Evaluation of the Agronomic Impacts on Yield-Scaled N2O Emission from Wheat and Maize Fields in China

Abstract

Contemporary crop production faces dual challenges of increasing crop yield while simultaneously reducing greenhouse gas emission. An integrated evaluation of the mitigation potential of yield-scaled nitrous oxide (N 2 O) emission by adjusting cropping practices can benefit the innovation of climate smart cropping. This study conducted a meta-analysis to assess the impact of cropping systems and soil management practices on area-and yield-scaled N 2 O emissions during wheat and maize growing seasons in China. Results showed that the yield-scaled N 2 O emissions of winter wheat-upland crops rotation and single spring maize systems were respectively 64.6% and 40.2% lower than that of winter wheat-rice and summer maize-upland crops rotation systems. Compared to conventional N fertilizer, application of nitrification inhibitors and controlled-release fertilizers significantly decreased yield-scaled N 2 O emission by 41.7% and 22.0%, respectively. Crop straw returning showed no significant impacts on area-and yield-scaled N 2 O emissions. The effect of manure on yield-scaled N 2 O emission highly depended on its application mode. No tillage significantly increased the yield-scaled N 2 O emission as compared to conventional tillage. The above findings demonstrate that there is great potential to increase wheat and maize yields with lower N 2 O emissions through innovative cropping technique in China.

Modelling nitrification inhibitor effects on N<sub>2</sub>O emissions after fall- and spring-applied slurry by reducing nitrifier NH<sub>4</sub><sup>+</sup> oxidation rate

“…Fig. 6) were consistent with findings in metaanalyses by Akiyama et al (2010) and Gilsanz et al (2016) that NI was more effective in reducing N 2 O emissions from a given land use when emissions were greater. These greater reductions were attributed in the model to heavy rainfall several days after application in 2016 ( Fig.…”

“…In a meta-analysis of field experiments conducted for 2008, Akiyama et al (2010) found average reductions of 38 ± 6 % in N 2 O emissions from NI, with some variation attributed to land use type and emission rates. Similar average reductions of 35 %-40 % were reported in more recent meta-analyses by Ruser and Schulz (2015), Gilsanz et al (2016), and Gao and Bian (2017). However the magnitudes of these reductions are uncertain because they vary with the rate and timing of fertilizer or slurry application, with land use and ecosystem type (Akiyama et al, 2010), and with application method (Zhu et al, 2016).…”

“…Reductions in N 2 O emissions modelled with all proposed values of I t=0 and K iNH 4 varied from 27 % to 41 % in 2015, and from 38 % to 57 % in 2016 (Table 9), close to the range of 42.6 % ± 5.5 % derived from meta-analyses of NI effects with cattle slurry by Gilsanz et al (2016). Further evaluation of these parameters should be undertaken in future studies in which measurements are taken at higher frequencies (e.g.…”

“…The first two parameters correspond to those in earlier models of NI for inhibition effectiveness (0.5-0.9) and duration (30-60 d; Cui et al, 2014;Del Grosso et al, 2009). These models have given reductions in N 2 O emissions with NI in agricultural crops of around 25 % (Cui et al, 2014), 10 % (Del Grosso et al, 2009) or less (Abalos et al, 2016), which are frequently smaller than reductions of 26 %-43 % and 24 %-46 % derived from meta-analyses of NI effects in agricultural crops by Akiyama et al (2010) and Gilsanz et al (2016) respectively. Direct effects on NI of soil water content and pH were not modelled here due to uncertainty in parameterization, although both affect nitrification and hence the magnitude of NI activity.…”

How Tillage and Fertilization Influence Soil N2O Emissions after Forestland Conversion to Cropland

“…Previous studies showed that the N fertilizer application rate was one of the key factors influencing soil N 2 O production [26]. Meanwhile, N fertilizer application rate also had considerable impacts on crop yield [41]. Therefore, it is very important to determine a reasonable rate of N fertilizer application in the Sichuan Basin after forestland conversion to cropland, which can simultaneously achieve high yield and mitigate soil N 2 O emission.…”