Denitrifying pathways dominate nitrous oxide emissions from managed grassland during drought and rewetting

Nitrous oxide is a powerful greenhouse gas whose atmospheric growth rate has accelerated over the past decade. Most anthropogenic N2O emissions result from soil N fertilization, which is converted to N2O via oxic nitrification and anoxic denitrification pathways. Drought-affected soils are expected to be well oxygenated; however, using high-resolution isotopic measurements, we found that denitrifying pathways dominated N2O emissions during a severe drought applied to managed grassland. This was due to a reversible, drought-induced enrichment in nitrogen-bearing organic matter on soil microaggregates and suggested a strong role for chemo- or codenitrification. Throughout rewetting, denitrification dominated emissions, despite high variability in fluxes. Total N2O flux and denitrification contribution were significantly higher during rewetting than for control plots at the same soil moisture range. The observed feedbacks between precipitation changes induced by climate change and N2O emission pathways are sufficient to account for the accelerating N2O growth rate observed over the past decade.

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Biochar and urease inhibitor mitigate NH3 and N2O emissions and improve wheat yield in a urea fertilized alkaline soil

Scientific Reports ◽

10.1038/s41598-021-96771-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Khadim Dawar ◽

Shah Fahad ◽

M. M. R. Jahangir ◽

Iqbal Munir ◽

Syed Sartaj Alam ◽

...

Keyword(s):

Nitrous Oxide ◽

Grain Yield ◽

Block Design ◽

N Uptake ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

Urease Inhibitor ◽

Alkaline Soil ◽

Total N ◽

N Assimilation

AbstractIn this study, we explored the role of biochar (BC) and/or urease inhibitor (UI) in mitigating ammonia (NH3) and nitrous oxide (N2O) discharge from urea fertilized wheat cultivated fields in Pakistan (34.01°N, 71.71°E). The experiment included five treatments [control, urea (150 kg N ha−1), BC (10 Mg ha−1), urea + BC and urea + BC + UI (1 L ton−1)], which were all repeated four times and were carried out in a randomized complete block design. Urea supplementation along with BC and BC + UI reduced soil NH3 emissions by 27% and 69%, respectively, compared to sole urea application. Nitrous oxide emissions from urea fertilized plots were also reduced by 24% and 53% applying BC and BC + UI, respectively, compared to urea alone. Application of BC with urea improved the grain yield, shoot biomass, and total N uptake of wheat by 13%, 24%, and 12%, respectively, compared to urea alone. Moreover, UI further promoted biomass and grain yield, and N assimilation in wheat by 38%, 22% and 27%, respectively, over sole urea application. In conclusion, application of BC and/or UI can mitigate NH3 and N2O emissions from urea fertilized soil, improve N use efficiency (NUE) and overall crop productivity.

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Contribution of the cotton irrigation network to farm nitrous oxide emissions

Soil Research ◽

10.1071/sr15273 ◽

2016 ◽

Vol 54 (5) ◽

pp. 651 ◽

Cited By ~ 7

Author(s):

B. C. T. Macdonald ◽

A. Nadelko ◽

Y. Chang ◽

M. Glover ◽

S. Warneke

Keyword(s):

Nitrous Oxide ◽

Surface Area ◽

Land Surface ◽

Irrigation System ◽

Minor Component ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

Deep Drainage ◽

Total N ◽

Irrigation Network

Nitrous oxide (N2O) is a potent greenhouse gas, and agriculture is the dominant source of N2O-N emissions. The Australian cotton industry requires high inputs of N to maintain high lint quality and yields; however, over-fertilisation with N is symptomatic of the industry. Up to 3.5% of N fertiliser applied is lost directly from cotton fields as N2O gas. Excess N may also be lost via erosion, deep-drainage, leaching and runoff, and may subsequently form indirect N2O emissions. The estimate by the Intergovernmental Panel on Climate Change (IPCC) suggests that 0.0025kg N2O-N is produced indirectly from groundwater and surface drainage for each kg N lost via runoff and leaching, although this estimate carries a large degree of uncertainty. This study is the first to address the lack of indirect N2O emission data from irrigated cotton-farming systems. Indirect emissions were determined from total N concentrations in irrigation runoff by using the IPCC emission factor and from measurements of dissolved N2O during the first four irrigations (October–December 2013). Total indirect N2O emissions from the surface of the irrigation network over 3 months when estimated by the dissolved-N2O method were 0.503±0.339kgha–1. By contrast, N2O emissions estimated by the IPCC methodology were 0.843±0.022kgha–1 irrigation surface area. Over the same period of measurement, direct land-surface emissions were 1.44kgN2O-Nha–1 field. Despite relatively high emissions per surface area, the irrigation network is only a minor component of the total farm area, and indirect emissions from the irrigation system contribute ~2.4–4% of the total N2O emissions and <0.02% of the applied N fertiliser.

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Improved Chamber Systems for Rapid, Real-Time Nitrous Oxide Emissions from Manure and Soil

Transactions of the ASABE ◽

10.13031/trans.12151 ◽

2017 ◽

Vol 60 (4) ◽

pp. 1235-1258 ◽

Cited By ~ 3

Author(s):

David B. Parker ◽

Kenneth D. Casey ◽

Richard W. Todd ◽

Heidi M. Waldrip ◽

Gary M. Marek ◽

...

Keyword(s):

Nitrous Oxide ◽

Greenhouse Gas ◽

Real Time ◽

Nitrous Oxide Emissions ◽

Chamber System ◽

Flux Chamber ◽

Total N ◽

Recirculating Flow ◽

Flux Measurements ◽

Flow Through

Abstract. Nitrous oxide (N2O) emission rates have traditionally been measured using non-flow-through (NFT), non-steady-state (NSS) chambers, which rely on measuring the increase in N2O concentration in the sealed chamber headspace over time. These flux measurements are very labor- and time-intensive, requiring three to four gas samples collected over a 30 to 60 min period, followed by laboratory N2O measurement with a gas chromatograph (GC) and subsequent flux rate calculation. The objective of this research was to develop and evaluate improved, real-time flux chamber designs that rapidly quantify N2O emissions from manure and soil. The first chamber system consisted of six square 0.95 m2 chamber pans. The chamber pans were mounted on a rail system to facilitate controlled indoor/outdoor laboratory research at a pilot scale. An aluminum lid was moved among the chamber pans. A second portable chamber system with a circular footprint (0.49 m internal dia.) was designed for use in field measurements. With both systems, N2O concentrations were measured each second with 0.1 ppb resolution by recirculating sample air through a real-time continuous N2O analyzer with return flow into the recirculating-flow-through (RFT-NSS) chamber. Performance and observational data are presented for different chamber vent designs, sealing mechanisms between the chamber pan and lid, recirculation pumps, and presence/absence of an internal fan that mixes headspace air within the sealed chamber. As examples of the repeatability and precision of the methodology, ten consecutive flux measurements were obtained using moist manure (32.6% wet basis water content, WCWB) within a 15 min period in which chamber pans were fitted with lids for 60 s and removed for 30 s. The mean calculated N2O flux was 43.08 ±0.89 mg N2O m-2 h-1. Using dry manure (WCWB = 10.8%), five consecutive flux measurements showed a very low, but consistent, flux that averaged 0.025 ±0.0016 mg N2O m-2 h-1. Five case study experiments demonstrate the usefulness of these chamber systems and highlight discoveries and lessons learned to enhance future research efforts. Major discoveries and observations include: (1) installation of a small internal fan within the chamber lids decreased N2O fluctuation over small time periods, allowing precise measurement of manure N2O fluxes as low as 0.0073 mg N2O m-2 h-1 during a 60 s measurement period; (2) two distinct N2O peaks were observed at 1 and 21 d following the addition of water to manure (initial WCWB = 32.6%), with the second peak accounting for 83% of the total N2O emitted over 45 d; and (3) there was notable diurnal variation in N2O fluxes due to temperature variation, even when the manure was dry (WCWB = 10.8%). These flux chamber systems proved to be more rapid, precise, and repeatable than traditional flux chamber methods and offer promise for future greenhouse gas emissions research on manure and soil. Keywords: Cattle, Chamber, Diurnal, Fan, Feedlot, Greenhouse gas, Manure, Precision.

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Nitrogen and organic matter losses during storage of cattle and pig manure

The Journal of Agricultural Science ◽

10.1017/s002185969700508x ◽

1998 ◽

Vol 130 (1) ◽

pp. 69-79 ◽

Cited By ~ 106

Author(s):

S. O. PETERSEN ◽

A.-M. LIND ◽

S. G. SOMMER

Keyword(s):

Nitrous Oxide ◽

Ammonia Volatilization ◽

Storage Period ◽

Cattle Manure ◽

Nitrous Oxide Emissions ◽

Pig Manure ◽

N Leaching ◽

Similar Amount ◽

Total N ◽

C And N

Solid pig manure (240 g kg1 DM) and solid cattle manure (150-180 g kg1 DM) were stored in an open storage facility during spring-summer and autumn conditions for periods of 9-14 weeks during 1994 and 1995. Concentrations of C, N, P and K were determined prior to and after storage, corrected for dry matter losses and distance from the surface. Temperature and, in experiments with pig manure, gas phase composition inside the manure heap were monitored during storage. Nitrogen losses as ammonia volatilization, nitrous oxide emission and leaching were measured, while total denitrification was estimated from mass balance calculations. For both cattle and pig manure there was little difference between seasons with respect to the pattern of decomposition, as reflected in temperature dynamics and C/N turnover. In contrast, there was a distinct difference between manure types. Pig manure was characterized by maximum temperatures of 60-70°C, although the concentrations of oxygen and methane clearly demonstrated that anaerobic conditions dominated the interior parts of the heap for several weeks. Losses of C and N from pig manure both amounted to c. 50%. In contrast, the temperature of cattle manure remained close to the air temperature throughout the storage period and cattle manure had lower, not significant losses of C and N. Leaching losses of N constituted 1-4% with both manure types. Ammonia volatilization from cattle manure constituted 4-5% of total N, and from pig manure 23-24%. In pig manure a similar amount of N (23-33%) could not be accounted for after storage, a loss that was attributed to denitrification. Nitrous oxide emissions amounted to <2% of estimated denitrification losses.

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Modeling Nitrous Oxide Emissions From Large-Scale Intensive Cropping Systems in the Southern Amazon

Frontiers in Sustainable Food Systems ◽

10.3389/fsufs.2021.701416 ◽

2021 ◽

Vol 5 ◽

Author(s):

Ciniro Costa ◽

Gillian L. Galford ◽

Michael T. Coe ◽

Marcia Macedo ◽

KathiJo Jankowski ◽

...

Keyword(s):

Nitrous Oxide ◽

Spatial Data ◽

Crop Production ◽

Large Scale ◽

Cropping Systems ◽

Field Measurements ◽

N Fertilization ◽

Nitrous Oxide Emissions ◽

Dndc Model ◽

Mato Grosso

Nitrogen (N) fertilizer use is rapidly intensifying on tropical croplands and has the potential to increase emissions of the greenhouse gas, nitrous oxide (N2O). Since about 2005 Mato Grosso (MT), Brazil has shifted from single-cropped soybeans to double-cropping soybeans with maize, and now produces 1.5% of the world's maize. This production shift required an increase in N fertilization, but the effects on N2O emissions are poorly known. We calibrated the process-oriented biogeochemical DeNitrification-DeComposition (DNDC) model to simulate N2O emissions and crop production from soybean and soybean-maize cropping systems in MT. After model validation with field measurements and adjustments for hydrological properties of tropical soils, regional simulations suggested N2O emissions from soybean-maize cropland increased almost fourfold during 2001–2010, from 1.1 ± 1.1 to 4.1 ± 3.2 Gg 1014 N-N2O. Model sensitivity tests showed that emissions were spatially and seasonably variable and especially sensitive to soil bulk density and carbon content. Meeting future demand for maize using current soybean area in MT might require either (a) intensifying 3.0 million ha of existing single soybean to soybean-maize or (b) increasing N fertilization to ~180 kg N ha−1 on existing 2.3 million ha of soybean-maize area. The latter strategy would release ~35% more N2O than the first. Our modifications of the DNDC model will improve estimates of N2O emissions from agricultural production in MT and other tropical areas, but narrowing model uncertainty will depend on more detailed field measurements and spatial data on soil and cropping management.

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Nitrogen removal and nitrous oxide emissions in woodchips biofilters treating agricultural drainage waters

10.5194/egusphere-egu2020-3318 ◽

2020 ◽

Author(s):

Joachim Audet ◽

Dominik Zak ◽

Carl Christian Hoffmann

Keyword(s):

Gas Chromatography ◽

Nitrous Oxide ◽

Nitrogen Removal ◽

Drainage Water ◽

Agricultural Landscapes ◽

Nitrous Oxide Emissions ◽

Temperate Climate ◽

Closed Chamber ◽

Total N ◽

N Removal

Eutrophication of aquatic ecosystems provoked by excess nitrogen (N) concentration is still a major concern worldwide with severe consequences such as hypoxia, biodiversity loss, and degradation of drinking water quality. To face these challenges, a novel N mitigation measure has emerged in the last decades consisting of biofilters made of woodchips. Drainage water from agricultural areas infiltrate through a layer of woodchips before it discharges to an aquatic recipient such as a ditch or a stream. The goal with this technique is to provide optimal conditions for denitrification i.e. an easy degradable carbon source (the woodchips) and an anaerobic environment. There is, however, some concerns regarding the emissions of the greenhouse gas nitrous oxide (N2O) which can be a by-product of denitrification.Here, we present results on N removal and N2O emissions from 9 biofilters differing in age (1&#8211;8 years) and representing a total of 18 years of monitoring. The biofilters were all located in agricultural catchments in Denmark (temperate climate conditions). Nitrogen removal in the biofilters was estimated using a mass balance approach measuring N species dissolved in the water (total N, nitrate, nitrite, ammonium) using time proportional automated samplers placed at inlet and outlet of the biofilters. Nitrous oxide emissions were measured every third week both as gaseous form at the surface of the biofilters (closed chamber technique and gas chromatography) and in dissolved form in the water phase at inlet and outlet of the biofilters (headspace technique and gas chromatography). We take advantage of this unique dataset to identify the factors enabling to maximize N removal while minimizing N2O emissions. Furthermore, we make a first assessment of the potential impact of the increasing number of biofilters on N2O emissions in agricultural landscapes.

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Influence of variable biochar concentration on yield-scaled nitrous oxide emissions, Wheat yield and nitrogen use efficiency

Scientific Reports ◽

10.1038/s41598-021-96309-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Khadim Dawar ◽

Saif-ur-Rahman ◽

Shah Fahad ◽

Syed Sartaj Alam ◽

Shah Alam Khan ◽

...

Keyword(s):

Nitrous Oxide ◽

N Uptake ◽

Wheat Yield ◽

Nitrous Oxide Emissions ◽

Total N ◽

Urea Treatment ◽

Amended Soils ◽

Use Efficiency ◽

The Impact ◽

Semi Arid

AbstractAn important source of the destructive greenhouse gas, nitrous oxide (N2O) comes from the use of ammonium based nitrogen (N) fertilizers that release N2O in the incomplete conversion (nitrification) of NH4+ to NO3ˉ1. Biochar has been shown to decrease nitrification rates and N2O emission. However, there is little information from semi-arid environments such as in Pakistan where conditions favor N2O emissions. Therefore, the object was to conduct field experiment to determine the impact of biochar rates in the presence or absence of urea amended soils on yield-scaled N2O emissions, and wheat yield and N use efficiency (NUE). The experiment on wheat (Triticum aestivum L.), had a randomized complete block design with four replications and the treatments: control, sole urea (150 kg N ha−1), 5 Mg biochar ha−1 (B5), 10 Mg biochar ha−1 (B10), urea + B5 or urea + B10. In urea amended soils with B5 or B10 treatments, biochar reduced total N2O emissions by 27 and 35%, respectively, over the sole urea treatment. Urea + B5 or + B10 treatments had 34 and 46% lower levels, respectively, of yield scaled N2O over the sole urea treatment. The B5 and B10 treatments had 24–38%, 9–13%, 12–27% and 35–43%, respectively greater wheat above-ground biomass, grain yield, total N uptake, and NUE, over sole urea. The biochar treatments increased the retention of NH4+ which likely was an important mechanism for reducing N2O by limiting nitrification. These results indicate that amending soils with biochar has potential to mitigate N2O emissions in a semi-arid and at the same time increase wheat productivity.

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Nitrous oxide emissions and maize yield as influenced by nitrogen fertilization and tillage operations in upland soil

Applied Biological Chemistry ◽

10.1186/s13765-021-00593-7 ◽

2021 ◽

Vol 64 (1) ◽

Author(s):

Sung Un Kim ◽

Hyun Ho Lee ◽

Sung Min Moon ◽

Hae Ri Han ◽

Chang Oh Hong

Keyword(s):

Nitrous Oxide ◽

Grain Yield ◽

Crop Yield ◽

N Fertilization ◽

Nitrous Oxide Emissions ◽

No Tillage ◽

Upland Soil ◽

Tillage Operation ◽

The Mean ◽

Tillage Operations

AbstractPrevious studies simply focused on determining nitrous oxide (N2O) emissions from the soil under different tillage operations and nitrogen (N) fertilizations without considering crop yield. Therefore, the objective of this study was to determine the effects of different tillage operations and N fertilizations on N2O emissions and crop yield from upland soil. Two different tillage operations [conventional tillage (CT) and no-tillage (NT)] and N fertilizations [without urea (WOU) and with 186 kg N ha−1 of urea (WU)] were established in a randomized block design with three replications on upland soil. Maize (Zea mays) was cultivated from 6th July to 4th October, 2018 (year 1), and from 15th April to 26th July, 2019 (year 2). The daily N2O flux did not peak soon after tillage operation and N fertilization, but it was more related to the change in water-filled pore space (WFPS). The mean value of WFPS across N fertilizations and seasons (years) was higher in CT than in NT. The changes of nitrification and denitrification rates could be attributed to the differences in WFPS between CT and NT. Nitrification was the predominant process producing N2O with CT, but denitrification was with NT. The application of urea increased cumulative N2O emissions, while CT also increased it compared with NT. The order of the mean values of cumulative N2O emissions across seasons from the highest to the lowest was as follows: CT + WU (7.12 kg N2O ha−1 year−1) > NT + WU (5.69 kg N2O ha−1 year−1) ≥ CT + WOU (5.02 kg N2O ha−1 year−1) > NT + WOU (4.24 kg N2O ha−1 year−1). Tillage operation did not affect the grain yield of maize or yield-scaled N2O emissions (YSNE). However, the application of urea increased the grain yield of maize and decreased YSNE, implying it could reduce N2O emission per unit of maize grain production. No-tillage management did not decrease YSNE value compared to CT operation, but N fertilization significantly decreased YSNE in the current study.

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Impacts of green manure on crop yield, nitrogen leaching and nitrous oxide emissions in sandy and clay soil lysimeters

Agricultural and Food Science ◽

10.23986/afsci.99202 ◽

2021 ◽

Vol 30 (2) ◽

Author(s):

Kristiina Regina ◽

Hannu Känkänen ◽

Pooja Singh

Keyword(s):

Nitrous Oxide ◽

Crop Yield ◽

Spring Wheat ◽

Green Manure ◽

Mineral Fertilizer ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

Total N ◽

Residual N ◽

Soil Lysimeters

We compared wheat yield, losses of nitrogen (N) in leaching, and gaseous losses as nitrous oxide (N2O) in silt and sand soil lysimeters. The studied cultivation systems were based on mineral fertilizer or mineral fertilizer together with clover green manure mulched at three different time points (August, October or May) before sowing of the main crop (either winter or spring wheat). Replacing 50–60% of mineral fertilizer N with green manure from a mixture of three clover species did not compromise the crop yield of winter or spring wheat. The results suggest that mulching of the green manure in the spring succeeding its sowing is the most beneficial practice with respect to environmental impacts. Total N leaching was higher from sandy soil than from silt loam whereas emissions of N2O were higher from the silt soil. Residual N from the clover biomass did not lead to an increase in leaching losses of N during the growing season or one year from the harvest. However, the residual N can be a source of high N2O emissions during the winter period in boreal climatic conditions.

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Fertilization of Two Container-grown Woody Ornamentals Based on Their Specific Nitrogen Accumulation Patterns

HortScience ◽

10.21273/hortsci.40.2.451 ◽

2005 ◽

Vol 40 (2) ◽

pp. 451-456 ◽

Cited By ~ 1

Author(s):

David R. Sandrock ◽

Anita N. Azarenko ◽

Timothy L. Righetti

Keyword(s):

Growth Rate ◽

N Uptake ◽

N Fertilization ◽

Silica Sand ◽

Production Cycle ◽

Nitrogen Accumulation ◽

N Accumulation ◽

Total N ◽

Slow Growth Rate ◽

Sliding Scale

Nitrogen accumulation patterns were established for Weigela florida (Bunge.) A. DC. `Red Prince' (fast growth rate) and Euonymus alatus (Thunb.) Sieb. `Compactus' (slow growth rate). From these, daily and biweekly N delivery schedules were designed to match N supply with N accumulation patterns of each taxon. Delivery schedules were sliding scales in that total N applied was controlled by independent increases (or decreases) of N concentration and solution volume. Daily and biweekly N delivery schedules were tested against a constant N rate (200 mg·L-1) and Osmocote 18N-2.6P-9.9K (The Scotts Co., Marysville, Ohio). Plants were grown in 3.8-L containers in 7 douglas fir bark: 2 sphagnum peatmoss: 1 silica sand (0.65 mm; by volume) outdoors in full sun on a gravel pad for 142 d. Within each taxon, Weigela and Euonymus grown with sliding-scale N fertilization schedules had similar total dry weights, leaf areas, and total plant N contents to plants grown with a constant N rate (200 mg·L-1) or Osmocote 18N-2.6P-9.9K. Sliding-scale liquid fertilization based on plant N requirements introduced less total N to the production cycle and resulted in higher N uptake efficiency than fertilization with a constant N rate of 200 mg·L-1. In general, liquid N fertilizer treatments resulted in plants with higher shoot to root ratios than plants treated with Osmocote 18N-2.6P-9.9K. Weigela and Euonymus treated with biweekly schedules were similar to plants treated with daily schedules (same total amount of N delivered with each treatment).

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