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Effects of Dry Matter Content and Temperature on Ammonia Loss from Surface-Applied Cattle Slurry
Abstract
Effects of increasing dry matter content in slurry on NH3 loss was measured with a wind tunnel system, whereby parameters affecting the volatilization can be estimated under controlled conditions. The effect of dry matter content on NH3 loss was measured using a slurry adjusted to different contents of dry matter. The slurry was prepared by mixing the fibrous and liquid fractions of a mechanically separated cattle slurry. Slurry was applied to a 5 cm high grass ley (Lolium multiflorum Lam.) and to barley (Hordeum vulgare L.) at a rate of 3 L m-2. The content of dry matter varied from 0.9 to 22% total N from 2.9 to 4.9 g N L-1, TAN (NH3 + NH4+) from 1.6 to 3.0 g N L-1 and pH from 7.0 to 7.9. The results indicated that NH3 volatilization increased with increasing slurry dry matter content. The accumulated 6-d loss ranged from 19 to 100% of applied TAN from slurries having a dry matter content of 0.9 and 15.6%, respectively. The accumulated NH3 loss after 6 h exposure was linearly related to dry matter content. In the periods of 6 to 12 h, 12 to 24 h and 24 h to 6 d the loss was nonlinearly related to dry matter content. If the results were adjusted for effects of pH and temperature, NH3 loss tended to be sigmoidally related to content of dry matter in all four periods. Therefore, changes in slurry dry matter content on NH3 loss seemed to be small if the dry matter content was higher than 12% or lower than 4%.
... In addition, the fed-batch reduced the dry matter content more effectively, and resulted in a SF digestate with 9.7% dry matter compared to 11.5% with the continuously fed reactors. Higher dry matter content in the digestate can lead to higher residual CH 4 when stored and higher NH 3 emissions when soil applied because of the low infiltration into the soil (Sommer and Olesen, 1991). Thus, a fed-batch set-up could be more beneficial for substrates with high dry matter, such as the source segregated solid faeces, because higher yield is obtained and a lower emission digestate could potentially be produced. ...
Source Segregation (SS) is a novel strategy in dairy housing that can reduce emissions and separate organic matter and nutrients more efficiently than traditional slurry solid-liquid separation. The anaerobic digestion (AD) methane yield of the SS fractions, however, is unknown. We aimed at unveiling the biomethane yield of these fractions by conducting AD experiments under different configurations: batch, continuous feeding, and fed-batch. In the batch test, the solid (SF) and liquid fraction (LF) from the SS system, a slurry collected from the pit (CS), and a self-made slurry (MF) were used as substrates. The results showed that the specific CH4 yields of the SF and MF were in same range and both higher than the CS. We concluded that SS can increase the CH4 yield of dairy excreta mainly by reducing losses in the animal house. The SF and MF were then compared in a continuously-fed thermophilic test, where SF had a higher specific (174 compared to 105 NL kg-1 VS) and volumetric (12.2 compared to 9.9 NL CH4 kg-1 excreta) yields. We concluded that the SF can effectively substitute slurry in AD without compromising the yield, possibly increasing economic viability by reducing transport costs and reactor size. Further, SF produced 356 NL CH4 kg-1 VS and a digestate with 1.8% lower dry matter in the fed-batch as compared to continuous feeding. Continuously stirred fed-batch can thus increase the CH4 yield of the SF and reduce the DM of its digestate potentially contributing to lower emissions in storage and field application.
... Up to 90% of feedyard NH 3 originates from urine deposited in animal pens [22,23], but the instantaneous magnitude of that loss depends strongly on weather conditions (temperature, precipitation, humidity, and wind), soil properties, pH, microbiological activities (e.g., urease activity), and management practices (Tables 1 and 2). Ammonia volatilization increases linearly with total ammoniacal nitrogen concentration (TAN), and curvilinearly with temperature, wind speed, and slurry pH [24,34,35]. Temperature and pH have been reported to be the most important factors influencing NH 3 volatilization [24], as the NH 3 /NH 4 + ratio is equilibrium dependent (Figures 3-5). ...
Northeast Colorado’s livestock operations have been identified as a major contributor to reactive nitrogen deposition in the Rocky Mountains National Park (RMNP). We present a review on the state of knowledge concerning the emission, transport, deposition, and mitigation of gaseous ammonia (NH3) from open-lot cattle feeding facilities located east of the Northern Front Range of the Rocky Mountains. Gaseous NH3 mitigation strategies discussed are related to diet manipulation and management practices. Crude protein content of 11% and condensed tannins of 8% reduced the NH3 emission by 43% and 57%, respectively. Ambiguous results for NH3 mitigation by using water sprinklers have been reported—an increase in NH3 emission by 27% and decrease of 27 to 56%. Manure harvesting should be evaluated in terms of maintaining proper moisture content, and not necessarily as a mitigation option. The use of chemical and physical manure amendments has shown a wide range in NH3 mitigation effectiveness, ranging from 19 to 98% for chemical and 0 to 43% for physical amendments, respectively. The review outlined the scientific basis, practicality, and expected efficacy of each management practice. The most plausible management practices to reduce NH3 emissions from corral surfaces in cattle feedyards are presented.
... De modellerede resultater er vist i Figur 1 og Tabel 1. Emissionsfaktoren stiger med stigende pH og tørstofniveau i den afgassede biomasse. Højere tørstofniveauer i den afgassede biomasse formodes at reducere infiltrationshastigheden ned i jorden, hvilket forlaenger perioden, hvor der er potentiale for afgasning af ammoniak til luften (Sommer & Olesen, 1991). Ligevaegten imellem ammoniak (NH3, gasform) og ammonium (NH4 + , vaeskeform) afhaenger af biomassens pH. ...
... In the literature data the dry matter was on average lower than the average dry matter value for digestates in Denmark based on available data (Table 5). These changes in characteristics can potentially change the emission factors drastically, as an increase in slurry dry matter on average increase ammonia emission when the digestate or slurry is surface applied (Häni et al., 2016;Misselbrook et al., 2005;Pedersen et al., 2022b;Sommer and Olesen, 1991). ...
Emission of greenhouse gases from liquid animal manure (slurry) can be reduced if slurry is treated through anaerobic digestion. The effluent from the reactor (digestate) can be utilized as a nutrient source for crop production if applied in the field. Physical and chemical properties of digestate vary considerably due to large variation in digester feedstock and operation, and these differences can affect ammonia emission following field application. Generally, there is a scarcity of literature assessing the downstream effects of anaerobic digestion of slurry on ammonia emission in the field, and different results have been reported. The present work summarizes current knowledge on ammonia emission after field application of digested slurry through a systematic literature review. Furthermore, implications of how the literature data are interpreted is evaluated with a focus on the current situation in Denmark, where the biogas industry is rapidly expanding. The potential effects of differences in pH and dry matter between raw slurry added to the digester and the digestate was evaluated with the ALFAM2 model. Overall, no consistent difference in emissions from digestate and undigested slurry was observed in literature data, likely due to opposing effects of consistent decreases in dry matter and increases in pH. However, due to the use of high dry matter co-substrates for biogas production in Denmark, the literature digestates are not representative of the current Danish conditions, where digestates may have high dry matter contents. Predictions from the AFLAM2 model show that the trend towards increasing dry matter contents of the digestates coupled with nearly universal elevated pH increases the risk of high ammonia emission. Better empirical documentation of emission is urgently needed, especially for high dry matter and high-viscosity digestate, along with new methods to mitigate emissions from land application of digestates with high emission potential.
... Soil conditions (moisture content, microtopography, porosity, and density) also impact NH 3 losses via interactions on turbulent diffusion of NH 3 from the manure surface and lateral transport, in addition to impacts on manure infiltration rates and surface roughness, which affect NH 3 losses [21]. Weather conditions also affect NH 3 loss [22][23][24][25]. Wind speed aids in the upward and sideways transport of NH 3 [14,15,24], although the effect of wind speed may not be a factor if manure incorporation occurs [26]. ...
Ammonia-nitrogen (NH3-N) loss from agriculture decreases crop yield potential and environmental quality. Incorporating animal manures by chisel plowing (CP) can reduce NH3 loss but may increase crop residue loss compared to lower disturbance incorporation methods and vertical tillage (VT). Few studies have evaluated VT efficacy for incorporating manure and reducing NH3 concentrations compared to traditional tillage tools, such as CP. Six trials during 2013 to 2016 were conducted to evaluate the impacts of manure incorporation method (CP, VT, or broadcast) and weather conditions at the time of application on NH3-N concentrations at a dairy research farm in central Wisconsin, USA. Passive samplers measured NH3-N concentrations at 30-cm above the ground during the first 0 to 24 and 24 to 48 h post-manure application/incorporation. Average NH3-N concentrations for CP and VT were 44 to 86% of broadcast and similar for most trials, while crop residue coverage for VT was greater than CP (39 and 22% of control plots, respectively). Concentrations of NH3-N were correlated with the amount of plot area covered by manure for the first (r = 0.56, p < 0.0001) and second measurement periods (r = 0.85, p < 0.0001). Results show that VT had comparable NH3-N concentration reductions to CP while conserving more crop residue.
... Aerobically stored manures when applied to field cause more ammonia losses as compared to anaerobically stored ones [15]. Ammonia loss from slurry is directly proportional to the dry matter content [16]. A comparison was made between ammonia volatilization from surface applied fresh and composted poultry manure under laboratory conditions. ...
Ammonia volatilization from animal slurry applied to agricultural fields reduces nitrogen use efficiency in agriculture and pollutes the environment. This work presents new versions of a model and database focused on this route of N loss. The public ALFAM2 database (https://github.com/AU-BCE-EE/ALFAM2-data) was expanded with ammonia emission and ancillary measurements for >700 additional field plots. The ALFAM2 model (https://github.com/AU-BCE-EE/ALFAM2, https://zenodo.org/records/13312251) was extended with the addition of an ammonia sink for more plausible predictions over extended durations and to better reflect the expected reduction in emission rate several days after slurry application. A new parameter set was developed for the model taking into account the newly available measurement data. Model efficiency improved to 0.67 for the parameter estimation subset (0.52 for cross-validation) and mean absolute error was around 10% of applied total ammoniacal nitrogen. As in earlier versions, predicted emission is sensitive to application method, slurry dry matter and pH, air temperature, and wind speed. A collection of parameter sets for estimating uncertainty in average predictions was developed using a bootstrap approach. Predicted uncertainty is not trivial, and is high for some variable combinations, highlighting the challenge of making predictions based on available measurement data. Still, this work has resulted in more accurate, comprehensive, transparent, and flexible tools for emission inventory and related work on ammonia loss from field-applied slurry.
Context
Manure deposition during livestock export voyages contributes to air ammonia levels, potentially affecting human and animal health if not managed. Mitigation strategies may include increased air change rates and application of bedding.
Aim
This study examined the effect of bedding application rate (BAR) and air change rate (ACH) on air ammonia (NH3) concentrations and pad properties, including pad surface condition, pH, moisture, and pad ammonium (NH4⁺) concentrations, for intensively housed beef cattle.
Methods
Six 7-day runs were conducted with 72 Bos indicus cross steers (mean liveweight ± s.d. = 338 ± 32 kg) housed in respiration chambers by using a 3 × 3 factorial design. The BARs were set to 0%, 50%, and 100% of the Australian Standards for the Export of Livestock (ASEL), and ACH were varied at 20, 35, and 52. Air NH3 was measured twice daily at three heights. Pad surface condition was collected with the first air NH3 measurement. Video footage captured standing and lying behaviours for each steer. Pad samples were collected on the final day for pad chemical analysis.
Key results
The ACH of 20 changes per hour resulted in higher air NH3 concentration than ACH of 35 and 52. Higher BAR led to lower pad pH and moisture, with slightly lower pad NH4⁺ concentration in 100% and 50% BAR than 0% BAR. Although air NH3 concentration on Day 7 was positively correlated with pad NH4⁺ concentration, BAR had no marked effect on air NH3 concentration (within the temperature range of this experiment). Drier and firmer pad surfaces were associated with each high BAR and high ACH. Moreover, high BAR increased the frequency of lying behaviour in steers.
Conclusions
These findings indicated that NH3 can be mitigated by optimising air changes to minimise air NH3 concentration and utilising bedding to minimise pad NH4⁺. This offers practical solutions for intensively housed beef cattle, such as livestock export voyages to improve human and animal welfare onboard.
Implications
The study results emphasised the importance of optimising ACH to maintain low air NH3 concentrations in livestock export conditions. Although there was no evidence that BAR affects air NH3 directly, it reduced pad NH4⁺ and improved pad conditions for overall animal comfort and environmental quality in confined housing with sufficient air changes.
To assess solid-liquid separation as a technology to reduce ammonia (NH3) emission from storage and field application of animal slurry, it is necessary to consider a possible higher NH3 loss from the solid fraction after application than from raw slurry, as well as losses during storage. A literature review was conducted, and a case study was developed for Denmark, including cattle slurry, pig slurry, and biogas digestate applied by trailing hose, trailing shoe, or open slot injection at five different periods of the year. Standard storage emission factors were used and emission factors after field application were estimated using the ALFAM2 model with input data for dry matter (DM), pH, total ammoniacal nitrogen (TAN), and separation efficiency all from the literature compilation. In general, a clear reduction in the emission factors after application of the liquid fraction was found relative to application of raw slurry in the literature data. Case study results provide some evidence that separation of cattle slurry or digestate, followed by storage and subsequent application by trailing hose or trailing shoe of the liquid fraction and broadcast application of the solid fraction reduces overall NH3 loss, with a higher
reduction when the solid fraction is incorporated by plowing after 4 h. This effect was not present for pig slurry. For all slurry types when the raw slurry and liquid fraction is applied by open slot injection, the overall reduction in emission due to separation is not present or even negative.
English peer-review publication of the results: https://doi.org/10.1016/j.jenvman.2022.116196
Ammonia-nitrogen (NH3 -N) loss from agriculture decreases crop yield potential and environ-mental quality. Incorporating animal manures by chisel plowing (CP) can reduce NH3 loss but may increase erosion and compaction potential compared to lower disturbance methods. Vertical tillage (VT) is designed to reduce disturbance and conserve more crop residue than CP, however its effect on NH3 loss from manure application is largely unknown. Six trials in corn production systems were conducted to evaluate the impacts of manure incorporation method (CP, VT, or broadcast) and weather conditions on NH3-N concentrations during 2013 to 2016 at a research farm in central Wisconsin, USA. Passive samplers were used to measure NH3-N concentrations at 30-cm above the ground during the first 0 to 24 and 24 to 48 hr post-application/incorporation. Average NH3 -N concentrations for CP and VT were 44 to 86% of surface broadcast and similar for most trials, while crop residue coverage was greater for VT than CP (39 and 22% of control plots, respectively). Concentrations of NH3 -N were correlated with the amount of plot area covered by manure for the first (r = 0.56, P<0.0001) and second measurement periods (r = 0.85, P<0.0001). Results show that VT had comparable NH3-N concentration reductions to CP while conserving more crop residue.
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