Nitrous Oxide Emission and Denitrifier Abundance in Two Agricultural Soils Amended with Crop Residues and Urea in the North China Plain

Abstract

The application of crop residues combined with Nitrogen (N) fertilizer has been broadly adopted in China. Crop residue amendments can provide readily available C and N, as well as other nutrients to agricultural soils, but also intensify the N fixation, further affecting N2O emissions. N2O pulses are obviously driven by rainfall, irrigation and fertilization. Fertilization before rainfall or followed by flooding irrigation is a general management practice for a wheat-maize rotation in the North China Plain. Yet, little is known on the impacts of crop residues combined with N fertilizer application on N2O emission under high soil moisture content. A laboratory incubation experiment was conducted to investigate the effects of two crop residue amendments (maize and wheat), individually or in combination with N fertilizer, on N2O emissions and denitrifier abundance in two main agricultural soils (one is an alluvial soil, pH 8.55, belongs to Ochri-Aquic Cambosols, OAC, the other is a lime concretion black soil, pH 6.61, belongs to Hapli-Aquic Vertosols, HAV) under 80% WFPS (the water filled pore space) in the North China Plain. Each type soil contains seven treatments: a control with no N fertilizer application (CK, N0), 200 kg N ha-1 (N200), 250 kg N ha-1 (N250), maize residue plus N200 (MN200), maize residue plus N250 (MN250), wheat residue plus N200 (WN200) and wheat residue plus N250 (WN250). Results showed that, in the HAV soil, MN250 and WN250 increased the cumulative N2O emissions by 60% and 30% compared with N250 treatment, respectively, but MN200 and WN200 decreased the cumulative N2O emissions by 20% and 50% compared with N200. In the OAC soil, compared with N200 or N250, WN200 and WN250 increased the cumulative N2O emission by 40%-50%, but MN200 and MN250 decreased the cumulative N2O emission by 10%-20%. Compared with CK, addition of crop residue or N fertilizer resulted in significant increases in N2O emissions in both soils. The cumulative N2O emissions from the treatments of 250 kg N ha-1 were 1.1–3.3 times higher than those of treatments with 200 kg N ha-1 in both soils with adding equal amounts of the same type of crop residue. Abundance of the 16S rRNA gene did not significantly change in all treatments in two soils, but the nosZ and nirS genes were more abundant in soils amended with crop residues compared with CK or N-only treatments. N2O emission, however, were not related to the abundance of denitrifier containing nirS or nosZ. The research provided some information regarding the effect of crop residues with N fertilizer on N2O emissions and denitrifier abundances in two soils. Our results imply the property of crop residue and rate of N fertilizer are important influencing factors of N2O emission when crop residues combined with N fertilizer are applied to different agricultural soils.

Nitrifier‐induced denitrification is an important source of soil nitrous oxide and can be inhibited by a nitrification inhibitor 3,4‐dimethylpyrazole phosphate

“…The stress values for both NMDS plots were lower than 0.12 indicating that these data were well-represented by the two-dimensional ordinations. [Colour figure can be viewed at wileyonlinelibrary.com] genetic potential for N 2 O production and consumption (Morales et al, 2010;Zhong et al, 2014;Gao et al, 2016). In our study, along with the changes in N 2 O production, the transcriptional level of AOB amoA gene was significantly decreased by DMPP in all alkaline soils, while no significant influence of DMPP on AOA transcripts was found in any of the studied soils (Fig.…”

“…The transcriptional analysis of the functional genes is a useful approach to identify the active microbes (Philippot and Hallin, ). The functional genes encoding the enzymes catalysing ammonia oxidation (AOA/AOB amoA genes) and denitrification (the narG , nirS/nirK , nosZ genes) are often used as the proxy for predicting the genetic potential for N 2 O production and consumption (Morales et al ., ; Zhong et al ., ; Gao et al ., ). In our study, along with the changes in N 2 O production, the transcriptional level of AOB amoA gene was significantly decreased by DMPP in all alkaline soils, while no significant influence of DMPP on AOA transcripts was found in any of the studied soils (Fig.…”

Soil nitrogen transformation responses to seasonal precipitation changes are regulated by changes in functional microbial abundance in a subtropical forest

“…One reason for this is the higher transpiration loss resulting from relatively bigger trees in the precip-change plots (tree height: 10.2 ± 5.0 m, DBH: 10.7 ± 6.3 cm) than that in the control plots (tree height: 7.7 ± 3.5 m, DBH: 9.5 ± 5.2 cm). There were no significant differences in these stand characteristics, but the bigger trees in precip-change plots might have had greater transpiration rates and therefore caused more soil water loss in the summer wet season (Gao et al, 2017). Another reason might be the large amount of precipitation added (55 mm per event).…”

Effect of cover crops on greenhouse gas emissions in an irrigated field under integrated soil fertility management

“…Conversely, it has been suggested that the higher C : N ratio of their residues as compared to those of legumes may provide energy (C) for denitrifiers, thereby leading to higher N 2 O losses in the presence of mineral N-NO − 3 from fertilizers (Sarkodie-Addo et al, 2003). In this sense, the presence of cereal residues can increase the abundance of denitrifying microorganisms (Gao et al, 2016), thus enhancing denitrification losses when soil conditions are favorable (e.g., high NO − 3 availability and soil moisture after rainfall or irrigation events, particularly in fine-textured soils) (Stehfest and Bouwman 2006;Baral et al, 2016). Furthermore, winter CCs can also abate indirect gaseous N losses through the reduction of leaching and subsequent emissions from water resources (Feyereisen et al, 2006).…”