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Article

Mitigating Ammonia Emissions from Liquid Manure Using a Commercially Available Additive Under Real-Scale Farm Conditions

by
Marcello Ermido Chiodini
1,2,*,
Michele Costantini
3,
Michele Zoli
3,
Daniele Aspesi
2,
Lorenzo Poggianella
4 and
Jacopo Bacenetti
3
1
Department of Agricultural and Environmental Sciences, University of Milan, Via Celoria 2, 20133 Milano, Italy
2
SOP Srl Società Benefit, Via Parco Alto Milanese, 1, Busto Arsizio, 21052 Varese, Italy
3
Department of Environmental Science and Policy, University of Milan, Via Celoria 2, 20133 Milano, Italy
4
Department of Land, Air and Water Resources, University of California, Davis, CA 95616, USA
*
Author to whom correspondence should be addressed.
Atmosphere 2025, 16(11), 1289; https://doi.org/10.3390/atmos16111289
Submission received: 7 October 2025 / Revised: 7 November 2025 / Accepted: 8 November 2025 / Published: 12 November 2025
(This article belongs to the Section Air Pollution Control)
Browse Figures
Versions Notes

Abstract

Ammonia (NH3) is a major anthropogenic pollutant originating from agricultural activity, particularly livestock operations. NH3 emissions from livestock slurry storage pose risks to environmental quality and human health. Reducing NH3 emissions aligns with several United Nations Sustainable Development Goals (SDGs), including SDG 3, SDG 12, SDG 14, and SDG 15. This study evaluates the performance of the commercially available SOP® LAGOON additive under real-scale farm conditions for mitigating NH3 emissions. Two adjacent slurry storage tanks of a dairy farm in Northern Italy were monitored from 27 May to 7 September: one treated with SOP® LAGOON and one left untreated (serving as a control). In the first month, the treated tank showed a 77% reduction in NH3 emissions. Emissions from the treated tank remained consistently lower than those from the control throughout the monitoring period, reaching an 87% reduction relative to the baseline levels by the end of the period. The results suggest that SOP® LAGOON is an effective and scalable strategy for reducing NH3 emissions from liquid manure storage, with practical implications for farmers and policy makers in regard to designing sustainable manure management practices.

1. Introduction

Ammonia (NH3) is a reduced nitrogen compound that, when emitted into the atmosphere [1], functions as a major anthropogenic pollutant with extensive environmental impacts, including degradation of soil health, water quality, air composition, ecosystems, and biodiversity [2].
Once released, atmospheric NH3 rapidly reacts with acidic species, such as sulfuric acid (H2SO4) from SOx, nitric acid (HNO3) from NOx, and hydrochloric acid (HCl), to form secondary inorganic aerosols (SIAs), including ammonium sulfate ((NH4)2SO4), ammonium nitrate (NH4NO3), and ammonium chloride (NH4Cl) [3,4]. These SIAs are key constituents of fine particulate matter (PM2.5), which is implicated in respiratory illnesses, acid deposition, eutrophication, and ecosystem disruption [5,6]. Studies have revealed that SIAs can constitute up to ~70% of the mass of PM2.5, consequently posing a threat to human health [7,8,9,10,11,12,13,14,15], with NH3 emissions driving much of this formation [16]. Exposure to PM2.5 contributes to an estimated 3.3 million premature deaths globally. In Europe, PM2.5 concentrations above World Health Organization (WHO) guidelines are associated with about 238,000 deaths annually [17]. In the U.S., the toll is approximately 12,000 deaths per year, with an estimated societal cost of USD 160 billion [18]. Agriculture-generated NH3 accounts for roughly 30% of PM2.5 in the U.S. and the Ganges Basin of India, about 50% in Europe, and between 15% and 23% in China [9,16,19,20,21].
Agricultural activities are the predominant source of NH3 emissions worldwide, accounting for approximately 81% globally and 93% in Europe [22,23,24]. Within this sector, slurry management is a major contributor, being responsible for up to 60% of emissions [2,21,25,26,27,28].
Moreover, NH3 is widely recognized as one of the primary odorants emitted from livestock manure storage, and its concentration in ambient air is positively correlated with odor intensity and community complaints [9,17,27].
Given its potential environmental and social impacts, ammonia has become a key target of international and national air quality policies. In Europe, common and national policies encourage the adoption of different strategies to mitigate NH3 emissions. In the European Union, the National Emission Ceilings Directive (EU) 2016/2284 [29] and the Industrial Emissions Directive (2010/75/EU) [30]—as recently amended by Directive (EU) 2024/1785 [31] to include large-scale livestock operations—provide the overarching regulatory context for emission reduction and the best available techniques. In Italy, these principles are implemented through Legislative Decree 152/2006 [32] and corresponding regional regulations, which establish emission control requirements for large livestock operations, typically above 500 Livestock Units.
Similar approaches are promoted in the United States through the EPA’s Air Emissions Framework for Animal Feeding Operations (EPA, 2005) [33] and the USDA NRCS Conservation Practice Standard Code 359 (Waste Treatment Lagoon) [34], the latter of which includes recommendations on design and management practices aimed at reducing NH3 losses from manure storage systems [29,30,32,33,34,35].
On farms, slurry must be stored before its application to fields to allow its evolution into a form more suitable for crop nutrient uptake. Slurry is typically transferred from livestock housing to outdoor storage facilities, such as aboveground or underground tanks and earthen lagoons. At the interface between the surface of manure and open air, volatilization from the surface area leads to NH3 emissions expressed as mass per surface area and time [2]. Recent field research [36] investigated ammonia concentrations and dry deposition around dairy farms, revealing that NH3 concentrations and deposition fluxes decline exponentially with an increase in the distance from the source [36,37]. This demonstrates that ammonia dispersion near liquid manure storage facilities is highly localized and strongly influenced by patterns and the size and layout of farms [36].
Furthermore, geographic and climatic factors markedly influence emission dynamics. Higher air temperatures greatly increase volatilization rates: emissions peak in summer and drop sharply during winter, even to near-zero when slurry surfaces freeze. On the other hand, wind speed exerts weaker but variable effects depending on surface turbulence and manure characteristics [37].
Minimizing NH3 loss also preserves the fertilizer value of the slurries and can increase crop yields [38] while reducing the environmental footprint of slurry management.
Among the mitigation strategies available, slurry coverage using different plastic and organic materials (e.g., straw), natural crust formation, and slurry acidification have been extensively studied. However, all these approaches present significant limitations in terms of potential undesired side effects, safety concerns, or high adoption costs. In light of these challenges, some local authorities (e.g., in Piedmont, Italy) have started to reduce the pressure on farmers to adopt impermeable covers as the sole compliance option [39]. This trend is consistent with the European regulatory framework, which—since Directive 2010/75/EU on industrial emissions [30], which was further reinforced by Directive (EU) 2024/1785 [31]—explicitly allows Member States to consider emerging technologies as valid alternatives to the established Best Available Techniques (BATs).
While slurry additives are receiving an increasing amount of attention, their versatility, efficacy, and cost-effectiveness have yet to be proven [40]. Moreover, the vast majority of the studies on these compounds have been conducted at the laboratory scale [2], thus providing only partial indications of their efficacy in real-scale applications.
Among additives, various forms of gypsum have demonstrated the ability to reduce the release of ammonia from cattle slurry. In a 660 L storage trial lasting 77 days, the authors of [41] found that gypsum reduced NH3 emissions by approximately 32% compared to an untreated control, a reduction attributed to its acidifying and mineral-stabilizing effects.
SOP LAGOON is a commercially available manure additive currently used by farmers in several countries. It is made of calcium sulfate dihydrate processed with SOP Inside proprietary technology. The processing technology, protected as a trade secret, is claimed to make the raw material more effective at lower dosages than traditionally applied and reported in the literature. Researchers [42,43] have tested other SOP Inside products, which, at minimal dosages, had significant effects on the target. Despite having the same chemical formula as gypsum, SOP LAGOON has already demonstrated [44,45,46] the ability to reduce NH3 and greenhouse gas (GHG) emissions at much lower dosages than reported for other types of gypsum in similar applications.
While a previous real-scale study [46] showed that SOP LAGOON reduced GHG emissions from slurry stored on a dairy farm, its ability to reduce NH3 emissions has been tested only at laboratory scale. In this study, we aimed to evaluate the performance of SOP LAGOON under real use conditions in reducing NH3 emissions in a full-scale slurry tank during the summer, when peak emissions are expected.

2. Materials and Methods

2.1. Site and Manure Management

In order to replicate the current, real-world operating conditions and guarantee that all the theses would be tested contemporarily, a multi variable study (i.e., involving comparing processed material with unprocessed raw material, multiple dosages, and comparison with other media) would require a farm with three slurry tanks of closely matched geometry, storage capacity, and filling/emptying schedules. At the time this study was conceived, securing a configuration with two parallel tanks had already proven extremely difficult. The trial was therefore conducted in 2021 between May and September on a commercial dairy farm in the Po Valley, Northern Italy. The region’s climate falls under the Cfa classification in the Köppen system (humid continental to subtropical). The farm is representative of typical housing and management practices in concentrated animal-feeding operations (CAFOs) and housed approximately 520 cows, half of which were in lactation. The on-site manure-handling facility consisted of two separate, identical, adjacent concrete storage tanks that were rectangular, with 3.5 m tall walls, 1.5 m of which buried below the ground, into which slurry was pumped after being collected from the barns via scrapers.
To maintain comparable slurry levels in both tanks throughout the experiment, the farm operators filled the tanks on alternate days with the same type of slurry collected from the dairy barn. Both tanks were mixed with a tractor-driven propeller mixer the day before emissions sampling to simulate routine farm operations and break up any surface crust.
The slurry levels in the tanks were also measured on gas-sampling days to ensure that the emitting surface-to-volume ratio remained comparable between tanks. The initial ratio was approximately 0.35 m2/m3 in both tanks. Subsequent measurements showed higher ratios, ranging from 0.4 to 0.5 m2/m3, as slurry was collected for field applications. The operators ensured that both tanks were gradually and evenly emptied in order to maintain uniform comparison conditions.
The additive tested, SOP® LAGOON (SQE034 + SQE610), consists of 100% calcium sulfate dihydrate (gypsum) processed using SOP’s proprietary technology—SOP Inside [47]—and has been marketed in Europe and North America since 2003. During the experiment, SOP LAGOON was added weekly to only one of the two tanks (SL), while the other tank remained untreated, serving as a control (UTC).
In order to replicate the current farm-use conditions, the dosage recommended by the company (based on the label and Technical Data Sheet) was applied. Every week, the additive was applied directly to the SL tank at a dose of 2 g for each animal (adult or heifer), contributing slurry to the tank. For the first four applications, an additional activation dose was added weekly at a rate of 4 g/m3 for the slurry already stored in the tank at the time of the first application. During the first four weeks, a total of 40 kg of the product was added. Subsequently, from week 5 until the end of the experiment, an additional 11 kg of product was added.
The initial application of SOP LAGOON took place on 27 May, immediately after the initial baseline measurement was taken.

2.2. Slurry Analysis

Before each measurement day, after being agitated, slurry was collected from different positions in the tanks and mixed. Two samples of approximately 2 L each, one for the SL tank and one for the UTC tank, were taken to the lab for the analyses.
The chemical composition of the slurry was analyzed to verify any treatment effects. The samples collected were stored in small, airtight containers and immediately refrigerated at 4 °C before laboratory analysis.
The samples were analyzed for different parameters: total solids (TS), volatile solids (VS), total Kjeldahl nitrogen (TKN), total ammoniacal nitrogen (TAN), pH, and total organic carbon. The analyses were conducted according to the Standard Methods for the Examination of Water and Wastewater [48].

2.3. Emission and Flux Determination

Ammonia emission measurements were performed five times from May to September in one-month intervals (with 14 days between the last two measurements).
According to the VERA protocol [49] and considering the tanks’ surfaces, five measurement points were established for each tank. A floating funnel was positioned at each measuring point, from which the air was sampled (Figure 1). The setup was designed to limit the influence of cross winds and contamination from other sources, thus allowing for accurate emissions sampling only from the local area.
The measurement system was designed according to the approach described in [50,51]. The makeup of the entire system was as follows (Figure 2):
  • There were PVC funnels floating via a suitable frame on the surface of the slurry. Each funnel had a diameter of 0.42 m and covered a surface of approximately 0.14 m2; the total covered area for each tank was approximately 0.7 m2, making it greater than the 0.5 m2 suggested by the aforementioned VERA protocol.
  • There were PTFE tubes connecting each floating funnel with a corresponding “lung flask.” The flasks were hermetically sealed with rubber stoppers.
  • There were two Dreschel acid traps with a volume of 500 mL, which were sealed and connected to each other. Each trap contained 300 mL of a solution of 1% boric acid.
  • One flow meter was placed behind the acid trap Drechsel.
  • One vacuum pump was positioned downstream of the system, with an air flux of 1.5 L/min.
According to the VERA protocol, 30 min sampling was performed for each floating funnel. From one point to another, after the 30 min sampling period, a 12 min flux with fresh air was run to clean the sampling system.
Blank measurements were taken before each ammonia-sampling procedure, and their average values were used to correct the emissions resulting from the sampling points.
The resulting total measuring time was over 7 h, thus allowing us to capture possible emissions variations linked to environmental changes during the day. The measurements were alternated between the SL and UTC tanks to ensure there were even conditions between the two tanks.
The ammonia concentration of the solution in the acid traps was determined off-site via titration with 0.01 N sulfuric acid in our university’s laboratory, in Milan.
The emission flows of the NH3 were finally calculated using Equation (1):
F = (Q × (Cin − Cout))/A
where
  • F is the NH3 flux (mg/m2,h);
  • Q is the air flow (m3/h);
  • Cin is the NH3 concentration in the air above the slurry surface, sampled via the funnel system (mg/m3);
  • Cout is the corresponding background NH3 air concentration (mg/m3);
  • A is the surface of the funnel (m2).

2.4. Statistical Analysis

The data were analyzed using the Analysis of Variance (ANOVA) procedure with SPSS version 28. Each sampling date was analyzed separately to evaluate statistical differences between treatments. For each treatment, the analysis was also performed between sampling dates to highlight differences between the dates.

3. Results

This section reports on the weather characteristics at the site of the experiment, the chemical analysis of the slurry, and the measurement of NH3 emissions.

3.1. Weather Characteristics

The weather parameters at the study area, obtained by the authors of [52], are reported in Figure 3, Figure 4 and Figure 5.
Over the trial period, from 27 May to 7 September 2021, the meteorological conditions recorded in the study area were typical of the warm-season regime of the Po Plain. The mean daily temperature over the entire period was approximately 24.4 °C. While daily temperatures reached a maximum of 37.3 °C, reflecting transient heatwave episodes, the minimum temperatures dropped to around 12 °C at the beginning and the end of the trial.
Total precipitation over the period amounted to approximately 120.6 mm and was distributed irregularly across the trial. Although not evenly distributed, this cumulative amount aligns with average seasonal rainfall observed in the central Po Plain. The rainfall regime was characterized by a few moderate precipitation events rather than continuous wet spells, suggesting that convective activity was likely a dominant mechanism, typical of summer meteorology in this region.
Humidity levels were moderately high, with a mean relative humidity of approximately 56.2%, supporting the persistence of a humid continental to subtropical environment (Cfa in the Köppen classification).
Wind conditions were relatively calm on average, with a mean value of 1.2 m/s. This is in line with the typical summer suppression of synoptic-scale winds in the area, where thermal gradients are weak and atmospheric circulation is often dominated by mesoscale or local valley-plain interactions. The moderate winds, raft–funnel design, and blank ammonia level measurements minimized the possible influence of de-localized ammonia sources to a minimum.
Sea-level pressure remained stable throughout the period, with a mean value of approximately 1014.3 hPa, further indicating the absence of significant barometric perturbations and the dominance of anticyclonic conditions.
Taken together, the observed atmospheric parameters indicate a summer season that was meteorologically typical for the area. The temperature, humidity, wind, and pressure patterns collectively reflect the traits of continental lowland summers in Northern Italy.

3.2. Slurry Chemical Characteristics

The results of the chemical analysis of the slurry are reported below (Table 1) as the average between the slurry sampled from the UTC and SL tanks.
The chemical composition of the slurry was in the range reported in the literature for dairy manure [53].
pH values, on the other hand, varied with both treatment and time. Table 2 shows the values measured in both tanks on the different sampling dates.
In SL, pH exhibited limited fluctuations around the same values, without significant differences, throughout the entire test period. In the UTC, the pH remained relatively stable across the first three dates, then exhibited a non-significant increase, and finally dropped on the last measurement date (−7.4% from the initial value, p = 0.040).

3.3. Ammonia Emissions

Table 3 shows the results regarding the tanks’ NH3 emissions as fluxes in mg NH3/m2,h.
The values on the first sampling date represent the average of all ten emission values measured in the two tanks before the first application of the SOP LAGOON additive.
After this measurement was taken, the additive was added to the SL tank according to the protocol described.
The emissions followed different trends between the SL and UTC tanks.
On the second sampling date, one month after the first application of SOP LAGOON, the emissions registered for SL were lower than the baseline by approximately 77% (p < 0.000), while the UTC showed no statistically significant (p = 0.590) differences.
Throughout the trial period (Table 3), NH3 emissions remained quite stable, with no statistically significant differences when comparing July to June or August to July, in both the SL and the UTC tanks. SL emissions showed a slight, non-statistically significant rebound after the initial drop on the third day of measurement, while an increase (not significant) was found on the fourth date for the UTC. Overall, the data showed consistently lower values in the SL-treated tank than the UTC tank after the initial date.
By the end of the experiment, emissions declined for both treatments. The emissions decreased further in the SL tank between August and September (−48%, p = 0.048), resulting in 87% lower emissions than at the beginning of the trial. In contrast, no significant variation (p = 0.206) was measured for the UTC during the same period.
The standard errors in Table 3 also show that the measurements taken for the SL tank exhibited, on average, less variability on the same sampling date than those acquired for the UTC.
The following table (Table 4) shows the correlation between the ammonia emissions and the environmental parameters.
Evidently, the temperatures, relatively stable during the test period, did not seem to influence the emissions. The UTC seemed to be strongly influenced by wind and pressure. The SL tank, on the contrary, was relatively unaffected by wind, while it appears to have a correlation with humidity and a moderate negative correlation with pressure.

4. Discussion

In this study, we replicated the real-world application of the additive SOP LAGOON (SL) and tested its effectiveness in reducing ammonia (NH3) emissions during manure storage in a real-scale scenario. We monitored two parallel slurry tanks on a commercial dairy farm, with the product, currently used by the farmers that purchase the product, applied at the dosage recommended by the manufacturer.
In conjunction with previous work conducted by the same research group [46], this study contributes to the limited body of evidence on the efficacy of slurry additives under real-scale conditions [2,54], helping to bridge the gap between laboratory trials and practical implementation.
Our analysis of NH3 emissions showed that SL application significantly mitigated emissions relative to those from an untreated open-air tank (UTC). Specifically, during the first month of treatment, NH3 emissions from the SL-treated tank were reduced by 77% compared to the baseline levels. This substantial reduction is consistent with previous laboratory-scale studies [44,45], where reductions in NH3 emissions between 45.9% and 100% were observed following the application of SOP LAGOON to manure water or fresh liquid manure, respectively, within one week from the first application. This study confirms the rapidity of the tested additive’s action, even in a real-scale scenario.
After the initial drop and throughout the trial period (Table 3), NH3 emission levels remained relatively stable, with the SL-treated tank consistently exhibiting lower values than the UTC tank under comparable environmental conditions.
By the end of the experiment, emissions had declined in both treatment tanks. The observed decline in NH3 emissions toward the end of the trial aligns with the well-established effects of meteorological drivers on volatilization dynamics.
Overall, the weather conditions recorded during the trial were typical for the region’s warm season, and their patterns are consistent with the seasonal dynamics of NH3 emissions from manure reported in long-term studies [25,36].
Air temperature is one of the primary factors affecting NH3 emissions, with lower temperatures decreasing the vapor pressure of ammonium and thus limiting volatilization from slurry surfaces. As previously reported in [25,55], a drop in temperature of even 5–10 °C can substantially reduce NH3 fluxes from uncovered slurry tanks. In this study, however, the correlation between NH3 emissions and ambient temperature was weak for both tanks, likely because of the relatively stable range of temperatures measured in the test period.
Wind speed also plays a role, albeit less linearly: moderate winds can enhance mass transfer of ammonia from the liquid surface to the atmosphere, particularly under turbulent conditions. However, as the authors of [37] noted, the effect of wind is limited when wind speeds are below 2 m/s, especially when surface agitation was minimal or controlled; such speeds were prevalent during this trial (mean = 1.2 m/s). Small air movements in the first layers of air above the surface of the slurry and below the funnels can significantly affect local NH3 concentration gradients, particularly in open, real-scale lagoons. In this study, wind speed showed a strong positive correlation with NH3 emissions in the UTC tank, consistent with earlier findings [56,57,58], while SL did not appear to be influenced by this meteorological factor.
Relative humidity and barometric pressure may also modulate NH3 fluxes indirectly. High relative humidity reduces the air–surface driving potential for ammonia (i.e., it lowers the water–vapor pressure deficit), thereby diminishing gas-phase mass transfer and limiting volatilization [56]. In addition, thermally stable atmospheric conditions and low-speed winds suppress vertical mixing and dispersion, allowing NH3 to accumulate locally [59,60,61]. In this work, NH3 emissions from the UTC tank correlated positively with wind and negatively with pressure. This finding can explain the emission drop measured at the end of the monitoring period, when wind speed decreased and barometric pressure increased relative to late August (Figure 4 and Figure 5).
While relative humidity appeared unrelated to NH3 fluxes in the UTC tank, it showed a moderate positive correlation in the SL treatment, differing from what is reported in the literature [56,59,60,61], possibly explaining the small, non-statistically significant emission rebound at the end of July, coinciding with a temporary rise in ambient humidity (Figure 4).
Overall, however, emissions from the SL-treated tank appeared much less affected by external meteorological factors than those from the UTC, suggesting the additive has a stabilizing effect on slurry surface dynamics.
Further research is recommended to investigate the effects of the additive in question in different seasons and locations in order to confirm and expand on these findings.
Following the manufacturer’s recommendations, the farm operators applied SL weekly throughout the trial. Emissions remained at consistently low levels, aligning with the observations reported in [46] on greenhouse gases. This result supports the findings of [44], who reported emission rebounds upon interruption of additive use. This finding indicates the importance of sustained application for long-term emission control, as per the manufacturer’s specifications.
The initial ammonia emissions measured (Table 3) from the tanks are consistent with previously reported values [2], reaffirming that slurry storage constitutes a major source of NH3. When normalized to the total ammonium nitrogen (TAN) content, the UTC treatment resulted in emissions equivalent to 3.2% of the TAN, consistent with the values reported in [25], while emissions from the SL-treated tank were markedly lower, at 1.1% of the TAN.
Notably, the variability in the NH3 emissions from the SL-treated tank was significantly lower than that observed for the UTC tank, as indicated by the standard errors in Table 3. This finding can be explained by the fact that even though both tanks were thoroughly agitated prior to sampling to replicate real farm conditions, the surface of the slurry in the UTC tank appeared more heterogeneous than that in the SL tank. According to farm workers, the SL-treated slurry required less agitation time, suggesting enhanced homogeneity relative to the UTC. This improved uniformity could have contributed to the observed stability in emission levels throughout the trial and their reduced variability across the treated surface on each sampling date (Table 3).
Moreover, although odor emissions were not directly measured in this study, the farm operators reported odors were less intense relative to the UTC when they were handling manure from the SL tank. This finding might be connected to the reduced levels of emissions of ammonia, one of the well-known precursors of foul odors from farms [62,63].
This work, conducted by monitoring emissions over 3.5 months at real farm-scale, strengthens the evidence of the additive’s effectiveness from previous work [44,45,46].
While various cover methods can reduce NH3 emissions during the storage phase [64], they also present some criticalities. Impermeable cover techniques can achieve reductions of 60 to 80% [2,65], but they require significant investment for installation, along with maintenance or replacement after a few years [66]. The emission reductions achieved with SL were comparable to those reported for fixed covers [2], but without the associated issues such as high installation costs or the accumulation of hazardous gases such as hydrogen sulfide (H2S) [67,68], which can be released when the covers are opened or during manure agitation and spreading.
Natural crust formation or coverage with straw [2] is frequently mentioned as a method for reducing NH3 emissions, akin to slurry store coverage, as specified in the Best Available Techniques (BAT) guidelines [69]. While these techniques can reduce emissions, they entail complex management and may lead to undesirable side effects, such as increasing nitrous oxide (N2O) emissions up to 100 times compared to uncovered lagoons [65,70,71,72], as well as operational difficulties for farmers, such as reducing the storage capacity of tanks [73]. Moreover, crust development is not entirely controllable. The thickness, extension, and persistence of crusts can vary significantly, leading to an inconsistent impact on emission reduction [65]. While having a similar or superior NH3 abatement capacity to natural cover (e.g., crust), SL has previously exhibited [44,45,46] the ability to reduce emissions of methane and other GHGs. Notably, previous work has shown that the additive tested reduced nitrogen emissions in the form of both NH3 and N2O. Since no apparent variation in the macroscopic chemical parameters occurred, future studies should investigate the entire nitrogen cycle to identify what nitrogen transformation pathways occur in regard to the SL-treated manure.
Slurry acidification decreases NH3 emissions efficiently as it modifies the chemical characteristics of slurry [74,75]. This treatment is typically performed by adding concentrated sulfuric acid (H2SO4) to the manure. While H2SO4 is one of the cheapest acids available [76], handling this material safely requires the installation of dedicated machinery, increasing the adoption and maintenance costs for this solution. Acidification via the addition of other materials, such as gypsum or phosphogypsum, has also been shown to reduce NH3 emissions, mitigating nitrogen loss from manure and minimizing odor. While some authors [77,78,79] have reported NH3 reductions ranging from 26% to 69%, other studies have shown that different types of gypsum can produce divergent and inconsistent effects [80,81,82]. For example, the authors of [81] observed that phosphogypsum lowered CH4 and NH3 emissions during poultry manure composting but tended to increase N2O emissions.
Previous studies [44,45,46] already quantified reductions in ammonia emissions, odors, and greenhouse gases induced by SOP Inside-treated gypsum, providing external support for the expected direction of the effects. While studying the effects of common gypsum in a real-scale scenario at the same dosages recommended for SL could have been interesting, employing three concurrent and comparable tanks (an untreated control, a gypsum-only tank, and a gypsum tank treated with SOP Inside) in a single dairy farm was not feasible in our region, as farms rarely operate three storage tanks with similar volumes, geometries, and filling schedules.
Acidification typically requires large amounts of material (up to 6 kg/m3 of H2SO4 or 3–23% of manure weight for gypsum) [78,80,81,82] and a subsequent pH correction before manure application to the soil [83], making it impractical for widespread use. Dairy cows typically produce between 50 and 60 L of slurry daily depending on diet, housing, and management practices [84]. On the dairy farm where this work was performed, up to 70 tons of gypsum per week would have been required to curb emissions, making the use of common gypsum a very impractical solution for reducing NH3 emissions. In contrast to these cited works on gypsum, this study and that conducted in [46] showed that SL achieved significant emission reductions at the recommended dosage, requiring minimal material input (4 g/m3, approximately 1 kg, per week).
Chemical analyses demonstrated that the application of SL did not compromise the liquid manure’s agronomic value as a fertilizer, a finding consistent with previous reports [44,45,46]. Further studies could investigate possible dosage effects, although they could be constrained by the infrastructure available on the farm selected.
Recently, the efficacy of other commercially available additives in reducing emissions has been investigated, yielding contrasting results. For example, the use of Eminex was associated with a potential increase in NH3 volatilization by up to 200% [85,86], while [87] found that additives such as Biochar, More than Manure, and Pro-Act had no significant effects on NH3 emissions and, in some cases, increased CO2 release. Moreover, as [40] pointed out, the cost associated with these techniques is not clear and might represent an obstacle to wide adoption.
According to the manufacturer, the recommended retail price for SOP LAGOON is under EUR 10 per head per year. It does not require any specialized equipment for application and, based on the results presented here, represents a cost-effective solution to reducing environmental emissions.
To the best of our knowledge, SOP LAGOON is currently the only additive that has been scientifically validated across all major dimensions of emission reduction—specifically with respect to ammonia and GHGs—during manure storage.
The authors of [44] performed a life cycle assessment (LCA) of manure treated with SOP LAGOON compared to the baseline scenario of untreated liquid manure, similar to the conditions tested here. Their findings showed that the use of this additive resulted in improvements, particularly in particulate matter, terrestrial acidification, and eutrophication parameters. This work confirms that under real-scale conditions, SOP LAGOON can serve as a valid tool for farmers, without negatively impacting their operations, and aligns with several United Nations Sustainable Development Goals (SDGs): it aligns with SDG 3 (Good Health and Well-being) because of its impact on reducing emissions of ammonia, a precursor of particulate matter; SDG 12 (Responsible Consumption and Production) for the small amount of materials required to achieve this emissions reduction; SDG 14 (Life Below Water), as limiting ammonia emissions reduces Marine Eutrophication; and SDG 15 (Life on Land), as the quality of the manure does not change in ways that impact the soil on which it will be applied.

5. Conclusions

Reducing emissions of ammonia (NH3) from livestock manure management remains a major scientific and policy priority, given its effects on air quality and ecosystem health.
In this real-scale farm trial, the SOP LAGOON additive consistently reduced NH3 volatilization from slurry storage by about 77% in the first month and up to 87% over the longer monitoring period compared with baseline levels.
Beyond the overall reduction, in this study, the treated slurry showed a more stable emission profile across varying meteorological conditions, suggesting that the additive enhances the physicochemical stability of the stored slurry and reduces its responsiveness to external drivers such as temperature and wind.
This stabilization under real operating conditions strengthens the evidence that mitigation strategies based on this additive can provide a reliable and scalable solution to lowering agricultural NH3 emissions while supporting more sustainable livestock management systems.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/atmos16111289/s1. Table S1: Chemical analysis of the two tanks during the trial.

Author Contributions

Conceptualization, M.E.C. and J.B.; methodology, M.E.C., J.B., M.C. and D.A.; software, M.E.C.; validation, M.E.C., J.B. and M.C.; formal analysis, J.B. and M.C.; investigation, J.B., M.C. and M.Z.; resources, M.E.C., J.B. and M.C.; data curation, M.E.C., J.B., M.C. and M.Z.; writing—original draft preparation, M.E.C. and J.B.; writing—review and editing, M.E.C., J.B., M.C. and L.P.; project administration, M.E.C. and J.B.; funding acquisition, J.B. and M.E.C. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded in part by LOMBARDY REGION, INNODRIVER-S3 -Edition 2019—Measure A-B, InnoADD, number 1742664, and in part by the SOP Srl Società Benefit.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in this study are included in the article/Supplementary Material. Further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare there are no conflicts of interest.

References

  1. Behera, S.N.; Sharma, M.; Aneja, V.P.; Balasubramanian, R. Ammonia in the Atmosphere: A Review on Emission Sources, Atmospheric Chemistry and Deposition on Terrestrial Bodies. Environ. Sci. Pollut. Res. 2013, 20, 8092–8131. [Google Scholar] [CrossRef] [PubMed]
  2. Kupper, T.; Häni, C.; Neftel, A.; Kincaid, C.; Bühler, M.; Amon, B.; VanderZaag, A. Ammonia and Greenhouse Gas Emissions from Slurry Storage—A Review. Agric. Ecosyst. Environ. 2020, 300, 106963. [Google Scholar] [CrossRef]
  3. Stelson, A.W.; Seinfeld, J.H. Thermodynamic Prediction of the Water Activity, NH4NO3 Dissociation Constant, Density and Refractive Index for the NH4NO3-(NH4)2SO4-H2O System at 25 °C. Atmos. Environ. 1982, 16, 2507–2514. [Google Scholar] [CrossRef]
  4. Doyle, G.J.; Tuazon, E.C.; Graham, R.A.; Mischke, T.M.; Winer, A.M., Jr.; Pitts, J.N. Simultaneous Concentrations of Ammonia and Nitric Acid in a Polluted Atmosphere and Their Equilibrium Relationship to Particulate Ammonium Nitrate; ACS Publications: Washington, DC, USA, 1979. [Google Scholar] [CrossRef]
  5. Ndegwa, P.M.; Hristov, A.N.; Arogo, J.; Sheffield, R.E. A Review of Ammonia Emission Mitigation Techniques for Concentrated Animal Feeding Operations. Biosyst. Eng. 2008, 100, 453–469. [Google Scholar] [CrossRef]
  6. Wang, S.; Nan, J.; Shi, C.; Fu, Q.; Gao, S.; Wang, D.; Cui, H.; Saiz-Lopez, A.; Zhou, B. Atmospheric Ammonia and Its Impacts on Regional Air Quality over the Megacity of Shanghai, China. Sci. Rep. 2015, 5, 15842. [Google Scholar] [CrossRef]
  7. Sutton, M.A.; Oenema, O.; Erisman, J.W.; Leip, A.; van Grinsven, H.; Winiwarter, W. Too Much of a Good Thing. Nature 2011, 472, 159–161. [Google Scholar] [CrossRef]
  8. Carnevale, C.; Pisoni, E.; Volta, M. A Non-Linear Analysis to Detect the Origin of PM10 Concentrations in Northern Italy. Sci. Total Environ. 2010, 409, 182–191. [Google Scholar] [CrossRef]
  9. Erisman, J.W.; Schaap, M. The Need for Ammonia Abatement with Respect to Secondary PM Reductions in Europe. Environ. Pollut. 2004, 129, 159–163. [Google Scholar] [CrossRef]
  10. Paulot, F.; Jacob, D.J. Hidden Cost of U.S. Agricultural Exports: Particulate Matter from Ammonia Emissions. Environ. Sci. Technol. 2014, 48, 903–908. [Google Scholar] [CrossRef]
  11. van Donkelaar, A.; Martin, R.V.; Li, C.; Burnett, R.T. Regional Estimates of Chemical Composition of Fine Particulate Matter Using a Combined Geoscience-Statistical Method with Information from Satellites, Models, and Monitors. Environ. Sci. Technol. 2019, 53, 2595–2611. [Google Scholar] [CrossRef]
  12. Gautam, S.; Patra, A.K.; Kumar, P. Status and Chemical Characteristics of Ambient PM2.5 Pollutions in China: A Review. Environ. Dev. Sustain. 2019, 21, 1649–1674. [Google Scholar] [CrossRef]
  13. Li, Y.J.; Sun, Y.; Zhang, Q.; Li, X.; Li, M.; Zhou, Z.; Chan, C.K. Real-Time Chemical Characterization of Atmospheric Particulate Matter in China: A Review. Atmos. Environ. 2017, 158, 270–304. [Google Scholar] [CrossRef]
  14. Cheng, Z.; Luo, L.; Wang, S.; Wang, Y.; Sharma, S.; Shimadera, H.; Wang, X.; Bressi, M.; de Miranda, R.M.; Jiang, J.; et al. Status and Characteristics of Ambient PM2.5 Pollution in Global Megacities. Environ. Int. 2016, 89–90, 212–221. [Google Scholar] [CrossRef] [PubMed]
  15. Philip, S.; Martin, R.V.; van Donkelaar, A.; Lo, J.W.-H.; Wang, Y.; Chen, D.; Zhang, L.; Kasibhatla, P.S.; Wang, S.; Zhang, Q.; et al. Global Chemical Composition of Ambient Fine Particulate Matter for Exposure Assessment. Environ. Sci. Technol. 2014, 48, 13060–13068. [Google Scholar] [CrossRef] [PubMed]
  16. Behera, S.N.; Sharma, M. Investigating the Potential Role of Ammonia in Ion Chemistry of Fine Particulate Matter Formation for an Urban Environment. Sci. Total Environ. 2010, 408, 3569–3575. [Google Scholar] [CrossRef]
  17. European Environment Agency. Health Impacts of Air Pollution in Europe. 2022. Available online: https://www.eea.europa.eu/publications/air-quality-in-europe-2022/health-impacts-of-air-pollution (accessed on 8 April 2025).
  18. Burns, A.M.; Chandler, G.; Dunham, K.J.; Carlton, A.G. Data Gap: Air Quality Networks Miss Air Pollution from Concentrated Animal Feeding Operations. Environ. Sci. Technol. 2023, 57, 20718–20725. [Google Scholar] [CrossRef]
  19. Bauer, S.E.; Tsigaridis, K.; Miller, R. Significant Atmospheric Aerosol Pollution Caused by World Food Cultivation. Geophys. Res. Lett. 2016, 43, 5394–5400. [Google Scholar] [CrossRef]
  20. Han, X.; Zhu, L.; Liu, M.; Song, Y.; Zhang, M. Numerical Analysis of Agricultural Emissions Impacts on PM2.5 in China Using a High-Resolution Ammonia Emission Inventory. Atmos. Chem. Phys. 2020, 20, 9979–9996. [Google Scholar] [CrossRef]
  21. Final Assessment Report on Ammonia. Available online: https://unece.org/fileadmin/DAM/env/documents/2020/AIR/WGSR/Final_Assessment_Report_on_Ammonia_v2_20201126_b.pdf (accessed on 8 April 2025).
  22. Sutton, M.A.; Bleeker, A.; Howard, C.; Erisman, J.W.; Abrol, Y.P.; Bekunda, M.; Datta, A.; Davidson, E.; Vries, W.; Oenema, O.; et al. Our Nutrient World: The Challenge to Produce More Food and Energy with Less Pollution. In Global Overview on Nutrient Management; UNEP, Ed.; Centre for Ecology & Hydrology: Edinburgh, UK, 2013. [Google Scholar]
  23. Air Pollution in Europe. Available online: https://www.eea.europa.eu/publications/national-emission-reduction-commitments-directive-2023 (accessed on 8 April 2025).
  24. Van Damme, M.; Clarisse, L.; Franco, B.; Sutton, M.A.; Erisman, J.W.; Wichink Kruit, R.; van Zanten, M.; Whitburn, S.; Hadji-Lazaro, J.; Hurtmans, D.; et al. Global, Regional and National Trends of Atmospheric Ammonia Derived from a Decadal (2008–2018) Satellite Record. Environ. Res. Lett. 2021, 16, 055017. [Google Scholar] [CrossRef]
  25. Kupper, T.; Eugster, R.; Sintermann, J.; Häni, C. Ammonia Emissions from an Uncovered Dairy Slurry Storage Tank over Two Years: Interactions with Tank Operations and Meteorological Conditions. Biosyst. Eng. 2021, 204, 36–49. [Google Scholar] [CrossRef]
  26. Sommer, S.G.; Zhang, G.Q.; Bannink, A.; Chadwick, D.; Misselbrook, T.; Harrison, R.; Hutchings, N.J.; Menzi, H.; Monteny, G.J.; Ni, J.Q.; et al. Algorithms Determining Ammonia Emission from Buildings Housing Cattle and Pigs and from Manure Stores. In Advances in Agronomy; Academic Press: Cambridge, MA, USA, 2006; Volume 89, pp. 261–335. [Google Scholar] [CrossRef]
  27. Zilio, M.; Orzi, V.; Chiodini, M.E.; Riva, C.; Acutis, M.; Boccasile, G.; Adani, F. Evaluation of Ammonia and Odour Emissions from Animal Slurry and Digestate Storage in the Po Valley (Italy). Waste Manag. 2020, 103, 296–304. [Google Scholar] [CrossRef]
  28. Aguirre-Villegas, H.A.; Besson, C.; Larson, R.A. Modeling Ammonia Emissions from Manure in Conventional, Organic, and Grazing Dairy Systems and Practices to Mitigate Emissions. J. Dairy Sci. 2024, 107, 359–382. [Google Scholar] [CrossRef]
  29. Directive (EU) 2016/2284 of the European Parliament and of the Council of 14 December 2016 on the Reduction of National Emissions of Certain Atmospheric Pollutants, Amending Directive 2003/35/EC and Repealing Directive 2001/81/EC. Available online: https://eur-lex.europa.eu/eli/dir/2016/2284/oj/eng (accessed on 28 October 2025).
  30. Directive 2010/75/EU of the European Parliament and of the Council of 24 November 2010 on Industrial Emissions (Integrated Pollution Prevention and Control). Available online: https://eur-lex.europa.eu/eli/dir/2010/75/oj/eng (accessed on 28 October 2025).
  31. Directive (EU) 2024/1785 of the European Parliament and of the Council of 24 April 2024 Amending Directive 2010/75/EU of the European Parliament and of the Council on Industrial Emissions (Integrated Pollution Prevention and Control) and Council Directive 1999/31/EC on the Landfill of Waste. Available online: https://eur-lex.europa.eu/eli/dir/2024/1785/oj/eng (accessed on 30 October 2025).
  32. DECRETO LEGISLATIVO n. 152—Norme in Materia Ambientale. Available online: https://www.normattiva.it/uri-res/N2Ls?urn:nir:stato:decreto.legislativo:2006-04-03;152 (accessed on 28 October 2025).
  33. U.S. Environmental Protection Agency. Emissions from Animal Feeding Operations; U.S. EPA: Washington, DC, USA, 2005. [Google Scholar]
  34. Code 359; Conservation Practice Standard Waste Treatment Lagoon. USDA: Washington, DC, USA, 2017.
  35. Directive (EU) 2024/1785 of the European Parliament and of the Council of 24 April 2024 Amending Directive 2010/75/EU of the European Parliament and of the Council on Industrial Emissions (Integrated Pollution Prevention and Control) and Council Directive 1999/31/EC on the Landfill of Waste (Text with EEA Relevance). 2024. Available online: http://data.europa.eu/eli/dir/2024/1785/oj/eng (accessed on 28 October 2025).
  36. Zapletal, M.; Mikuska, P. Ammonia Emissions and Dry Deposition in the Vicinity of Dairy Farms. Atmósfera 2019, 32, 337–350. [Google Scholar] [CrossRef]
  37. Grant, R.H.; Boehm, M.T. Ammonia Emissions from Differing Manure Storage Facilities at Two Midwestern Free-Stall Dairies. Atmosphere 2020, 11, 1108. [Google Scholar] [CrossRef]
  38. ten Hoeve, M.; Nyord, T.; Peters, G.M.; Hutchings, N.J.; Jensen, L.S.; Bruun, S. A Life Cycle Perspective of Slurry Acidification Strategies under Different Nitrogen Regulations. J. Clean. Prod. 2016, 127, 591–599. [Google Scholar] [CrossRef]
  39. Soluzioni Innovative per i Reflui Degli Allevamenti. Regione Piemonte. Available online: https://www.regione.piemonte.it/web/pinforma/notizie/soluzioni-innovative-per-reflui-degli-allevamenti (accessed on 28 May 2025).
  40. Wang, Y.; Xu, H.; Wang, Y.; Wang, W.; Wang, X.; Zhang, H.; Zhu, Z.; Dong, H. Achieving Overall Low Greenhouse Gas and Ammonia Emissions from Digested Pig Slurry during Storage and after Field Application by Maintaining a Micro-Oxygen Level at the Storage Stage. J. Environ. Chem. Eng. 2025, 13, 116712. [Google Scholar] [CrossRef]
  41. Owusu-Twum, M.Y.; Kelleghan, D.; Gleasure, G.; Connolly, S.; Forrestal, P.; Lanigan, G.J.; Richards, K.G.; Krol, D.J. Mitigation of Ammonia and Methane Emissions with Manure Amendments during Storage of Cattle Slurry. Waste Manag. Res. 2025, 43, 568–579. [Google Scholar] [CrossRef]
  42. Maris, S.C.; Capra, F.; Ardenti, F.; Chiodini, M.E.; Boselli, R.; Taskin, E.; Puglisi, E.; Bertora, C.; Poggianella, L.; Amaducci, S.; et al. Reducing N Fertilization without Yield Penalties in Maize with a Commercially Available Seed Dressing. Agronomy 2021, 11, 407. [Google Scholar] [CrossRef]
  43. Meggio, F.; Chiodini, M.E.; Broggio, M.; Poggianella, L.; Acutis, M. Responses on Vegetative Growth, Yield and Quality with the Application of Resonant® Fortify White Fertilizer in Vitis vinifera L. Cv. Chardonnay. Italus Hortus 2024, 31, 29. [Google Scholar] [CrossRef]
  44. Borgonovo, F.; Conti, C.; Lovarelli, D.; Ferrante, V.; Guarino, M. Improving the Sustainability of Dairy Slurry by A Commercial Additive Treatment. Sustainability 2019, 11, 4998. [Google Scholar] [CrossRef]
  45. Peterson, C.B.; El Mashad, H.M.; Zhao, Y.; Pan, Y.; Mitloehner, F.M. Effects of SOP Lagoon Additive on Gaseous Emissions from Stored Liquid Dairy Manure. Sustainability 2020, 12, 1393. [Google Scholar] [CrossRef]
  46. Chiodini, M.E.; Costantini, M.; Zoli, M.; Bacenetti, J.; Aspesi, D.; Poggianella, L.; Acutis, M. Real-Scale Study on Methane and Carbon Dioxide Emission Reduction from Dairy Liquid Manure with the Commercial Additive SOP LAGOON. Sustainability 2023, 15, 1803. [Google Scholar] [CrossRef]
  47. SOP Farm. Available online: https://www.sopfarm.com/en (accessed on 28 May 2025).
  48. Standard Methods for the Examination of Water and Wastewater—Laura Bridgewater, American Public Health Association, American Water Works Association, Water Environment Federation—Google Libri. Available online: https://books.google.it/books/about/Standard_Methods_for_the_Examination_of.html?id=dd2juAAACAAJ&redir_esc=y (accessed on 14 December 2022).
  49. VERA Test Protocol. Available online: https://www.vera-verification.eu/app/uploads/sites/9/2019/05/VERA_Test_protocol_slurryseparation_v3_2018_final.pdf (accessed on 8 April 2025).
  50. Balsari, P.; Airoldi, G.; Dinuccio, E.; Gioelli, F. Ammonia Emissions from Farmyard Manure Heaps and Slurry Stores—Effect of Environmental Conditions and Measuring Methods. Biosyst. Eng. 2007, 97, 456–463. [Google Scholar] [CrossRef]
  51. Finzi, A.; Mattachini, G.; Lovarelli, D.; Riva, E.; Provolo, G. Technical, Economic, and Environmental Assessment of a Collective Integrated Treatment System for Energy Recovery and Nutrient Removal from Livestock Manure. Sustainability 2020, 12, 2756. [Google Scholar] [CrossRef]
  52. Open Meteo. Available online: https://open-meteo.com/ (accessed on 8 August 2025).
  53. Martínez-Suller, L.; Azzellino, A.; Provolo, G. Analysis of Livestock Slurries from Farms across Northern Italy: Relationship between Indicators and Nutrient Content. Biosyst. Eng. 2008, 99, 540–552. [Google Scholar] [CrossRef]
  54. Regueiro, I.; Coutinho, J.; Fangueiro, D. Alternatives to Sulfuric Acid for Slurry Acidification: Impact on Slurry Composition and Ammonia Emissions during Storage. J. Clean. Prod. 2016, 131, 296–307. [Google Scholar] [CrossRef]
  55. Misselbrook, T.; Hunt, J.; Perazzolo, F.; Provolo, G. Greenhouse Gas and Ammonia Emissions from Slurry Storage: Impacts of Temperature and Potential Mitigation through Covering (Pig Slurry) or Acidification (Cattle Slurry). J. Environ. Qual. 2016, 45, 1520–1530. [Google Scholar] [CrossRef]
  56. Sommer, S.G.; Olesen, J.E.; Christensen, B.T. Effects of Temperature, Wind Speed and Air Humidity on Ammonia Volatilization from Surface Applied Cattle Slurry. J. Agric. Sci. 1991, 117, 91–100. [Google Scholar] [CrossRef]
  57. Ni, J. Mechanistic Models of Ammonia Release from Liquid Manure: A Review. J. Agric. Eng. Res. 1999, 72, 1–17. [Google Scholar] [CrossRef]
  58. Montes, F.; Rotz, C.A.; Chaoui, H.I. Process Modeling of Ammonia Volatilization from Ammonium Solution and Manure Surfaces: A Review with Recommended Models. Trans. ASABE 2009, 52, 1707–1720. [Google Scholar] [CrossRef]
  59. Tomas, J.M.; Pourquie, M.J.B.M.; Jonker, H.J.J. Stable Stratification Effects on Flow and Pollutant Dispersion in Boundary Layers Entering a Generic Urban Environment. Bound.-Layer Meteorol. 2016, 159, 221–239. [Google Scholar] [CrossRef]
  60. Steeneveld, G.J.; van de Wiel, B.J.H.; Holtslag, A.A.M. Diagnostic Equations for the Stable Boundary Layer Height: Evaluation and Dimensional Analysis. J. Appl. Meteorol. Clim. 2007, 46, 212–225. [Google Scholar] [CrossRef]
  61. Phillips, S.B.; Arya, S.P.; Aneja, V.P. Ammonia Flux and Dry Deposition Velocity from Near-Surface Concentration Gradient Measurements over a Grass Surface in North Carolina. Atmos. Environ. 2004, 38, 3469–3480. [Google Scholar] [CrossRef]
  62. Wang, Y.; Xue, W.; Zhu, Z.; Yang, J.; Li, X.; Tian, Z.; Dong, H.; Zou, G. Mitigating Ammonia Emissions from Typical Broiler and Layer Manure Management—A System Analysis. Waste Manag. 2019, 93, 23–33. [Google Scholar] [CrossRef] [PubMed]
  63. Nie, E.; Zheng, G.; Ma, C. Characterization of Odorous Pollution and Health Risk Assessment of Volatile Organic Compound Emissions in Swine Facilities. Atmos. Environ. 2020, 223, 117233. [Google Scholar] [CrossRef]
  64. VanderZaag, A.C.; Gordon, R.J.; Glass, V.M.; Jamieson, R.C. Floating Covers to Reduce Gas Emissions from Liquid Manure Storages: A Review. Appl. Eng. Agric. 2008, 24, 657–671. [Google Scholar] [CrossRef]
  65. VanderZaag, A.; Amon, B.; Bittman, S.; Kuczyński, T. Ammonia Abatement with Manure Storage and Processing Techniques. In Costs of Ammonia Abatement and the Climate Co-Benefits; Reis, S., Howard, C., Sutton, M.A., Eds.; Springer: Dordrecht, The Netherlands, 2015; pp. 75–112. [Google Scholar] [CrossRef]
  66. Symeon, G.K.; Akamati, K.; Dotas, V.; Karatosidi, D.; Bizelis, I.; Laliotis, G.P. Manure Management as a Potential Mitigation Tool to Eliminate Greenhouse Gas Emissions in Livestock Systems. Sustainability 2025, 17, 586. [Google Scholar] [CrossRef]
  67. Stenglein, R.M.; Clanton, C.J.; Schmidt, D.R.; Jacobson, L.D.; Janni, K.A. Covers for Mitigating Odor and Gas Emissions in Animal Agriculture: An Overview. Air Qual. Educ. Anim. Agric. 2011, 1–9. Available online: https://lpelc.org/wp-content/uploads/2019/03/Covers-overview-FINAL_1.pdf (accessed on 28 October 2025).
  68. Nicolai, R.; Pohl, S.; Schmidt, D. Covers for Manure Storage Units; SDSU: San Diego, CA, USA, 2004. [Google Scholar]
  69. European Commission; Joint Research Centre. Best Available Techniques (BAT) Reference Document for the Intensive Rearing of Poultry or Pigs: Industrial Emissions Directive 2010/75/EU (Integrated Pollution Prevention and Control); Publications Office: Luxembourg, 2017. [Google Scholar]
  70. Guarino, M.; Fabbri, C.; Brambilla, M.; Valli, L.; Navarotto, P. Evaluation of Simplified Covering Systems to Reduce Gaseous Emissions from Livestock Manure Storage. Trans. ASABE 2006, 49, 737–747. [Google Scholar] [CrossRef]
  71. Vanderzaag, A.; Gordon, R.; Jamieson, R.; Burton, D.; Stratton, G. Gas Emissions from Straw Covered Liquid Dairy Manure During Summer Storage and Autumn Agitation. Trans. ASABE 2009, 52, 599–608. [Google Scholar] [CrossRef]
  72. Hansen, R.R.; Nielsen, D.A.; Schramm, A.; Nielsen, L.P.; Revsbech, N.P.; Hansen, M.N. Greenhouse Gas Microbiology in Wet and Dry Straw Crust Covering Pig Slurry. J. Environ. Qual. 2009, 38, 1311–1319. [Google Scholar] [CrossRef]
  73. Smith, K.; Cumby, T.; Lapworth, J.; Misselbrook, T.; Williams, A. Natural Crusting of Slurry Storage as an Abatement Measure for Ammonia Emissions on Dairy Farms. Biosyst. Eng. 2007, 97, 464–471. [Google Scholar] [CrossRef]
  74. Fangueiro, D.; Hjorth, M.; Gioelli, F. Acidification of Animal Slurry—A Review. J. Environ. Manag. 2015, 149, 46–56. [Google Scholar] [CrossRef] [PubMed]
  75. Hjorth, M.; Cocolo, G.; Jonassen, K.; Abildgaard, L.; Sommer, S.G. Continuous In-House Acidification Affecting Animal Slurry Composition. Biosyst. Eng. 2015, 132, 56–60. [Google Scholar] [CrossRef]
  76. Eriksen, J.; Sørensen, P.; Elsgaard, L. The Fate of Sulfate in Acidified Pig Slurry during Storage and Following Application to Cropped Soil. J. Environ. Qual. 2008, 37, 280–286. [Google Scholar] [CrossRef] [PubMed]
  77. Lim, S.-S.; Park, H.-J.; Hao, X.; Lee, S.-I.; Jeon, B.-J.; Kwak, J.-H.; Choi, W.-J. Nitrogen, Carbon, and Dry Matter Losses during Composting of Livestock Manure with Two Bulking Agents as Affected by Co-Amendments of Phosphogypsum and Zeolite. Ecol. Eng. 2017, 102, 280–290. [Google Scholar] [CrossRef]
  78. Tubail, K.; Chen, L.; Michel, F.C., Jr.; Keener, H.M.; Rigot, J.F.; Klingman, M.; Kost, D.; Dick, W.A. Gypsum Additions Reduce Ammonia Nitrogen Losses During Composting of Dairy Manure and Biosolids. Compos. Sci. Util. 2008, 16, 285–293. [Google Scholar] [CrossRef]
  79. Febrisiantosa, A.; Ravindran, B.; Choi, H.L. The Effect of Co-Additives (Biochar and FGD Gypsum) on Ammonia Volatilization during the Composting of Livestock Waste. Sustainability 2018, 10, 795. [Google Scholar] [CrossRef]
  80. Li, Y.; Luo, W.; Li, G.; Wang, K.; Gong, X. Performance of Phosphogypsum and Calcium Magnesium Phosphate Fertilizer for Nitrogen Conservation in Pig Manure Composting. Bioresour. Technol. 2018, 250, 53–59. [Google Scholar] [CrossRef]
  81. Yang, F.; Li, G.; Shi, H.; Wang, Y. Effects of Phosphogypsum and Superphosphate on Compost Maturity and Gaseous Emissions during Kitchen Waste Composting. Waste Manag. 2015, 36, 70–76. [Google Scholar] [CrossRef]
  82. Chiumenti, A.; da Borso, F.; Pezzuolo, A.; Sartori, L.; Chiumenti, R. Ammonia and Greenhouse Gas Emissions from Slatted Dairy Barn Floors Cleaned by Robotic Scrapers. Res. Agric. Eng. 2018, 64, 26–33. [Google Scholar] [CrossRef]
  83. Loide, V.; Saue, T.; Võsa, T.; Tamm, K. The Effect of Acidified Slurry on Crop Uptake and Leaching of Nutrients from a Loamy Topsoil. Acta Agric. Scand. Sect. B—Soil Plant Sci. 2020, 70, 31–38. [Google Scholar] [CrossRef]
  84. Font-Palma, C. Methods for the Treatment of Cattle Manure—A Review. C 2019, 5, 27. [Google Scholar] [CrossRef]
  85. Holtkamp, F.; Clemens, J.; Trimborn, M. Calcium Cyanamide Reduces Methane and Other Trace Gases during Long-Term Storage of Dairy Cattle and Fattening Pig Slurry. Waste Manag. 2023, 161, 61–71. [Google Scholar] [CrossRef]
  86. Rocha, A.S.; Morales, B.; El Mashad, H.M.; Pan, Y.; Zhao, Y.; Mitloehner, F.M. Effect of Eminex® on Greenhouse Gas and Ammonia Emissions from Dairy Slurry and Lagoon Wastewater. Sustainability 2024, 16, 5778. [Google Scholar] [CrossRef]
  87. Holly, M.; Larson, R. Effects of Manure Storage Additives on Manure Composition and Greenhouse Gas and Ammonia Emissions. Trans. ASABE 2017, 60, 449–456. [Google Scholar] [CrossRef]
Atmosphere 16 01289 g001
Figure 1. Funnels floating on top of the liquid manure. The Teflon tubes connecting the funnel to the gas analyzer are clearly visible.
Figure 1. Funnels floating on top of the liquid manure. The Teflon tubes connecting the funnel to the gas analyzer are clearly visible.
Atmosphere 16 01289 g001
Atmosphere 16 01289 g002
Figure 2. System for sampling and measuring NH3 air concentrations from above the two-slurry storage tank.
Figure 2. System for sampling and measuring NH3 air concentrations from above the two-slurry storage tank.
Atmosphere 16 01289 g002
Atmosphere 16 01289 g003
Figure 3. Maximum, mean, and minimum temperature and amount of rain in the area where the trial was conducted.
Figure 3. Maximum, mean, and minimum temperature and amount of rain in the area where the trial was conducted.
Atmosphere 16 01289 g003
Atmosphere 16 01289 g004
Figure 4. Wind speed and relative humidity at the trial area.
Figure 4. Wind speed and relative humidity at the trial area.
Atmosphere 16 01289 g004
Atmosphere 16 01289 g005
Figure 5. Atmospheric pressure at the trial area.
Figure 5. Atmospheric pressure at the trial area.
Atmosphere 16 01289 g005
Table 1. Average chemical characteristics of the slurry.
Table 1. Average chemical characteristics of the slurry.
VariableValue
TS (%) 8.43 ± 0.12
VS (% TS) 74.25 ± 0.50
TKN (g/kg) 3.70 ± 0.06
TAN (g/kg) 1.69 ± 0.03
TAN (% TKN)0.46 ± 0.01
Organic Carbon (% DM)40.20 ± 0.20
TKN: Total Kjeldahl Nitrogen; TAN: Total Ammoniacal Nitrogen; TS: total solids; VS: volatile solids; DM: Dry Matter. ±Standard Error (SE).
Table 2. Slurry pH values.
Table 2. Slurry pH values.
Date
Treatment5/276/307/278/289/7
UTC6.75 Aa ± 0.107.02 Aa ± 0.096.73 Aa ± 0.157.30 Aa ± 0.166.25 Ab ± 0.09
SL7.60 Aa ± 0.167.31 Aa ± 0.157.70 Ba ± 0.117.32 Aa ± 0.147.43 Ba ± 0.22
UTC = untreated control. SL = SOP LAGOON. Different capital letters indicate significant differences between treatments on the same sampling date; different lowercase letters indicate differences across the testing dates within the same treatment. ±Standard Error (SE).
Table 3. Average ammonia emission value from slurry tanks.
Table 3. Average ammonia emission value from slurry tanks.
TreatmentDate
5/276/307/278/279/7
mgNH3/m2, hmgNH3/m2, hmgNH3/m2, hmgNH3/m2, hmgNH3/m2, h
UTC7.63 Aa ± 0.506.52 Aa ± 2.265.03 Aa ± 1.685.96 Aa ± 1.373.94 Aa ± 0.51
SL7.63 Aa ± 0.501.76 Bb ± 0.482.55 Aa ± 0.481.91 Ba ± 0.281.00 Bb ± 0.27
UTC = untreated control; SL = SOP LAGOON. Different capital letters indicate significant differences between treatments on the same sampling date; different lowercase letters indicate differences across the testing dates within the same treatment. ±Standard Error (SE).
Table 4. Correlation coefficients (r) between the ammonia emissions and the environmental parameters for the five test days.
Table 4. Correlation coefficients (r) between the ammonia emissions and the environmental parameters for the five test days.
VariableUTCSL
Temperature +0.11+0.21
Humidity−0.01+0.71
Wind+0.97+0.21
Pressure−0.99−0.52
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Chiodini, M.E.; Costantini, M.; Zoli, M.; Aspesi, D.; Poggianella, L.; Bacenetti, J. Mitigating Ammonia Emissions from Liquid Manure Using a Commercially Available Additive Under Real-Scale Farm Conditions. Atmosphere 2025, 16, 1289. https://doi.org/10.3390/atmos16111289

AMA Style

Chiodini ME, Costantini M, Zoli M, Aspesi D, Poggianella L, Bacenetti J. Mitigating Ammonia Emissions from Liquid Manure Using a Commercially Available Additive Under Real-Scale Farm Conditions. Atmosphere. 2025; 16(11):1289. https://doi.org/10.3390/atmos16111289

Chicago/Turabian Style

Chiodini, Marcello Ermido, Michele Costantini, Michele Zoli, Daniele Aspesi, Lorenzo Poggianella, and Jacopo Bacenetti. 2025. "Mitigating Ammonia Emissions from Liquid Manure Using a Commercially Available Additive Under Real-Scale Farm Conditions" Atmosphere 16, no. 11: 1289. https://doi.org/10.3390/atmos16111289

APA Style

Chiodini, M. E., Costantini, M., Zoli, M., Aspesi, D., Poggianella, L., & Bacenetti, J. (2025). Mitigating Ammonia Emissions from Liquid Manure Using a Commercially Available Additive Under Real-Scale Farm Conditions. Atmosphere, 16(11), 1289. https://doi.org/10.3390/atmos16111289

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