Characterization of a Technosol developed from deposited flue‐dust slurry and release of inorganic contaminants

A flue dust originaly enriched in metal sulfides evolved as a by‐product of Cu smelting. The dust was deposited as slurry in unsealed heaps. It is characterized by very high contents of toxic metals such as Pb and Zn. The slurry is a source of soil, sediment, and water contamination. We studied a Technosol profile developed from deposited flue‐dust slurry by means of chemical and mineralogical characterization (SEM‐EDX, XRD, FTIR, DTA‐MS, XRF, Pb isotopes), by open‐flow and closed‐flow column experiments on contaminant release under water‐saturated conditions, and by geochemical modeling to evaluate release processes and to quantify aqueous contaminant concentrations. Besides ash particles and quartz, the flue‐dust slurry contains Fe oxides, silicates, sulfates, and sulfides (in varying states of weathering). In both column approaches, metal concentrations exceed inspection values. The concentration patterns in both experimental column approaches indicate near‐equilibrium mineral dissolution. Geochemical modeling reveals partial dissolution of sulfates and precipitation of secondary carbonates. Their precipitation prevents complete sulfate dissolution, which would have led to even higher aqueous metal concentrations and contaminant export. The combination of detailed material characterization, column experiments, and modeling allows for quantitative and qualitative estimation of contaminant release into the soil solution.     

Reconstructing Past Rates of Atmospheric Dust Deposition in the Athabasca Bituminous Sands Region Using Peat Cores from Bogs

Open‐pit mining of the Athabasca Bituminous Sands generates considerable quantities of mineral dusts, but there is no published record of the amount of material deposited in the surrounding environment via the atmosphere since the industry began in 1967. Contemporary and past rates of atmospheric dust deposition were reconstructed using age‐dated peat cores (²¹⁰Pb and ¹⁴C) collected from five bogs in the vicinity of mines and upgraders and from two bogs far removed from industrial activities. The main objective of this study was to quantify the impact of industry on dust emissions, and to do this, the variation in natural “background” rates of mineral matter accumulation also had to be determined. A second objective was to characterize the size, mineralogical composition, and morphology of the particulate matter emitted to better understand potential environmental consequences of dust emissions. The concentrations of acid insoluble ash and Th (a surrogate for insoluble mineral matter) were determined to calculate dust accumulation rates. Scanning electron microscopy with energy‐dispersive X‐ray analysis failed to reveal much variation in mineralogical composition, but near industry, the size of the particles was more variable. The abundance of fly ash particles increased with depth, which suggests that emissions from upgrader stacks may have declined over time. A comparison of acid‐insoluble ash inventories with the pH of the porewaters suggests that the acid‐soluble ash fraction of the dusts deposited may have impacted the chemical composition of the bog waters. Copyright © 2017 John Wiley & Sons, Ltd.     

Rapid microbial stabilization of unconsolidated sediment against wind erosion and dust generation

Purpose  

Mineral dust pollution is a concern for human health due to the reaction of mineral particles in the organism and their role as pathogen carriers. Human activity generates unconsolidated sediments that become a dust source. This study investigates the effect of microbial growth on dust stabilization through aggregation in order to help alleviate this problem.     

Enhancing phosphorus availability,soil organic carbon,maize productivity and farm profitability through biochar and organic–inorganic fertilizers in an irrigated maize agroecosystem under semi‐arid climate

Biochar amendments offer promising potential to improve soil fertility, soil organic carbon (SOC) and crop yields; however, a limited research has explored these benefits of biochar in the arid and semi‐arid regions. This two‐year field study investigated the effects of Acacia tree biomass‐derived biochar, applied at 0 and 10 t ha^?1 rates with farmyard manure (FYM) or poultry manure (PM) and mineral phosphorus (P) fertilizer combinations (100 kg P ha^‐1), on maize (Zea mays L.) productivity, P use efficiency (PUE) and farm profitability. The application of biochar with organic–inorganic P fertilizers significantly increased soil P and SOC contents than the sole organic or inorganic P fertilizers. Addition of biochar and PM as 100% P source resulted in the highest soil P (104% increase over control) and SOC contents (203% higher than control). However, maize productivity and PUE were significantly higher under balanced P fertilizer (50% organic + 50% mineral fertilizer) with biochar and the increase was 110%, 94% and 170% than 100%‐FYM, 100%‐PM and 100% mineral fertilizer, respectively. Maize productivity and yield correlated significantly positively with soil P and SOC contents These positive effects were possibly due to the ability of biochar to improve soil properties, P availability from organic–inorganic fertilizers and SOC which resulted in higher PUE and maize productivity. Despite the significant positive relationship of PUE with net economic returns, biochar incorporation with PM and mineral fertilizer combination was economically profitable, whereas FYM along biochar was not profitable due to short duration of the field experiments.     

Short-Term Influence of Clinker Dust and Wood Ash on Macronutrients and Growth in Norway Spruce (Picea abies) and Scots Pine (Pinus sylvestris) Seedlings

The effects of clinker dust and wood ash on Norway spruce and Scots pine seedlings were compared in buried pots. Clinker dust (0.5 kg m^?2) and wood ash (0.5 kg m^?2) were applied to the surface of a nutrient-poor mineral soil. In the second year, the increase in soil pH by the dust and ash were larger than in the first year. Both alkaline treatments caused a large increase in the needle potassium (K) concentration. An excess of soil K relative to magnesium (Mg) was observed by decreased Mg concentration in needles shortly after treatment. However, Mg concentration in needles stayed in the sufficiency range. Current results confirmed earlier findings that despite a positive effect on base cation nutrition, wood ash has a low potential for increasing the biomass of forest stands on mineral soils due to the N limitation in these soils.     

An Indigenous Soil Bacterium Facilitates the Mitigation of Rocky Desertification in Carbonate Mining Areas

Carbonate minerals are extensively distributed across China, and their special rock structures make them vulnerable to land damage through mining, leading to rocky desertification. Soil microorganisms play an important role in mineral weathering. However, little is known about the utilization of the mineral‐weathering microorganisms to alleviate the problem of rocky desertification in mines. In the present study, the mineral‐solubilizing bacterium NL‐11 was isolated from soil around weathered dolostones and identified as Bacillus thuringiensis based on the Biolog identification system and 16S rDNA sequence analysis. The mineral dissolution experiments revealed that inoculation with the live bacterium significantly increased the mineral sample dissolution via significantly enhancing Ca and Mg release, with increase values of 303·27 and 50·55 mg L⁻¹ respectively, compared with that with the inactivated bacterium. Moreover, the acetic acid secreted by strain NL‐11 markedly decreased the size of particle diameter (quantified with a laser diffraction particle size analyser) through reducing pH value. The eroded traces were observed by scanning electron microscopy analysis, and the results further verified the erosional effects of this strain. In addition, this bacterium contributed to the establishment and proliferation of plants by providing nutrient elements, such as phosphorus (P) and potassium (K). Our study not only provided an efficient bacterial strain NL‐11 but also enriched the technologies to mitigate problems associated with ecological restorations of carbonate mines. Copyright © 2017 John Wiley & Sons, Ltd.     

FIELD OBSERVATIONS OF WINDBLOWN SAND AND DUST IN THE TAKIMAKAN DESERT,NW CHINA,AND INSIGHTS INTO MODERN DUST SOURCES

Despite the importance of desert dust at global and regional scales, its exact provenance is often unclear. The Taklimakan Desert in northwest China is a common source of high‐frequency regional dust storms and is also a large source of global dust production. On the basis of field observations and the determination of the fraction of aeolian dust in surface samples, we characterized the relative intensity of windblown sand/dust processes in the Taklimakan and the volume of dust emitted (PM₁₀) during these processes. Major dust sources were degraded lands on the eastern desert margin, the Gobi and alluvial, fluvial and aeolian sediments occurring on the desert margin. These areas have high PM₁₀ emission capacity due to high‐surface PM₁₀ concentrations and intensive windblown sand/dust activity. Despite having intensive windblown sand activity, the central desert had lower PM₁₀ dust emission capacity (<1·6 kg day⁻¹ m⁻² in spring, <0·08 kg day⁻¹ m⁻² in other seasons) due to lower surface PM₁₀ fraction. The dry Taitema Lake bed was a source of potentially high dust emissions (at least 4·4–17 kg day⁻¹ m⁻² for the monitoring period) due to the intensity windblown sand/dust activities, despite low PM₁₀ concentrations. The dry river beds on the southeastern desert margin had lower dust emission potential due to low PM₁₀ concentrations and windblown sand/dust activity. Most dust emission sources lie in the paths of prevailing winds, leading to aeolian dust transported to and deposited in the desert hinterland or Hotan, Yutian and Minfeng areas, where wind stream convergence leads to high‐frequency dust storms. Copyright © 2011 John Wiley & Sons, Ltd.     

Evolution, Sources and Distribution of Mineral Particles and Amorphous Phase of Atmospheric Aerosol in An Industrial and Mediterranean Coastal Area

The aim of this work is to propose a methodology that helps to learn about the distribution of different types of solid compounds in atmospheric aerosol, collected in an industrial area located in a Mediterranean basin that produces mineral raw materials. The work is developed from TSP samples collected daily in an open area near a ceramic production facility with a High Volume TSP sampler. The sampler permits the collection of sufficient daily quantities of particulate sample for subsequent X-ray diffraction characterisation and quantification. The results have shown that atmospheric aerosol in the area are dominated by particles coming from combustion processes, mainly vehicular traffic, and dust emissions originating when raw materials are transferred and treated. Combustion particles present a seasonal evolution. Mineral particles are mainly dependent upon weekly industrial activity and their contents suffer high increases during periods of atmospheric particle accumulation which are produced when certain meteorological conditions exist. Data have also shown an approximation of the particle distribution in aerosol from different source origins (vehicular traffic, dust emissions, secondary formation, marine aerosols). During days with intermediate pollution levels (which suppose 60% of the total) combustion particles compromise around 55 to 60% of the TSP while mineral particles coming from industrial dust emissions make up 20% of the TSP. In time intervals of atmospheric particulate accumulation these particle levels in the air can reach the legislated guideline values. During these episodes, mineral contents coming mainly from dust emissions compromise more than the 50% of the aerosol.     

基于铅稳定同位素的多金属复合污染土壤源解析新思路——以西南地区某矿区农田为例

本文以我国西南某矿区典型多金属复合污染农田土壤为例,基于铅(Pb)稳定同位素分析,结合矿物学分析,对土壤Pb来源进行定量解析,并针对其他重金属来源进行外推。同位素源解析结果表明,人为源对于土壤重金属的贡献率高达61%～89%,矿渣浸沥与矿区道路扬尘为主要的污染途径。矿物学分析能够辅助印证Pb稳定同位素分析结果,在一定程度上克服由于污染源信号重叠造成的源解析困难。通过相关分析,可以将Pb同位素源解析的结果合理外推,在一定程度上解释其他重金属元素的来源。本文提出的源解析新思路能够高效、准确地解析多金属复合污染土壤中重金属元素的来源,尤其适用于我国土壤多金属复合污染集中连片存在、成因复杂的现状,具有很强的现实意义。     

Effects of humus content,farmyard manuring,and mineral‐N fertilization on yields and soil properties in a long‐term trial

Investigations carried out at Field F3 of the Halle long‐term fertilization trials using data from 1974 to 1983 showed that with adequate supply of mineral N‐fertilizer soil organic matter (SOM) had no significant effects of yield. Similarly enhanced SOM did not justify a reduction of mineral N (Stumpe et al., 2000). The studies presented here examine the effects of the SOM differences existing after the termination of those trials in 1986 up until 1997 (then mainly differences of hardly decomposable SOM) in comparison to farmyard manuring with enhanced mineral N application (3‐factor‐experiment). As with total SOM, hardly decomposable SOM did not directly affect yields. The effects of FYM treatment observed at lower mineral‐N levels were compensated for by enhanced mineral‐N supply. The direct effect of FYM (40 t ha^—1) corresponded to a mineral‐N supply of about 60 kg ha^—1 and the residual effect to about 20 kg ha^—1. The differences of the C‐content in the soil at the beginning of the present studies continued throughout the experimental period of 12 years. In addition, significant differentiation has been caused by FYM and N fertilization in comparison to unfertilized treatments. The major finding is that differences in SOM content do not lead to yield differences on physically good soils (chernozem‐like soils) if appropriate compensation by mineral‐N fertilization takes place.     

The effect of biochar with biogas digestate or mineral fertilizer on fertility,aggregation and organic carbon content of a sandy soil: Results of a temperate field experiment

Substitution of mineral fertilizers with organic soil amendments is postulated to improve productivity‐relevant soil properties such as aggregation and organic matter (OM) content. However, there is a lack of studies analyzing the effects of biochar and biogas digestate versus mineral fertilizer on soil aggregation and OM dynamics under temperate field conditions. To address this research gap, a field experiment was sampled four years after establishment on a sandy Cambisol in Germany where mineral fertilizer or liquid biogas digestate was applied with or without 3 or 40 Mg biochar ha^?1 (produced at 650°C). Soil samples were analyzed for soil organic carbon (SOC) content, pH, cation exchange capacity, bulk density, water‐holding capacity, microbial biomass, aggregate size class distribution, and the SOC content associated with these size classes. 40 Mg biochar ha^?1 significantly increased SOC content in all fractions, especially free particulate OM and the 2–0.25 mm fraction. The yield of small macroaggregates (2–0.25 mm) was increased by biochar, but cation exchange capacity, water‐holding capacity, and pH were not consistently improved. Thus, high‐temperature biochar applied to a sandy soil under temperate conditions is primarily recommended to increase SOC content, which could contribute to climate change mitigation if this C remains sequestered over the long‐term. Fertilizer type did not significantly affect SOC content or other measured properties of the sandy Cambisol, suggesting that replacement of mineral fertilizer with digestate has a neutral effect on soil fertility. Co‐application of biochar with digestate provided no advantages for soil properties compared to co‐application with mineral fertilizer. Thus, independent utilization of these organic amendments is equally suitable.     

基于文献计量学分析泥沙来源研究进展与热点

明确流域或区域泥沙来源对水土保持措施科学布局有重要意义。为了更好地掌握泥沙来源研究的发展动态,研究借助文献计量方法与可视化工具——CiteSpace软件,对中国知网(CNKI)总库和Web of Science数据库迄今关于泥沙来源的所有文献进行收集分析,探寻当前该领域的研究热点,为未来的发展研究提供参考。对检索获取的6 000余篇中文和英文文献的分析发现,当前泥沙来源研究的主要对象包括淤地坝、小流域、河流与盆地。研究热点主题主要包括泥沙输移、泥沙形态和土壤侵蚀; 热点研究内容注重对环境效应、影响因素等进行综合研究; 热点研究手段是复合指纹识别技术。关键词突现图和时区图展现的前沿研究趋势显示,在重点研究区要重建流域泥沙来源历史的演变规律; 指纹识别法作为热点研究手段则亟需科学的试验设计来验证该方法的准确性; 将来的研究则侧重于形成类似“复合指纹系统工具”的工具,服务于流域管理、侵蚀泥沙产生的环境风险预测等方面。     

Global Model Simulations of the Transport of Asian and Sahara Dust: Total Deposition of Dust Mass in Japan

We simulated the global transport of dust emitted from all major dust source regions on earth by using a global three-dimensional chemical transport model for the year 2000. A modified dust emission flux scheme and an advanced nonlocal diffusion scheme for accurately determining the atmospheric eddy diffusivity in the atmospheric boundary layer were implemented to improve the chemical transport model. We specifically examined and analyzed dust storms that occurred in China and northern Africa. Four scenarios representing the global transport of dust from dust storms originating in the Loess region and the Gobi, Takla Makan, and Sahara deserts, respectively, were simulated. The results of each scenario were then compared with those resulting from all major dust source regions on earth, to identify which deserts have a major impact on dust transport and its deposition in Japan. The dust from the Sahara desert, most from the western part that was found in this study, reached Japan in 9–10 days, while Gobi and Loess region dust took 2 to 3 days, and 4 days for Takla Makan dust. The model-calculated monthly total deposition of dust mass from all major dust source regions was compared with comprehensive measurements of total deposition collected at sampling stations distributed over Japan, and good agreement was generally found. From these analyses, it was also indicated that dust emitted from other deserts, including the Turkestan, Iranian, and Arabian, could have a significant impact on dust deposition on Japan.     

Short‐term response of the Ca cycle of a montane forest in Ecuador to low experimental CaCl2 additions

The tropical montane forests of the E Andean cordillera in Ecuador receive episodic Sahara‐dust inputs particularly increasing Ca deposition. We added CaCl₂ to isolate the effect of Ca deposition by Sahara dust to tropical montane forest from the simultaneously occurring pH effect. We examined components of the Ca cycle at four control plots and four plots with added Ca (2 × 5 kg ha^–1 Ca annually as CaCl₂) in a random arrangement. Between August 2007 and December 2009 (four applications of Ca), we determined Ca concentrations and fluxes in litter leachate, mineral soil solution (0.15 and 0.30 m depths), throughfall, and fine litterfall and Al concentrations and speciation in soil solutions. After 1 y of Ca addition, we assessed fine‐root biomass, leaf area, and tree growth. Only < 3% of the applied Ca leached below the acid organic layer (pH 3.5–4.8). The added CaCl₂ did not change electrical conductivity in the root zone after 2 y. In the second year of fertilization, Ca retention in the canopy of the Ca treatment tended to decrease relative to the control. After 2 y, 21% of the applied Ca was recycled to soil with throughfall and litterfall. One year after the first Ca addition, fine‐root biomass had decreased significantly. Decreasing fine‐root biomass might be attributed to a direct or an indirect beneficial effect of Ca on the soil decomposer community. Because of almost complete association of Al with dissolved organic matter and high free Ca²⁺ : Al³⁺ activity ratios in solution of all plots, Al toxicity was unlikely. We conclude that the added Ca was retained in the system and had beneficial effects on some plants.     

Effects of growth regulators on mineral nutrition of tomato

This research deals with the effects of exogenous growth regulators on mineral nutrition of the tomato plant (Lyeopersieon esaulentum Mill. cv. Miguel Pereira). To study the influence on mineral nutrition, (2‐chloroethyl) trimethylammonium chloride (CCC) , at concentration of 2,000 ppm, succinic acid‐2, 2‐dimethylhydrazide (SADH) (4,000 ppm), gibberellic acid (GA) (100 ppm), (2‐chloroethyl) phosphonic acid (CEPA) (200 ppm), indole‐3‐acetic acid (IAA) (100 ppm) and 6‐furfurylamino purine (FAP) (500 ppm) were applied. Higher levels of nitrogen, calcium and magnesium occurred in the stem of plants sprayed with CCC. Treatments with FAP, SADH and CEPA caused an increase in nitrogen level in the stem. CEPA also increased calcium content in stems. These growth regulators did not alter the levels of macronutrients in the leaves in relation to control.     

Research on the Components of Dust Fall in Hohhot in Comparison with Surface Soil Components in Different Lands of Inner Mongolia Plateau

The dust fall in a region is closely related to upwind sources. Dust fall from sandstorms has a strong influence on industry, agriculture, and daily life. Hohhot, the capital of Inner Mongolia Autonomous Region, is downwind of the Inner Mongolia Plateau and experiences frequent sandstorms during the spring monsoon season. This study investigated the relationship between dust fall in the Hohhot area and surface soils on the Inner Mongolia Plateau. Samples of dust fall from Hohhot and surface soils from the plateau were analyzed for major and trace elements. The SiO₂ content of dust fall from sandstorms differs from that of the plateau soils by only 2.77%, indicating that the main dust fall source for Hohhot is surface soils from the plateau. Dust samples from coal smoke, roads, and buildings were used for comparison. The As content in dust fall from sandstorms is greater than that found in the plateau soils and in dust from non-sandstorm days. This indicates that As is added to the sand during transport from the plateau by coal factories near Hohhot. The second most important dust source is traffic, as evidenced by Pb contents. Preventing erosion of sand upwind of Hohhot during the spring monsoon is key to improving and managing air quality in the Hohhot region. This can be accomplished through management of the farm grassland areas.     

Studying the function of ecosystem in preventing aeolian dust emission in the dryland areas of China

Aeolian dust emissions can cause many environmental hazards, like accelerating land degradation and desertification, polluting air, harming human health, and so on. The dryland areas of China (DAC) are hot spots of aeolian dust emissions. To date, many efforts have been paid to researching dust emissions processes and effects, but research studies on ecosystems' function in preventing dust emissions are still very limited. In this study, we investigated the function of DAC ecosystems in preventing dust emissions, and the corresponding driving factors through integrated wind erosion modelling system (IWEMS) modelling. The main results indicate that: (1) from 2001 to 2020, the ecosystems of DAC prevented the emission of dust ~40,554 Tg, approximately 15 times as much as the total actual dust emission (~2776 Tg); (2) the function of DAC ecosystems in preventing dust emissions was relatively strong in spring and winter; (3) grassland ecosystems had the strongest function in preventing dust emissions among all the land cover types, avoiding the emission of dust ~20,857 Tg over 2001–2020; (4) dust emission prevention function provided by the DAC ecosystems benefits almost every region of China, which provides a theoretical basis for formulating ecological compensation policies; and (5) the changes in dust emissions were dominated by wind speed in most areas of DAC.     

果园生草对氮素表层累积及径流损失的影响

为了正确认识生草覆盖对果园面源污染的防控作用和推进生态果园建设,采用模拟试验的方法,研究了果园生草覆盖、生草刈割和清耕3种管理措施对氮素表层累积及其流失特性的影响。结果表明:鼠茅草大量腐解时期(9月)生草覆盖处理土壤表层(0—1cm)矿质氮含量分别是生草刈割和清耕处理的2.6倍和4.5倍,与此同时,果园生草覆盖处理径流液中矿质氮浓度相比刈割和清耕处理分别提高42.6%和20.9%;与清耕相比,生草覆盖使降雨地表径流量显著降低88.3%~98.7%,渗漏量增加42.1%~97.6%。综合3次降雨,生草覆盖使矿质氮的径流损失比清耕降低90%,并且增加深层(25cm)渗漏89.6%。综上可见,虽然果园生草覆盖增加快速降解时期矿质态氮表层累积数量,但减少径流水损失效果显著,进而明显减少氮素径流损失,提高果园土壤的保水保肥能力,对解决坡地果园面源污染问题意义重大。     

Evaluation of cement kiln flue dust as a potassium and sulfate fertilizer

Abstract

The main objective of this study was to determine the efficacy of cement kiln flue dust as a substitute for potassium sulfate fertilizer. Chemical and X‐ray diffraction analyses revealed that the flue dust contained about 20.7% K of which 9.1% was present as aphthitalite (K₃Na(SO₄)₂) , 4.4% as sylvite (KCl) and the remaining 7.2% as arcanite (K₂SO₄) . Accordingly, about 80% of the potassium in the dust was present as sulfates, though it contained 30% total sulfate and 15% Ca.

The effects of flue dust were compared to some or all of the following fertilizers: KCl, K₂SO₄ and a synthetic fertilizer, on 11 soils ranging in texture from sand to clay in three greenhouse experiments. The synthetic fertilizer was made from K₂SO₄ and CaSO₄.2H₂O which were applied at the same rate of K and Ca as contained in the flue dust. The experimental results show that flue dust is as effective a K source as any of the fertilizers tested as it increased potato, barley and alfalfa yields and tissue and soil K concentrations to the same level. Furthermore, the flue dust increased the tissue sulfur concentration and the quantities of available sulfate in soils to the same level as potassium sulfate. Finally, the Ca contained in flue dust increased the concentration of this element in potato tops and soils when grown on eight coarse textured soils. The flue dust had, however, no effect on soil pH on any of the soils tested.     

Primed N2O emission from native soil nitrogen: A 15N‐tracing laboratory experiment

Soils can naturally be a source of the potent greenhouse gas nitrous oxide (N₂O). By contrast, the largest anthropogenic source of N₂O is the application of nitrogen (N) fertilizer on agricultural soil, but it is unclear if fertilizer‐supported N₂O emission only originates from the fertilizer N directly or through additionally stimulated N₂O production from native soil N. Even though native soil N also includes mineral N already in soil before fertilizer application, organic N is the principal native N pool and thereby provides for mineral N cycling and N₂O emission. Here, we tested (1) the contribution of native soil N to N₂O emission after mineral N fertilizer application and (2) whether it is affected by different soil organic matter (SOM) contents by conducting a laboratory ¹⁵N‐tracing experiment with agricultural soil from a long‐term field trial with two treatments. Both field treatments are fertilized with mineral N, whereas only one of the two receives liquid manure causing higher SOM content. Soil sampling was conducted in March 2016 shortly before fertilizer application in the field. The application of ¹⁵N‐labeled fertilizer more than doubled the N₂O production from native N sources compared to the non‐fertilized control incubations. This primed N₂O production contributed by 5–8% to the fertilizer‐induced N₂O emission after one week of incubation and was similar for both field treatments regardless of liquid manure application. Therefore, further research is needed to link N₂O priming to its potential production pathways and sources. While the observed effect may be important in soils, the amount of applied N fertilizer remains the largest concern being responsible for the majority of N₂O emission.