Properties Of Manure Research Articles

Rainfall-induced fecal indicator organisms transport from manured fields: Model sensitivity analysis

Microbial quality of surface waters attracts attention due to food- and waterborne disease outbreaks. Fecal indicator organisms (FIOs) are commonly used for the microbial pollution level evaluation. Models predicting the fate and transport of FIOs are required to design and evaluate best management practices that reduce the microbial pollution in ecosystems and water sources and thus help to predict the risk of food and waterborne diseases. In this study we performed a sensitivity analysis for the KINEROS/STWIR model developed to predict the FIOs transport out of manured fields to other fields and water bodies in order to identify input variables that control the transport uncertainty. The distributions of model input parameters were set to encompass values found from three-year experiments at the USDA-ARS OPE3 experimental site in Beltsville and publicly available information. Sobol' indices and complementary regression trees were used to perform the global sensitivity analysis of the model and to explore the interactions between model input parameters on the proportion of FIO removed from fields. Regression trees provided a useful visualization of the differences in sensitivity of the model output in different parts of the input variable domain. Environmental controls such as soil saturation, rainfall duration and rainfall intensity had the largest influence in the model behavior, whereas soil and manure properties ranked lower. The field length had only moderate effect on the model output sensitivity to the model inputs. Among the manure-related properties the parameter determining the shape of the FIO release kinetic curve had the largest influence on the removal of FIOs from the fields. That underscored the need to better characterize the FIO release kinetics. Since the most sensitive model inputs are available in soil and weather databases or can be obtained using soil water models, results indicate the opportunity of obtaining large-scale estimates of FIO transport from fields based on publicly available rather than site-specific information.

Impact of Anaerobic Digestion of Liquid Dairy Manure on Ammonia Volatilization Process

<abstract> <bold><sc>Abstract.</sc></bold> The goal of this study was to determine the effect of anaerobic digestion (AD) on ammonia volatilization from liquid dairy manure, in storage or treatment lagoon, prior to land application. Physical and chemical properties of liquid dairy manure, which may affect ammonia volatilization, were determined before and after AD. The properties of interest included particle size distribution (PSD), total solids (TS), volatile solids (VS), viscosity, pH, total ammoniacal nitrogen (TAN), and ionic strength (IS). The overall mass transfer coefficient of ammonia (K_oL) and the NH₃ fraction of TAN (β) for the undigested (UD) and AD manures were then experimentally determined in a laboratory convective emission chamber (CEC) at a constant wind speed of 1.5 m s^-1 and fixed air temperature of 25°C at manure temperatures of 15°C, 25°C, and 35°C. The PSD indicated non-normal left-skewed distributions for both AD and UD manures particles, suggestive of heavier concentrations of particles toward the lower particle size range. The volume median diameters (VMD) for solids from UD and AD were not significantly different (p= 0.65), but the geometric standard deviations (GSD) were significantly different (p = 0.001), indicating slightly larger particles but more widely distributed solids in UD manure than in AD manure. Results also indicated significantly higher pH, TAN, ionic strength (IS), and viscosity in AD manure. The β for AD manure, determined under identical conditions (air temperature, liquid temperature, and airflow), was significantly higher (p < 0.001) than for UD manure. However, mass transfer of ammonia (K_oL) was significantly lower for AD manure than for UD manure (p < 0.001). Overall, these findings suggest that AD of dairy manure significantly increased initial ammonia volatilization potential from liquid dairy manure, with the largest increase (~61%) emanating from increased ammonium dissociation. The initial flux of ammonia, at 15°C, was ~16% more from AD manure than from UD manure.

Degradation of veterinary antibiotics and hormone during broiler manure composting

The fate of nine veterinary antibiotics and one hormone in broiler manure during 40days of composting was investigated. Results showed that composting can significantly reduce the concentration of veterinary antibiotics and hormone in broiler manure, making application of the post-compost manure safer for soil application. More than 99% of the nine antibiotics and one hormone involved in this study were removed from the manure during 40days of composting. The target antibiotics and hormone showed short half-life in broiler manure composting, ranging from 1.3 to 3.8days. The relationship between the physico-chemical properties of soil, manure and manure compost and its veterinary antibiotic and hormone concentration was statistically evaluated by Pearson correlation matrix. The concentration of veterinary antibiotics and hormone in manure compost was suggested to be affected by physico-chemical properties such as pH, temperature, total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP) and metal contents.

Combustion Fuel Properties of Manure and Compost from Paved and Unpaved Cattle Feedlots as Modified by Annual Precipitation

Research was conducted to determine the effects of feedlot surfacing materials (soil/unpaved vs. fly-ash paved), partial composting and/or storage in windrow or greenhouse, and wet year (2005) vs. dry year (2006) feedlot conditions on cattle feedlot biomass (FB) characteristics pertinent to combustion or gasification processes involving reburn or co-firing with coal or lignite as described elsewhere. Bulk quantities of FB were harvested from 12 fly-ash paved pens and six soil-surfaced pens in a 400-head research cattle feedlot near Bushland, Texas. FB was windrow-composted, and samples were analyzed using proximate, ultimate, and elemental ash analyses. Higher heating value (HHV) before composting (termed raw manure, RM) was significantly higher for FB harvested from paved pens (termed low ash, or LA-FB) vs. soil-surfaced pens (termed high ash, or HA-FB) on a dry basis and dry ash-free (DAF) basis for both study years. Ash content (dry matter basis) was significantly lower and volatile matter (VM), carbon (fixed and total), and hydrogen were significantly higher for LA-FB (paved pens) vs. HA-FB (unpaved pens) for both years of the study. As-harvested HHV averaged 6,304 and 8,190 kJ kg-1 w.b. (2,710 and 3,521 BTU lb-1 w.b.) for HA-FB for the wet and dry years, respectively, and as-harvested HHV for LA-FB averaged 13,407 and 13,224 kJ kg-1 w.b. (5,764 and 5,685 BTU lb-1 w.b.) for the wet and dry years. Partial composting (PC) in windrows (for 51 to 55 days in 2005 or 91 days in 2006) reduced HHV w.b. by an average (both years) of 11.4% for the resulting HA-FB-PC and 14.8% for the resulting LA-FB-PC. The LA-FB-PC was significantly different from HA-FB-PC for all proximate and ultimate analysis parameters for both 2005 and 2006 manure, with the exception of 2006 wet-basis HHV. Heating value on a DAF basis averaged 20,984 kJ kg-1 (9,022 BTU lb-1) for LA-FB-PC and 18,941 kJ kg-1 (8,143 BTU lb-1) for HA-FB-PC. Greenhouse storage for 9 to 12 months of the 2005 harvested LA-FB-RM and LA-FB-PC preserved fuel quality better than did continuous storage of LA-FB-PC in a windrow, probably because lower moisture conditions were maintained under greenhouse storage conditions (7.7% to 13.4% w.b. final range) compared with uncovered windrow storage (17.4% final moisture content). Elemental analysis of ash from LA-FB was higher than from HA-FB for Ca, P, Cl, K, Mg, Na, and S, but was lower for Si, Al, Ti, and Fe without or with partial composting. Metal contents were similar for both high-ash and low-ash FB.

Manure management for greenhouse gas mitigation

Ongoing intensification and specialisation of livestock production lead to increasing volumes of manure to be managed, which are a source of the greenhouse gases (GHGs) methane (CH4) and nitrous oxide (N2O). Net emissions of CH4 and N2O result from a multitude of microbial activities in the manure environment. Their relative importance depends not only on manure composition and local management practices with respect to treatment, storage and field application, but also on ambient climatic conditions. The diversity of livestock production systems, and their associated manure management, is discussed on the basis of four regional cases (Sub-Saharan Africa, Southeast Asia, China and Europe) with increasing levels of intensification and priorities with respect to nutrient management and environmental regulation. GHG mitigation options for production systems based on solid and liquid manure management are then presented, and potentials for positive and negative interactions between pollutants, and between management practices, are discussed. The diversity of manure properties and environmental conditions necessitate a modelling approach for improving estimates of GHG emissions, and for predicting effects of management changes for GHG mitigation, and requirements for such a model are discussed. Finally, we briefly discuss drivers for, and barriers against, introduction of GHG mitigation measures for livestock production. There is no conflict between efforts to improve food and feed production, and efforts to reduce GHG emissions from manure management. Growth in livestock populations are projected to occur mainly in intensive production systems where, for this and other reasons, the largest potentials for GHG mitigation may be found.

Determination of some rheological properties of cow manure using a shear vane

Knowledge about rheological properties of biomass is necessary for optimization of pelleting process as well as the design of devices with optimum energy and pressure to determine the effect of different variables on the density and durability of produced pellets. Therefore, in this study a shear vane was used to determine the rheological properties of biomass materials and some rheological properties of cow manure. The experiments were done at moisture content levels of 35, 40 and 45% (w.b.), and rotational speed of the shear vane test chamber in three levels of 0.1, 0.2 and 0.3 rpm. The analysis of variance of moisture content and rotational speed of the chamber on the measured traits using SAS software showed that the rotational speed has no significant effect on none of the traits at 1% level. The independent effect of moisture content was significant on all the traits. The interaction between moisture content and rotational speed of the chamber was not significant on any of the traits. The highest maximum torque, maximum shear stress and maximum yield stress were achieved at 35% moisture content and rotational speed of 0.1 rpm. The lowest maximum torque, minimum shear stress and minimum yield stress was found at 40% moisture content and rotational speed of 0.1 rpm.

Changes in chemical and microbiological properties of rabbit manure in a continuous-feeding vermicomposting system

In the present study the potential of the earthworm Eisenia fetida to process large amounts of waste was evaluated through continuous feeding reactors in which new layers of rabbit manure were added sequentially to form an age gradient inside the reactors. An optimal moisture level, ranging from 66% to 76%, was maintained throughout the process using an automatic watering system. The pH was close to 8.3, but decreased to 7.6 after 200d of vermicomposting. No changes in electrical conductivity through the profile of layers were detected. Based on comparisons of phospholipid fatty acid (PLFA) profiles and microbial activity measurements (basal respiration), a decrease in the levels of bacteria and fungi in layers corresponding to vermicomposting times of more than 200d occurred. This points to a higher degree of stabilisation in the final product, which is of utmost importance for its safe use as an organic amendment.

Effects of Organic Dairy Manure on Soil Phosphatase Activity, Available Soil Phosphorus, and Growth of Sorghum-Sudangrass

Organic dairy (OD) production is increasing in the Northeastern United States due to consumer demand. Some physicochemical properties of OD manure differ from conventional dairy (CD) manure, which could influence nutrient cycling and soil fertility differently when OD manure is applied as fertilizer to meet plant N demands. Effects of OD manure on activities of acid phosphomonoesterase (ACP), alkaline phosphomonoesterase (ALP), phosphodiesterase (PDE), available soil phosphorus (P), and plant growth were investigated in a greenhouse study, where sorghum-sudangrass (Sorghum bicolor subsp. drummondii) was fertilized with manures from 13 organic dairies in Maine, CD manure, or NH4NO3. Soil phosphatase activities and modified Morgan P were determined at planting and after 16 weeks of plant growth. Plant growth did not differ (P > 0.05) when fertilized with OD and CD manures or inorganic fertilizer. However, there was a wide range in growth with OD manure, which was negatively correlated to manure C:N and C:P (P < 0.05) ratios. After 16 weeks, OD manure amended soils had higher modified Morgan P than soils with inorganic fertilizer (P < 0.05), but there was no difference between OD and CD manured soils (P > 0.05). Of the three soil phosphatases, ACP activity was highest and increased with OD manure similarly to CD manure. There was a negative correlation (P < 0.01) between ACP activity and manure C:P ratio, suggesting that manure C content influences P cycling and may reduce P availability in soils amended with OD manure, in a manner similar to CD manure.

Effects of Reed Straw, Zeolite, and Superphosphate Amendments on Ammonia and Greenhouse Gas Emissions from Stored Duck Manure

Stored poultry manure can be a significant source of ammonia (NH) and greenhouse gases (GHGs), including nitrous oxide (NO), methane (CH), and carbon dioxide (CO) emissions. Amendments can be used to modify physiochemical properties of manure, thus having the potential to reduce gas emissions. Here, we lab-tested the single and combined effects of addition of reed straw, zeolite, and superphosphate on gas emissions from stored duck manure. We showed that, over a period of 46 d, cumulative NH emissions were reduced by 61 to 70% with superphosphate additions, whereas cumulative NO emissions were increased by up to 23% compared with the control treatment. Reed straw addition reduced cumulative NH, NO, and CH emissions relative to the control by 12, 27, and 47%, respectively, and zeolite addition reduced cumulative NH and NO emissions by 36 and 20%, respectively. Total GHG emissions (as CO-equivalents) were reduced by up to 27% with the additions of reed straw and/or zeolite. Our results indicate that reed straw or zeolite can be recommended as amendments to reduce GHG emissions from duck manure; however, superphosphate is more effective in reducing NH emissions.

KINETICS OF THIN LAYER DRYING OF POULTRY MANURE

The poultry industry is one of the largest and fastest growing sectors of livestock production in the world. The estimated 2010 world flock was over 18 billion birds with a yearly manure output of 22 million tonnes. Storage and disposal of raw poultry manure has become an environmental problem because of the associated air, water and soil pollution. Environmental and health problems such as odor and pathogens that may arise during and after land application of raw manure can be eliminated by drying. Dried manure can be utilized as a soil conditioner to improve soil tilth and reduce the problems associated with soil compaction and as a feed for ruminants because of its high nitrogen content. The aim of this study was to investigate the kinetics of thin layer drying of poultry manure and evaluate the effects of drying with heated air on the chemical and biological properties of manure. The effects of temperature and depth of manure layer were evaluated. The profile of the moisture content of poultry manure followed an exponential decay curve. The moisture decay constant was affected by the drying temperature and the depth of the manure layer. At the three temperature levels studied, the time required to dry poultry manure in 1 cm-deep layer was the least, followed by 2 and 3 cm-deep layers, respectively. The diffusion coefficient increased with both temperature and depth of drying layer, but did not show a linear increase with either variable. The optimum depth for drying manure (at which the highest drying effectiveness occurred) was 3 cm. Drying manure at 40-60°C resulted in the loss of 44-55% of the total Kjeldahl nitrogen, with losses increasing with both the temperature and depth of manure. The pH of the manure decreased from the initial value of 8.4 before drying to about 6.6 after drying. The odor analysis indicated that dried poultry manure did not have an offensive odor. Drying achieved 65.3 and 69.3% reductions in odor intensity and offensiveness, respectively. Reductions in the number of bacteria, mold/yeast and E.coli were 65-99, 74-99 and 99.97% respectively. The greatest reductions in microbial population occurred at the highest temperatures (60°C) and the thinest manure depths (1 cm). Heated air drying of poultry manure at temperatures between 40 and 60°C was effective in killing pathogens and removing odor.

Effects of Laying-Hen Strain on Manure Properties and Ammonia Emission

Ammonia (NH3) emissions from laying hens are affected by nutrient content of the diet, manure quantity, and manure properties such as moisture content, nitrogen content, and pH. These production traits may vary with strain of the hen. However, limited information is available concerning the effects of laying-hen genetics on manure properties and NH3 emission. This study was conducted to comparatively quantify production performance, manure properties, and NH3 emissions (through N mass balance) of four white-egg-laying strains (Hy-Line W-36, Hy-Line W-98, Lohmann LSL Lite, and Bovans White) and four brown-egg-laying strains (Hy-Line Brown, Lohmann Brown, ISA Brown, and Bovans Brown) during two production periods of 27-28 weeks (P1) and 35-36 weeks (P2) of age. The diets were formulated to meet the nutritional needs of the brown and white hens. As a result, crude protein contents during P1 and P2 were, respectively, 13.2% and 15.2% for the brown hens but 14.5% and 17.4% for the white hens. The results showed that the brown and white hens had similar hen-day egg production (97.5% to 89.2% for brown hens and 96.0% to 88.2% for white hens) and egg mass output (57.1 to 52.6 g d-1 hen-1 for brown hens and 55.6 to 51.2 g d-1 hen-1 for white hens) but different feed consumption (112 to 98 g d-1 hen-1 for brown hens and 101 to 93 g d-1 hen-1 for white hens, p < 0.01) and feed efficiency (1.97 to 1.87 g feed g-1 egg for brown hens and 1.82 g feed g-1 egg for white hens, p < 0.0001 and p = 0.11). The higher feed consumption for the brown hens stemmed from their heavier body mass (1.81 to 1.78 kg vs. 1.56 to 1.53 kg for white hens). Manure moisture content was higher for the brown hens than for the white hens, although the dry-matter manure production was not significantly different. The results further revealed that under the experimental conditions (i.e., higher CP contents of the diet for the white hens than for the brown hens) the white hens had higher NH3 emissions than the brown hens as expressed per hen (37% to 19% higher, p = <0.001 to 0.016), per animal unit (AU, 500 kg live body mass; 59% to 39% higher, p = 0.0007 to 0.007), per unit of egg mass output (41% to 24% higher, p = 0.01 to 0.09), per unit of feed N consumed (39% to 27% higher, p = 0.01 to <0.0001), and per unit of dry manure (56% to 39% higher, p = 0.001 to 0.007). Certain differences existed in production performance among strains within the brown or white hens, but no differences in NH3 emissions were detected. Because of the relatively small sample size (number of hens involved) and the relatively short monitoring period, the results should be referenced with these limitations in mind. Further larger-scale studies with longer monitoring periods to verify these findings are warranted.

Influence of tillage on degradation kinetics using the litterbag method

A litterbag experiment was carried out in a tillage trial near Göttingen, Germany, comparing the long-term effects of mouldboard plough and rotary harrow on organic matter dynamics. The aim was to investigate the C loss and N balances in litterbags filled with N-poor, lignin-rich wheat straw and N-rich, lignin-poor maize residues, simulating the properties of green manures. The litterbags were buried at 0–5 and 15–20 cm depth and one fourth of them were removed after 3, 6, 9, and 12 months, respectively. The C loss rates, corrected for soil input into the litterbags, were significantly affected by tillage and bury depth and showed significant litter material × bury depth interactions. These were caused by generally higher C loss rates in the plough treatment, especially at 15–20 cm depth, and in the litterbags with maize residues. More soil was transferred to the litterbags in the plough treatment than in the rotary harrow treatment and more soil was found in the litterbags at 0–5 cm than at 15–20 cm depth. A smaller amount of stable aggregates in the surrounding soil is the most plausible explanation for this higher soil input. Nearly 40% of maize residue C was lost in the first three months from November to February, followed by a further exponentially decreasing loss of 40% over the next 9 months. Almost no wheat straw C was lost in the first three months, followed by a nearly linear loss of 60% over the next 9 months. The N balance showed strong N losses in the litterbags with maize residues for all exposure periods. In contrast, the N balance was always positive for wheat straw. The N balances, corrected for soil input, revealed significant bury depth effects and exposure period × bury depth interactions, but no significant tillage effects.

An Empirical Model of Ammonium Ion Dissociation in Liquid Dairy Manure

Emission of ammonia (NH3) from lagoons or other similar animal manure holding structures not only degrades environmental quality but also lowers the fertilizer value of the liquid effluent. In general, NH3 emissions from these facilities depend on the concentration of free NH3 in the liquid (NH3(aq)), which is a function of the dissociation of ammonium ions (NH4+). The dissociation of NH4+ is dependent on manure properties, including temperature, pH, ionic strength, and total suspended solids (TSS) concentration. The dissociation constant of NH4+ (Kd) in flushed dairy manure was determined at a pH of 9, temperatures of 5C, 15C, 25C, and 35C, and total solids (TS) contents of 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% w/w, and a regression model was obtained. The Kd value increased by approximately 1.6 for every 10C rise in temperature. The data also indicated a logarithmic decay in Kd with an increase in the concentration of TS in the liquid. The coefficient of determination (R2) of 0.97 for the nonlinear empirical model of Kd as a function of both temperature and TS concentration demonstrated good fit to the experimental data. The Kd values in the dairy manure with 1.5% TS were 117%, 87%, 61%, and 54% compared to the theoretical Kd values in pure water-ammonium solutions at 5C, 15C, 25C, and 35C, respectively. Similar trends were observed at other TS concentrations, suggesting that the effects of solids were more significant at elevated temperatures. The results of this study emphasize the need for including both the TS concentration and the temperature in models of Kd for liquid dairy manure, in addition to ensuring that the entire ranges of TS and temperature encountered in the region where the model will be used are covered.

Livestock manure improves acid soil productivity under a cold northern Alberta climate

The acid-ameliorating properties of feedlot cattle manure on barley and canola productivity in acid soils were evaluated from 2003 to 2007 at Fort Vermilion and Beaverlodge research stations in northern Alberta, Canada. Treatments included Control, NP fertilizer, Lime + NP fertilizer and manure at 80 (M80) and 160 (M160) Mg ha-1. Manure and lime were applied once in 2003 and NP fertilizer was applied annually. Manure significantly increased soil pH from around 4 to &gt;5 and this increase persisted over the 4-yr period. At Fort Vermilion, M160 reduced soil 0.01 M CaCl2 extractable Al and Mn contents from 2.9 and 11.7 mg kg-1 (Control) to 1.1 and 8.9 mg kg-1 and barley straw Mn content from 313 (Control) to 220 mg kg-1. Soil P (Mehlich 3) and K (0.01 M CaCl2 extractable) contents in M160 were more than two times those in the Control, while values from fertilizer treatments were not different from the Control. Crop grain N, P and K uptakes and yields in M160 were twice those of the Control. In northern Alberta, manure application to acid soils at a rate of 160 Mg ha-1 once every 4 yr had the same effectiveness as Lime + NP fertilizer in increasing soil pH and improving soil fertility and crop productivity at the field scale.

Chemical and physical properties of organic residues

Due to human activity, large amounts of organic residue are generated daily. Therefore, an adequate use in agricultural activities requires the characterization of the main properties. The chemical and physical characterization is important when planning the use and management of organic residue. In this study, chemical and physical properties of charcoal, coffee husk, pine-bark, cattle manure, chicken manure, coconut fiber, sewage sludge, peat, and vermiculite were determined. The following properties were analyzed: N-NH4+, N-N0(3)-, and total concentrations of N, P, S, K, Ca, Mg, Mn, Zn, Cu, and B, as well as pH, Electrical Conductivity (EC) and bulk density. Coffee husk, sewage sludge, chicken manure and cattle manure were generally richer in nutrients. The EC values of these residues were also the highest (0.08 - 40.6 dS m-1). Peat and sewage sludge had the highest bulky density. Sodium contents varied from 0 to 4.75 g kg-1, with the highest levels in chicken manure, cattle manure and sewage sludge. Great care must be taken when establishing proportions of organic residues in the production of substrates with coffee husk, cattle or chicken manure or sewage sludge in the calculation of the applied fertilizer quantity in crop fertilization programs.

Litter decomposition in fertilizer treatments of vegetable crops under irrigated subtropical conditions

In the coastal Batinah plain of Oman, a litterbag experiment was carried out in an irrigated field, investigating the effects of organic fertilization and mineral fertilization on the cultivation of carrots and cauliflower. Two straw varieties and two green-harvested crops were used, simulating the properties of green manures. The loss of C in the litterbags declined in the order maize (−94%) > alfalfa (−89%) > wheat (−80%) > canola (−69%). For all these materials, the concentration of muramic acid, as an indicator of bacterial C, as well as galactosamine was generally increased in comparison with the initial values. In contrast, fungal glucosamine and consequently also the ratio of fungal C/bacterial C declined for canola and wheat straw. The loss of N, P, and S was generally smaller than that of C and showed strong substrate-specific patterns. Fertilization and crop cultivation had no effect on C losses. Organic fertilization resulted in significant increases in S, Mg, and Al in the litterbags in comparison with mineral fertilization. Cultivation of carrots led to significantly lower ash, N, P, Ca, K, Na, and Al concentrations than cultivation of cauliflower. Organic fertilization and carrot cultivation both led to stronger fungal colonization of the litter retained in the litterbags in comparison with mineral fertilization and cauliflower cultivation, respectively. More information is required on the interactions between initial plant surface colonizing microorganisms and soil-derived colonizers.

Experimental balance to estimate efficiency in the use of nitrogen in rabbit breeding

Defining the composition and properties of manure in livestock production is critical in order to minimise possible environmental impacts stemming from its management. In this study, a nitrogen balance was carried out during two identical fattening periods (Experiments 1 and 2) in growing rabbits from weaning (age 28 d and live weight about 0.6 kg) to slaughter (age 61 d and live weight about 1.8 kg). The breeding conditions were typical for Spanish rabbit production. The objectives were to quantify the total nitrogen excreted by the animals and to estimate the average efficiency in the use of this nutrient, in comparison to other species. Animal weight, feed intake, and the production of faeces and urine were monitored weekly in a set of eight cages with nine rabbits in each, performing weekly analyses for nitrogen content in feed, urine and faeces. The overall nitrogen excretion was 50.2 g N per animal in Experiment 1 and 46.9 g N per animal in Experiment 2, which corresponded to about 58% of the total nitrogen intake. Urine and faeces contributed to overall nitrogen excretion in approximately the same proportions. The nitrogen excretion ratio was 40 grams per kilogram of animal produced. According to this ratio, rabbit breeding is less efficient in the use of nitrogen than raising broilers, but more than fattening pigs.

Greenhouse gas emissions when composting manure from cattle fed wheat dried distillers’ grains with solubles

Dried distillers’ grains with solubles (DDGS) are a co-product of ethanol production that is increasingly available for use as a livestock feed. Including DDGS in diets could affect animal manure properties and impact manure management strategies. The objectives of this study were to investigate changes in the rate of greenhouse gas (GHG) emissions during composting and final properties of manure compost when DDGS is included in feedlot cattle diets. Treatments were: (1) Control; manure from cattle fed a typical finishing diet containing barley (Hordeumvulgare L.) grain and silage and (2) DDGS; manure from cattle fed a finishing diet with 60% DDGS from wheat (Triticumaestivum L.) in the dietary ration. Manure, consisting of feces, urine and wood shavings, was composted in open windrows. Samples were collected for analysis at initiation and completion of composting. Greenhouse gas surface fluxes were collected weekly during the first 4 weeks and every 2–3 weeks for the remainder of the composting period. The DDGS compost had lower total C, but similar total N (TN) content relative to Control, reflecting the initial manure conditions. The DDGS compost also had higher moisture, higher water-extractable NH4+ and NO3−, a greater fraction of TN in available form, and a lower pH than the Control. The O2 consumption and N2O emission from DDGS compost were higher, whereas CO2 and CH4 emissions were similar to Control. The higher N2O emissions from DDGS compost were likely related to the high water-extractable N content in DDGS manure. Increased use of DDGS in feedlot diets may have environmental repercussions that include greater emissions of GHG (N2O) during manure composting. From an end user perspective, enhanced availability of N could increase the nutrient value of the compost for crop production.

Reduction of compost phytotoxicity during the process of decomposition

Hog manure from windrows composted at different operating strategies was used in a bioassay to determine phytotoxicity. Twelve windows that differed in composting strategies (i.e. turning frequency and moisture content adjustment) were built. The effects of hog manure water extracts on seed germination and primary root growth of cress ( Lepidum sativum L.) was measured. The germination index (GI, a product of relative seed germination and root elongation) was related to the chemical characteristics (electrical conductivity, nitrogen compounds, C:N ratio, heavy metals and humification parameters) of the hog manure. The water-extractable chemical properties of the hog manure that showed the highest negative correlation with GI were extractable Cu, extractable Zn and NH 4 + N , demonstrating that these chemical compounds gradually decrease during composting due to transformation to other compounds and immobilization effects. A GI > 80 (an indicator of the disappearance of phytotoxicity) was reached when the concentrations of NH 4 + –N, extractable Cu, and extractable Zn were ⩽ 2 g kg −1, ⩽ 15 mg kg −1, and ⩽ 15 mg kg −1, respectively. Multiple regression analysis revealed that NH 4 + –N was the most important factors affecting the phytotoxicity of the hog manure. Composting strategies employed affected the speed of composting, time of maturation, and disappearance of phytotoxicity. The disappearance of phytotoxicity corresponded with the time of maturation of the hog manure. If optimum composting conditions (windrows turned every 4 d with weekly moisture adjustment to 60%) are met, phytotoxicity disappears within 56 d.

Nitrogen mineralization potential of three animal manures applied on a sandy clay loam soil

Understanding the dynamics of N forms applied as manure is germane for appropriate rate and timing of applications of manure. Manure characterization and laboratory incubation were conducted for 120 days to study the mineralization of poultry, cattle and goat manures. Results showed that manure properties differ. Net immobilization of N was recorded for goat and cattle manures while poultry manure mineralized marginally. The relationship between N release and time is polynomial (cubic). The release phases were: initial rapid N release at 0–30 days; phase of constant release; 40–55 days; decline phase in N release 70–90 days and sharp increase in N release at 120 days. Increasing the N rates of manures above 120 kg N ha −1 will improve their potential as plant nutrient sources. Complementing the manures with inorganic N fertilizers in integrated nutrient management will also improve its quality and effectiveness.