Intensive measurement of nitrous oxide emissions from a corn–soybean–wheat rotation under two contrasting management systems over 5 years

Abstract

No-tillage (NT), a practice that has been shown to increase carbon sequestration in soils, has resulted in contradictory effects on nitrous oxide (N 2 O) emissions. Moreover, it is not clear how mitigation practices for N 2 O emission reduction, such as applying nitrogen (N) fertilizer according to soil N reserves and matching the time of application to crop uptake, interact with NT practices. N 2 O fluxes from two management systems [conventional (CP), and best management practices: NT 1reduced fertilizer (BMP)] applied to a corn (Zea mays L.), soybean (Glycine max L.), winter-wheat (Triticum aestivum L.) rotation in Ontario, Canada, were measured from January 2000 to April 2005, using a micrometeorological method. The superimposition of interannual variability of weather and management resulted in mean monthly N 2 O fluxes ranging from À1.9 to 61.3 g N ha À1 day À1 . Mean annual N 2 O emissions over the 5-year period decreased significantly by 0.79 from 2.19 kg N ha À1 for CP to 1.41 kg N ha À1 for BMP. Growing season (May-October) N 2 O emissions were reduced on average by 0.16 kg N ha À1 (20% of total reduction), and this decrease only occurred in the corn year of the rotation. Nongrowing season (November-April) emissions, comprised between 30% and 90% of the annual emissions, mostly due to increased N 2 O fluxes during soil thawing. These emissions were well correlated (r 2 5 0.90) to the accumulated degree-hours below 0 1C at 5 cm depth, a measure of duration and intensity of soil freezing. Soil management in BMP (NT) significantly reduced N 2 O emissions during thaw (80% of total reduction) by reducing soil freezing due to the insulating effects of the larger snow cover plus corn and wheat residue during winter. In conclusion, significant reductions in net greenhouse gas emissions can be obtained when NT is combined with a strategy that matches N application rate and timing to crop needs.

Atmospheric constraints on 2004 emissions of methane and nitrous oxide in North America from atmospheric measurements and a receptor-oriented modeling framework

“…Application of this scaling factor for the full year, or different time windows worsens model-data agreement. This temporal application of the scaling is mostly consistent with the enhanced emissions being agriculturally related: flux measurements at an agricultural site in Ontario, Canada (similar latitude to LEF) find nitrous oxide emissions peaks occurring roughly in this same time domain (Wagner-Riddle et al 2007). …”

Potential for biological nitrification inhibition to reduce nitrification and N2O emissions in pasture crop–livestock systems

“…In addition, this implies that further applications may not be effective in increasing yields in the future (Cassman and Pingali, 1995;Tilman et al, 2002;Cassman et al, 2003;Zhang et al, 2008). Several changes in agricultural management practices during the twentieth century led to the development of high-nitrifying soil environments, and they are largely responsible for N loss (through NO 3 2 leaching and gaseous N emissions (N 2 O, NO)) and N pollution of the environment (NO 3 2 pollution of water bodies and global warming) (Vitousek et al, 1997a and1997b;Matson et al, 1998;Tilman et al, 2001 andDinnes et al, 2002;Wagner-Riddle et al, 2007;Turner et al, 2008).…”

Wavelet analysis of wintertime and spring thaw CO2 and N2O fluxes from agricultural fields

“…This demonstrates that the N 2 O fluxes for the replicate plots had small differences in temporal variation while N 2 O fluxes from BM and CONV treatments showed a large difference in their time series. Wagner-Riddle et al (2007) concluded that N 2 O emissions were significantly different between CONV and BM treatments using seasonal totals obtained from the time series shown here. The wavelet analysis presented here shows that there were differences in the temporal trends of the flux time series for each treatment, in addition to the magnitude difference in emission totals.…”

“…Hourly concentration differences between two heights were measured on each of the four plots and hourly fluxes were determined according to Wagner-Riddle et al (2007). Due to the sequential plot sampling, a maximum of 6 hourly flux values were calculated for each plot per day (e.g.…”

“…Van Bochove et al, 2000;Dö rsch et al, 2004). Spring thaw emissions can represent up to 70% of annual N 2 O emissions (Lemke et al, 1998;Wagner-Riddle and Thurtell, 1998;Dö rsch et al, 2004;Teepe et al, 2004;Wagner-Riddle et al, 2007). Spring thaw emissions of CO 2 can represent 10-30% of annual C budget, but most research has examined boreal and arctic wetlands (Brooks et al, 1997;Alm et al, 1999;Grogan et al, 2001).…”