Effects of Irrigation on N2O Emissions in a Maize Crop Grown on Different Soil Types in Two Contrasting Seasons

Crop management and soil properties affect greenhouse gas (GHG) emissions from cropping systems. Irrigation is one of the agronomical management practices that deeply affects soil nitrous oxide (N2O) emissions. Careful management of irrigation, also concerning to soil type, might mitigate the emissions of this powerful GHG from agricultural soils. In the Mediterranean area, despite the relevance of the agricultural sector to the overall economy and sustainable development, the topic of N2O emissions does not have the same importance as N2O fluxes in temperate agricultural areas. Only some research has discussed N2O emissions from Mediterranean cropping systems. Therefore, in this study, N2O emissions from different soil types (sandy-loam and clay soils) were analyzed in relation to the irrigation of a maize crop grown in two contrasting seasons (2009–2010). The irrigation was done using a center pivot irrigation system about twice a week. The N2O emissions were monitored throughout the two-years of maize crop growth. The emissions were measured with the accumulation technique using eight static chambers (four chambers per site). Nitrogen fertilizer was applied in the form of ammonium sulphate and urea with 3,4 dimethylpyrazole phosphate (DMPP) nitrification inhibitors. In 2009, the N2O emissions and crop biomass measured in both soil types were lower than those measured in 2010. This situation was a lower amount of water and nitrogen (N) available to the crop. In 2010, the N2O fluxes were higher in the clay site than those in the sandy-loam site after the first fertilization, whereas an opposite trend was found after the second fertilization. The soil temperature, N content, and soil humidity were the main drivers for N2O emission during 2009, whereas during 2010, only the N content and soil humidity affected the nitrous oxide emissions. The research has demonstrated that crop water management deeply affects soil N2O emissions, acting differently for denitrification and nitrification. The soil properties affect N2O emission by influencing the microclimate conditions in the root zone, conditioning the N2O production.

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Nitrous oxide emission and nitrogen use efficiency in response to nitrophosphate, N-(n-butyl) thiophosphoric triamide and dicyandiamide of a wheat cultivated soil under sub-humid monsoon conditions

Biogeosciences Discussions ◽

10.5194/bgd-11-13571-2014 ◽

2014 ◽

Vol 11 (9) ◽

pp. 13571-13603 ◽

Cited By ~ 1

Author(s):

W. X. Ding ◽

Z. M. Chen ◽

H. Y. Yu ◽

J. F. Luo ◽

G. Y. Yoo ◽

...

Keyword(s):

Nitrous Oxide ◽

Sandy Loam ◽

Wheat Yield ◽

Nitrification Inhibitor ◽

Growth Period ◽

N2o Emission ◽

N Fertilizer ◽

N2o Emissions ◽

Nitrification Inhibitors ◽

Use Efficiency

Abstract. A field experiment was designed to study the effects of nitrogen (N) source and urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) or nitrification inhibitor dicyandiamide (DCD) on nitrous oxide (N2O) emission and N use efficiency (NUE) in a sandy loam soil. Six treatments including no N fertilizer (control), N fertilizer urea alone (U), urea plus NBPT (NBPT), urea plus DCD (DCD), urea plus NBPT and DCD (NBPT + DCD), and nitrate-based fertilizer nitrophosphate (NP) were designed and implemented separately during the wheat growth period. Seasonal cumulative N2O emissions with urea alone amounted to 0.49 ± 0.12 and were significantly (P < 0.05) reduced to 0.28 ± 0.03, 0.31 ± 0.01 and 0.26 ± 0.01kg N2O-N ha−1 by application of DCD, NBPT and NBPT + DCD, respectively. Cumulative N2O emissions from NP were 0.28 ± 0.01kg N2O-N ha−1. A single N2O flux peak was identified following basal fertilization, and DCD and/or NBPT inhibition effects mainly occurred during the peak emission period. The NP application significantly (P < 0.05) increased wheat yield by 12.3% and NUE from 28.8% (urea alone) to 35.9%, while urease and/or nitrification inhibitors showed a slight increase effect. Our results clearly indicated that the application of urea as basal fertilizer, but not as supplemental fertilizer, together with DCD and NBPT is an effective practice to reduce N2O emissions. The application of NP instead of urea would be an optimum agricultural strategy for reducing N2O emissions and increasing crop yield and NUE for wheat cultivation in soils of the North China Plain.

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Effect of variability in soil properties plus model complexity on predicting topsoil water content and nitrous oxide emissions

Soil Research ◽

10.1071/sr18080 ◽

2018 ◽

Vol 56 (8) ◽

pp. 810 ◽

Cited By ~ 2

Author(s):

Iris Vogeler ◽

Rogerio Cichota

Keyword(s):

Nitrous Oxide ◽

Soil Properties ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Soil Profile ◽

Nitrous Oxide Emissions ◽

Soil Types ◽

N2o Emissions ◽

Silt Loam

Despite the importance of soil physical properties on water infiltration and redistribution, little is known about the effect of variability in soil properties and its consequent effect on contaminant loss pathways. To investigate the effects of uncertainty and heterogeneity in measured soil physical parameters on the simulated movement of water and the prediction of nitrous oxide (N2O) emissions, we set up the Agricultural Production Systems sIMulator (APSIM) for different soil types in three different regions of New Zealand: the Te Kowhai silt loam and the Horotiu silt loam in the Waikato region, and the Templeton silt loam in the Canterbury region, and the Otokia silt loam and the Wingatui silt loam in the Otago region. For each of the soil types, various measured soil profile descriptions, as well as those from a national soils database (S-map) were used when available. In addition, three different soil water models in APSIM with different complexities (SWIM2, SWIM3, and SoilWat) were evaluated. Model outputs were compared with temporal soil water content measurements within the top 75mm at the various experimental sites. Results show that the profile description, as well as the soil water model used affected the prediction accuracy of soil water content. The smallest difference between soil profile descriptions was found for the Templeton soil series, where the model efficiency (NSE) was positive for all soil profile descriptions, and the RMSE ranged from 0.055 to 0.069m3/m3. The greatest difference was found for the Te Kowhai soil, where only one of the descriptions showed a positive NSE, and the other two profile descriptions overestimated measured topsoil water contents. Furthermore, it was shown that the soil profile description highly affects N2O emissions from urinary N deposited during animal grazing. However, the relative difference between the emissions was not always related to the accuracy of the measured soil water content, with soil organic carbon content also affecting emissions.

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Contribution and Driving Mechanism of N2O Emission Bursts in a Chinese Vegetable Greenhouse after Manure Application and Irrigation

Sustainability ◽

10.3390/su11061624 ◽

2019 ◽

Vol 11 (6) ◽

pp. 1624

Author(s):

Wenchao Cao ◽

Su Liu ◽

Zhi Qu ◽

He Song ◽

Wei Qin ◽

...

Keyword(s):

Nitrous Oxide ◽

Soil Properties ◽

N2o Emission ◽

Field Monitoring ◽

Nitrous Oxide Emissions ◽

Integrated Analysis ◽

N2o Emissions ◽

Driving Mechanism ◽

Manure Application ◽

Greenhouse Vegetable

Solar greenhouse vegetable fields have been found to be hotspots of nitrous oxide (N2O) emissions in China, mainly due to excessive manure application and irrigation. Pulses of N2O emissions have been commonly reported by field monitoring works conducted in greenhouse fields, though their significance regarding total N2O emissions and the driving mechanism behind them remain poorly understood. N2O fluxes were monitored in situ using a static opaque chamber method in a typical greenhouse vegetable field. Then, laboratory incubations were conducted under different soil moisture and manure application gradients to monitor nitrous oxide emissions and related soil properties, using a robotized incubation system. Field monitoring showed that the occurrence of clear N2O emission bursts closely followed fertilization and irrigation events, accounting for 76.7% of the annual N2O efflux. The soil N2O flux increased exponentially with the water-filled pore space (WFPS), causing extremely high N2O emissions when the WFPS was higher than 60%. During the lab incubation, emission bursts led to N2O peaks within 40 h, synchronously changing with the transit soil NO2−. An integrated analysis of the variations in the gas emission and soil properties indicated that the denitrification of transit NO2− accumulation was the major explanation for N2O emission bursts in the greenhouse filed. Nitrous oxide emission bursts constituted the major portion of the N2O emissions in the Chinese greenhouse soils. Nitrite (NO2−) denitrification triggered by fertilization and irrigation was responsible for these N2O emission pulses. Our results clarified the significance and biogeochemical mechanisms of N2O burst emissions; this knowledge could help us to devise and enact sounder N2O mitigation measures, which would be conducive to sustainable development in vegetable greenhouse fields.

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Nitrous oxide emission and nitrogen use efficiency in response to nitrophosphate, N-(n-butyl) thiophosphoric triamide and dicyandiamide of a wheat cultivated soil under sub-humid monsoon conditions

Biogeosciences ◽

10.5194/bg-12-803-2015 ◽

2015 ◽

Vol 12 (3) ◽

pp. 803-815 ◽

Cited By ~ 34

Author(s):

W. X. Ding ◽

Z. M. Chen ◽

H. Y. Yu ◽

J. F. Luo ◽

G. Y. Yoo ◽

...

Keyword(s):

Nitrous Oxide ◽

Sandy Loam ◽

Wheat Yield ◽

Nitrification Inhibitor ◽

Growth Period ◽

N2o Emission ◽

N Fertilizer ◽

N2o Emissions ◽

Nitrification Inhibitors ◽

Use Efficiency

Abstract. A field experiment was designed to study the effects of nitrogen (N) source and urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) or nitrification inhibitor dicyandiamide (DCD) on nitrous oxide (N2O) emission and N use efficiency (NUE) in a sandy loam soil. Six treatments including no N fertilizer (control), N fertilizer urea alone (U), urea plus NBPT (NBPT), urea plus DCD (DCD), urea plus NBPT and DCD (NBPT plus DCD) and nitrate-based fertilizer nitrophosphate (NP) were designed and implemented separately during the wheat growth period. Seasonal cumulative N2O emissions with urea alone amounted to 0.49 ± 0.12 kg N2O-N ha−1 and were significantly (P < 0.05) reduced to 0.28 ± 0.03, 0.31 ± 0.01 and 0.26 ± 0.01 kg N2O-N ha−1 by application of DCD, NBPT and NBPT plus DCD, respectively. Cumulative N2O emissions from NP were 0.28 ± 0.01 kg N2O-N ha−1. A single N2O flux peak was identified following basal fertilization, and DCD and/or NBPT inhibition effects mainly occurred during the peak emission period. The NP application significantly (P < 0.05) increased wheat yield by 12.3% and NUE from 28.8% (urea alone) to 35.9%, while urease and/or nitrification inhibitors showed a slight increase effect. Our results clearly indicated that the application of urea as basal fertilizer, but not as supplemental fertilizer, together with DCD and NBPT is an effective practice to reduce N2O emissions. The application of NP instead of urea would be an optimum agricultural strategy for reducing N2O emissions and increasing crop yield and NUE for wheat cultivation in soils of the North China Plain.

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Nitrous Oxide Emissions in Pineapple Cultivation on a Tropical Peat Soil

Sustainability ◽

10.3390/su13094928 ◽

2021 ◽

Vol 13 (9) ◽

pp. 4928

Author(s):

Alicia Vanessa Jeffary ◽

Osumanu Haruna Ahmed ◽

Roland Kueh Jui Heng ◽

Liza Nuriati Lim Kim Choo ◽

Latifah Omar ◽

...

Keyword(s):

Nitrous Oxide ◽

Soil Temperature ◽

Peat Soil ◽

Farming Systems ◽

N2o Emission ◽

Nitrous Oxide Emissions ◽

Natural State ◽

N2o Emissions ◽

Wet Season ◽

Peat Soils

Farming systems on peat soils are novel, considering the complexities of these organic soil. Since peat soils effectively capture greenhouse gases in their natural state, cultivating peat soils with annual or perennial crops such as pineapples necessitates the monitoring of nitrous oxide (N2O) emissions, especially from cultivated peat lands, due to a lack of data on N2O emissions. An on-farm experiment was carried out to determine the movement of N2O in pineapple production on peat soil. Additionally, the experiment was carried out to determine if the peat soil temperature and the N2O emissions were related. The chamber method was used to capture the N2O fluxes daily (for dry and wet seasons) after which gas chromatography was used to determine N2O followed by expressing the emission of this gas in t ha−1 yr−1. The movement of N2O horizontally (832 t N2O ha−1 yr−1) during the dry period was higher than in the wet period (599 t N2O ha−1 yr−1) because of C and N substrate in the peat soil, in addition to the fertilizer used in fertilizing the pineapple plants. The vertical movement of N2O (44 t N2O ha−1 yr−1) was higher in the dry season relative to N2O emission (38 t N2O ha−1 yr−1) during the wet season because of nitrification and denitrification of N fertilizer. The peat soil temperature did not affect the direction (horizontal and vertical) of the N2O emission, suggesting that these factors are not related. Therefore, it can be concluded that N2O movement in peat soils under pineapple cultivation on peat lands occurs horizontally and vertically, regardless of season, and there is a need to ensure minimum tilling of the cultivated peat soils to prevent them from being an N2O source instead of an N2O sink.

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Emission factors for estimating fertiliser-induced nitrous oxide emissions from clay soils in Australia’s irrigated cotton industry

Soil Research ◽

10.1071/sr16091 ◽

2016 ◽

Vol 54 (5) ◽

pp. 598 ◽

Cited By ~ 12

Author(s):

Peter Grace ◽

Iurii Shcherbak ◽

Ben Macdonald ◽

Clemens Scheer ◽

David Rowlings

Keyword(s):

Nitrous Oxide ◽

Meta Analysis ◽

Exponential Model ◽

N2o Emission ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

Tier 2 ◽

Cotton Industry ◽

Greenhouse Gas Inventories ◽

N Rates

As a significant user of nitrogen (N) fertilisers, the Australian cotton industry is a major source of soil-derived nitrous oxide (N2O) emissions. A country-specific (Tier 2) fertiliser-induced emission factor (EF) can be used in national greenhouse gas inventories or in the development of N2O emissions offset methodologies provided the EFs are evidence based. A meta-analysis was performed using eight individual N2O emission studies from Australian cotton studies to estimate EFs. Annual N2O emissions from cotton grown on Vertosols ranged from 0.59kgNha–1 in a 0N control to 1.94kgNha–1 in a treatment receiving 270kgNha–1. Seasonal N2O estimates ranged from 0.51kgNha–1 in a 0N control to 10.64kgNha–1 in response to the addition of 320kgNha–1. A two-component (linear+exponential) statistical model, namely EF (%)=0.29+0.007(e0.037N – 1)/N, capped at 300kgNha–1 describes the N2O emissions from lower N rates better than an exponential model and aligns with an EF of 0.55% using a traditional linear regression model.

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Nitrous oxide emission from Australian agricultural lands and mitigation options: a review

Soil Research ◽

10.1071/sr02064 ◽

2003 ◽

Vol 41 (2) ◽

pp. 165 ◽

Cited By ~ 379

Author(s):

Ram C. Dalal ◽

Weijin Wang ◽

G. Philip Robertson ◽

William J. Parton

Keyword(s):

Nitrous Oxide ◽

Global Warming ◽

N2o Emission ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

Tropical Savannas ◽

Agricultural Lands ◽

Mineral N ◽

N2o Production ◽

Mitigation Options

Increases in the concentrations of greenhouse gases, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and halocarbons in the atmosphere due to human activities are associated with global climate change. The concentration of N2O has increased by 16% since 1750. Although atmospheric concentration of N2O is much smaller (314 ppb in 1998) than of CO2 (365 ppm), its global warming potential (cumulative radiative forcing) is 296 times that of the latter in a 100-year time horizon. Currently, it contributes about 6% of the overall global warming effect but its contribution from the agricultural sector is about 16%. Of that, almost 80% of N2O is emitted from Australian agricultural lands, originating from N fertilisers (32%), soil disturbance (38%), and animal waste (30%). Nitrous oxide is primarily produced in soil by the activities of microorganisms during nitrification, and denitrification processes. The ratio of N2O to N2 production depends on oxygen supply or water-filled pore space, decomposable organic carbon, N substrate supply, temperature, and pH and salinity. N2O production from soil is sporadic both in time and space, and therefore, it is a challenge to scale up the measurements of N2O emission from a given location and time to regional and national levels.Estimates of N2O emissions from various agricultural systems vary widely. For example, in flooded rice in the Riverina Plains, N2O emissions ranged from 0.02% to 1.4% of fertiliser N applied, whereas in irrigated sugarcane crops, 15.4% of fertiliser was lost over a 4-day period. Nitrous oxide emissions from fertilised dairy pasture soils in Victoria range from 6 to 11 kg N2O-N/ha, whereas in arable cereal cropping, N2O emissions range from <0.01% to 9.9% of N fertiliser applications. Nitrous oxide emissions from soil nitrite and nitrates resulting from residual fertiliser and legumes are rarely studied but probably exceed those from fertilisers, due to frequent wetting and drying cycles over a longer period and larger area. In ley cropping systems, significant N2O losses could occur, from the accumulation of mainly nitrate-N, following mineralisation of organic N from legume-based pastures. Extensive grazed pastures and rangelands contribute annually about 0.2 kg N/ha as N2O (93 kg/ha per year CO2-equivalent). Tropical savannas probably contribute an order of magnitude more, including that from frequent fires. Unfertilised forestry systems may emit less but the fertilised plantations emit more N2O than the extensive grazed pastures. However, currently there are limited data to quantify N2O losses in systems under ley cropping, tropical savannas, and forestry in Australia. Overall, there is a need to examine the emission factors used in estimating national N2O emissions; for example, 1.25% of fertiliser or animal-excreted N appearing as N2O (IPCC 1996). The primary consideration for mitigating N2O emissions from agricultural lands is to match the supply of mineral N (from fertiliser applications, legume-fixed N, organic matter, or manures) to its spatial and temporal needs by crops/pastures/trees. Thus, when appropriate, mineral N supply should be regulated through slow-release (urease and/or nitrification inhibitors, physical coatings, or high C/N ratio materials) or split fertiliser application. Also, N use could be maximised by balancing other nutrient supplies to plants. Moreover, non-legume cover crops could be used to take up residual mineral N following N-fertilised main crops or mineral N accumulated following legume leys. For manure management, the most effective practice is the early application and immediate incorporation of manure into soil to reduce direct N2O emissions as well as secondary emissions from deposition of ammonia volatilised from manure and urine.Current models such as DNDC and DAYCENT can be used to simulate N2O production from soil after parameterisation with the local data, and appropriate modification and verification against the measured N2O emissions under different management practices.In summary, improved estimates of N2O emission from agricultural lands and mitigation options can be achieved by a directed national research program that is of considerable duration, covers sampling season and climate, and combines different techniques (chamber and micrometeorological) using high precision analytical instruments and simulation modelling, under a range of strategic activities in the agriculture sector.

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Quantifying nitrous oxide emissions from the foliage of cotton, maize and soybean crops

Crop and Pasture Science ◽

10.1071/cp14301 ◽

2015 ◽

Vol 66 (7) ◽

pp. 689 ◽

Cited By ~ 4

Author(s):

I. Rochester ◽

C. Wood ◽

B. Macdonald

Keyword(s):

Nitrous Oxide ◽

Zea Mays L ◽

Cropping Systems ◽

Time Of Day ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

N2o Flux ◽

Gossypium Hirsutum L ◽

Cotton Plants ◽

Glycine Max L

Nitrous oxide (N2O) is a potent greenhouse gas, contributing to global warming. Most of the N2O emitted from cropping systems is derived from the soil and is closely related to the use of nitrogen (N) fertiliser. However, several reports have shown that small, yet significant, portions of the N2O flux from cropping systems are emitted from the crop foliage. This research aimed to quantify N2O emissions from the foliage of field-grown cotton (Gossypium hirsutum L.), and included maize (Zea mays L.) and soybean (Glycine max L.) for comparison. We also aimed to identify differences in the timing of N2O emissions from foliage during the day and over an irrigation cycle. Individual plants were isolated from the soil, and the atmosphere surrounding the encapsulated plants was sampled over a 30-min period. Subplots that were previously fertilised with urea at 0, 80, 160, 240 and 320 kg N ha–1 and then sown to cotton were used to measure N2O flux from plants on three occasions. N2O flux from cotton foliage was also measured on five occasions during an 11-day irrigation cycle and at five times throughout one day. N2O flux from foliage accounted for a small but significant portion (13–17%) of the soil–crop N2O flux. N2O flux from foliage varied with plant species, and the time of day the flux was measured. N2O flux from cotton plants was closely related to soil water content. Importantly, the application of N fertiliser was not related to the N2O flux from cotton plants. The most plausible explanation of our results is that a proportion of the N2O that was evolved in the soil was transported through the plant via evapotranspiration, rather than being evolved within the plant. Studies that exclude N2O emissions from crop foliage will significantly underestimate the N2O flux from the system.

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Nitrous oxide emission from dairy farming systems in the Netherlands

Netherlands Journal of Agricultural Science ◽

10.18174/njas.v45i3.510 ◽

1997 ◽

Vol 45 (3) ◽

pp. 347-360 ◽

Cited By ~ 15

Author(s):

G.L. Velthof ◽

O. Oenema

Keyword(s):

Nitrous Oxide ◽

The Netherlands ◽

Nutrient Management ◽

Farming Systems ◽

Farming System ◽

N2o Emission ◽

Dairy Farming ◽

N Leaching ◽

N2o Emissions ◽

Nutrient Emissions

A large part of the nitrogen (N) input in dairy farming systems in the Netherlands is lost from the system via N leaching and volatilization of gaseous N compounds, including the greenhouse gas nitrous oxide (N2O). The aim of the present study was to quantify N2O emission from dairy farming systems in the Netherlands, using a whole-farm approach. A total of 14 N2O sources was identified and emission factors were derived for each of these using the literature. Figures are presented for the amounts of N2O produced/kg herbage N produced (ranging from 4 to 89 g N2O-N kg-1 herbage N), depending on soil type and grassland management. Using Monte Carlo simulations, variations in mean total N2O emissions from the different sources were calculated for 3 model dairy farming systems differing in nutrient management. These different farming systems were chosen to assess the effect of improved nutrient management on total N2O emission. The total direct annual N2O emissions ranged from 15.4 +or-9.4 kg N2O-N/ha for the average dairy farming system in the 1980s to 5.3 +or-2.6 kg N2O-N/ha for a prototype of an economically feasible farming system with acceptable nutrient emissions. Leaching-derived, grazing-derived and fertilizer-derived N2O emissions were the major N2O sources on dairy farming systems. The total direct N2O emissions accounted for 3.2 to 4.6% of the N surplus on the dairy farming systems, suggesting that only a small amount of N was lost as N2O. Total N2O emissions from dairy farming systems in the Netherlands were 13.7+or-5.1 Gg N/year, which is about 35% of the estimated total N2O emission in the Netherlands. It is concluded that improvement of nutrient management of dairy farming systems will significantly decrease the N2O emissions from these systems, and thus the total N2O emission in the Netherlands.

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Nitrous Oxide Emission from Forage Plantain and Perennial Ryegrass Swards Is Affected by Belowground Resource Allocation Dynamics

Agronomy ◽

10.3390/agronomy11101936 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1936

Author(s):

John Kormla Nyameasem ◽

Enis Ben Halima ◽

Carsten Stefan Malisch ◽

Bahar S. Razavi ◽

Friedhelm Taube ◽

...

Keyword(s):

Resource Allocation ◽

Nitrous Oxide ◽

Plantago Lanceolata ◽

Belowground Biomass ◽

Soil Microbial Activity ◽

N2o Emission ◽

N2o Emissions ◽

Soil Microbial ◽

Use Efficiency ◽

N Use

Soil–plant interactions affecting nitrous oxide (N2O) are not well-understood, and experimental data are scarce. Therefore, a greenhouse experiment was conducted in a 3 × 3 full factorial design, comprising three mineral N fertilizer rates (0, 150 and 300 kg N ha−1) applied to monoculture swards and a binary mixture of Plantago lanceolata and Lolium perenne. The parameters measured included daily N2O emissions, aboveground (AG) and belowground biomass (BG), N and C yields, as well as leucine aminopeptidase (LAP) activity in the soil as an indicator for soil microbial activity. Nitrous oxide emission and LAP were measured using the static chamber method and fluorimetric microplate assays, respectively. Cumulative N2O emissions were about two times higher for P. lanceolata than L. perenne monoculture swards or the mixture (p < 0.05). The binary mixtures also showed the highest N use efficiency and LAP activity, which significantly (p < 0.05) correlated with the C concentration in the belowground biomass. Plantago lanceolata was generally ineffective at reducing N2O emissions, probably due to the young age of the swards. Among the biological factors, N2O emission was significantly associated with biomass productivity, belowground C yield, belowground N use efficiency and soil microbial activity. Thus, the results suggested belowground resource allocation dynamics as a possible means by which swards impacted N2O emission from the soils. However, a high N deposition might reduce the N2O mitigation potential of grasslands.

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