In-vitro method and model to estimate methane emissions from liquid manure management on pig and dairy farms in four countries.

Methane (CH4) emissions from manure management on livestock farms are a key source of greenhouse gas emissions in some regions and for some production systems, and the opportunities for mitigation may be significant if emissions can be adequately documented. We investigated a method for estimating CH4 emissions from liquid manure (slurry) that is based on anaerobic incubation of slurry collected from commercial farms. Methane production rates were used to derive a parameter of the Arrhenius temperature response function, lnA', representing the CH4 production potential of the slurry at the time of sampling. Results were used for parameterization of an empirical model to estimate annual emissions with daily time steps, where CH4 emissions from individual sources (barns, outside storage tanks) can be calculated separately. A monitoring program was conducted in four countries, i.e., Denmark, Sweden, Germany and the Netherlands, during a 12-month period where slurry was sampled to represent barn and outside storage on finishing pig and dairy farms. Across the four countries, lnA' was higher in pig slurry compared to cattle slurry (p < 0.01), and higher in slurry from barns compared to outside storage (p < 0.01). In a separate evaluation of the incubation method, in-vitro CH4 production rates were comparable with in-situ emissions. The results indicate that lnA' in barns increases with slurry age, probably due to growth or adaptation of the methanogenic microbial community. Using lnA' values determined experimentally, empirical models with daily time steps were constructed for finishing pig and dairy farms and used for scenario analyses. Annual emissions from pig slurry were predicted to be 2.5 times higher than those from cattle slurry. Changing the frequency of slurry export from the barn on the model pig farm from 40 to 7 d intervals reduced total annual CH4 emissions by 46 %; this effect would be much less on cattle farms with natural ventilation. In a scenario with cattle slurry, the empirical model was compared with the current IPCC methodology. The seasonal dynamics were less pronounced, and annual CH4 emissions were lower than with the current methodology, which calls for further investigations. Country-specific models for individual animal categories and point sources could be a tool for assessing CH4 emissions and mitigation potentials at farm level.

Nitrogen inputs by irrigation is a missing link in the agricultural nitrogen cycle and related policies in Europe.

Irrigation, one of the 28 agri-environmental indicators defined in the European Common Agricultural Policy, is often neglected in agricultural nitrogen (N) budgets, while it can be a considerable source of N in irrigated agriculture. The annual N input from irrigation water sources (NIrrig) to cropping systems was quantified for Europe for 2000-2010 at a resolution of 10 × 10 km, accounting for crop-specific gross irrigation requirements (GIR) and surface- and groundwater nitrate concentration. GIR were computed for 20 crops, while spatially explicit nitrate concentration in groundwater was derived using a random forest model. We show that although GIR were relatively stable (46-60 km3 yr-1), the Nirrig in Europe increased over the 10-year period (184 to 259 Gg N yr-1), approximately 68 % of which occurred in the Mediterranean region. The main hotspots appeared in areas with both high irrigation requirements and high groundwater nitrate concentration, reaching up to averaged values of 150 kg N ha-1 yr1. These were mainly located in Mediterranean Europe (Greece, Portugal and Spain) and to a lesser extent in Northern Europe (The Netherlands, Sweden and Germany). By not including NIrrig, environmental and agricultural policies are underestimating the real extent of N pollution hotspots in European irrigated systems.

DATAMAN: A global database of methane, nitrous oxide, and ammonia emission factors for livestock housing and outdoor storage of manure.

Livestock manure management systems can be significant sources of nitrous oxide (N2 O), methane (CH4 ), and ammonia (NH3 ) emissions. Many studies have been conducted to improve our understanding of the emission processes and to identify influential variables in order to develop mitigation techniques adapted to each manure management step (animal housing, outdoor storage, and manure spreading to land). The international project DATAMAN (http://www.dataman.co.nz) aims to develop a global database on greenhouse gases (N2 O, CH4 ) and NH3 emissions from the manure management chain to refine emission factors (EFs) for national greenhouse gas and NH3 inventories. This paper describes the housing and outdoor storage components of this database. Relevant information for different animal categories, manure types, livestock buildings, outdoor storage, and climatic conditions was collated from published peer reviewed research, conference papers, and existing databases published between 1995 and 2021. In the housing database, 2024 EFs were collated (63% for NH3 , 19.5% for CH4 , and 17.5% for N2 O). The storage database contains 654 NH3 EFs from 16 countries, 243 CH4 EFs from 13 countries, and 421 N2 O EFs from 17 countries. Across all gases, dairy cattle and swine production in temperate climate zones are the most represented animal and climate categories. As for the housing database, the number of EFs for the tropical climate zone is under-represented. The DATAMAN database can be used for the refinement of national inventories and better assessment of the cost-effectiveness of a range of mitigation strategies.

Vitamin D status in Armenian women: a stratified cross-sectional cluster analysis.

BACKGROUND: Vitamin D plays a critical role in skeletal development and maintenance, thus sufficiency is an important goal for public health programs. Given the absence of foods fortified in vitamin D in Armenia, we hypothesized that vitamin D insufficiency would be widespread. METHODS: We conducted a random modified cluster model survey of vitamin D status of women in the country. We measured 25-hydroxyvitamin D [25(OH)D] by liquid chromatography mass spectrometry in dried blood spot samples and utilized a questionnaire to assess lifestyle factors. RESULTS: In summer, we sampled 1206 participants from 40 communities in Armenia. Mean 25-OH D level among women aged 18-24 was 20 ± 8 ng/mL; aged 25-64 was 21 ± 7 ng/mL; and >65 was 18 ± 8 ng/mL. The country-wide mean of the entire female population was 20 ± 8 ng/mL. A majority (>54%) had 25-OH D levels <20 ng/mL with nearly 13% having 25-OH D levels <12 ng/mL. Participants who reported calcium, vitamin D, or multivitamin supplementation had higher levels of 25-OH D (p values 0.004, 0.0002, and 0.03 respectively) as did pre- vs. postmenopausal women (p = 0.01), pregnant vs. nonpregnant women (p = <0.0001), and women who had experienced a sunburn in the past year (p = 0.004). CONCLUSION: In Armenia, there is a high prevalence of vitamin D insufficiency. This information provides data that can be used to inform public health directives to address this pervasive threat to optimal health.

Ammonia and nitrous oxide emission factors for excreta deposited by livestock and land-applied manure.

Manure application to land and deposition of urine and dung by grazing animals are major sources of ammonia (NH3 ) and nitrous oxide (N2 O) emissions. Using data on NH3 and N2 O emissions following land-applied manures and excreta deposited during grazing, emission factors (EFs) disaggregated by climate zone were developed, and the effects of mitigation strategies were evaluated. The NH3 data represent emissions from cattle and swine manures in temperate wet climates, and the N2 O data include cattle, sheep, and swine manure emissions in temperate wet/dry and tropical wet/dry climates. The NH3 EFs for broadcast cattle solid manure and slurry were 0.03 and 0.24 kg NH3 -N kg-1 total N (TN), respectively, whereas the NH3 EF of broadcast swine slurry was 0.29. Emissions from both cattle and swine slurry were reduced between 46 and 62% with low-emissions application methods. Land application of cattle and swine manure in wet climates had EFs of 0.005 and 0.011 kg N2 O-N kg-1 TN, respectively, whereas in dry climates the EF for cattle manure was 0.0031. The N2 O EFs for cattle urine and dung in wet climates were 0.0095 and 0.002 kg N2 O-N kg-1 TN, respectively, which were three times greater than for dry climates. The N2 O EFs for sheep urine and dung in wet climates were 0.0043 and 0.0005, respectively. The use of nitrification inhibitors reduced emissions in swine manure, cattle urine/dung, and sheep urine by 45-63%. These enhanced EFs can improve national inventories; however, more data from poorly represented regions (e.g., Asia, Africa, South America) are needed.

Development of a groundwater contamination index based on the agricultural hazard and aquifer vulnerability: Application to Portugal.

Reducing nitrate leaching may not result in a significant improvement of groundwater quality. The amount of nitrate reaching groundwater depends not only on the hazard related to agricultural activities but also on-site specific groundwater vulnerability. Using national databases and other compiled datasets, the agricultural hazard was calculated as the ratio of (i) the nitrate leached estimated from the N surplus, and (ii) the water surplus, a proxy of the percolating water below the root zone. By combining the hazard with a multi-parameter groundwater vulnerability, a spatially explicit groundwater contamination risk, developed for mainland Portugal, was computed for 1999 and 2009. Results show an increase from 8,800 to 82,679 ha of the territory rated with a very high contamination risk. The priority areas were successfully screened by the Index, coinciding with the current Vulnerable Zones, although additional hotspots were detected in southern Portugal. Percolation, including both irrigation activity and precipitation, was found to be a key driver for the groundwater contamination risk due to its opposite effects in the hazard and in the vulnerability. Reducing nitrogen leaching may be insufficient to reduce the risk of nitrate contamination if there is a relatively larger reduction in precipitation. This index is particularly useful when applied to contrasting situations of vulnerability and hazard, which require distinct mitigation measures to mitigate groundwater contamination.

DATAMAN: A global database of nitrous oxide and ammonia emission factors for excreta deposited by livestock and land-applied manure.

Nitrous oxide (N2 O), ammonia (NH3 ), and methane (CH4 ) emissions from the manure management chain of livestock production systems are important contributors to greenhouse gases (GHGs) and NH3 emitted by human activities. Several studies have evaluated manure-related emissions and associated key variables at regional, national, or continental scales. However, there have been few studies focusing on the drivers of these emissions using a global dataset. An international project was created (DATAMAN) to develop a global database on GHG and NH3 emissions from the manure management chain (housing, storage, and field) to identify key variables influencing emissions and ultimately to refine emission factors (EFs) for future national GHG inventories and NH3 emission reporting. This paper describes the "field" database that focuses on N2 O and NH3 EFs from land-applied manure and excreta deposited by grazing livestock. We collated relevant information (EFs, manure characteristics, soil properties, and climatic conditions) from published peer-reviewed research, conference papers, and existing databases. The database, containing 5,632 observations compiled from 184 studies, was relatively evenly split between N2 O and NH3 (56 and 44% of the EF values, respectively). The N2 O data were derived from studies conducted in 21 countries on five continents, with New Zealand, the United Kingdom, Kenya, and Brazil representing 86% of the data. The NH3 data originated from studies conducted in 17 countries on four continents, with the United Kingdom, Denmark, Canada, and The Netherlands representing 79% of the data. Wet temperate climates represented 90% of the total database. The DATAMAN field database is available at http://www.dataman.co.nz.

MECHANISMS IN ENDOCRINOLOGY: Vitamin D and COVID-19.

The SARS-CoV-2 virus responsible for the COVID-19 pandemic has generated an explosion of interest both in the mechanisms of infection leading to dissemination and expression of this disease, and in potential risk factors that may have a mechanistic basis for disease propagation or control. Vitamin D has emerged as a factor that may be involved in these two areas. The focus of this article is to apply our current understanding of vitamin D as a facilitator of immunocompetence both with regard to innate and adaptive immunity and to consider how this may relate to COVID-19 disease. There are also intriguing potential links to vitamin D as a factor in the cytokine storm that portends some of the most serious consequences of SARS-CoV-2 infection, such as the acute respiratory distress syndrome. Moreover, cardiac and coagulopathic features of COVID-19 disease deserve attention as they may also be related to vitamin D. Finally, we review the current clinical data associating vitamin D with SARS-CoV-2 infection, a putative clinical link that at this time must still be considered hypothetical.

Residues of xenobiotics in the environment and phytotoxic activity in Armenia.

The article presents the results of a dynamic study (spring, summer, and fall) of the residues of certain xenobiotics such as organochlorine pesticides (OCPs), synthetic surfactants (SSs) in surface water, soil, sludge, snow and phytotoxic activity in Ararat and Lori marzes of Armenia (2016-2017). A comparative analysis of the environmental status showed that all pollutants studied such as γ-hexachlorocyclohexane (γ-HCH), 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (4,4'-DDT), and p-p'-dichlorodiphenyldichloroethylene (4,4'-DDE) were identified in Ararat marz with the average concentrations and detection rates higher than in Lori marz. The prominent contaminant was γ-HCH. The findings indicated the concentrations of OCPs below of regulatory concern. In Ararat marz an increase in the number of sterile pollen grains of certain wild plants was revealed (14.8-26.0%), compared with Lori marz with the levels within the contingent standard of 5-11%. The phytotoxic activity of soil samples from the Ararat marz studied on Avena sativa seedlings was significantly higher in the summer-fall period. These data correlated with monitoring findings showed an increase in the levels of γ-HCH, 4,4'-DDT, SS in the soil and sludge sampled in summer-fall in Ararat marz. This difference in the environmental status can be considered as the result of active agriculture in Ararat marz, whose share of contribution to a relevant branch of the economy of Armenia is two times higher than in Lori marz, 15.4% and 7.9%, respectively. Mentioned rates of agricultural production may be one of the reasons for the environmental deterioration in Ararat marz. The detection of 4,4-DDT, γ-HCH residues testifies the circulation of these formulations in the environment indicating their use in recent past and confirming their persistence. Although since the 70s of the last century the application of OCPs in the Republic of Armenia has been prohibited. The current situation may be explained by low awareness of farmers on different issues related to the safe management of pesticides. To ensure safe working conditions and raise awareness among the farmers we have developed "Recommendations on Safety requirements when working with pesticides" that are approved by the State Service for Food Safety at the Ministry of Agriculture of RA and included in the reference booklets for farmers as guiding information. Our study shows the understanding of associations between the deterioration of the environmental status and share of agriculture contribution to the economy that provides the evidence for future research programs.

A STRATIFIED CROSS-SECTIONAL CLUSTER MODEL SURVEY OF IODINE NUTRITION IN ARMENIA AFTER A DECADE OF UNIVERSAL SALT IODIZATION.

Objective: Iodine is a necessary nutrient for the synthesis of thyroid hormones and essential in human development. Being naturally deficient in iodine, Armenia launched a national universal salt iodization (USI) strategy in 2004. Although high rates of goiter continued to be reported, iodine status has not been studied since 2005. Therefore, this study sought to assess the current situation of population iodine nutrition in Armenia. Methods: We used a selective cross-sectional model to recruit three groups: school-age children (SAC), pregnant women (PW), and nonpregnant women of reproductive age (WRA) from each province. We collected casual urine and table salt samples from each participant, which were analyzed for iodine concentration. A repeat urine sample was collected in a subset of participants to adjust the results for within-person variation in iodine concentration. Group-wise urinary iodine concentrations (UICs) were compared with international reference criteria for iodine status. Results: Urine samples were collected from 1,125 participants from 13 different towns in Armenia; a total of 1,078 participants were included in the final analysis: 361 SAC (mean age, 10.5 years, 46.6% female), 356 PW (mean age, 26.1 years), and 361 WRA (mean age, 35.5 years). Population and geographically weighted median UIC were: SAC, 242 µg/L ([25th percentile] 203 to [75th percentile] 289 µg/L); PW, 226 µg/L (209 to 247 µg/L); WRA, 311 µg/L (244 to 371 µg/L). A total of 1,041 table salt samples were sufficient for laboratory analysis: 973 (93.4%) of the salt iodine measurements were within the national standard range of 40 ± 15 mg/kg. Conclusion: The results of household salt sampling indicated a successful USI strategy. While the present study did not achieve a truly representative sample of Armenia's population, the UIC results support the conclusion that iodine deficiency has not recurred and is not an underlying factor for any remaining high goiter prevalence in Armenia. Abbreviations: PW = pregnant women; SAC = school-age children; SI = salt iodine; UIC = urinary iodine concentration; USI = universal salt iodization; WHO = World Health Organization; WRA = women of reproductive age.

Neonatal thyrotropin (TSH) screening as a tool for monitoring iodine nutrition in Armenia.

BACKGROUND: Neonatal thyrotropin (TSH) is influenced not only by the infant's own thyroid function, but also by maternal thyroid status, and can thus provide a general index of thyroid health in the community. METHODS: In 2012, the Republic of Armenia implemented a program of universal neonatal hypothyroidism screening by means of measuring the serum TSH level. The Arabkir Medical Center in Yerevan, Armenia, has maintained records of neonatal TSH screening data comprising nearly 100% of all births in Armenia from 2012 through 2016. We analyzed these data to determine the frequency of neonatal TSH levels higher than the cut point of 5 mIU/L, indicative of sufficient iodine nutrition status, and to detect any time dependence over years or regional variation. RESULTS: A total of 127,177 records from 2012 to 2016 were included. The geographic distribution of neonatal TSH records was reflective of the population of Armenia; the national percentage of records over 5 mIU/L ranged from a high of 2.88% in 2012 to a low of 1.71% in 2016. Minimal regional variation was noted, from a 2012-2016 cumulative high of 2.93% of records over 5 mIU/L in Shirak province to a low of 0.95% in the Vayots Dzor province. CONCLUSIONS: From all years and from all regions, values were consistently and uniformly below the cut point of 5 mIU/L. These results show no evidence of iodine deficiency in Armenia, and suggest that neonatal TSH may be a useful tool for monitoring iodine nutrition in Armenia.

Constituent analysis of iodine intake in Armenia.

OBJECTIVE: We sought to assess the universal salt iodization (USI) strategy in Armenia by characterizing dietary iodine intake from naturally occurring iodine, salt-derived iodine in processed foods and salt-derived iodine in household-prepared foods. DESIGN: Using a cross-sectional cluster survey model, we collected urine samples which were analysed for iodine and sodium concentrations (UIC and UNaC) and household salt samples which were analysed for iodine concentration (SI). SI and UNaC data were used as explanatory variables in multiple linear regression analyses with UIC as dependent variable, and the regression parameters were used to estimate the iodine intake sources attributable to native iodine and iodine from salt in processed foods and household salt. SETTING: Armenia is naturally iodine deficient; in 2004, the government mandated a USI strategy. SUBJECTS: We recruited school-age children (SAC), pregnant women (PW) and non-pregnant women of reproductive age (WRA). RESULTS: From thirteen sites covering all provinces, sufficient urine and table salt samples were obtained from 312 SAC, 311 PW and 332 WRA. Findings revealed significant differences between groups: contribution of native iodine ranged from 81% in PW to 46% in SAC, while household salt-derived iodine contributed from 19% in SAC to 1% in PW. CONCLUSIONS: Differences between groups may reflect differences in diet. In all groups, household and processed food salt constituted a significant part of total iodine intake, highlighting the success and importance of USI in ensuring iodine sufficiency. There appears to be leeway to reduce salt intake without adversely affecting the iodine status of the population in Armenia.

A comparison of disaggregated nitrogen budgets for Danish agriculture using Europe-wide and national approaches.

Spatially detailed information on agricultural nitrogen (N) budgets is relevant to identify regions where there is a need for a reduction in inputs in view of various forms of N pollution. However, at the scale of the European Union, there is a lack of consistent, reliable, high spatial resolution data necessary for the calculation of regional N losses. To gain insight in the reduction in uncertainty achieved by using higher spatial resolution input data. This was done by comparing spatially disaggregated agricultural N budgets for Denmark for the period 2000-2010, generated by two versions of the European scale model Integrator, a version using high spatial resolution national data for Denmark (Integrator-DK) and a version using available data at the EU scale (Integrator-EU). Results showed that the national N fluxes in the N budgets calculated by the two versions of the model were within 1-5% for N inputs by fertilizer and manure excretion, but inputs by N fixation and N mineralisation differed by 50-100% and N uptake also differed by ca 25%, causing a difference in N leaching and runoff of nearly 50%. Comparison with an independently derived Danish national budget appeared generally to be better with Integrator-EU results in 2000 but with Integrator-DK results in 2010. However, the spatial distribution of manure distribution and N losses from Integrator-DK were closer to observed distributions than those from Integrator-EU. We conclude that close attention to local agronomic practices is needed when using a leaching fraction approach and that for effective support of environmental policymaking, Member States need to collect or submit high spatial resolution agricultural data to Eurostat.

Characterization of Cellular Immune Responses in Thai Individuals With and Without HIV-Associated Neurocognitive Disorders.

HIV-associated neurocognitive disorder (HAND) remains a challenge despite antiretroviral therapy (ART), and has been linked to monocyte/macrophage (M/M) migration to the brain. Due to the potential impact of T cell effector mechanisms in eliminating activated/HIV-infected M/M, T cell activation may play a role in the development of HAND. We sought to investigate the relationship between cognition and both CD8+ T cell activation (HLA-DR+/CD38+) and HIV-specific CD8+ T cell responses at the time of HIV diagnosis and 12 months postinitiation of ART. CD8+ T cell activation was increased in HAND compared to cognitive normal (NL) individuals and correlated directly with plasma viral load and inversely with the cognitive status. In addition, Gag-specific cytolytic activity (CD107a/b+) was decreased in HAND compared with NL individuals and correlated with their neurological testing, suggesting a potential role of cytotoxic CD8+ T cells in the mechanism of HAND development.

IODINE NUTRITION IN THE REPUBLIC OF ARTSAKH (NAGORNO KARABAKH).

OBJECTIVE: Iodine is a required nutrient for thyroid function. The mountainous terrain in the Republic of Artsakh (Nagorno Karabakh) in the south Caucasus suggests that it is likely to be endogenously deficient in iodine. The region is heavily dependent on neighboring Armenia for food imports including iodized salt. Since 2005, iodine is a government-sanctioned compulsory supplemental ingredient in salt in Armenia. However, there has never been a study of iodine nutrition in Artsakh. We sought to determine the level of iodine nutrition in Artsakh and the iodine content of table salt in the region. METHODS: Using a cross-sectional modified cluster model, we measured urine and salt iodine concentrations from a representative sample of children living in Artsakh. From 30 schools throughout the territory, we obtained 772 urine samples from children aged 8 to 10, and 323 samples of table salt. Repeat urine samples from 18.6% of participants were obtained. RESULTS: The median adjusted urinary iodine content was 203 µg/L (mean 206 µg/L, 95% confidence interval 202-210), within the range indicating sufficient iodine nutrition. There were small but statistically significant differences between the 8 administrative regions; however, there were no differences between individual sites. We found that 97.2% of table salt samples tested had iodine concentrations within the standard of 25 to 55 mg/kg. CONCLUSION: Among school-age children in Artsakh, iodine nutrition is adequate, and the salt is appropriately iodized. These results illustrate the remarkable success of the Armenian salt iodization program in providing sufficient but not excessive iodine to the mountainous territory of Artsakh. Abbreviation: UIC = urinary iodine concentration.

Practice effect and normative data of an HIV-specific neuropsychological testing battery among healthy Thais.

OBJECTIVE: A longitudinal cohort study was conducted in Bangkok, Thailand between 2008 and 2013 in order to determine the practice effect of serial neuropsychological testing and establish normative data among normal (HIV-uninfected) Thai volunteers. MATERIAL AND METHOD: The authors enrolled 511 cognitively healthy individuals (HIV-uninfected, no drug abuse or other previous/current neurological or psychological conditions) to assess baseline performance on a HIV-specific neuropsychological testing battery. Ninety-nine subjects were re-assessed at 6 and 12 months to evaluate practice effects. RESULTS: The mean age of the 99 subjects completing longitudinal visits was 49.2 years and 53 were male. The authors identified improved mean raw scores on most neuropsychological tests with repeated measurements; however only change in WHO Auditory Verbal Learning Test (AVLT) scores (learning, attention, immediate and delayed recall tasks) met statistical significance, with larger differences seen between baseline and 6-month compared to 6 and 12 months follow-up. Older age correlated with poorer baseline raw score, and was a predictor of worse performance at 6 months and 12 months on several tasks. Level of education was associated with practice effects on several tests. No similar effects were observed with gender. CONCLUSION: The authors identified improved performance after repeated measurements revealing a significant practice effect on an HIV-specific neuropsychological testing battery employed in Bangkok, Thailand. Main predictors were age and educational attainment.

Life cycle assessment of pig slurry treatment technologies for nutrient redistribution in Denmark.

Animal slurry management is associated with a range of impacts on fossil resource use and the environment. The impacts are greatest when large amounts of nutrient-rich slurry from livestock production cannot be adequately utilised on adjacent land. To facilitate nutrient redistribution, a range of different technologies are available. This study comprised a life cycle assessment of the environmental impacts from handling 1000 kg of pig slurry ex-animal. Application of untreated pig slurry onto adjacent land was compared with using four different treatment technologies to enable nutrient redistribution before land application: (a) separation by mechanical screw press, (b) screw press separation with composting of the solid fraction, (c) separation by decanter centrifuge, and (d) decanter centrifuge separation with ammonia stripping of the liquid fraction. Emissions were determined based on a combination of values derived from the literature and simulations with the Farm-N model for Danish agricultural and climatic conditions. The environmental impact categories assessed were climate change, freshwater eutrophication, marine eutrophication, terrestrial acidification, natural resource use, and soil carbon, nitrogen and phosphorus storage. In all separation scenarios, the liquid fraction was applied to land on the pig-producing (donor) farm and the solid fraction transported to a recipient farm and utilised for crop production. Separation, especially by centrifuge, was found to result in a lower environmental impact potential than application of untreated slurry to adjacent land. Composting and ammonia stripping either slightly increased or slightly decreased the environmental impact potential, depending on the impact category considered. The relative ranking of scenarios did not change after a sensitivity analysis in which coefficients for field emissions of nitrous oxide, ammonia and phosphorus were varied within the range cited in the literature. Therefore, the best technology to implement in a given situation depends on the environmental problem in question, local policy, cost and practicality.

Effect of Livestock Slurry Ozonation and Separation on pH, Particles, and Phosphate.

Applying slurry to arable land as fertilizer increases the risk of phosphorus (P) runoff and thereby increases the risk of eutrophication. Solid-liquid separation can reduce the excess application of P, and this study focused on the use of ozonation as an alternative chemical pretreatment for separation to improve P separation efficiency. Sow and cattle slurries were separated by screw press and flocculation+filtration. The screw press and flocculation liquid fractions and raw slurries were treated with no ozone or with low-, medium-, or high-ozone doses and then separated by centrifugation. The pH, particle size distribution, dry matter, and dissolved phosphate (PO) concentrations were measured. For separations without ozonation, pH increased by 0.15 to 0.87 pH units, and correlation analysis showed that the dissolved PO concentration decreased with increasing pH and particle removal efficiency. During ozonation, pH increased, and a shift in particle size distribution in the liquid fraction combined with an improved dry matter separation indicated particle aggregation. Ozonation thus affected the parameters found to affect dissolved PO separation, and at the highest ozone dose, dissolved PO separation efficiency increased by 7 to 81%. An ozonation pretreatment may therefore promote removal of dissolved PO from the liquid fraction during separation.

Modelling the potential of slurry management technologies to reduce the constraints of environmental legislation on pig production.

Limits on land applications of slurry nitrogen (N) and phosphorus (P) are used to restrict losses of nutrients caused by livestock production. Here, we used a model to assess technologies that enable a more even geographic distribution of slurry nutrients to land. Technologies included were screw press slurry separation, with or without solid fraction composting, centrifuge separation with or without liquid fraction ammonia (NH3) stripping, and anaerobic digestion. Regulatory constraints were placed first on the application in slurry of N, then P, then N and P both on the producing (donor) and receiving (recipient) farms. Finally, a constraint preventing an increase in donor farm NH3 emissions was imposed. Separation had little effect on N losses per unit mass of slurry, but NH3 stripping led to a reduction. Centrifuge separation allowed a greater increase in pig production than a screw press, especially with P regulation. NH3 stripping was only advantageous with N regulation or when combined with NH3 scrubbing of pig housing ventilation air, when donor farm NH3 emissions were a constraint. There was a production penalty for using composting or anaerobic digestion. The choice of appropriate slurry management option therefore depends on the focus of the regulation. Nuanced and therefore complex regulations are necessary to take advantage of synergies and avoid cross-policy conflicts and incongruencies.