Can nitrogen fertiliser and nitrification inhibitor management influence N2O losses from high rainfall cropping systems in South Eastern Australia?

Tillage does not increase nitrous oxide emissions under dryland canola (Brassica napus L.) in a semiarid environment of south-eastern Australia

“…These losses are comparable to those recorded for rain-fed wheat from a strongly acid soil in a temperate region in southeastern Australia, where emissions were in the range of 0-12.5 g N 2 O-N/ha.day and the annual losses were 200-270 g N 2 O-N/ha (Barker-Reid et al 2005), but nearly double those from a canola crop grown in a sandy soil in a semiarid Mediterranean environment in Western Australia (Barton et al 2010) where annual N 2 O emission was 80 and 128 g N 2 O-N/ha from non-N-and N-fertilised canola respectively. In contrast, the average daily N 2 O emission rate measured at the current site (0.48-0.61 g N 2 O-N/ha.day) was only a fraction of that measured under a canola crop on raised and flat seedbeds in a high-rainfall environment in south-west Victoria (Harris et al 2013) where the average daily N 2 O emission rate was up to 215 g N 2 O-N/ha during July-September 2011. Harris et al (2013) concluded that denitrification was the main process leading to high N 2 O emissions during the wet period in the high-rainfall cropping system.…”

“…In contrast, the average daily N 2 O emission rate measured at the current site (0.48-0.61 g N 2 O-N/ha.day) was only a fraction of that measured under a canola crop on raised and flat seedbeds in a high-rainfall environment in south-west Victoria (Harris et al 2013) where the average daily N 2 O emission rate was up to 215 g N 2 O-N/ha during July-September 2011. Harris et al (2013) concluded that denitrification was the main process leading to high N 2 O emissions during the wet period in the high-rainfall cropping system. No obvious periods of waterlogging were observed at the current site, reflecting the Table 3.…”

“…There is a clear need for primary producers to implement methods aimed at reducing overall N 2 O emissions. Research has attributed the majority of N 2 O emitted from soil to the following soil microbial processes: (i) nitrification, in which soil bacteria convert ammonium into nitrate (NO 3 -); (ii) denitrification, in which soil microbes consume soil NO 3 -under anaerobic conditions; (iii) assimilatory NO 3 -reduction, in which NO 3 -is converted to nitrite; and (iv) dissimilatory NO 3 -reduction, in which NO 3 -is converted to ammonium (Mosier et al 1998;Dalal et al 2003;Harris et al 2013). Therefore, activities that affect these soil microbial processes could have a significant impact on N 2 O emissions (Dalal et al 2003).…”

“…Increasing application rates of nitrogen (N) fertiliser has been previously shown to increase N 2 O emissions in broadacre cropping systems across a range of environments (Dalal et al 2003;Harris et al 2013;Schwenke and Haigh 2015), attributable to higher availability of N vulnerable to gaseous loss and to an imbalance between N availability in the soil and demand by the crop. Tillage is known to elevate levels of plantavailable soil N due to mineralisation of soil organic matter.…”

Influence of enhanced efficiency fertilisation techniques on nitrous oxide emissions and productivity response from urea in a temperate Australian ryegrass pasture

“…We hypothesised that any denitrification would be largely N 2 during this time and N 2 O emissions would be minimal (Ciarlo et al 2008). Recent work by Friedl et al (2016) found that the N 2 /(N 2 +N 2 O) ratio increased with increasing soil moisture (to 100% water filled pore space, WFPS) in sub-tropical pastures, and Harris et al (2013) hypothesised that this was the reason for low N 2 O emissions from cropping sites during periods when soil WFPS exceeded 90%.…”