Elevating soil pH does not reduce N2O emissions from urine deposited onto pastoral soils

Abstract. To meet increasing demands, tea plantations are rapidly expanding in China. Although the emissions of nitrous oxide (N2O) and nitric oxide (NO) from tea plantations may be substantially influenced by soil pH reduction and intensive nitrogen fertilization, process model-based studies on this issue are still rare. In this study, the process-oriented biogeochemical model, Catchment Nutrient Management Model – DeNitrification-DeComposition (CNMM-DNDC), was modified by adding tea growth-related processes that may induce a soil pH reduction. Using a dataset for intensively managed tea plantations at a subtropical site, the performances of the original and modified models for simulating the emissions of both gases subject to different fertilization alternatives and stand ages were evaluated. Compared with the observations in early stage of a tea plantation, the original and modified models showed comparable performances for simulating the daily gas fluxes (with Nash-Sutcliffe index (NSI) of 0.10 versus 0.18 for N2O and 0.32 versus 0.33 for NO), annual emissions (with NSI of 0.81 versus 0.94 for N2O and 0.92 versus 0.94 for NO) and annual direct emission factors (EFds). The observations and simulations consistently demonstrated that short-term replacement of urea with oilcake stimulated N2O emissions by ~ 62 % and ~ 36 % and mitigated NO emissions by ~ 25 % and ~ 14 %, respectively. The model simulations resulted in a positive dependence of EFd of either gas against nitrogen doses, implicating the importance of model-based quantification of this key parameter for inventory. In addition, the modified model with pH-related scientific processes showed overall inhibitory effects on the gases emissions in the mid to later stages during a full tea lifetime. In conclusion, the modified CNMM-DNDC exhibits the potential for quantifying N2O and NO emissions from tea plantations under various conditions. Nevertheless, wider validation is still required for simulation of long-term soil pH variations and emissions of both gases from tea plantations.

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Influence of soil pH on NOxand N2O emissions from bovine urine applied to soil columns

New Zealand Journal of Agricultural Research ◽

10.1080/00288233.2011.607831 ◽

2011 ◽

Vol 54 (4) ◽

pp. 285-301 ◽

Cited By ~ 15

Author(s):

S Khan ◽

TJ Clough ◽

KM Goh ◽

RR Sherlock

Keyword(s):

Soil Ph ◽

N2o Emissions ◽

Soil Columns ◽

Bovine Urine

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Nitrous oxide emission from two acidic soils as affected by dolomite application

Soil Research ◽

10.1071/sr14129 ◽

2014 ◽

Vol 52 (8) ◽

pp. 841 ◽

Cited By ~ 23

Author(s):

Muhammad Shaaban ◽

Qian Peng ◽

Shan Lin ◽

Yupeng Wu ◽

Jinsong Zhao ◽

...

Keyword(s):

Nitrous Oxide ◽

Microbial Biomass ◽

Organic Carbon ◽

Soil Ph ◽

Microbial Biomass Carbon ◽

Rice Paddy ◽

N2o Emission ◽

N2o Emissions ◽

Biomass Carbon ◽

Acidic Soils

The effect of dolomite (CaMg(CO3)2) application on nitrous oxide (N2O) emission was examined in a laboratory study with soil from a rice paddy–rapeseed rotation (PR soil, pH 5.25) and from a rice paddy–fallow–flooded rotation soil (PF soil, pH 5.52). The soils were treated with 0, 0.5 (L) and 1.5 (H) g dolomite 100 g–1 soil. Results showed that N2O emissions were higher in control treatments (untreated dolomite) in both soils. Application of dolomite decreased N2O emissions significantly (P ≤ 0.001) as soil pH increased in both soils. The H treatment was more effective than the L treatment for the reduction of N2O emissions. The H treatment decreased the cumulative N2O emissions by up to 73.77% in PR soil and 64.07% in PF soil compared with the control. The application of dolomite also affected concentrations of dissolved organic carbon, microbial biomass carbon, ammonium and nitrate in soils, which related to N2O emission. The results suggest that dolomite not only counteracts soil acidification but also has the potential to mitigate N2O emissions in acidic soils.

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The combined effects of nitrification inhibitor and biochar incorporation on yield-scaled N<sub>2</sub>O emissions from an intensively managed vegetable field in southeastern China

Biogeosciences Discussions ◽

10.5194/bgd-11-15185-2014 ◽

2014 ◽

Vol 11 (10) ◽

pp. 15185-15214 ◽

Cited By ~ 2

Author(s):

B. Li ◽

C. H. Fan ◽

Z. Q. Xiong ◽

Q. L. Li ◽

M. Zhang

Keyword(s):

Soil Ph ◽

Nitrification Inhibitor ◽

N2o Emissions ◽

Southeastern China ◽

Vegetable Field ◽

Significant Difference ◽

Group Treatments ◽

Intensively Managed ◽

Vegetable Yield ◽

Biochar Amendment

Abstract. The influences of nitrification inhibitor (NI) and biochar incorporation on yield-scaled N2O in a vegetable field were studied using the static chamber method and gas chromatography. An experiment was conducted in an intensively managed vegetable field with 7 consecutive vegetable crops in 2012–2014 in southeastern China. With equal annual amounts of N (1217.3 kg N ha−1 yr−1), 6 treatments under 3 biochar amendment rates, namely, 0 t ha−1 (C0), 20 t ha−1 (C1), and 40 t ha−1 (C2), with compound fertilizer (CF) or urea mixed with chlorinated pyridine (CP) as NI, were studied in these field experiments. The results showed that although no significant influence on soil organic carbon (SOC) content or total nitrogen (TN), CP could result in a significant increase in soil pH during the experimental period. CP significantly decreased cumulative N2O emissions by 15.9–32.1% while increasing vegetable yield by 9.8–41.9%. Thus, it also decreased yield-scaled N2O emissions significantly. In addition to the differential responses of the soil pH, biochar amendment significantly increased SOC and TN. Additionally, compared with the treatments without biochar addition, cumulative N2O emissions showed no significant difference in the CF or the CP group treatments but increased slightly (but not significantly) by 7.9–18.3% in the CP group treatments. Vegetable yield was enhanced by 7.1–49.5% compared with the treatments without biochar amendment, and the yield-scaled N2O emissions were thus decreased significantly. Furthermore, treatments applied with CP and biochar incorporation slightly increased yield-scaled N2O emissions by 9.4%, on average, compared with CP-C0. Therefore, the incorporation of CP could serve as an appropriate practice for increasing vegetable yield and mitigating N2O emissions in intensively managed vegetable fields and should be further examined in various agroecosystems.

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Phylogenetic and functional potential links pH and N2O emissions in pasture soils

Scientific Reports ◽

10.1038/srep35990 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 29

Author(s):

Md Sainur Samad ◽

Ambarish Biswas ◽

Lars R. Bakken ◽

Timothy J. Clough ◽

Cecile A. M. de Klein ◽

...

Keyword(s):

Community Composition ◽

Soil Ph ◽

Nitrogen Loss ◽

Microbial Community Composition ◽

Amplicon Sequencing ◽

Community Diversity ◽

N2o Emissions ◽

Emission Ratio ◽

Functional Potential ◽

Denitrification Gene

Abstract Denitrification is mediated by microbial, and physicochemical, processes leading to nitrogen loss via N2O and N2 emissions. Soil pH regulates the reduction of N2O to N2, however, it can also affect microbial community composition and functional potential. Here we simultaneously test the link between pH, community composition, and the N2O emission ratio (N2O/(NO + N2O + N2)) in 13 temperate pasture soils. Physicochemical analysis, gas kinetics, 16S rRNA amplicon sequencing, metagenomic and quantitative PCR (of denitrifier genes: nirS, nirK, nosZI and nosZII) analysis were carried out to characterize each soil. We found strong evidence linking pH to both N2O emission ratio and community changes. Soil pH was negatively associated with N2O emission ratio, while being positively associated with both community diversity and total denitrification gene (nir & nos) abundance. Abundance of nosZII was positively linked to pH, and negatively linked to N2O emissions. Our results confirm that pH imposes a general selective pressure on the entire community and that this results in changes in emission potential. Our data also support the general model that with increased microbial diversity efficiency increases, demonstrated in this study with lowered N2O emission ratio through more efficient conversion of N2O to N2.

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A Sustainable Approach for Improving Soil Properties and Reducing N2O Emissions Is Possible through Initial and Repeated Biochar Application

Agronomy ◽

10.3390/agronomy11030582 ◽

2021 ◽

Vol 11 (3) ◽

pp. 582

Author(s):

Ján Horák ◽

Tatijana Kotuš ◽

Lucia Toková ◽

Elena Aydın ◽

Dušan Igaz ◽

...

Keyword(s):

Soil Properties ◽

Soil Ph ◽

N2o Emission ◽

N Fertilization ◽

Temperate Climate ◽

Emissions Reduction ◽

N2o Emissions ◽

Application Rates ◽

Pros And Cons ◽

The Impact

Recent findings of changing climate, water scarcity, soil degradation, and greenhouse gas emissions have brought major challenges to sustainable agriculture worldwide. Biochar application to soil proves to be a suitable solution to these problems. Although the literature presents the pros and cons of biochar application, very little information is available on the impact of repeated application. In this study, we evaluate and discuss the effects of initial and reapplied biochar (both in rates of 0, 10, and 20 t ha−1) combined with N fertilization (at doses of 0, 40, and 80 kg ha−1) on soil properties and N2O emission from Haplic Luvisol in the temperate climate zone (Slovakia). Results showed that biochar generally improved the soil properties such as soil pH(KCl) (p ≤ 0.05; from acidic towards moderately acidic), soil organic carbon (p ≤ 0.05; an increase from 4% to over 100%), soil water availability (an increase from 1% to 15%), saturated hydraulic conductivity (an increase from 5% to 95%). The effects were more significant in the following cases: repeated rather than single biochar application, higher rather than lower biochar application rates, and higher rather than lower N fertilization levels. Initial and repeated biochar applications, leading to N2O emissions reduction, can be related to increased soil pH(KCl).

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The effect of soil pH and dicyandiamide (DCD) on N2O emissions and ammonia oxidiser abundance in a stimulated grazed pasture soil

Journal of Soils and Sediments ◽

10.1007/s11368-014-0888-2 ◽

2014 ◽

Vol 14 (8) ◽

pp. 1434-1444 ◽

Cited By ~ 24

Author(s):

Aimee Robinson ◽

Hong Jie Di ◽

Keith C. Cameron ◽

Andriy Podolyan ◽

Jizheng He

Keyword(s):

Soil Ph ◽

N2o Emissions ◽

Grazed Pasture ◽

Pasture Soil

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Can liming mitigate N2O fluxes from a urine-amended soil?

Soil Research ◽

10.1071/sr02079 ◽

2003 ◽

Vol 41 (3) ◽

pp. 439 ◽

Cited By ~ 41

Author(s):

T. J. Clough ◽

R. R. Sherlock ◽

F. M. Kelliher

Keyword(s):

Soil Ph ◽

Pore Space ◽

Field Capacity ◽

N2o Emissions ◽

N2o Production ◽

Synthetic Urine ◽

Loam Soil ◽

N2o Fluxes ◽

Treatment Application ◽

Urine Treatment

Soil pH affects N2O production mechanisms. The ratio of N2O to N2 may decrease with increasing soil pH during denitrification. Two laboratory experiments were performed to examine the effect of liming on N2O emissions following synthetic urine applications over 42 and 60 days. A silt loam soil at field capacity (water-filled pore space of 57% after treatment application) was adjusted with Ca(OH)2 to produce soils ranging from pH 4.7 to 7.7. The first experiment employed 4 treatments: a control, KNO3 (500 kg N/ha), and synthetic urine at 500 kg N/ha and 1000 kg N/ha. A second experiment used 15N labelled urea in synthetic urine at 500 kg N/ha. The main effect of lime was to promote nitrification, which markedly affected N2O fluxes. After 60 days, the 500 kg N/ha synthetic urine treatment limed to pH 6.1 produced more N2O (0.82% of N applied) than any other soil pH. No optimum soil pH was found for the synthetic urine treatment at 1000 kg N/ha with nitrification incomplete after 60 days. N2O production via nitrifiers dominated the N2O production pathway with large residual NO3– pools. Denitrification was not enhanced since no 15N labelled N2 was detected. However, before any final conclusions can be drawn about the efficacy of liming as a mitigation tool it is vital that the effect of liming on possible denitrification mechanisms and products also be assessed, following nitrification and formation of a nitrate pool. Application of synthetic urine also initiated a priming effect with more carbon evolved as CO2 than was applied.

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