Global metaanalysis of the nonlinear response of soil nitrous oxide (N ₂ O) emissions to fertilizer nitrogen

Abstract

Nitrous oxide (N 2 O) is a potent greenhouse gas (GHG) that also depletes stratospheric ozone. Nitrogen (N) fertilizer rate is the best single predictor of N 2 O emissions from agricultural soils, which are responsible for ∼50% of the total global anthropogenic flux, but it is a relatively imprecise estimator. Accumulating evidence suggests that the emission response to increasing N input is exponential rather than linear, as assumed by Intergovernmental Panel on Climate Change methodologies. We performed a metaanalysis to test the generalizability of this pattern. From 78 published studies (233 site-years) with at least three N-input levels, we calculated N 2 O emission factors (EFs) for each nonzero input level as a percentage of N input converted to N 2 O emissions. We found that the N 2 O response to N inputs grew significantly faster than linear for synthetic fertilizers and for most crop types. N-fixing crops had a higher rate of change in EF (ΔEF) than others. A higher ΔEF was also evident in soils with carbon >1.5% and soils with pH <7, and where fertilizer was applied only once annually. Our results suggest a general trend of exponentially increasing N 2 O emissions as N inputs increase to exceed crop needs. Use of this knowledge in GHG inventories should improve assessments of fertilizer-derived N 2 O emissions, help address disparities in the global N 2 O budget, and refine the accuracy of N 2 O mitigation protocols. In low-input systems typical of sub-Saharan Africa, for example, modest N additions will have little impact on estimated N 2 O emissions, whereas equivalent additions (or reductions) in excessively fertilized systems will have a disproportionately major impact.fertilizer response | greenhouse gas emissions | agriculture | bioenergy | greenhouse gas mitigation

A novel and effective technology for mitigating nitrous oxide emissions from land-applied manures

“…The vermiculite additions corresponded to an application equivalent of 0.27-7 t/ha across the treatments. The manure and urea quantities were chosen to represent a N loading rate of 150 kg N/ha and 50 kg N/ha in our pots, which covers a range of typical N addition rates to agricultural soils (Gregorich et al 2014;Shcherbak et al 2014). The combinations of manures and vermiculite incubations are shown in Table 1.…”

Responses of soil nitrous oxide production and abundances and composition of associated microbial communities to nitrogen and water amendment

“…Globally, soils a r e m a j o r s o u r c es o f N 2 O e m i s s i on s , a n d 60 % (3.5 Tg N year −1 ) of N 2 O emissions are derived from arable soils (Goldberg and Gebauer 2009;IPCC 2013). There is little doubt that increasing atmospheric concentration of N 2 O is primarily caused by the excessive use of nitrogen (N) fertilizer (Davidson 2009;Shcherbak et al 2014;Zhu et al 2015). However, N 2 O production from N fertilizer depends mainly on soil properties but also by soil moisture and the type of N fertilizer (Zhu et al 2013b;Cheng et al 2014;Wang et al 2016a;Zhang et al 2016).…”

Nitrogen fertiliser-induced changes in N2O emissions are attributed more to ammonia-oxidising bacteria rather than archaea as revealed using 1-octyne and acetylene inhibitors in two arable soils

“…Increasing application of mineral N fertiliser and the expansion of arable soils contributes to over half of anthropogenic N 2 O production over the past few decades (Davidson 2009;Smith et al 2012;Shcherbak et al 2014). Therefore, it is necessary to understand the microbial mechanism of N 2 O emission from soil in order to develop future mitigation strategies and achieve sustainable agriculture practices.…”