scholarly journals Water regime affects soil N2O emission and tomato yield grown under different types of fertilisers

2017 ◽  
pp. 74-79 ◽  
Author(s):  
Luca Vitale ◽  
Anna Tedeschi ◽  
Franca Polimeno ◽  
Lucia Ottaiano ◽  
Giuseppe Maglione ◽  
...  
Keyword(s):  
Water Supply ◽  
Plant Biomass ◽  
N Uptake ◽  
Photochemical Efficiency ◽  
N2o Emission ◽  
Fruit Production ◽  
N2o Emissions ◽  
Mineral Fertiliser ◽  
N2o Fluxes ◽  
Reduced Water

Tomato plants were subjected to three fertilisation treatments (M: mineral fertiliser; DMPP: mineral fertiliser + 3,4- dimethylpyrazole phosphate; OM: NKP + organic animal manure) in combination with two water regimes (100% and 50% evapotranspiration). Plant biomass, fruit production, nitrogen use efficiency (NUE) and N uptake, maximal PSII photochemical efficiency, Fv/Fm and cumulative soil N2O emission were determined. Well-watered OM plants showed higher values of biomass, fruit production, NUE and N uptake than M and DMPP plants; cumulative N2O fluxes were lower in DMPP plots than in M and OM plots. The reduced water supply determined a drop in crop biomass, fruit production, NUE and N uptake, and cumulative N2O fluxes in M and OM treatments that were higher in OM plots, whereas it determined a significant rise in cumulative N2O fluxes in DMPP plots that was lower in absolute term compared to M and OM plots recorded under well-water irrigation. It can be concluded that DMPP added-fertiliser has a good performance in semiarid environment resulting a better nitrogen source compared to conventional and organo-mineral fertilisers under reduced water supply, able to preserve crop yield and to determine soil N2O emissions (as expressed in CO2 eq) not dangerous for global environment.

scholarly journals Water Salinity Should Be Reduced for Irrigation to Minimize Its Risk of Increased Soil N2O Emissions

2018 ◽  
Vol 15 (10) ◽  
pp. 2114 ◽  
Author(s):  
Qi Wei ◽  
Junzeng Xu ◽  
Linxian Liao ◽  
Yawei Li ◽  
Haiyu Wang ◽  
...  
Keyword(s):  
Saline Water ◽  
N2o Emission ◽  
Salinity Level ◽  
N2o Emissions ◽  
Low Salinity ◽  
Nitrogen Inputs ◽  
Salinity Levels ◽  
N2o Fluxes ◽  
Moisture Dynamics ◽  
Irrigated Soils

To reveal the effect of irrigation salinity on soil nitrous oxide (N2O) emission, pot experiments were designed with three irrigation salinity levels (NaCl and CaCl2 of 1, 2.5 and 4 g/L equivalence, Ec = 3.6, 8.1 and 12.7 ds/m), either for 0 kg N/ha (N0) or 120 kg N/ha (N120) nitrogen inputs. N2O emissions from soils irrigated at different salinity levels varied in a similar pattern which was triggered by soil moisture dynamics. Yet, the magnitudes of pulse N2O fluxes were significantly varied, with the peak flux at 5 g/L irrigation salinity level being much higher than at 2 and 8 g/L. Compared to fresh water irrigated soils, cumulative N2O fluxes were reduced by 22.7% and 39.6% (N0), 29.1% and 39.2% (N120) for soils irrigated with 2 and 8 g/L saline water, while they were increased by 87.7% (N0) and 58.3% (N120) for soils irrigated with 5 g/L saline water. These results suggested that the effect degree of salinity on consumption and production of N2O might vary among irrigation salinity ranges. As such, desalinating brackish water to a low salinity level (such as 2 g/L) before it is used for irrigation might be helpful for solving water resources crises and mitigating soil N2O emissions.

scholarly journals Greenhouse gas (N2O and CH4) fluxes under nitrogen-fertilised dryland wheat and barley on subtropical Vertosols: risk, rainfall and alternatives

Soil Research ◽  
2016 ◽  
Vol 54 (5) ◽  
pp. 634 ◽  
Author(s):  
Graeme D. Schwenke ◽  
David F. Herridge ◽  
Clemens Scheer ◽  
David W. Rowlings ◽  
Bruce M. Haigh ◽  
...  
Keyword(s):  
N Uptake ◽  
Nitrification Inhibitor ◽  
N2o Emission ◽  
N2o Emissions ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Mineral N ◽  
Before And After ◽  
Ch4 Uptake ◽  
Crop N Uptake

The northern Australian grains industry relies on nitrogen (N) fertiliser to optimise yield and protein, but N fertiliser can increase soil fluxes of nitrous oxide (N2O) and methane (CH4). We measured soil N2O and CH4 fluxes associated with wheat (Triticum aestivum) and barley (Hordeum vulgare) using automated (Expts 1, 3) and manual chambers (Expts 2, 4, 5). Experiments were conducted on subtropical Vertosol soils fertilised with N rates of 0–160kgNha–1. In Expt 1 (2010), intense rainfall for a month before and after sowing elevated N2O emissions from N-fertilised (80kgNha–1) wheat, with 417gN2O-Nha–1 emitted compared with 80g N2O-Nha–1 for non-fertilised wheat. Once crop N uptake reduced soil mineral N, there was no further treatment difference in N2O. Expt 2 (2010) showed similar results, however, the reduced sampling frequency using manual chambers gave a lower cumulative N2O. By contrast, very low rainfall before and for several months after sowing Expt 3 (2011) resulted in no difference in N2O emissions between N-fertilised and non-fertilised barley. N2O emission factors were 0.42, 0.20 and –0.02 for Expts 1, 2 and 3, respectively. In Expts 4 and 5 (2011), N2O emissions increased with increasing rate of N fertiliser. Emissions were reduced by 45% when the N fertiliser was applied in a 50:50 split between sowing and mid-tillering, or by 70% when urea was applied with the nitrification inhibitor 3,4-dimethylpyrazole-phosphate. Methane fluxes were typically small and mostly negative in all experiments, especially in dry soils. Cumulative CH4 uptake ranged from 242 to 435g CH4-Cha–1year–1, with no effect of N fertiliser treatment. Considered in terms of CO2 equivalents, soil CH4 uptake offset 8–56% of soil N2O emissions, with larger offsets occurring in non-N-fertilised soils. The first few months from N fertiliser application to the period of rapid crop N uptake pose the main risk for N2O losses from rainfed cereal cropping on subtropical Vertosols, but the realisation of this risk is dependent on rainfall. Strategies that reduce the soil mineral N pool during this time can reduce the risk of N2O loss.

A two-year field assessment on the effect of slow release of nitrogenous fertiliser on N2O emissions from a wheat cropping system

Soil Research ◽  
2017 ◽  
Vol 55 (2) ◽  
pp. 191 ◽  
Author(s):  
Nirmali Bordoloi ◽  
K. K. Baruah
Keyword(s):  
Field Experiments ◽  
Plant Biomass ◽  
Global Climate ◽  
Cropping System ◽  
N2o Emission ◽  
N2o Emissions ◽  
Wheat Field ◽  
Grain Productivity ◽  
Coated Urea ◽  
Fertiliser Application

Nitrous oxide (N2O) is considered a major contributor to global climate change in addition to carbon dioxide and methane. A significant quantity of N2O emission originates from agriculture, largely from high rates of fertiliser application. We studied N2O emissions from wheat field to evaluate the effect of different forms of fertilisers and the potential for emission reduction. Field experiments were conducted for two consecutive seasons with four fertilisers, namely inorganic fertiliser (NPK), starch-coated urea (SCU), neem-coated urea (NCU), and urea alone (UA) in a tropical wheat ecosystem. Gas samples were collected from the field at weekly intervals using the static chamber technique and analysed with a gas chromatograph. The cumulative N2O emissions were higher from the NPK amended field (3.19kgN2O-Nha–1) followed by UA (3.05kg N2O-N ha–1). The SCU, NCU, and UA amendments decreased the total N2O emissions by 23%, 12%, and 4%, respectively (P<0.05) over the application of NPK. The results indicate a good correlation of N2O emissions with soil organic carbon, soil NO3–-N, NH4+-N, leaf area, and plant biomass. The application of SCU resulted in higher grain productivity and was the most effective substitute for conventional fertiliser in terms of reducing N2O emissions from a tropical wheat ecosystem.

scholarly journals CH<sub>4</sub> and N<sub>2</sub>O dynamics in the boreal forest–mire ecotone

2015 ◽  
Vol 12 (2) ◽  
pp. 281-297 ◽  
Author(s):  
B. Tupek ◽  
K. Minkkinen ◽  
J. Pumpanen ◽  
T. Vesala ◽  
E. Nikinmaa
Keyword(s):  
Ground Water ◽  
N2o Emission ◽  
N2o Emissions ◽  
Summer Drought ◽  
Drought Period ◽  
Local Climate ◽  
N2o Fluxes ◽  
Ch4 And N2o ◽  
Water Saturated ◽  
Boreal Landscapes

Abstract. In spite of advances in greenhouse gas research, the spatiotemporal CH4 and N2O dynamics of boreal landscapes remain challenging, e.g., we need clarification of whether forest–mire transitions are occasional hotspots of landscape CH4 and N2O emissions during exceptionally high and low ground water level events. In our study, we tested the differences and drivers of CH4 and N2O dynamics of forest/mire types in field conditions along the soil moisture gradient of the forest–mire ecotone. Soils changed from Podzols to Histosols and ground water rose downslope from a depth of 10 m in upland sites to 0.1 m in mires. Yearly meteorological conditions changed from being exceptionally wet to typical and exceptionally dry for the local climate. The median fluxes measured with a static chamber technique varied from −51 to 586 μg m−2 h−1 for CH4 and from 0 to 6 μg m−2 h−1 for N2O between forest and mire types throughout the entire wet–dry period. In spite of the highly dynamic soil water fluctuations in carbon rich soils in forest–mire transitions, there were no large peak emissions in CH4 and N2O fluxes and the flux rates changed minimally between years. Methane uptake was significantly lower in poorly drained transitions than in the well-drained uplands. Water-saturated mires showed large CH4 emissions, which were reduced entirely during the exceptional summer drought period. Near-zero N2O fluxes did not differ significantly between the forest and mire types probably due to their low nitrification potential. When upscaling boreal landscapes, pristine forest–mire transitions should be regarded as CH4 sinks and minor N2O sources instead of CH4 and N2O emission hotspots.

scholarly journals Nitrous Oxide Emission from Grazing Is Low across a Gradient of Plant Functional Diversity and Soil Conditions

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 223
Author(s):  
John Kormla Nyameasem ◽  
Carsten S. Malisch ◽  
Ralf Loges ◽  
Friedhelm Taube ◽  
Christof Kluß ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
N Uptake ◽  
N2o Emission ◽  
Soil Conditions ◽  
N2o Emissions ◽  
Mineral N ◽  
Grazed Pastures ◽  
Growing Seasons ◽  
Nitrogen Inputs ◽  
Organically Managed

Nitrous oxide (N2O) emissions from pastures can vary significantly depending on soil and environmental conditions, nitrogen (N) input, as well as the plant’s ability to take up the N. We tested the hypothesis that legume-based N sources are characterized by significantly lower emission factors than mineral N based dairy systems. Therefore, this study monitored N2O emissions for a minimum of 100 days and up to two growing seasons across a gradient of plant species diversity. Emissions were measured from both grazed pastures and a controlled application of urine and dung using the static chamber method. About 90% of the simulated experiments’ accumulated N2O emissions occurred during the first 60–75 days. The average accumulated N2O emissions were 0.11, 0.87, 0.99, and 0.21 kg ha−1 for control, dung, urine patches, and grazed pastures, respectively. The N uptake efficiency at the excreta patch scale was about 70% for both dung and urine. The highest N2O-N emission factor was less than half compared with the IPCC default (0.3 vs. 0.77), suggesting an overestimation of N2O-N emissions from organically managed pastures in temperate climates. Plant diversity showed no significant effect on N2O emission. However, functional groups were significant (p < 0.05). We concluded that legume-containing pasture systems without a fertilizer addition generally appear capable of utilizing nitrogen inputs from excreta patches efficiently, resulting in low N2O emissions.

scholarly journals Soil N2O Emissions under Different N Rates in an Oil Palm Plantation on Tropical Peatland

Agriculture ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 213 ◽  
Author(s):  
Auldry Chaddy ◽  
Lulie Melling ◽  
Kiwamu Ishikura ◽  
Ryusuke Hatano
Keyword(s):  
Oil Palm ◽  
N Uptake ◽  
N2o Emission ◽  
N Fertilization ◽  
Mitigation Strategies ◽  
N2o Emissions ◽  
N Availability ◽  
Tropical Peatland ◽  
Oil Palm Plantation ◽  
N Rates

(1) Background: Nitrogen (N) fertilization on drained tropical peatland will likely stimulate peat decomposition and mineralization, enhancing N2O emission from the peat soil. (2) Methods: A field experiment was conducted to quantify the N2O emissions from soil in an oil palm plantation (Elaeis guineensis Jacq.) located in a tropical peatland in Sarawak, Malaysia, under different rates of N fertilizers. The study was conducted from January 2010 to December 2013 and resumed from January 2016 to December 2017. Nitrous oxide (N2O) flux was measured every month using a closed chamber method for four different N rates; control—without N (T1), 31.1 kg N ha−1 yr−1 (T2), 62.2 kg N ha−1 yr−1 (T3), and 124.3 kg N ha−1 yr−1 (T4); (3) Results: Application of the N fertilizer significantly increased annual cumulative N2O emissions for T4 only in the years 2010 (p = 0.017), 2011 (p = 0.012), 2012 (p = 0.007), and 2016 (p = 0.048). The highest average annual cumulative N2O emissions were recorded for T4 (41.5 ± 28.7 kg N ha−1 yr−1), followed by T3 (35.1 ± 25.7 kg N ha−1 yr−1), T1 (25.2 ± 17.8 kg N ha−1 yr−1), and T2 (25.1 ± 15.4 kg N ha−1 yr−1), indicating that the N rates of 62.2 kg N ha−1 yr−1 and 124.3 kg N ha−1 yr−1 increased the average annual cumulative N2O emissions by 39% and 65%, respectively, as compared to the control. The N fertilization had no significant effect on annual oil palm yield (p = 0.994). Alternating between low (deeper than −60 cm) and high groundwater level (GWL) (shallower than −60 cm) enhanced nitrification during low GWL, further supplying NO3− for denitrification in the high GWL, and contributing to higher N2O emissions in high GWL. The emissions of N2O ranged from 17 µg N m−2 hr−1 to 2447 µg N m−2 hr−1 and decreased when the water-filled pore space (WFPS) was between 70% and 96%, suggesting the occurrence of complete denitrification. A positive correlation between N2O emissions and NO3− at 70–96% WFPS indicated that denitrification increased with increased NO3− availability. Based on their standardized regression coefficients, the effect of GWL on N2O emissions increased with increased N rate (p < 0.001). Furthermore, it was found that annual oil palm yields negatively correlated with annual N2O emission and NO3− for all treatments. Both nitrification and denitrification increased with increased N availability, making both processes important sources of N2O in oil palm cultivation on tropical peatland.; and (4) Conclusions: To improve understanding of N2O mitigation strategies, further studies should consider plant N uptake on N2O emissions, at least until the completion of the planting.

scholarly journals Global soil nitrous oxide emissions in a dynamic carbon-nitrogen model

2015 ◽  
Vol 12 (21) ◽  
pp. 6405-6427 ◽  
Author(s):  
Y. Huang ◽  
S. Gerber
Keyword(s):  
Nitrous Oxide ◽  
Elevated Co2 ◽  
N Uptake ◽  
N2o Emission ◽  
Nitrous Oxide Emissions ◽  
N Fixation ◽  
N Availability ◽  
Plant N Uptake ◽  
Biological N Fixation ◽  
N2o Fluxes

Abstract. Nitrous oxide (N2O) is an important greenhouse gas that also contributes to the depletion of stratospheric ozone. Due to its high temporal and spatial heterogeneity, a quantitative understanding of terrestrial N2O emission and its variabilities and responses to climate change are challenging. We added a soil N2O emission module to the dynamic global land model LM3V-N, and tested its sensitivity to mechanisms that affect the level of mineral nitrogen (N) in soil such as plant N uptake, biological N fixation, amount of volatilized N redeposited after fire, and nitrification-denitrification. We further tested the relationship between N2O emission and soil moisture, and assessed responses to elevated CO2 and temperature. Results extracted from the corresponding gridcell (without site-specific forcing data) were comparable with the average of cross-site observed annual mean emissions, although differences remained across individual sites if stand-level measurements were representative of gridcell emissions. Processes, such as plant N uptake and N loss through fire volatilization that regulate N availability for nitrification-denitrification have strong controls on N2O fluxes in addition to the parameterization of N2O loss through nitrification and denitrification. Modelled N2O fluxes were highly sensitive to water-filled pore space (WFPS), with a global sensitivity of approximately 0.25 TgN per year per 0.01 change in WFPS. We found that the global response of N2O emission to CO2 fertilization was largely determined by the response of tropical emissions with reduced N2O fluxes in the first few decades and increases afterwards. The initial reduction was linked to N limitation under higher CO2 level, and was alleviated through feedbacks such as biological N fixation. The extratropical response was weaker and generally positive, highlighting the need to expand field studies in tropical ecosystems. We did not find synergistic effects between warming and CO2 increase as reported in analyses with different models. Warming generally enhanced N2O efflux and the enhancement was greatly dampened when combined with elevated CO2, although CO2 alone had a small effect. The differential response in the tropics compared to extratropics with respect to magnitude and sign suggests caution when extrapolating from current field CO2 enrichment and warming studies to the globe.

Nitrous oxide emission factor from cattle urine and dung in native grassland of the Pampa biome, South Brazil

Soil Research ◽  
2020 ◽  
Vol 58 (2) ◽  
pp. 198 ◽  
Author(s):  
Janquieli Schirmann ◽  
Diego Fernandes de Bastos ◽  
Douglas Adams Weiler ◽  
Murilo G. Veloso ◽  
Jeferson Dieckow ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Emission Factor ◽  
Live Weight ◽  
N2o Emission ◽  
N2o Emissions ◽  
Native Grassland ◽  
Tier 1 ◽  
N2o Fluxes ◽  
The Impact ◽  
South Brazil

Native grassland supports extensive livestock production in the Pampas of South America, but the impact of cattle excreta on nitrous oxide (N2O) emissions remains unknown in this biome. The objective of this study was to determine the N2O emission factor (EF-N2O, % of N applied that is emitted as N2O) for urine and dung from beef cattle grazing on native grasslands. A field trial was conducted under low and moderate forage allowances (FA4 and FA12; i.e. 4 and 12 kg dry matter/100 kg live weight respectively) during the 30th year of a long-term grassland experiment on a Typic Paleudult in South Brazil. Urine and dung were applied onto separate patches, at rates equivalent to one average urination or defecation; and N2O fluxes were monitored with closed static chambers over 338 days. In adjacent microplots receiving the same excreta treatment, water-filled pore space, nitrate, ammonium and extractable dissolved organic carbon were monitored in the top 0.1 m of soil. Averaged across the forage allowances, daily soil N2O fluxes were low in the control without excreta (1.3 g N ha–1), but increased upon application of dung (3.8 g N ha–1) and urine (66 g N ha–1). The annual N2O emission and the EF-N2O for urine were greater under FA12 than FA4, but no difference was observed for dung. The positive relationships between N2O-N emissions and ammonium intensity and nitrate intensity suggest that N2O may have been produced concurrently by nitrification, nitrifier/denitrification and denitrification. On average, the EF-N2O was almost 10 times higher for urine than for dung (0.74% vs 0.08%), both much lower than the IPCC’s Tier 1 default value of 2%. Our findings reinforce the need for disaggregating the EF-N2O for urine and dung and of revising the IPCC’s Tier 1 EF-N2O.

scholarly journals Short-term effects of biogas digestate and cattle slurry application on greenhouse gas emissions affected by N availability from grasslands on drained fen peatlands and associated organic soils

2014 ◽  
Vol 11 (22) ◽  
pp. 6187-6207 ◽  
Author(s):  
T. Eickenscheidt ◽  
A. Freibauer ◽  
J. Heinichen ◽  
J. Augustin ◽  
M. Drösler
Keyword(s):  
N Uptake ◽  
Organic Fertilizers ◽  
Strong Increase ◽  
Organic Soils ◽  
N2o Emissions ◽  
N Availability ◽  
Cattle Slurry ◽  
Chamber Method ◽  
Biogas Digestate ◽  
N2o Fluxes

Abstract. A change in German energy policy has resulted in a strong increase in the number of biogas plants in Germany. As a consequence, huge amounts of nutrient-rich residues, the by-products of the fermentative process, are used as organic fertilizers. Drained peatlands are increasingly used to satisfy the huge demand for fermentative substrates (e.g., energy crops, grass silage) and the digestate is returned to the peatlands. However, drained organic soils are considered as hot spots for nitrous oxide (N2O) emissions and organic fertilization is additionally known to increase N2O emissions from managed grasslands. Our study addressed the questions (a) to what extent biogas digestate and cattle slurry application increase N2O and methane (CH4) fluxes as well as the mineral nitrogen use efficiency (NUEmin) and grass yield, and (b) how different soil organic matter contents (SOMs) and nitrogen contents promote the production of N2O. In addition NH3 volatilization was determined at one application event to obtain first clues with respect to the effects of soil and fertilizer types. The study was conducted at two sites within a grassland parcel, which differed in their soil organic carbon (SOC) and N contents. At each site (named Corg-medium and Corg-high) three plots were established: one was fertilized five times with biogas digestate, one with cattle slurry, and the third served as control plot. On each plot, fluxes of N2O and CH4 were measured on three replicates over 2 years using the closed chamber method. For NH3 measurements we used the calibrated dynamic chamber method. On an annual basis, the application of biogas digestate significantly enhanced the N2O fluxes compared to the application of cattle slurry and additionally increased the plant N-uptake and NUEmin. Furthermore, N2O fluxes from the Corg-high treatments significantly exceeded N2O fluxes from the Corg-medium treatments. Annual cumulative emissions ranged from 0.91 ± 0.49 to 3.14 ± 0.91 kg N ha−1 yr−1. Significantly different CH4 fluxes between the investigated treatments or the different soil types were not observed. Cumulative annual CH4 exchange rates varied between −0.21 ± 0.19 and −1.06 ± 0.46 kg C ha−1 yr−1. Significantly higher NH3 losses, NUEmin and grass yields from treatments fertilized with biogas digestate compared to those fertilized with cattle slurry were observed. The total NH3 losses following the splash plate application were 18.17 kg N ha−1 for the digestate treatments and 3.48 kg N ha−1 for the slurry treatments (36 and 15% of applied NH4+–N). The observed linear increase of 16 days' cumulative N2O–N exchange or annual N2O emissions, with mean groundwater level and ammonium application rate, reveals the importance of site-adapted N fertilization and the avoidance of N surpluses in Corg-rich grasslands.

scholarly journals Nitrous oxide emissions from crop rotations including wheat, rapeseed and dry pea

2012 ◽  
Vol 9 (7) ◽  
pp. 9289-9314 ◽  
Author(s):  
M. H. Jeuffroy ◽  
E. Baranger ◽  
B. Carrouée ◽  
E. de Chezelles ◽  
M. Gosme ◽  
...  
Keyword(s):  
Oilseed Rape ◽  
Ghg Emissions ◽  
Global Scale ◽  
N2o Emission ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
N Fixation ◽  
Biological Fixation ◽  
Mineral N ◽  
N2o Fluxes

Abstract. Approximately 65% of anthropogenic emissions of N2O, a potent greenhouse gas, originate from soils at global scale, and particularly after N fertilisation of the main crops in Europe. Thanks to their capacity to fix atmospheric N2 through biological fixation, legumes allow to reduce N fertilizer use, and possibly N2O emission. Nevertheless, the decomposition of crop organic matter during the crop cycle and during the residue decomposition, and possibly the N fixation process itself, could lead to N2O emissions. The objective of this study was to quantify N2O emissions from a dry pea crop (Pisum sativum, harvested at maturity) and from the subsequent crops in comparison with N2O emissions from wheat and oilseed-rape crops, fertilized or not, in various rotations. A field experiment was conducted during 4 consecutive years, aiming at comparing the emissions during the pea crop, in comparison with those during the wheat (fertilized or not) or oilseed rape crops, and after the pea crop, in comparison with other preceding crops. N2O fluxes were measured using static chambers. In spite of low N2O fluxes, mainly linked with the site soil characteristics, fluxes during the crop were significantly lower for pea and unfertilized wheat than for fertilized wheat and oilseed rape. The effect of the preceding crop was not significant, while soil mineral N at harvest was higher after pea. These results, combined with the emission reduction allowed by the production and transport of the N fertiliser not applied on the pea crop, should be confirmed in a larger range of soil types. Nevertheless, they demonstrate the absence of N2O emission linked to the symbiotic N fixation process, and allow us to estimate the decrease of N2O emissions to 20–25% by including one pea crop in a three-year rotation. At a larger scale, this reduction of GHG emissions at field level has to be cumulated with the reduction of GHG emissions linked with the lower level of production and transport of the N fertiliser not applied on the pea crop.

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