Precipitation of liquid swine manure phosphates using magnesium smelting by-products

Swine manure contains considerable amounts of total (P) and soluble phosphorus (PO(4)-P) which may increase the soil P content when applied in excess to crop requirements and, consequently, risk water eutrophication. The feasibility of using magnesium (Mg) from the by-product of electrolysis and foundries (BPEF) for the removal of P from liquid swine manure was studied by adding up to 3 g of Mg as BPEF per liter of nursery (NU) and grower-finisher (GF) swine manure in 25-L plastic buckets. Changes in P and other elements were monitored for up to 360 h. Small amounts of Mg as BPEF (0.5 and 1.0 g Mg L(-1) manure) reduced the total P concentration of the liquid fraction by 70 to 95% of both manure types with respect to the control treatment of mixed raw manure. A settling period of 8 h or more was necessary to significantly reduce the liquid fraction's total P concentration for both manure types. Reduction of PO(4)-P varied from 96 to 100% in the liquid fractions for both manure types, which along with natural settling, explains most of the total P reduction in that fraction. The addition of BPEF did not influence the N content of manure. The low P liquid fraction can be safely applied to saturated P soils whereas the high P solid fraction offers the opportunity of transporting manure to agricultural soils deficient in P. Since N is conserved, both liquid and solid fractions could be valuable fertilizer manure by-products.     

Management strategy impacts on ammonia volatilization from swine manure

Ammonia emitted from manure can have detrimental effects on health, environmental quality, and fertilizer value. The objective of this study was to measure the potential for reduction in ammonia volatilization from swine (Sus scrofa domestica) manure by temperature control, stirring, addition of nitrogen binder (Mohave yucca, Yucca schidigera Roezl ex Ortgies) or urease inhibitor [N-(n-butyl) thiophosphoric triamide (NBPT)], segregation of urine from feces, and pH modification. Swine manure [total solids (TS) = 7.6-11.2%, total Kjeldahl nitrogen (TKN) = 3.3-6.2 g/L, ammonium nitrogen NH(+)(4)-N = 1.0-3.3 g/L] was stored for 24, 48, 72, or 96 h in 2-L polyvinyl chloride vessels. The manure was analyzed to determine pre- and post-storage concentrations of TS and volatile solids (VS), TKN, and NH(+)(4)-N. The concentration of accumulated ammonia N in the vessel headspace (HSAN), post-storage, was measured using grab sample tubes. Headspace NH(3) concentrations were reduced 99.3% by segregation of urine from feces (P < 0.0001). Stirring and NBPT (152 microL/L) increased HSAN concentration (119 and 140%, respectively). Headspace NH(3) concentration increased by 2.7 mg/m(3) for every 1 degree C increase in temperature over 35 degrees C. Slurry NH(+)(4)-N concentrations were reduced by segregation (78.3%) and acidification to pH 5.3 (9.4%), and increased with stirring (4.8%) and increasing temperature (0.06 g/L per 1 degree C increase in temperature over 35 degrees C). Temperature control, urine-feces segregation, and acidification of swine manure are strategies with potential to reduce or slow NH(+)(4)-N formation and NH(3) volatilization.     

Odor and gas release from anaerobic treatment lagoons for swine manure

Odor and gas release from anaerobic lagoons for treating swine waste affect air quality in neighboring communities but rates of release are not well documented. A buoyant convective flux chamber (BCFC) was used to determine the effect of lagoon loading rate on measured odor and gas releases from two primary lagoons at a simulated wind speed of 1.0 m s(-1). Concentrations of ammonia (NH3), hydrogen sulfide (H2S), carbon dioxide (CO2), sulfur dioxide (SO2), and nitric oxide (NO) in 50-L air samples were measured. A panel of human subjects, whose sensitivity was verified with a certified reference odorant, evaluated odor concentration, intensity, and hedonic tone. Geometric mean odor concentrations of BCFC inlet and outlet samples and of downwind berm samples were 168 +/- 44 (mean +/- 95% confidence interval), 262 +/- 60, and 114 +/- 38 OU(E) m(-3) (OU(E), European odor unit, equivalent to 123 microg n-butanol), respectively. The overall geometric mean odor release was 2.3 +/- 1.5 OU(E) s(-1) m(-2) (1.5 +/- 0.9 OU s(-1) m(-2)). The live mass specific geometric mean odor release was 13.5 OU(E) s(-1) AU(-1) (animal unit = 500 kg live body mass). Overall mean NH3, H2S, CO2 and SO2 releases were 101 +/- 24, 5.7 +/- 2.0, 852 +/- 307, and 0.5 +/- 0.4 microg s(-1) m(-2), respectively. Nitric oxide was not detected. Odor concentrations were directly proportional to H2S and CO2 concentrations and odor intensity, and inversely proportional to hedonic tone and SO2 concentration (P < 0.05). Releases of NH3, H2S, and CO2 were directly proportional (P < 0.05) to volatile solids loading rate (VSLR).     

Phosphorus runoff from incorporated and surface-applied liquid swine manure and phosphorus fertilizer

Excessive fertilization with organic and/or inorganic P amendments to cropland increases the potential risk of P loss to surface waters. The objective of this study was to evaluate the effects of soil test P level, source, and application method of P amendments on P in runoff following soybean [Glycine max (L.) Merr.]. The treatments consisted of two rates of swine (Sus scrofa domestica) liquid manure surface-applied and injected, 54 kg P ha(-1) triple superphosphate (TSP) surface-applied and incorporated, and a control with and without chisel-plowing. Rainfall simulations were conducted one month (1MO) and six months (6MO) after P amendment application for 2 yr. Soil injection of swine manure compared with surface application resulted in runoff P concentration decreases of 93, 82, and 94%, and P load decreases of 99, 94, and 99% for dissolved reactive phosphorus (DRP), total phosphorus (TP), and algal-available phosphorus (AAP), respectively. Incorporation of TSP also reduced P concentration in runoff significantly. Runoff P concentration and load from incorporated amendments did not differ from the control. Factors most strongly related to P in runoff from the incorporated treatments included Bray P1 soil extraction value for DRP concentration, and Bray P1 and sediment content in runoff for AAP and TP concentration and load. Injecting manure and chisel-plowing inorganic fertilizer reduced runoff P losses, decreased runoff volumes, and increased the time to runoff, thus minimizing the potential risk of surface water contamination. After incorporating the P amendments, controlling erosion is the main target to minimize TP losses from agricultural soils.     

Reducing phosphorus runoff from swine manure with dietary phytase and aluminum chloride

Phosphorus (P) runoff from fields fertilized with swine (Sus scrofa) manure has been implicated in eutrophication. Dietary modification and manure amendments have been identified as best management practices to reduce P runoff from manure. This study was conducted to compare the effects of dietary modification and aluminum chloride (AlCl3) manure amendments on reducing P in swine manure and runoff. Twenty-four pens of nursery swine were fed either a normal diet or a phytase-amended diet. Each pen was connected to a separate manure pit, which was treated with AlCl3 to give final concentrations in the liquid manure of 0 (control), 0.25, 0.50, or 0.75% (v/v). Manure was collected and applied to plots cropped with tall fescue (Festuca arundinacea Schreb.), and simulated rainfall was applied at 50 mm h(-1), sufficient to generate a minimum of 30 min of continuous runoff. Samples of manure and runoff were analyzed for P and Al concentrations. Phytase reduced manure soluble reactive phosphorus (SRP) by 17%, while AlCl3 reduced manure SRP by as much as 73% compared with normal manure. Phosphorus runoff was reduced from 5.7 to 2.6 mg P L(-1) (a 53% reduction) using AlCl3. The mean SRP concentration in runoff from phytase diets without AlCl3 was 7.1 mg P L(-1) during the first rainfall simulation. When phytase and AlCl3 were used together, both manure SRP and P runoff were reduced more than if either treatment were used without the benefit of the other. Use of AlCl3 did not increase soluble Al in manure or Al lost in runoff. Results from this study indicate that producers should use dietary manipulation with phytase and AlCl3 manure amendments to reduce potential P losses from fields fertilized with swine manure.     

Phosphorus fractionation in manure from swine fed traditional and low-phytate corn diets

Traditional corn (Zea mays L.) (TC), the primary grain used in swine (Sus scrofa) diets, stores a majority of its P as phytate, which is largely unavailable for digestion by nonruminant animals. Low-phytate corn (LPC) contains similar amounts of total P but a smaller percentage of P as phytate. When fed to swine, LPC increases P utilization and reduces P content of manure. While differences in P content between manure from animals fed TC and LPC diets have been documented, solubility and lability of manure P have not been compared. Manure P was characterized in manure from swine fed either LPC or TC diets in 2000 and 2001. Total P was lower (20 vs. 34 g kg(-1)) and N to P ratio was higher (4.5 vs. 3.3) in LPC manure than in TC manure. Manures were sequentially extracted with deionized water, 0.5 M NaHCO3, 0.1 M NaOH, and 1.0 M HCl. Extracts were analyzed for inorganic and total P. Most P (approximately 80%) in the extracts was in the inorganic form. Concentration of P in the water-extractable fraction was lower for LPC manure (10.2 g kg(-1) in 2000 and 9.7 g kg(-1) in 2001) than for TC manure (13.6 g kg(-1) in 2000 and 17.0 g kg(-1) in 2001). Percentage of total P in each extract was in the order of: H2O (60%), HCl (22%), NaHCO3 (12%), NaOH (8%), and residue (<1%). Total P and distribution of P in extracts indicates swine are able to utilize more P contained in LPC feed but the composition of P excreted in LPC manure is similar to TC manure. Solubility, crop availability, and lability of P in LPC manure should be similar to that of TC manure.     

Effects of alum and aluminum chloride on phosphorus runoff from swine manure

Phosphorus (P) runoff from fields fertilized with swine (Sus scrofa domesticus) manure may contribute to eutrophication. The objective of this study was to evaluate the effect of aluminum sulfate (alum) and aluminum chloride applications to swine manure on P runoff from small plots cropped to tall fescue (Festuca arundinacea Shreb.). There were six treatments in this study: (i) unfertilized control plots, (ii) untreated manure, (iii) manure with alum at 215 mg Al L(-1), (iv) manure with aluminum chloride at 215 mg Al L(-1), (v) manure with alum at 430 mg Al L(-1), and (vi) manure with aluminum chloride at 430 mg Al L(-1). Manure application rates were equivalent to approximately 125 kg N ha(-1). Alum and aluminum chloride additions lowered soluble reactive phosphorus (SRP) levels from about 130 mg P L(-1) to approximately 30 mg P L(-1) at low rates. At high rates, SRP levels in swine manure were around 1 mg P L(-1). Soluble reactive P concentrations in runoff were 5.50, 3.66, 3.00, 0.87, 0.87, and 0.55 mg P L(-1), for normal manure, low alum, low aluminum chloride, high alum, high aluminum chloride, and unfertilized control plots, respectively. Hence, high alum and aluminum chloride reduced SRP concentrations in runoff by 84% and were not statistically different from SRP concentrations in runoff from unfertilized control plots. These data indicate that treating swine manure with alum or aluminum chloride could result in significant reductions in nonpoint-source P runoff.     

Greenhouse gas emissions from two soils receiving nitrogen fertilizer and swine manure slurry

The interactive effects of soil texture and type of N fertility (i.e., manure vs. commercial N fertilizer) on N(2)O and CH(4) emissions have not been well established. This study was conducted to assess the impact of soil type and N fertility on greenhouse gas fluxes (N(2)O, CH(4), and CO(2)) from the soil surface. The soils used were a sandy loam (789 g kg(-1) sand and 138 g kg(-1) clay) and a clay soil (216 g kg(-1) sand, and 415 g kg(-1) clay). Chamber experiments were conducted using plastic buckets as the experimental units. The treatments applied to each soil type were: (i) control (no added N), (ii) urea-ammonium nitrate (UAN), and (iii) liquid swine manure slurry. Greenhouse gas fluxes were measured over 8 weeks. Within the UAN and swine manure treatments both N(2)O and CH(4) emissions were greater in the sandy loam than in the clay soil. In the sandy loam soil N(2)O emissions were significantly different among all N treatments, but in the clay soil only the manure treatment had significantly higher N(2)O emissions. It is thought that the major differences between the two soils controlling both N(2)O and CH(4) emissions were cation exchange capacity (CEC) and percent water-filled pore space (%WFPS). We speculate that the higher CEC in the clay soil reduced N availability through increased adsorption of NH(4)(+) compared to the sandy loam soil. In addition the higher average %WFPS in the sandy loam may have favored higher denitrification and CH(4) production than in the clay soil.     

Enzymatic hydrolysis of organic phosphorus in swine manure and soil

Organic phosphorus (Po) exists in many chemical forms that differ in their susceptibility to hydrolysis and, therefore, bioavailability to plants and microorganisms. Identification and quantification of these forms may significantly contribute to effective agricultural P management. Phosphatases catalyze reactions that release orthophosphate (Pi) from Po compounds. Alkaline phosphatase in tris-HCl buffer (pH 9.0), wheat (Triticum aestivum L.) phytase in potassium acetate buffer (pH 5.0), and nuclease P1 in potassium acetate buffer (pH 5.0) can be used to classify and quantify Po in animal manure. Background error associated with different pH and buffer systems is observed. In this study, we improved the enzymatic hydrolysis approach and tested its applicability for investigating Po in soils, recognizing that soil and manure differ in numerous physicochemical properties. We applied (i) acid phosphatase from potato (Solanum tuberosum L.), (ii) acid phosphatases from both potato and wheat germ, and (iii) both enzymes plus nuclease P1 to identify and quantify simple labile monoester P, phytate (myo-inositol hexakis phosphate)-like P, and DNA-like P, respectively, in a single pH/buffer system (100 mM sodium acetate, pH 5.0). This hydrolysis procedure released Po in sequentially extracted H2O, NaHCO3, and NaOH fractions of swine (Sus scrofa) manure, and of three sandy loam soils. Further refinement of the approach may provide a universal tool for evaluating hydrolyzable Po from a wide range of sources.     

Influence of phytase on water-soluble phosphorus in poultry and swine manure

The effect of dietary non-phytin phosphorus (NPP) and phytase (PHY) concentration on total phosphorus (TP) and water-soluble phosphorus (WSP) excretion was determined. Diets tested in broiler experiments were: National Research Council nutrient requirements for non-phytin phosphorus (NRC), NRC + PHY, reduced non-phytin phosphorus (RED), and RED + PHY. Turkey and swine experiment diets included NRC, RED, and RED + PHY. For all experiments, except broiler Experiment 1, excreta were: (i) boiled, antibiotic added, then frozen; (ii) boiled, antibiotic added, incubated (37 degrees C for 72 h), then frozen; and (iii) incubated, boiled, antibiotic added, then frozen. In Experiment 1, excreta were collected and frozen or incubated for 24 or 48 h. In broiler Experiment 1, WSP was not affected by phytase but increased with post-excretion incubation. In a broiler Experiment 2, reducing NPP resulted in reduced excreta TP and WSP (11.3 to 8.3 and 5.3 to 2.7 g kg(-1)). Feeding RED + PHY diets resulted in less TP and WSP (7.6 and 0.6 g kg(-1)) as compared with NRC + PHY (11.2 and 3.9 g kg(-1), Experiment 3). Incubation resulted in increased WSP, irrespective of phytase addition such that WSP as a percent of TP was similar among treatments. Addition of antibiotics before incubation prevented the increase in WSP. Similar results were observed with turkey and swine. Therefore, when phytase is used properly (i.e., with a simultaneous reduction of NPP), WSP or WSP as a percent of TP are not affected. The increase in WSP as a percent of TP post-excretion is a function of excreta microbial activity and not dietary phytase addition.     

Simultaneous chemical and sensory characterization of volatile organic compounds and semi-volatile organic compounds emitted from swine manure using solid phase microextraction and multidimensional gas chromatography-mass spectrometry-olfactometry

Swine manure is associated with emissions of odor, volatile organic compounds (VOCs) and other gases that can affect air quality on local and regional scales. In this research, a solid phase microextraction (SPME) and novel multidimensional gas chromatography-mass spectrometry-olfactometry (MDGC-MS-O) system were used to simultaneously identify VOCs and related odors emitted from swine manure. Gas samples were extracted from manure headspace using Carboxen/polydimethylsiloxane (PDMS) 85-microm SPME fibers. The MDGC-MS-O system was equipped with two columns in series with a system of valves allowing transfer of samples between columns (heartcutting). The heartcuts were used to maximize the isolation, separation, and identification of compounds. The odor impact of separated compounds was evaluated by a trained panelist for character and intensity. A total of 295 compounds with molecular weights ranging from 34 to 260 were identified. Seventy one compounds had a distinct odor. Nearly 68% of the compounds for which reaction rates with OH* radicals are known had an estimated atmospheric lifetime <24 h.     

Manipulation of dietary protein and nonstarch polysaccharide to control swine manure emissions

Odor and greenhouse gas (GHG) emissions from stored pig (Sus scrofa) manure were monitored for response to changes in the crude protein level (168 or 139 g kg(-1), as-fed basis) and nonstarch polysaccharide (NSP) content [i.e., control, or modified with beet pulp (Beta vulgaris L.), cornstarch, or xylanase] of diets fed to pigs in a production setting. Each diet was fed to one of eight pens of pigs according to a 2 x 4, full-factorial design, replicated over three time blocks with different groups of animals and random assignment of diets. Manure from each treatment was characterized and stored in a separate, ventilated, 200-L vessel. Repeated measurements of odor, carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions from the vessels were taken every two weeks for eight weeks. Manure from high-protein diets had higher sulfur concentration and pH (P < or = 0.05). High-NSP (beet pulp) diets resulted in lower manure nitrogen and ammonia concentrations and pH (P < or = 0.05). Odor level and hedonic tone of exhaust air from the storage vessel headspaces were unaffected by the dietary treatments. Mean CO2 and CH4 emissions (1400 and 42 g d(-1) m(-3) manure, respectively) increased with lower dietary protein (P < or = 0.05). The addition of xylanase to high-protein diets caused a decrease in manure CO2 emissions, but an increase when added to low-protein diets (P < or = 0.05). Nitrous oxide emissions were negligible. Contrary to other studies, these results do not support the use of dietary protein reduction to reduce emissions from stored swine manure.     

Soil nitrous oxide emissions following band-incorporation of fertilizer nitrogen and swine manure

Treatment of liquid swine manure (LSM) offers opportunities to improve manure nutrient management. However, N2O fluxes and cumulative emissions resulting from application of treated LSM are not well documented. Nitrous oxide emissions were monitored following band-incorporation of 100 kg N ha(-1) of either mineral fertilizer, raw LSM, or four pretreated LSMs (anaerobic digestion; anaerobic digestion + flocculation: filtration; decantation) at the four-leaf stage of corn (Zea mays L.). In a clay soil, a larger proportion of applied N was lost as N2O with the mineral fertilizer (average of 6.6%) than with LSMs (3.1-5.0%), whereas in a loam soil, the proportion of applied N lost as N2O was lower with the mineral fertilizer (average of 0.4%) than with LSMs (1.2-2.4%). Emissions were related to soil NO3 intensity in the clay soil, whereas they were related to water-extractable organic C in the loam soil. This suggests that N2O production was N limited in the clay soil and C limited in the loam soil, and would explain the interaction found between N sources and soil type. The large N2O emission coefficients measured in many treatments, and the contradicting responses among N sources depending on soil type, indicate that (i) the Intergovernmental Panel on Climate Change (IPCC) default value (1%) may seriously underestimate N2O emissions from fine-textured soils where fertilizer N and manure are band-incorporated, and (ii) site-specific factors, such as drainage conditions and soil properties (e.g., texture, organic matter content), have a differential influence on emissions depending on N source.     

Phosphorus composition of manure from swine fed low-phytate grains: evidence for hydrolysis in the animal

Including low-phytic-acid grains in swine diets can reduce P concentrations in manure, but the influence on manure P composition is relatively unknown. To address this we analyzed manure from swine fed one of four barley (Hordeum vulgare L.) varieties. The barley types consisted of wild-type barley (CDC bold, normal barley diet) and three low-phytic-acid mutant barleys that contained similar amounts of total P but less phytic acid. The phytic acid concentrations in the mutant barleys were reduced by 32% (M422), 59% (M635), and 97% (M955) compared with that in the wild-type barley, respectively. Phosphorus concentrations were approximately one-third less in manures from animals fed low-phytic-acid barleys compared with those fed the wild-type variety. Phytic acid constituted up to 55% of the P in feed, but only trace concentrations were detected in NaOH-EDTA extracts of all manures by solution (31)P nuclear magnetic resonance (NMR) spectroscopy. Phosphate was the major P fraction in the manures (86-94% extracted P), with small concentrations of pyrophosphate and simple phosphate monoesters also present. The latter originated mainly from the hydrolysis of phospholipids during extraction and analysis. These results suggest that phytic acid is hydrolyzed in swine, possibly in the hind gut by intestinal microflora before being excreted in feces, even though the animals have little phytase activity in the gut and derive little nutritional benefit from phytate P. We conclude that feeding low-phytic-acid grains reduces total manure P concentrations and the manure P is no more soluble than P generated from normal barley diets.     

Biological nutrient removal from pre-treated landfill leachate in a sequencing batch reactor

Biological treatment of landfill leachate usually results in low nutrient removals because of high chemical oxygen demand (COD), high ammonium-N content and the presence of toxic compounds such as heavy metals. Landfill leachate with high COD content was pre-treated by coagulation-flocculation with lime followed by air stripping of ammonia at pH=12. Nutrient removal from pre-treated leachate was carried out using a lab-scale sequencing batch reactor (SBR). Three different operations consisting of different numbers of steps were tested and their performances were compared. These operations were the three-step anaerobic (An)/anoxic (Ax)/oxic (Ox); the four-step (An/Ox/Ax/Ox), and the five-step (An/Ax/Ox/Ax/Ox) operations with total residence time of seven hours each. Experiments were carried out using three consecutive operations with a total cycle time of 21 h at a constant sludge age of 10 days. The lowest effluent nutrient levels were realized by using the five-step operation which resulted in effluent COD, NH4-N and PO4-P contents of 1,400, 107 and 65 mg l(-1), respectively, at the end of 21 h. Addition of domestic wastewater (1/1, v/v) and powdered activated carbon (PAC, 1 g l(-1)) to the pre-treated leachate improved nutrient removals in the five-step SBR operation, resulting in 75% COD, 44% NH4-N and 44% PO4-P removals after 21 hours of operation.     

Biochar and manure affect calcareous soil and corn silage nutrient concentrations and uptake

Carbon-rich biochar derived from the pyrolysis of biomass can sequester atmospheric CO, mitigate climate change, and potentially increase crop productivity. However, research is needed to confirm the suitability and sustainability of biochar application to different soils. To an irrigated calcareous soil, we applied stockpiled dairy manure (42 Mg ha dry wt) and hardwood-derived biochar (22.4 Mg ha), singly and in combination with manure, along with a control, yielding four treatments. Nitrogen fertilizer was applied when needed (based on preseason soil test N and crop requirements) in all plots and years, with N mineralized from added manure included in this determination. Available soil nutrients (NH-N; NO-N; Olsen P; and diethylenetriaminepentaacetic acid-extractable K, Mg, Na, Cu, Mn, Zn, and Fe), total C (TC), total N (TN), total organic C (TOC), and pH were evaluated annually, and silage corn nutrient concentration, yield, and uptake were measured over two growing seasons. Biochar treatment resulted in a 1.5-fold increase in available soil Mn and a 1.4-fold increase in TC and TOC, whereas manure produced a 1.2- to 1.7-fold increase in available nutrients (except Fe), compared with controls. In 2009 biochar increased corn silage B concentration but produced no yield increase; in 2010 biochar decreased corn silage TN (33%), S (7%) concentrations, and yield (36%) relative to controls. Manure produced a 1.3-fold increase in corn silage Cu, Mn, S, Mg, K, and TN concentrations and yield compared with the control in 2010. The combined biochar-manure effects were not synergistic except in the case of available soil Mn. In these calcareous soils, biochar did not alter pH or availability of P and cations, as is typically observed for acidic soils. If the second year results are representative, they suggest that biochar applications to calcareous soils may lead to reduced N availability, requiring additional soil N inputs to maintain yield targets.     

Chicken manure biochar as liming and nutrient source for acid Appalachian soil

Acid weathered soils often require lime and fertilizer application to overcome nutrient deficiencies and metal toxicity to increase soil productivity. Slow-pyrolysis chicken manure biochars, produced at 350 and 700°C with and without subsequent steam activation, were evaluated in an incubation study as soil amendments for a representative acid and highly weathered soil from Appalachia. Biochars were mixed at 5, 10, 20, and 40 g kg into a Gilpin soil (fine-loamy, mixed, active, mesic Typic Hapludult) and incubated in a climate-controlled chamber for 8 wk, along with a nonamended control and soil amended with agronomic dolomitic lime (AgLime). At the end of the incubation, soil pH, nutrient availability (by Mehlich-3 and ammonium bicarbonate diethylene triamine pentaacetic acid [AB-DTPA] extractions), and soil leachate composition were evaluated. Biochar effect on soil pH was process- and rate-dependent. Biochar increased soil pH from 4.8 to 6.6 at the high application rate (40 g kg), but was less effective than AgLime. Biochar produced at 350°C without activation had the least effect on soil pH. Biochar increased soil Mehlich-3 extractable micro- and macronutrients. On the basis of unit element applied, increase in pyrolysis temperature and biochar activation decreased availability of K, P, and S compared to nonactivated biochar produced at 350°C. Activated biochars reduced AB-DTPA extractable Al and Cd more than AgLime. Biochar did not increase NO in leachate, but increased dissolved organic carbon, total N and P, PO, SO, and K at high application rate (40 g kg). Risks of elevated levels of dissolved P may limit chicken manure biochar application rate. Applied at low rates, these biochars provide added nutritional value with low adverse impact on leachate composition.     

Phosphate uptake and release rates with different carbon sources in biological nutrient removal using a SBR

A three-step sequencing batch reactor (SBR) was used for nutrient removal from synthetic wastewater with different glucose-organic acid mixtures (1/1). Acetic, butyric, propionic and citric acids were used as organic acids along with glucose. The operation consisted of anaerobic, anoxic and oxic (An/Ax/Ox) phases with durations of 2/1/4.5h. Sludge age was kept constant for 10 days. Phosphate release and uptake rates were determined for different glucose-organic acid mixtures in the feed wastewater. Maximum phosphate uptake (8.1mgPl(-1)h(-1)) and release rates (2.23mgPl(-1)h(-1)) were obtained with the glucose-citric acid mixture. The highest (96%) percent phosphate removal at the end of the nutrient removal cycle (7.5h) was also obtained with the glucose-citric acid mixture while the glucose-acetic acid mixture resulted in comparable percent phosphate removal (95%).     

Pathogen survival in swine manure environments and transmission of human enteric illness--a review

The influence of zoonotic pathogens in animal manure on human health and well-being as a direct or indirect cause of human enteric illness is examined. Available international data are considered, but the study is focused on the developing situation in western Canada, where it is certain there will be further rapid growth in livestock numbers, particularly hogs. Major pathogens considered are Escherichia coli O157:H7, Salmonella, Campylobacter, Yersinia, Cryptosporidium, and Giardia. Canada is now the leading exporter of pork internationally, but recent increases in production contrast with constant domestic levels of pork consumption and declining levels of foodborne illness caused by pork. Effects of increased levels of manure production are not quantifiable in terms of effects on human health. The presence of major pathogens in manure and movement to human food sources and water are considered on the basis of available data. Survival of the organisms in soil, manure, and water indicate significant variability in resistance to environmental challenge that are characteristic of the organisms themselves. Generally, pathogens survived longer in environmental samples at cool temperatures but differences were seen in liquid and solid manure. Based on actual data plus some data extrapolated from cattle manure environments, holding manure at 25 degrees C for 90 d will render it free from the pathogens considered above.     

Risk assessment of unsuitable winter conditions for manure and nutrient application across Ontario

Practical guidelines addressing the timing of manure and nutrient application must consider the concerns of the farm operators while ensuring the protection of the environment. An approach was developed and analyzed through case studies to determine the first recommended day in the spring, and the last in the fall, for manure and nutrient application based on probability analysis. Since most manure and nutrient application guidelines recommend avoiding adverse conditions, the three criteria established to perform a risk assessment were: (i) a frost depth greater than 0.05 m; (ii) a snow accumulation of greater than 0.05 m; and (iii) a soil volumetric water content greater than or equal to that of the plastic limit for the soil. Climatic data and typical soil information for seven locations in Ontario were used to model volumetric soil water contents, frost depths, and snow accumulation from the simultaneous heat and water (SHAW) model for a 48-yr period (1954-2001). Applying the three criteria to the modeled output, the average range between the least limiting probability (0.1, or one in ten year occurrence) and the greatest limiting probability (0.001, or one in one thousand year occurrence) analyzed among the locations was 16 d in the spring as compared to 29 d in the fall. Although geographical location affected the predicted spring start and fall end recommended manure and nutrient application dates, local climate and soil hydraulic properties also played an important part in the determination of these days. Overall the prediction method developed performed reasonably well and provided insight into the environmental factors influencing manure and nutrient application timing.