without fertilization and crop residual as the control plots in agricultural fields (Zou et al, 2005b;Alluvione et al, 2010;Ma et al, 2010). Our incipient understanding about the control treatment was that the influence of human activities on the field was as small as possible, and thus, the field without crop and irrigation was designed as the control plot which was similar with the design of Dusenbury et al (2008).…”