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 Short-term effects of biogas digestate and cattle slurry application on greenhouse gas emissions from high organic carbon grasslands

2014 ◽  
Vol 11 (4) ◽  
pp. 5765-5809 ◽  
Author(s):  
T. Eickenscheidt ◽  
A. Freibauer ◽  
J. Heinichen ◽  
J. Augustin ◽  
M. Drösler
Keyword(s):  
Organic Carbon ◽  
Application Rate ◽  
Organic Fertilizers ◽  
Organic Soils ◽  
N2o Emissions ◽  
Cattle Slurry ◽  
Closed Chamber ◽  
Chamber Method ◽  
Biogas Digestate ◽  
N2o Fluxes

Abstract. The change in the German energy policy resulted in a strong development of biogas plants in Germany. As a consequence, huge amounts of nutrient rich residues remain from the fermentative process, which are used as organic fertilizers. Drained peatlands are increasingly used to satisfy the huge demand for fermentative substrates 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, methane (CH4) and ammonia (NH3) fluxes as well as the mineral nitrogen use efficiency (NUEmin), and (b) how different soil organic matter contents (SOM) promote the production of N2O. The study was conducted at two areas within a grassland parcel, which differed in their soil organic carbon (SOC) contents. At each area (named Corg-medium and Corg-high) two sites were established, one was fertilized five times with biogas digestate and one with cattle slurry. For each treatment, fluxes of N2O and CH4 were measured over two 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 NUEmin. Furthermore, N2O fluxes from the Corg-high site significantly exceeded N2O fluxes from the Corg-medium sites. Annual cumulative emissions ranged from 0.91 ± 0.49 kg N ha−1 yr−1 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 kg C ha−1 yr−1 and −1.06 ± 0.46 kg C ha−1 yr−1. Significantly higher NH3 losses from treatments fertilized with biogas digestate compared to those fertilized with cattle slurry were observed. The total NH3 losses following 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 rather annual N2O emissions, due to a higher mean groundwater level and a higher application rate of NH4+-N, reveal the importance of site adapted N fertilization and the avoidance of N surpluses in Corg rich grasslands.

scholarly journals High-Temperature Hay Biochar Application into Soil Increases N2O Fluxes

Agronomy ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 109 ◽  
Author(s):  
Jordi Escuer-Gatius ◽  
Merrit Shanskiy ◽  
Kaido Soosaar ◽  
Alar Astover ◽  
Henn Raave
Keyword(s):  
High Temperature ◽  
Soil Amendment ◽  
Organic Fertilizer ◽  
Organic Fertilizers ◽  
Soil Conditions ◽  
N2o Emissions ◽  
Cattle Slurry ◽  
N Losses ◽  
Production Temperature ◽  
N2o Fluxes

Biochar has been proposed as an amendment that can improve soil conditions, increase harvest yield, and reduce N losses through NO3− leaching and N2O emissions. We conducted an experiment to test the hay biochar mitigation effect on N2O emissions depending on its production temperature. The pot experiment consisted of the soil amendment with three different production temperature biochars (300 °C, 550 °C, 850 °C) alone and in combination with three different organic fertilizers (cattle slurry, slurry digestate, vinasse), in growth chamber conditions. The effects of biochar and fertilizer were both significant, but the interaction biochar:fertilizer was not. The amendment with the three fertilizer types and with the highest production temperature biochar resulted in significantly higher cumulative N2O fluxes. Biochar did not show a mitigation effect on N2O emissions when applied with organic fertilizer. Cumulative emissions were higher with biochar addition, with increasing emissions for increasing biochar production temperature. Our results support the idea that biochar cannot be considered as a universal tool for the reduction of N2O emissions.

scholarly journals Review of key causes and sources for N<sub>2</sub>O emissions and NO<sub>3</sub>-leaching from organic arable crop rotations

2018 ◽  
Author(s):  
Sissel Hansen ◽  
Randi Berland Frøseth ◽  
Maria Stenberg ◽  
Jarosław Stalenga ◽  
Jørgen E. Olesen ◽  
...  
Keyword(s):  
Organic Matter ◽  
Nitrate Leaching ◽  
Organic Production ◽  
Crop Rotations ◽  
Organic Fertilizers ◽  
N2o Emissions ◽  
Catch Crops ◽  
Arable Crop ◽  
N2o Fluxes ◽  
The Impact

Abstract. The emissions of nitrous oxide (N2O) and leaching of nitrate (NO3) have considerable negative impacts on climate and the environment. Although these environmental burdens are on average less per unit area in organic than in non-organic production, they are not smaller per unit of product. If organic farming is to maintain its goal of being an environmentally friendly production system, these emissions should be mitigated. We discuss the impact of possible triggers within organic arable farming practice for the risk of N2O emissions and NO3 leaching under European climatic conditions, and possible strategies to reduce these. Organic arable crop rotations can be characterised as diverse with frequent use of legumes, intercropping and organic fertilizers. The soil organic matter content and share of active organic matter, microbial and faunal activity are higher, soil structure better and yields lower, than in non-organic, arable crop rotations. Soil mineral nitrogen (SMN), N2O emissions and NO3 leaching are low under growing crops, but there is high potential for SMN accumulation and losses after crop termination or crop harvest. The risk for high N2O fluxes is increased when large amounts of herbage or organic fertilizers with readily available nitrogen (N) and carbon are incorporated into the soil or left on the surface. Freezing/thawing, drying/rewetting, compacted and/or wet soil and mixing with rotary harrow further enhance the risk for high N2O fluxes. These complex soil N dynamics mask the correlation between total N-input and N2O emissions from organic arable crop rotations. Incorporation of N rich plant residues or mechanical weeding followed by bare fallow increases the risk of nitrate leaching. In contrast, strategic use of deep-rooted crops with long growing seasons in the rotation reduces nitrate leaching risk. Reduced tillage can reduce N leaching if yields are maintained. Targeted treatment and use of herbage from green manures, crop residues and catch crops will increase N efficiency and reduce N2O emissions and NO3 leaching. Continued regular use of catch crops has the potential to reduce NO3 leaching but may enhance N2O emissions. A mixture of legumes and non-legumes (for instance grasses or cereals) are as efficient a catch crop as monocultures of non-legume species.

scholarly journals Regulation of N<sub>2</sub>O emissions from acid organic soil drained for agriculture: Effects of land use and season

2019 ◽  
Author(s):  
Arezoo Taghizadeh-Toosi ◽  
Lars Elsgaard ◽  
Tim J. Clough ◽  
Rodrigo Labouriau ◽  
Vibeke Ernstsen ◽  
...  
Keyword(s):  
Pyrite Oxidation ◽  
Acid Volatile Sulfide ◽  
Organic Soils ◽  
N2o Emissions ◽  
N Availability ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Mineral N ◽  
Total Reduction ◽  
Reduction Capacity

Abstract. Drained organic soils are extensively used for cereal and high-value cash crop production or as grazing land, but emissions of nitrous oxide (N2O) are enhanced by the drainage and cultivation. A study was conducted to investigate the regulation of N2O emissions in a raised bog area drained for agriculture. The area has been classified as potentially acid sulfate soil, and we hypothesised that pyrite oxidation was a potential driver of N2O emissions. Two sites with rotational grass, and two sites with a potato crop, were equipped for monitoring of N2O emissions, as well as sub-soil N2O concentrations at 5, 10, 20, 50 and 100 cm depth, during spring and autumn 2015. Precipitation, air and soil temperature, soil moisture, water table (WT) depth, and soil mineral N were recorded during weekly field campaigns. In late April and early September, intact cores were collected to 1 m depth at adjacent grassland and potato sites for analysis of soil properties, which included acid volatile sulfide (AVS) and chromium-reducible sulfur (CRS) to quantify, respectively, iron monosulfide (FeS) and pyrite (FeS2), as well as total reactive iron (TRFe) and nitrite (NO2−). Soil organic matter composition and total reduction capacity was also determined. The soil pH varied between 4.7 and 5.4. Equivalent soil gas phase concentrations of N2O ranged from around 10 µL L−1 at grassland sites to several hundred µL L−1 at potato sites, in accordance with lower soil mineral N concentrations at grassland sites. Total N2O emissions during 152–174 days were 3–6 kg N2O-N ha−1 for rotational grass, and 19–21 kg N2O-N ha−1 for potato sites. Statistical analyses by graphical models showed that soil N2O concentration in the capillary fringe was the strongest predictor for N2O emissions in spring, and for grassland sites also in the autumn. For potato sites in the autumn, nitrate (NO3−) availability in the top soil, together with temperature, were the main controls on N2O emissions. Pyrite oxidation coupled with NO3− reduction could not be dismissed as a source of N2O, but the total reduction capacity of the peat soil was much higher than explained by the FeS2 concentration. The concentrations of TRFe were also much higher than pyrite concentrations, and potentially chemodenitrification could have been a source of N2O during WT drawdown in spring. The N2O emissions associated with rapid soil wetting and WT rise in autumn were consistent with biological denitrification. Soil N availability and seasonal WT changes were important controls of N2O emissions.

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 Ecological controls on N<sub>2</sub>O emission in surface litter and near-surface soil of a managed grassland: modelling and measurements

2016 ◽  
Vol 13 (12) ◽  
pp. 3549-3571 ◽  
Author(s):  
Robert F. Grant ◽  
Albrecht Neftel ◽  
Pierluigi Calanca
Keyword(s):  
Soil Properties ◽  
Spatial Variation ◽  
Surface Soil ◽  
N Uptake ◽  
N2o Emissions ◽  
N Availability ◽  
Area Index ◽  
Large Variability ◽  
Near Surface ◽  
Intensively Managed

Abstract. Large variability in N2O emissions from managed grasslands may occur because most emissions originate in surface litter or near-surface soil where variability in soil water content (θ) and temperature (Ts) is greatest. To determine whether temporal variability in θ and Ts of surface litter and near-surface soil could explain this in N2O emissions, a simulation experiment was conducted with ecosys, a comprehensive mathematical model of terrestrial ecosystems in which processes governing N2O emissions were represented at high temporal and spatial resolution. Model performance was verified by comparing N2O emissions, CO2 and energy exchange, and θ and Ts modelled by ecosys with those measured by automated chambers, eddy covariance (EC) and soil sensors on an hourly timescale during several emission events from 2004 to 2009 in an intensively managed pasture at Oensingen, Switzerland. Both modelled and measured events were induced by precipitation following harvesting and subsequent fertilizing or manuring. These events were brief (2–5 days) with maximum N2O effluxes that varied from  <  1 mgNm−2h−1 in early spring and autumn to  >  3 mgNm−2h−1 in summer. Only very small emissions were modelled or measured outside these events. In the model, emissions were generated almost entirely in surface litter or near-surface (0–2 cm) soil, at rates driven by N availability with fertilization vs. N uptake with grassland regrowth and by O2 supply controlled by litter and soil wetting relative to O2 demand from microbial respiration. In the model, NOx availability relative to O2 limitation governed both the reduction of more oxidized electron acceptors to N2O and the reduction of N2O to N2, so that the magnitude of N2O emissions was not simply related to surface and near-surface θ and Ts. Modelled N2O emissions were found to be sensitive to defoliation intensity and timing which controlled plant N uptake and soil θ and Ts prior to and during emission events. Reducing leaf area index (LAI) remaining after defoliation to half that under current practice and delaying harvesting by 5 days raised modelled N2O emissions by as much as 80 % during subsequent events and by an average of 43 % annually. Modelled N2O emissions were also found to be sensitive to surface soil properties. Increasing near-surface bulk density by 10 % raised N2O emissions by as much as 100 % during emission events and by an average of 23 % annually. Relatively small spatial variation in management practices and soil surface properties could therefore cause the large spatial variation in N2O emissions commonly found in field studies. The global warming potential from annual N2O emissions in this intensively managed grassland largely offset those from net C uptake in both modelled and field experiments. However, model results indicated that this offset could be adversely affected by suboptimal land management and soil properties.

scholarly journals Effect of Nitrification Inhibitors on N2O Emissions after Cattle Slurry Application

Agronomy ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1174 ◽  
Author(s):  
Christina Herr ◽  
Thomas Mannheim ◽  
Torsten Müller ◽  
Reiner Ruser
Keyword(s):  
Management Practice ◽  
Ghg Emissions ◽  
N2o Emissions ◽  
Nitrification Inhibitors ◽  
Ghg Emission ◽  
Cattle Slurry ◽  
Closed Chamber ◽  
Study Region ◽  
Silage Maize ◽  
N2o Fluxes

Cattle slurry injection (INJ) has shown to be an efficient measure to reduce ammonia (NH3) losses from soils but it might also significantly increase nitrous oxide (N2O) emissions, which can dominate the total greenhouse gas (GHG) release in silage maize production (Zea mays L.). Nitrification inhibitors (NIs) are known for their potential to mitigate N2O. Therefore, we tested the effect of NIs added to cattle slurry before INJ on N2O fluxes from a Haplic Luvisol under silage maize in southwest Germany. We determined N2O fluxes at least weekly, with the closed chamber method over two full years. NIs differ in their chemical and physical behavior and we therefore tested a range of commercially available NIs: 3,4-dimethylpyrazole phosphate, 3,4-dimethylpyrazol succinic acid, a mixture of both, nitrapyrin, dicyandiamide, and 1,2,4 triazol and 3-methylpyrazol. Although not significant, INJ treatments with NI showed lower mean annual N2O emissions than the INJ treatment without NI in the 1st year. The emission reduction by NI of 46% in the 2nd year was statistically significant. In both years, we did not find any difference in N2O release, crop yield, or nitrogen removal between the different NI treatments. In the 1st year, which was extraordinary dry and warm, emission factors (EFs) for all INJ treatments were 4 to 8-fold higher than default EF from the IPCC. Even in the 2nd year, only three NI treatments reached EFs within the range provided by the IPCC. Direct N2O accounted for between 81 and 91% of the total GHG emission. Area- and yield-related GHG emission of the broadcast application with subsequent incorporation was in both years in the statistical class with lowest emission. In contrast, INJ with NIs showed similar GHG emissions in only one year, and consequently, incorporation was found to be the optimum management practice for livestock farmers in our study region.

scholarly journals Ecological Controls on N<sub>2</sub>O Emission in Surface Litter and Near-surface Soil of a Managed Pasture: Modelling and Measurements

2016 ◽  
Author(s):  
R. F. Grant ◽  
A. Neftel ◽  
P. Calanca
Keyword(s):  
Field Experiments ◽  
Surface Soil ◽  
N Uptake ◽  
Terrestrial Ecosystems ◽  
Sensitivity Study ◽  
N2o Emissions ◽  
N Availability ◽  
Large Variability ◽  
Near Surface ◽  
Intensively Managed

Abstract. Large variability in N2O emissions from managed grasslands may occur because most emissions originate in surface litter or near-surface soil where variability in soil water content (θ) and temperature (Ts) is greatest. To determine whether temporal variability in θ and Ts of surface litter and near-surface soil could explain that in N2O emissions, a simulation experiment was conducted with ecosys, a comprehensive mathematical model of terrestrial ecosystems in which processes governing N2O emissions were represented at high temporal and spatial resolution. Model performance was verified by comparing N2O emissions, CO2 and energy exchange, and θ and Ts modelled by ecosys with those measured by automated chambers, eddy covariance (EC) and soil sensors at an hourly time-scale during several emission events from 2004 to 2009 in an intensively managed pasture at Oensingen, Switzerland. Both modelled and measured events were induced by precipitation following harvesting and subsequent fertilizing or manuring. These events were brief (2 – 5 days) with maximum N2O effluxes that varied from < 1 mg N m-2 h-1 in early spring and autumn to > 3 mg N m-2 h-1 in summer. Only very small emissions were modelled or measured outside these events. In the model, emissions were generated almost entirely in surface litter or near-surface (0 – 2 cm) soil, at rates driven by N availability with fertilization vs. N uptake with grassland regrowth, and by O2 limitation from wetting relative to O2 demand from respiration. In the model, NOx availability relative to O2 limitation governed both the reduction of more oxidized electron acceptors to N2O and the reduction of N2O to N2, so that the magnitude of N2O emissions was not simply related to surface and near-surface θ and Ts. Modelled N2O emissions were found to be sensitive to defoliation intensity and timing (relative to that of fertilization) which controlled plant N uptake and soil θ and Ts prior to and during emission events. In a model sensitivity study, reducing LAI remaining after defoliation to one-half that under current practice and delaying harvesting by 5 days raised N2O emissions by as much as 80% during subsequent events and by an average of 43% annually. The global warming potential from annual N2O emissions in this intensively managed grassland largely offset those from net C uptake in both modelled and field experiments. However model results indicated that this offset could be adversely affected by suboptimal harvest intensity and timing.

scholarly journals Nitrous oxide emission hotspots from organic soils in Europe

2014 ◽  
Vol 11 (6) ◽  
pp. 9135-9182
Author(s):  
T. Leppelt ◽  
R. Dechow ◽  
S. Gebbert ◽  
A. Freibauer ◽  
A. Lohila ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Greenhouse Gas ◽  
Ph Value ◽  
A Priori ◽  
Emission Factors ◽  
Organic Soils ◽  
N2o Emissions ◽  
The European Union ◽  
Study Results ◽  
N2o Fluxes

Abstract. Organic soils are a main source of direct nitrous oxide (N2O) emissions, an important greenhouse gas (GHG). Observed N2O emissions from organic soils are highly variable in space and time which causes high uncertainties in national emission inventories. Those uncertainties could be reduced when relating the upscaling process to a priori identified key drivers by using available N2O observations from plot scale in empirical approaches. We used the empirical fuzzy modelling approach MODE to identify main drivers for N2O and utilize them to predict the spatial emission pattern of European organic soils. We conducted a meta study with a total amount of 659 annual N2O measurements which was used to derive separate models for different land use types. We applied our models to available, spatial explicit input driver maps to upscale N2O emissions on European level and compared the inventory with recently published IPCC emission factors. The final statistical models explained up to 60% of the N2O variance. Our study results showed that cropland and grasslands emitted the highest N2O fluxes 0.98 ± 1.08 and 0.58 ± 1.03 g N2O-N m−2 a−1, respectively. High fluxes from cropland sites were mainly controlled by low soil pH-value and deep drained groundwater tables. Grassland hotspot emissions were strongly related to high amount of N-fertilizer inputs and warmer winter temperatures. In contrast N2O fluxes from natural peatlands were predominantly low (0.07±0.27 g N2O-N m−2 a−1) and we found no relationship with the tested drivers. The total inventory for direct N2O emissions from organic soils in Europe amount up to 149.5 Gg N2O-N a−1, which included also fluxes from forest and peat extraction sites and exceeds the inventory calculated by IPCC emission factors of 87.4 Gg N2O-N a−1. N2O emissions from organic soils represent up to 13% of total European N2O emissions reported in the European Union (EU) greenhouse gas inventory of 2011 from only 7% of the EU area. Thereby the model demonstrated that with up to 85% the major part of the inventory is induced by anthropogenic management, which shows the significant reduction potential by rewetting and extensivation of agricultural used peat soils.

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.

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