Nitrous oxide emissions from cultivated black soil: A case study in Northeast China and global estimates using empirical model

Abstract

Manure application is effective in promoting soil carbon sequestration, but its impact on N2O emission is not well understood. A field experiment was conducted in a maize‐cultivated black soil in Northeast China with six treatments: inorganic fertilizer (NPK), 75% inorganic fertilizer N plus 25% pig (PM1) or chicken (CM1) manure N, 50% inorganic fertilizer N plus 50% pig (PM2) or chicken (CM2) manure N, and no N fertilizer (CK). Annual N2O emission significantly increased from 0.34 kg N ha−1 for CK to 0.86 kg N ha−1 for NPK and further to 1.65, 1.02, 1.17, and 0.93 kg N ha−1 for PM1, CM1, PM2, and CM2, respectively. A 15N tracing study showed that 71–79% of total N2O was related to nitrification at 30–70% water‐filled pore space (WFPS), and heterotrophic nitrification contributed 49% and 25% to total N2O at 30% and 70% WFPS, respectively. In an incubation, N2O emission was only stimulated when nitrate and glucose were applied together at 60% WFPS, indicating that denitrification was carbon limited. PM had a stronger effect on denitrification than CM due to higher decomposability, and the lower N2O emission at higher manure application rate was associated with decreased mineral N supply. After compiling a worldwide database and establishing an empirical model that related N2O emissions (kg N ha−1) to precipitation (Pr, m) and fertilizer N application rate (Nr, kg N ha−1) (N2O = 1.533Pr + 0.0238PrNr), annual N2O emission from global‐cultivated black soil applied with inorganic fertilizer N was estimated as 347 Gg N. Our results suggested that N2O emission from cultivated black soils in China was low primarily due to low precipitation and labile organic carbon availability, and would be stimulated by manure application; thus, increased N2O emission should be taken into consideration as applying manure increases soil organic carbon sequestration.

Effects of different forms of plant-derived organic matter on nitrous oxide emissions

“…3,4,7,8,33,34,38,39 In the present study, nitrier denitrication might contribute greatly to the production of N 2 O, since the study soil had a relatively low level of organic C and the application of maize residues could gradually release new labile DOC to the soil, which resulted in an increase in soil microbial activity and led to low-oxygen conditions, and thus enhanced the nitrier denitrication. 40 The study soil should be C limited and the increase of C inputs via the application of maize residues could increase the N 2 O emission.…”

“…2 However, these benets may be offset if crop residues substantially increase soil N 2 O emissions. [3][4][5][6] The major soil processes related to N 2 O production are nitrication and denitrication, which are controlled mainly by substrates (e.g., NH 4 + -N, NO 3 due to the hydrolysis of polymers present in the crop residues, 8 and this soluble form of available C accounts for up to 20% of the total C in crop residues. 9 The dissolved organic carbon (DOC) represents a readily available and degradable resource to microorganisms and is considered as a good index of C availability.…”

Stimulation of N2O emission by manure application to agricultural soils may largely offset carbon benefits: a global meta‐analysis

“…For example, effect sizes for poultry (mean 45.4%, 95% CI: 7.8-159.2%) manure were greater than those for cattle manure (mean: 28.7%, 95% CI: 5.2-67.2%) (Fig. 1b), although cattle manure contained a relatively larger inorganic N pool than poultry manure per unit (Chen et al, 2014). The significantly greater N 2 O emissions by application of poultry manure were likely due to their higher content of easily decomposable organic C (e.g., DOC and volatile fatty acids) relative to cattle manure (Kirchmann, 1991;Kirchmann & Lundvall, 1993;Chadwick et al, 2000;Velthof et al, 2003).…”

“…Soil N 2 O is mainly produced by microbial nitrification or denitrification, which are dependent on multiple factors, including the availability of carbon and nitrogen substrate as well as oxygen, soil properties (texture and pH), and environmental conditions (Firestone & Davidson, 1989;Groffman & Tiedje, 1991). Manure application by mediating the availability of soil inorganic N and bioavailable organic C as substrates for microbial N 2 O production and consumption may affect N 2 O emissions in agricultural soils (Baggs et al, 2000;Ball et al, 2004;Rochette et al, 2004;Aguilera et al, 2013;Thangarajan et al, 2013;Chen et al, 2014;Zhou et al, 2016a). In addition to direct effects, manure application could indirectly regulate soil N 2 O emissions by changing soil aeration, specifically oxygen availability at microsites with the decomposition of organic matter (Xu et al, 2008).…”

High-Temperature Hay Biochar Application into Soil Increases N2O Fluxes

“…This would explain why biochar amendment does not reduce emissions with organic fertilization. In fact, organic carbon input can promote anaerobic conditions, even at low water-filled pore space (WFPS) values, increasing denitrification potential and N 2 O emissions [79].…”