Assessment of nitrogen ceilings for Dutch agricultural soils to avoid adverse environmental impacts.
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In the Netherlands, high traffic density and intensive animal husbandry have led to high emissions of reactive nitrogen (N) into the environment. This leads to a series of environmental impacts, including: (1) nitrate (NO3) contamination of drinking water, (2) eutrophication of freshwater lakes, (3) acidification and biodiversity impacts on terrestrial ecosystems, (4) ozone and particle formation affecting human health, and (5) global climate change induced by emissions of N2O. Measures to control reactive N emissions were, up to now, directed towards those different environmental themes. Here we summarize the results of a study to analyse the agricultural N problem in the Netherlands in an integrated way, which means that all relevant aspects are taken into account simultaneously. A simple N balance model was developed, representing all crucial processes in the N chain, to calculate acceptable N inputs to the farm (so-called N ceiling) and to the soil surface (application in the field) by feed concentrates, organic manure, fertiliser, deposition, and N fixation. The N ceilings were calculated on the basis of critical limits for NO 3 concentrations in groundwater, N concentrations in surface water, and ammonia (NH3) emission targets related to the protection of biodiversity of natural areas. Results show that in most parts of the Netherlands, except the western and the northern part, the N ceilings are limited by NH 3 emissions, which are derived from critical N loads for nature areas, rather than limits for both ground- and surface water. On the national scale, the N ceiling ranges between 372 and 858 kton year(-1) depending on the choice of critical limits. The current N import is 848 kton year(-1). A decrease of nearly 60% is needed to reach the ceilings that are necessary to protect the environment against all adverse impacts of N pollution from agriculture. (+info)
An assessment of ammonia emissions from dairy facilities in Pennsylvania.
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A survey of 715 Holstein dairy farms in Pennsylvania was used to construct demographics for the average Holstein dairy farm. The average Holstein dairy farm was composed of 69 lactating cows; 11 nonlactating, pregnant cows; 44 heifers; and 18 calves. Milk production averaged 27.3 kg (60.0 lb). Crop area averaged 73.6 ha. Milk production, crop area and type, average county yields, and herd animal groups were used to construct a typical feeding program for these farms. Typical rations were constructed for six feeding groups (three milk production groups, one nonlactating group, two heifer groups) to meet milk production, pregnancy, and growth requirements. Rations were constructed based on three forage qualities (excellent, average, and poor) typically observed on Pennsylvania dairy farms. Data for animal description (milk production, body weight, growth, and pregnancy status) and ration components and amounts consumed for each animal group were input into the excretion model of the Dairy Nutrient Planner computer program (DNP). Excretion of fecal N and dry matter (DM), urinary N, and total P and K were produced for each animal group and used to assess potential volatile losses of N. Work at the Marshak Dairy, New Bolton Center, indicates the majority of urinary N is rapidly lost as ammonia from dairy facilities. Based on this observation, the losses of N as ammonia were estimated to be 4.63, 4.62, and 4.28 tonne/year for the farm with excellent, average, and poor quality forages, respectively. Volatile losses of N may be reduced most by controlling levels of urea in urine. Urinary N may be reduced through dietary manipulation of protein and carbohydrate sources. Conversion of urea to ammonia may be reduced by altering the pH of barn floors and gutters. Entrapment of ammonia may be accomplished by acidification of manure slurry. Atmospheric ammonia contributes to acid rain, eutrophication of estuaries and lakes, and particulate air pollution. Reduction of ammonia emissions from dairy barns can significantly reduce atmospheric pollution and improve air and water quality. (+info)
Managing ammonia emissions from dairy cows by amending slurry with alum or zeolite or by diet modification.
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Animal agriculture is a significant source of atmospheric ammonia. Ammonia (NH3) volatilization represents a loss of plant available N to the farmer and a potential contributor to eutrophication in low-nitrogen input ecosystems. This research evaluated on-farm slurry treatments of alum or zeolite and compared three diets for lactating dairy cows in their effectiveness to reduce NH3 emissions. NH3 emissions were compared using a group of mobile wind tunnels. The addition of 2.5% alum or 6.25% zeolite to barn-stored dairy slurry reduced NH3 volatilization by 60% and 55%, respectively, compared to untreated slurry. The alum conserved NH3 by acidifying the slurry to below pH 5, while the zeolite conserved ammonia by lowering the solution-phase nitrogen through cation exchange. The use of alum or zeolite also reduced soluble phosphorus in the slurry. NH3 loss from fresh manure collected from lactating dairy cows was not affected by three diets containing the same level of crude protein but differing in forage source (orchardgrass silage vs. alfalfa silage) or neutral detergent fiber (NDF) content (30% vs. 35% NDF). NH3 losses from the freshly excreted manures occurred very rapidly and included the urea component plus some unidentified labile organic nitrogen sources. NH3 conservation strategies for fresh manures will have to be active within the first few hours after excretion in order to be most effective. The use of alum or zeolites as an on-farm amendment to dairy slurry offers the potential for significantly reducing NH3 emissions. (+info)
Effect of soil type and fertilization level on mineral concentration of pasture: potential relationships to ruminant performance and health.
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A three-year study was conducted to measure the effects of varying levels of dairy slurry application on mineral concentration of forages from three soils types. Slurry was applied to orchardgrass (Dactylis glomerata [L.] cv. Pennlate) growing in 60-cm diameter drainage lysimeters to measure the effect of four levels of slurry (urine and feces) N application (0, 168, 336, and 672 kg of N.ha-1.yr-1) on mineral (P, K, Ca, Mg) concentration of the forage on three soil types (Hagerstown, Hartleton, and Rayne). The results were then related to potential effects on performance and health of grazing ruminants. Forage P was not affected by slurry application (mean = 0.46% of DM). Forage grown on the Hartleton soil had the highest (P < 0.05) P concentration (0.6% of DM). Forage K increased (P < 0.05) with increased slurry (2.50, 2.85, 3.22, and 3.45% of DM, respectively), and was lowest (P < 0.05) for forage grown on the Rayne soil (2.69% of DM). Forage Ca decreased (P < 0.05) with increased slurry (0.59, 0.56, 0.50, and 0.49% of DM, respectively) and was not affected by soil type. Forage Mg also decreased (P < 0.05) with increased slurry (0.25, 0.24, 0.24, and 0.23% of DM, respectively), and was highest (P < 0.05) for the Hartleton soil (0.27% of DM). The variable results in mineral concentration associated with soil type may have, in part, been due to prior soil fertility. The P and Mg concentrations in all treatments were generally adequate for grazing ruminants. The K concentrations were high in relation to NRC recommendations for prepartum dairy cows, which might predispose them to milk fever. The Ca concentrations were inadequate for lactating dairy cows. Comprehensive forage testing and diet formulation based on individual farm situations is the best strategy to ensure proper mineral nutrition of grazing animals. (+info)
Identification of a new ribosomal protection type of tetracycline resistance gene, tet(36), from swine manure pits.
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Previously, only one ribosome protection type of a tetracycline resistance gene, tetQ, had been identified in Bacteroides spp. During an investigation of anaerobic bacteria present in swine feces and manure storage pits, a tetracycline-resistant Bacteroides strain was isolated. Subsequent analysis showed that this new Bacteroides strain, Bacteroides sp. strain 139, did not contain tetQ but contained a previously unidentified tetracycline resistance gene. Sequence analysis showed that the tetracycline resistance gene from Bacteroides sp. strain 139 encoded a protein (designated Tet 36) that defines a new class of ribosome protection types of tetracycline resistance. Tet 36 has 60% amino acid identity over 640 aa to TetQ and between 31 and 49% amino acid identity to the nine other ribosome protection types of tetracycline resistance genes. The tet(36) region was not observed to transfer from Bacteroides sp. strain 139 to another Bacteroides sp. under laboratory conditions. Yet tet(36) was found in other genera of bacteria isolated from the same swine manure pits and from swine feces. Phylogenetic analysis of the tet(36)-containing isolates indicated that tet(36) was present not only in the Cytophaga-Flavobacter-Bacteroides group to which Bacteroides sp. strain 139 belongs but also in gram-positive genera and gram-negative proteobacteria, indicating that horizontal transfer of tet(36) is occurring between these divergent phylogenetic groups in the farm environment. (+info)
Ammonia, volatile fatty acids, phenolics, and odor offensiveness in manure from growing pigs fed diets reduced in protein concentration.
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The objective of this study was to investigate whether reducing dietary CP concentration decreases fecal VFA, manure ammonia (NH3) emission and odor, and urinary phenolic metabolites. Six barrows were allotted to one of six dietary treatments in a Latin square design. Treatments consisted of four corn-soybean meal based diets containing 15, 12, 9, and 6% CP, a casein-based diet containing 15% CP, and a protein-free diet (0% protein). Crystalline AA were included in the 12, 9, and 6% CP diets. The casein-based and protein-free diets were used to determine basal endogenous contribution of VFA, phenolics, NH3, and manure odor. Pigs were housed individually in metabolism cages to allow total collection of feces and urine. Feces and urine were collected and pooled within pig and period. Feces and urine were analyzed for VFA and phenolic metabolite concentrations, respectively. Feces and urine were then mixed, stored, and fermented at room temperature for 30 d. For NH3 determination, headspace air was sampled from manure slurries at 24, 48, and 72 h after fermentation. Slurry samples were placed into vials, capped, and randomized before odor panel evaluation. Odor offensiveness was classified on severity: 1 = non-offensive; 2 = mildly offensive; 3 = moderately offensive; 4 = strongly offensive; and 5 = extremely offensive. Reducing dietary CP increased (P < 0.05) fecal VFA concentrations but did not affect phenolic concentrations in urine. Manure NH3 emission was reduced (P < 0.05) as dietary CP concentration decreased from 15 to 0%. The 15% diet had the least offensive manure slurry with odor qualitative ranking of 2.58 (i.e., mild-moderately offensive). Compared with the 15% CP diet, manure from the 9 and 6% CP diets was found to be more offensive (P < 0.05), with qualitative rankings of 2.92 and 3.10, respectively. Odor qualitative rank for the 12% CP, protein-free diet, and casein-based diet did not differ from that of the 15% CP diet. These results indicate that reduction in dietary CP concentrations decreases manure NH3 emission, but it does not diminish manure odor offensiveness and fecal VFA concentrations. (+info)
Swine manure composition affects the biochemical origins, composition, and accumulation of odorous compounds.
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Odors from swine production facilities are associated with the storage and decomposition of manure. Diet is linked to manure composition and will likely affect odor, but the microbial mechanisms responsible for manure decomposition and odor production are poorly understood. To identify the sources of odor during manure fermentation, substrates (starch, casein, and cellulose) were added to slurries of fresh swine manure, and the anaerobic accumulation of fermentation products and the consumption of substrates were measured relative to no addition of substrates. Volatile fatty acids and alcohols were the dominant fermentation products in all treatments. The total VFA concentration from starch treatment was greater (P < 0.001) than for all other treatments. Branched-chain VFA and aromatic compounds accumulated in all treatments, but accumulation in the casein treatments was greater (P < 0.001) than in all other treatments. Thus, addition of carbohydrate to swine manure slurries did not circumvent protein fermentation, as was previously observed in cattle manure slurries. Based on substrate loss, starch and protein fermentation were equivalent in all treatments, with losses of each exceeding 4% of the DM. Substrate additions had a limited effect on the overall accumulation of odor compounds in manure and on odor compound composition. Compared with the results of the earlier fermentation study of fresh cattle manure, swine manure fermentation produced less lactate and more products of protein fermentation (branched-chain VFA and aromatic ring compounds). We hypothesize that differences in manure organic matter composition between cattle and swine, a result of diet and digestion, select for bacterial communities that are adapted to the available substrate composition. (+info)
Inactivation of poliovirus type 1 in mixed human and swine wastes and by bacteria from swine manure.
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The persistence of poliovirus type 1 (PO1) in mixed septic tank effluent and swine manure slurry was determined, and the antiviral effects of several bacterial cultures isolated from swine manure slurry were demonstrated. In two field experiments, PO1 was consistently inactivated more rapidly in the mixed waste than in the control Dulbecco's phosphate-buffered saline (D-PBS). D values (time [in days] for a 90% reduction of virus titer) were 18.7 and 29.9 for the mixed waste and 56.5 and 51.8 for the D-PBS control, respectively. The virus inactivation in the mixed waste was temperature dependent. A comparison of PO1 inactivation in raw mixed waste, autoclaved mixed waste, and bacterium-free filtrate of raw mixed waste at the same pH and temperatures provided an initial demonstration that the virus inactivation in the mixed waste is related, at least in part, to microbial activity. At 25 degrees C, the D value was 6.8 for the mixed waste, 11.2 for the autoclaved mixed waste, and 10.5 for the bacterium-free filtrate of raw mixed waste. At 37 degrees C, D values were 1.3, 3.9, and 3.1 for these three suspending media, respectively. Three bacterial isolates which had shown antiviral effects in a screening test each caused virus inactivation in autoclaved mixed waste, in which the effect of other microorganisms was excluded. Inhibition of PO1 inactivation by protease inhibitors suggests that the virus inactivation in the mixed waste was due in part to proteolytic enzymes produced by bacteria in the waste. (+info)