Gaseous Nitrogen Emissions Research Articles

Effects of ammonium-based nitrogen addition on soil nitrification and nitrogen gas emissions depend on fertilizer-induced changes in pH in a tea plantation soil

Tea (Camellia sinensis L.) plants have an optimal pH range of 4.5–6.0, and prefer ammonium (NH4+) over nitrate (NO3−); strong soil acidification and nitrification are thus detrimental to their growth. Application of NH4+-based fertilizers can enhance nitrification and produce H+ that can inhibit nitrification. However, how soil acidification and nitrification are interactively affected by different NH4+-based fertilizers in tea plantations remains unclear. The objective of this research was to evaluate the effect of the application of different forms and rates of NH4+-based fertilizers on pH, net nitrification rates, and N2O and NO emissions in an acidic tea plantation soil. We conducted a 35-day aerobic incubation experiment using ammonium sulphate, urea and ammonium bicarbonate applied at 0, 100 or 200 mg N kg−1 soil. Urea and ammonium bicarbonate significantly increased both soil pH and net nitrification rates, while ammonium sulphate did not affect soil pH but reduced net nitrification rates mainly due to the acidic nature of the fertilizer. We found that the effect of different NH4+-based nitrogen on soil nitrification depended on the impact of the fertilizers on soil pH, and nitrification played an important role in NO emissions, but not in N2O emissions. Overall, urea and ammonium bicarbonate application decoupled crop N preference and the form of N available in spite of increasing soil pH. We thus recommend the co-application of urease and nitrification inhibitors when urea is used as a fertilizer and nitrification inhibitors when ammonium bicarbonate is used as a fertilizer in tea plantations.

Carbon dioxide and gaseous nitrogen emissions from biochar‐amended soils under wastewater irrigated urban vegetable production of Burkina Faso and Ghana

AbstractTo quantify carbon (C) and nitrogen (N) losses in soils of West African urban and peri‐urban agriculture (UPA) we measured fluxes of CO2‐C, N2O‐N, and NH3‐N from irrigated fields in Ouagadougou, Burkina Faso, and Tamale, Ghana, under different fertilization and (waste‐)water regimes. Compared with the unamended control, application of fertilizers increased average cumulative CO2‐C emissions during eight cropping cycles in Ouagadougou by 103% and during seven cropping cycles in Tamale by 42%. Calculated total emissions measured across all cropping cycles reached 14 t C ha−1 in Ouagadougou, accounting for 73% of the C applied as organic fertilizer over a period of two years at this site, and 9 t C ha−1 in Tamale. Compared with unamended control plots, fertilizer application increased N2O‐N emissions in Ouagadougou during different cropping cycles, ranging from 37 to 360%, while average NH3‐N losses increased by 670%. Fertilizer application had no significant effects on N2O‐N losses in Tamale. While wastewater irrigation did not significantly enhance CO2‐C emissions in Ouagadougou, average CO2‐C emissions in Tamale were 71% (1.6 t C ha−1) higher on wastewater plots compared with those of the control (0.9 t C ha−1). However, no significant effects of wastewater on N2O‐N and NH3‐N emissions were observed at either location. Although biochar did not affect N2O‐N and NH3‐N losses, the addition of biochar could contribute to reducing CO2‐C emissions from urban garden soils. When related to crop production, CO2‐C emissions were higher on control than on fertilized plots, but this was not the case for absolute CO2‐C emissions.

Spatial Variation of Reactive Nitrogen Emissions From China's Croplands Codetermined by Regional Urbanization and Its Feedback to Global Climate Change

AbstractReactive gaseous nitrogen (Ngr) emissions significantly affect Earth's climate system. Disagreement exists, however, over Ngr contributions to short‐ versus long‐term climate forcing, from local to global scales and among different gaseous forms, including NH3, NOx, and N2O. Here, we provide a comprehensive inventory of Ngr from China's croplands based on a new bottom‐up, mass flow‐based approach integrated with fine‐resolution agricultural activity data and nitrogen emission factors. We demonstrate that China's croplands emit about 8.87 Tg N to the atmosphere in 2014. Across different prefectures, Ngr emission per capita conforms to a “Kuznets curve,” that is, first increases then decreases, along the gradient of increasing urbanization. Ngr emission per gross domestic productivity (GDP) decreases exponentially with increasing urbanization or per capita GDP. Furthermore, climate change impact analyses suggest that the global‐scale warming effect of China's cropland N2O emissions dominate over local cooling effects ascribed to its NH3 and NOx emissions.

The effects of biochar and nitrification inhibitors on reactive nitrogen gas (N2O, NO and NH3) emissions in intensive vegetable fields in southeastern China

ABSTRACT Application of biochar and nitrification inhibitors (NIs) to soil has been suggested as a strategy for mitigating climate change and promoting nitrogen use efficiency. However, few studies have focused on how N2O, NO and NH3 emissions and vegetable yield are affected by simultaneous biochar and NI application in vegetable fields. This study aims to investigate the effects of biochar and 3,4-dimethylpyrazole phosphate (DMPP, one type of NIs) amendment on reactive nitrogen gas emissions (GNrEs), vegetable yield, and reactive gaseous N intensity (GNrI) in an intensive vegetable field. There were three treatments: U: urea, UB: urea combined with biochar, UDMPP: urea combined with DMPP. The results show that biochar amendment increased NH3 volatilization by 92.8% (p < 0.05) compared to that under the U treatment. DMPP application abated significantly NO and GNrEs by 49.9% and 21.4%, respectively, compared to those of the U treatment. No significant differences were observed in GNrI among all three treatments; however, DMPP addition had more potential to reduce GNrI than biochar application, based on their results compared to those of the U treatment. Our findings suggest that DMPP application is a suitable practice to reduce GNrEs and maintain yields in intensive vegetable fields.

Differences in labile soil organic matter explain potential denitrification and denitrifying communities in a long-term fertilization experiment

Content and quality of organic matter (OM) may strongly affect the denitrification potential of soils. In particular, the impact of soil OM fractions of differing bioavailability (soluble, particulate, and mineral-associated OM) on denitrification remains unresolved. We determined the potential N2O and N2 as well as CO2 production for samples of a Haplic Chernozem from six treatment plots (control, mineral N and NP, farmyard manure - FYM, and FYM + mineral N or NP) of the Static Fertilization Experiment Bad Lauchstädt (Germany) as related to OM properties and denitrifier gene abundances. Soil OM was analyzed for bulk chemical composition (13C-CPMAS NMR spectroscopy) as well as water-extractable, particulate, and mineral-associated fractions. Soils receiving FYM had more total OM and larger portions of labile fractions such as particulate and water-extractable OM. Incubations were run under anoxic conditions without nitrate limitation for seven days at 25 °C in the dark to determine the denitrification potential (N2O and N2) using the acetylene inhibition technique. Abundances of nirS, nirK, and nosZ (I + II) genes were analyzed before and after incubation. The denitrification potential, defined as the combined amount of N released as N2O + N2 over the experimental period, was larger for plots receiving FYM (25.9–27.2 mg N kg−1) than pure mineral fertilization (17.1–19.2 mg N kg−1) or no fertilization (12.6 mg N kg−1). The CO2 and N2O production were well related and up to three-fold larger for FYM-receiving soils than under pure mineral fertilization. The N2 production differed significantly only between all manured and non-manured soils. Nitrogenous gas emissions related most closely to water-extractable organic carbon (WEOC), which again related well to free particulate OM. The larger contribution of N2 production in soils without FYM application, and thus, with less readily decomposable OM, coincided with decreasing abundances of nirS genes (NO2− reductase) and increasing abundances of genes indicating complete denitrifying organisms (nosZ I) during anoxic conditions. Limited OM sources, thus, favored a microbial community more efficient in resource use. This study suggests that WEOC, representing readily bioavailable OM, is a straightforward indicator of the denitrification potential of soils.

Eye on China

The following topics are under this section: Could Jurassic Park become a Reality? Brightening the Future with Liquid Sunshine New Gene Therapy for Huntington’s Disease Proves Successful in Mice Fight or Flight? Distinguishing between Two Species of Red Pandas Freeze-drying Soil for Studying Reactive Nitrogen Gas Emissions Remodelling the Future of Air Pollution Studies

Effects of pyrolysis conditions on migration and distribution of biochar nitrogen in the soil-plant-atmosphere system

The use of biochar to amend soil has been gaining increasing attention in recent years. In this study, the 15N tracer technique was used together with elemental analysis-stable isotope ratio analysis and gas isotope mass spectrometry to characterise biochar, soil, plant, and gas samples in order to explore the nitrogen transport mechanisms in the biochar-soil-plant-atmosphere system during the process of returning biochar to the soil (RBS). The results showed that the nitrogen retention rate of biochar was negatively correlated with the pyrolysis temperature during the preparation process, but was less affected by the pyrolysis atmosphere. In the RBS process, the migration of biochar nitrogen to plants was significantly greater than that of straw nitrogen, and it showed an overall decreasing trend with the increase in pyrolysis temperature, but was less influenced by the pyrolysis atmosphere. At temperatures of 300–500 °C, the pyrolysis atmosphere had a slightly smaller effect on the migration of biochar nitrogen to the air, plant, and soil system, and the pyrolysis temperature was much more important. However, the activation with CO2 gas at a higher temperature (600 °C) significantly enhanced the pore structure of biochar, particularly the structure of small pores; therefore, biochar prepared under a CO2 atmosphere at 600 °C reduces gaseous nitrogen emissions better than that under a N2 atmosphere. In the future, more pyrolysis conditions should be examined and their optimal combination should be further explored to reduce gaseous nitrogen emissions.

Comparisons of the effects of different drying methods on soil nitrogen fractions: Insights into emissions of reactive nitrogen gases (HONO and NO)

Reactive nitrogen (Nr) emission from soils, e.g., nitrous acid (HONO) and nitric oxide (NO), is a key process of the global nitrogen (N) cycle and has significant implications for atmospheric chemi...

Use of urease and nitrification inhibitors to reduce gaseous nitrogen emissions from fertilizers containing ammonium nitrate and urea

Nitrogen (N) fertilizers increase agricultural yields, but also lead to the release of the greenhouse gases nitrous oxide (N2O) and ammonia (NH3). This not only reduces the efficiency of N use, but also results in climate change and loss of biodiversity. The use of nitrification inhibitors may improve the efficiency of N use and reduce the emission of greenhouse gases. We tested three inhibitors (NZONE MAX, Piadin and N-(n-butyl) thiophosphoric triamide (NBPT)) added to two common N fertilizers (urea and urea ammonium nitrate (UAN)) and determined emissions of CO2, N2O and NH3 to evaluate the effectiveness of these three inhibitors and to improve our understanding of the soil nitrogen cycle. NBPT effectively reduced NH3 volatilization by 50% (from 3.0 g NH3-N m−2 in urea alone to 1.4 g NH3-N m−2 in urea + NBPT). Piadin decreased N2O emissions (from 0.98 g N2O-N m−2 in urea alone to 0.15 g N2O-N m−2 in urea + Piadin and from 0.81 g N2O-N m−2 in UAN alone to 0.39 g N2O-N m−2 in UAN + Piadin) by inhibiting the conversion of NH4+ to NO3−. However, although Piadin was found to be an effective nitrification inhibitor, the risk of higher NH3 emissions (from 3.0 g NH3-N m−2 in urea alone to 4.5 g NH3-N m−2 in urea + Piadin) with the addition of Piadin cannot be neglected in environmental and economical evaluations.

Simultaneous quantification of N2 , NH3 and N2 O emissions from a flooded paddy field under different N fertilization regimes.

Gaseous nitrogen (N) emissions, especially emissions of dinitrogen (N2 ) and ammonia (NH3 ), have long been considered as the major pathways of N loss from flooded rice paddies. However, no studies have simultaneously evaluated the overall response of gaseous N losses to improved N fertilization practices due to the difficulties to directly measure N2 emissions from paddy soils. We simultaneously quantified emissions of N2 (using membrane inlet mass spectrometry), NH3 and nitrous oxide (N2 O) from a flooded paddy field in southern China over an entire rice-growing season. Our field experiment included three treatments: a control treatment (no N addition) and two N fertilizer (220kgN/ha) application methods, the traditional surface application of N fertilizer and the incorporation of N fertilizer into the soil. Our results show that over the rice-growing season, the cumulative gaseous N losses from the surface application treatment accounted for 13.5% (N2 ), 19.1% (NH3 ), 0.2% (N2 O) and 32.8% (total gaseous N loss) of the applied N fertilizer. Compared with the surface application treatment, the incorporation of N fertilizer into the soil decreased the emissions of NH3 , N2 and N2 O by 14.2%, 13.3% and 42.5%, respectively. Overall, the incorporation of N fertilizer into the soil significantly reduced the total gaseous N loss by 13.8%, improved the fertilizer N use efficiency by 14.4%, increased the rice yield by 13.9% and reduced the gaseous N loss intensity (gaseous N loss/rice yield) by 24.3%. Our results indicate that the incorporation of N fertilizer into the soil is an effective agricultural management practice in ensuring food security and environmental sustainability in flooded paddy ecosystems.

The Future of Meat, episode 367, February 13, 2019, Freakonomics Podcast.

<i>The Future of Meat</i>, episode 367, February 13, 2019, Freakonomics Podcast.

Carbohydrate-rich supplements can improve nitrogen use efficiency and mitigate nitrogenous gas emissions from the excreta of dairy cows grazing temperate grass

Temperate pasture species constitute a source of protein for dairy cattle. On the other hand, from an environmental perspective, their high N content can increase N excretion and nitrogenous gas emissions by livestock. This work explores the effect of energy supplementation on N use efficiency (NUE) and nitrogenous gas emissions from the excreta of dairy cows grazing a pasture of oat and ryegrass. The study was divided into two experiments: an evaluation of NUE in grazing dairy cows, and an evaluation of N-NH3 and N-N2O volatilizations from dairy cow excreta. In the first experiment, 12 lactating Holstein × Jersey F1 cows were allocated to a double 3 × 3 Latin square (three experimental periods of 17 days each) and subjected to three treatments: cows without supplementation (WS), cows supplemented at 4.2 kg DM of corn silage (CS) per day, and cows supplemented at 3.6 kg DM of ground corn (GC) per day. In the second experiment, samples of excreta were collected from the cows distributed among the treatments. Aliquots of dung and urine of each treatment plus one blank (control – no excreta) were allotted to a randomized block design to evaluate N-NH3 and N-N2O volatilization. Measurements were performed until day 25 for N-NH3 and until day 94 for N-N2O. Dietary N content in the supplemented cows was reduced by 20% (P < 0.001) compared with WS cows, regardless of the supplement. Corn silage cows had lower N intake (P < 0.001) than WS and GC cows (366 v. 426 g/day, respectively). Ground corn supplementation allowed cows to partition more N towards milk protein compared with the average milk protein of WS cows or those supplemented with corn silage (117 v. 108 g/day, respectively; P < 0.01). Thus, even though they were in different forms, both supplements were able to increase (P < 0.01) NUE from 27% in WS cows to 32% in supplemented cows. Supplementation was also effective in reducing N excretion (761 v. 694 g/kg of Nintake; P < 0.001), N-NH3 emission (478 v. 374 g/kg of Nmilk; P < 0.01) and N-N2O emission (11 v. 8 g/kg of Nmilk; P < 0.001). Corn silage and ground corn can be strategically used as feed supplements to improve NUE, and they have the potential to mitigate N-NH3 and N-N2O emissions from the excreta of dairy cows grazing high-protein pastures.

Ammonia and Greenhouse Gas Emissions of Different Types of Livestock and Poultry Manure During Storage

HighlightsCarbon and nitrogen gas emissions from manure storage were influenced by manure characteristics.The main GHG contributor for dairy cattle, beef cattle, and broiler manure was methane.The main GHG contributor for laying hen manure was nitrous oxide (N2O).N2O emissions of the five types of manure were comparable with the IPCC recommended value.Abstract. Livestock manure management is an important source of greenhouse gases (GHGs) and ammonia (NH3) emissions from agriculture. Large amounts of manure are produced in China, while little research is available on the gas emission characteristics from different manure sources. The GHG and NH3 emissions from pig manure (PM), dairy cattle manure (DCM), beef cattle manure (BCM), layer manure (LM), and broiler manure (BM) during storage were monitored using the dynamic emission chamber method to compare the differences in gas emission characteristics among the five manure types and elucidate the key factors causing the differences. The results indicated that C and N gas emissions from manure storage were influenced by manure characteristics. The total CO2-eq (without CO2) emissions from PM, DCM, BCM, LM, BM were, respectively, 49.98 ±3.53, 1160.4 ±55.22, 692.16 ±42.98, 61.99 ±1.92, and 72.52 ±3.45 g per kg of dry basis manure during 77-day storage. The main GHG contributor for DCM, BCM, and BM was methane (CH4), accounting for 65% to 94%, and the main GHG contributor for LM was nitrous oxide (N2O). For PM, CH4 and N2O contributed equally to the total emissions. The N2O emissions of the five manure types were 0.002 to 0.013 kg N2O-N kg-1 N and were comparable with the IPCC recommended value. Keywords: Ammonia, Animal manure, Emission, Methane, Nitrous oxide.

GASES DE NITROGÊNIO REATIVO COMO PRECURSORES DO AEROSSOL ATMOSFÉRICO: REAÇÕES DE FORMAÇÃO, PROCESSOS DE CRESCIMENTO E IMPLICAÇÕES AMBIENTAIS

REACTIVE NITROGEN GASES AS PRECURSORS OF ATMOSPHERIC AEROSOL: FORMATION REACTIONS, GROWTH PROCESSES AND ENVIRONMENTAL IMPLICATIONS. The increased emissions of reactive nitrogen gases from anthropogenic sources to the atmosphere has been pointed out as responsible for triggering a series of environmental problems at the local, regional, and global scale. Among the many consequences associated with the excess of reactive nitrogen in the environment is the increase of atmospheric aerosol formation. In this way, the present review article aims to provide an overview of the main aerosol formation reactions from the reactive nitrogen gases, their growth processes, and removal from the atmosphere. The paper also addresses the implications of increasing the atmospheric aerosol load, including effects on the planet’s radiative forcing, cloud formation and precipitation, macronutrient dispersion, visibility and human health. The possible relationship between the long-term exposure to these pollutants and COVID-19 fatality is also discussed. The need for more information related to reactive nitrogen gases and atmospheric aerosols is urgent since they act on fundamental processes on planet Earth and their quantity and composition have been abruptly changed over the last hundred years. Therefore, further investigations on this topic should be stimulated and better integrated in order to guide normative decisions and the delineation of possible solutions.

Evaluating the ecotoxicity of nitrification inhibitors using terrestrial and aquatic test organisms

BackgroundThe increasing demand for food and animal fodder worldwide has led to an intensified agriculture with an increasing use of nitrogen fertilizers. More recently, nitrate leaching and gaseous nitrogen emissions have become the focus of environmental discussions and climate politics. One approach to reduce such negative impacts is the use of nitrification inhibitors (NIs) that have shown to effectively reduce nitrogen losses to the groundwater and the air. However, ecotoxic effects of NIs have been studied to a limited extent only. Therefore, two commercial NIs (Piadin and Vizura) and an active ingredient of another NI, dicyandiamide (DCD), were assayed using various ecotoxicological biotests and test species: the Lemna Growth Inhibition Test (Lemna gibba), the Seed Germination/Root Elongation Toxicity Test (Agrostemma githago, Fagopyrum esculentum, Glycine max, Hordeum vulgare, Lunaria annua, Zea mays), the Seedling Emergence and Seedling Growth Test (A. githago, F. esculentum, Z. mays) and the marine Luminescent Bacteria Test (Aliivibrio fischeri). The fresh water L. gibba and the bacterium A. fischeri were exposed to different test concentrations in liquid growth media, whereas the terrestrial plants were exposed to the test substances diluted/dissolved in deionized water and added to the solid growth medium.ResultsDicyandiamide did not show ecotoxic effects in any test conducted. Piadin and Vizura showed ecotoxic effects throughout all experiments. Frond number and frond area of L. gibba were inhibited with increasing concentrations of both substances with Piadin leading to an earlier inhibition and therefore lower EC50 values. In the Seed Germination Test, Vizura generally inhibited seed germination and root development more effectively than Piadin. Regarding both substances, the endpoint root length was much more sensitive than the endpoint germination. In the Seedling Emergence Test, Z. mays was the least sensitive and the rare weed species A. githago the most sensitive species with regard to the tested endpoints and both substances. A. fischeri was strongly inhibited by Vizura, whereas Piadin had barely effects on the bacteria.ConclusionAll findings indicate ecotoxic effects of Piadin and Vizura, especially on the aquatic species L. gibba and on the root development of several terrestrial plant species. However, the origins of the ecotoxic properties remain unclear as both substances contain a mixture of—to some extent unknown—chemical compounds.

Effects of Changes in Nitrogen Availability on Nitrogen Gas Emissions in a Tropical Forest During a Drought

AbstractAtmospheric nitrogen (N) deposition in tropical forests may increase substantially in coming decades, stimulating a concomitant increase of soil N gas emissions. At the same time, climate change may increase the prevalence of drought, altering the processes that produce these gases (dominantly aerobic nitrification and anaerobic denitrification). This alteration is of particular concern if global changes increase the fraction of N gas released as nitrous oxide (N2O; a greenhouse gas) relative to dinitrogen (N2). To simulate the effects of atmospheric N deposition on the amount and species of soil N gas emissions, we installed fertilized ion exchange resin bags across a hillslope in the Luquillo Experimental Forest of Puerto Rico. Our experiment took place during a severe drought, providing opportunities to consider how N addition and dry soil conditions interact. After 2 months of fertilization, we measured denitrification potential using a denitrification enzyme assay, which utilizes anoxic incubations where N and carbon limitation are relieved and nitrification is inhibited. We also measured N2 and N2O emissions using a Nitrogen Free Air Recirculation Method (NFARM), which quantifies emissions from both nitrification and denitrification. Data from these two methods suggest that N inputs stimulated N2O emissions associated with aerobic nitrification. Our data suggest that soil drying during the drought decreased N2 emissions associated with anaerobic denitrification and changed the spatial patterns of emissions in the landscape. Together these results suggest that, at least during a drought, N inputs increase N2O emissions associated with nitrification, which may represent a positive feedback to climate change.

Adding Phosphate Fertilizer and Apple Waste to Pig Manure during Composting Mitigates Nitrogen Gas Emissions and Improves Compost Quality

Calcium superphosphate and apple ( Mill.) waste can be used for controlling N loss and improving compost quality during composting, whereas integrated addition of the two additives on composting process remains unexplored. Therefore, this study was conducted to investigate the effects of combined use of calcium superphosphate and apple waste on NH and NO emissions and compost quality during pig manure and wheat ( L.) straw composting. Mixtures of pig manure and wheat straw were combined with 6% phosphate fertilizer (PF), 15% apple waste (AW), 3% phosphate fertilizer + 7.5% apple waste (PA1), or 1.8% phosphate fertilizer + 10.5% apple waste (PA2) based on dry weight of the initial mixtures; a treatment with no additives served as a control (CK). The PF treatment took 3 d longer to reach thermophilic phase than the CK, PA1, and PA2 treatments. The treatments of PF and PA1 reduced NH and NO emissions by 67 and 45%, respectively. Moreover, N loss in PF and PA1 treatments (31.8 and 30.1%, respectively) was significantly less than in the CK. A pot experiment showed that application of the compost with PA1 treatment could increase plant height and dried biomass of Chinese pakchoi ( L. ssp.). We recommend adding 3% phosphate fertilizer and 7.5% apple waste to pig manure during composting.

Winter-Season Gaseous Nitrogen Emissions in Subtropical Climate: Impacts of Pig Slurry Injection and Nitrification Inhibitor.

Controlling nitrogen (N) losses from pig slurry (PS) is a challenge under no-till because amendments are left on the soil surface. We investigated the potential of shallow injection of PS, with and without addition of the nitrification inhibitor dicyandiamide (DCD), to abate gaseous ammonia (NH) and nitrous oxide (NO) emissions in winter crops in subtropical soils. Injection was compared with surface broadcasting of PS, with and without DCD. The significance of winter season on annual NO emissions was assessed. Injecting PS reduced NH volatilization compared with surface application. However, this reduction was partly offset because NO emissions increased by 77% (+1.53 kg NO-N ha) when PS was injected. Adding DCD to injected PS reduced NO emission below levels of surface-broadcast PS without the inhibitor, indicating that DCD may be a management option when injecting PS. Compared with a reference urea treatment, PS without DCD increased cumulative NO emissions 5.7-fold (from 613 to 3515 g NO-N ha) when injected, and 3.2-fold (from 613 to 1980 g NO-N ha) when surface applied. Adding DCD significantly reduced emissions with injected PS, whereas reduction was not always significant with surface-applied PS. Nitrous oxide emissions during the winter cropping season contributed 30 to 44% of annual emissions, indicating that controlling gaseous N losses in that season is required to reduce the environmental footprint of the whole cropping system. Overall, combining PS injection with DCD was an efficient practice for reducing winter-season gaseous N losses from no-till soils under subtropical climate.

Soil Wet Spots Drive Agricultural Nitrogen Gas Emissions

A new study offers novel insights into the mechanisms driving gas releases in agricultural regions.

Wastewater nitrogen budgets can be resolved by complementary functional gene and physicochemical methods

A nitrogen budget for wastewater stabilisation ponds in tropical northern Australia indicated a deficit between influent and effluent Total Nitrogen of ≈46.5%. Stable nitrogen isotope ratios in pond waters and gas emission measurements showed that the deficit was a result of loss of mainly dinitrogen gas while emissions of nitrous oxide and ammonia were minor. We explored spatial and temporal patterns of nitrogen cycling across the pond system by analysing diversity and function of denitrification (nosZ) and Anammox (hzsA) genes known to be responsible for nitrogen gas emission. The relative gene abundance and activity supported the physicochemical evidence that the budgetary nitrogen deficit was largely due to dinitrogen gas emission. Contrary to expectation, most of the dinitrogen gas emissions appeared to occur after the first facultative pond despite nosZ genes being abundant and active. This suggests that other barriers to effective denitrification existed in the facultative pond. The dominant abundance and activity of hzsA genes in the final maturation pond indicated that dinitrogen gas emissions from this pond were likely associated with the Anammox process.