Demonstration of swine carcass composting as part of an environmentally friendly production system

Carcass composting is not a new technology, but it has excellent potential to be part of a swine production system that uses solid bedding

Swine Carcass Composting as Part of an Environmentally Friendly Production System

As a consequence of normal swine production, mortalities must be handled on a daily basis. Average death losses of 4100 kg/year (9,000 lbs/year) per 100 sows pose a significant management and disposal task for Iowa swine producers. Several methods of disposal have been used for this costly and time-consuming task

Laboratory Determination of Compost Modeling Parameters

Physical and biological parameters of corn stalks, silage, and oat straw were determined and the variation of airflow characteristics and biological activity were evaluated under varying moisture contents. The predicted air-filled porosity showed high correlation with measured airfilled porosity over the all materials. A reliable model of air-filled porosity made it possible to predict the effect of varying moisture content and compost bed height on air-filled porosity and permeability. The air-filled porosity decreased with increasing moisture content and compost depth for all materials. Corn stalks and oat straw air-filled porosity was in the range of 69-97% over the all moisture levels and bed heights tested. Silage showed a wider range of air filled porosity than the other two materials, varying from 43 to 89%. The effective particle size of all three materials increased with increasing moisture content from 20% to 80%of WHC. Permeability increased with increasing air filled porosity and decreasing bulk density, but the relationship between permeability and moisture content is complex. Permeability decreased for all materials with increasing moisture content from 20% WHC to 50% WHC, regardless of the depth of the compost bed. Since the particle size increased dramatically near saturation, the influence of aggregated particle size on the permeability is not significant at these relatively low moisture levels. But the permeability increased with increasing moisture level from 50% to 80% WHC at moderate to shallow simulated bed depths (Corn stalks: 2.1 m, Oat straw: 1.5m, Silage: 0.8 m). This results from the relatively large particle size aggregations under high moisture conditions, which compensate for the effect of reduced air filled porosity by compaction and moisture content at moderate to shallow bed depths. In this study the maximum wet bulk density and mechanical strength decreased with increasing the moisture content. The optimum moisture contents for respiration rate of corn stalks, oat straw, and silage are 81%, 64%, and 78% respectively. The method described for determining physical and biological properties under varying moisture content and compost bed depths will be very useful for designing and modeling composting process with a variety of materials

Environmental Impacts of Emergency Livestock Mortality Composting—Leachate Release and Soil Contamination

A 3-year study was conducted in Iowa to evaluate the feasibility of using composting for emergency disposal of cattle mortalities. During the study, 49 metric tons of 450 kg cattle carcasses were composted in 27 replicated unturned windrow test units constructed during three different seasons of the year. Each test unit contained 1.8 metric tons of carcasses enveloped in one of 5 different materials: corn silage, ground cornstalks, straw/manure, leaves, or a soil/compost blend. Due to their water absorbing capacity and ability to evaporate absorbed water, the volume of leachate released into the soil was generally less than 5% of the 500-600 mm of precipitation that fell on the test units. Chemical analysis of 1.2 m deep soil cores collected from beneath the composting test units prior to and following composting showed statistically significant increases in chloride concentrations at all depths beneath composting test units constructed from silage, cornstalks, straw, and the soil/compost blend. Statistically significant increases in % total carbon (silage test units only) and % total nitrogen (silage, cornstalk, straw/manure test units) were limited to the top 15 cm of soil. Increases in these pollutants were moderate, amounting to less than 5X, 0.2X and 0.4 X respectively of chloride, % total carbon, % total N concentrations prior to composting. Statistically significant increases in total ammonia-nitrogen were noted at depths of up to 90 cm beneath test units constructed with silage or leaves, and at 30 cm and 15 cm depths respectively beneath test units constructed with straw/manure and cornstalks. The ammonia-nitrogen increases were large, ranging from 40-160 X of pre-composting levels of ammonia in the topsoil. When compared with the groundwater pollution potential of carcass burial, however, the estimated total mass of N contained in the composted cattle carcasses was 4-10 X the increases in total N measured in the soil beneath the composting test units

Estimation of optimum moisture levels for biodegradation of compost bulking materials

Moisture affects the physical and biological properties of compost and other solid state fermentation matrices. Aerobic microbial systems experience different respiration rates (oxygen uptake and CO2 evolution) as a function of moisture content and material type. In this study the microbial respiration rates of 13 compost-bulking materials were measured by a pressure sensor method at 6 different moisture levels. The experimentally determined respiration quotient (RQ) values were used to calculate CO2 respiration rates from O2 consumption. The RQ values of all materials were around 1.0 except for silage, oat straw and leaves which were about 1.5. A wide range of respiration and heat production rates were observed for different materials, with alfalfa hay, silage, oat straw, and turkey litter having the highest values. These four compost-bulking agents may be particularly suitable for improving internal temperature and pathogen destruction rates for disease-related mortality composting. Optimum moisture content was determined based on measurements across a range that spans the maximum respiration rate. A mechanistic model of moisture kinetics was also used to predict the optimum moisture levels. There was good agreement between experimental observations and modeled optimum moisture content. The optimum moisture content of each material was observed near WHC, which ranged from near 65 to over 85% on a wet basis for all materials except a highly stabilized yard waste compost (optimum around 30% w.b.). This study demonstrates the importance of moisture content on the biodegradability of organic materials and specific respiration rates of each material. The results can be used to develop moisture management and process control strategies to maintain compost and cover materials in an acceptable range

Feasibility of Hoop Structures for Market Swine in Iowa: Pig Performance, Pig Environment, and Budget Analysis

Hoop structures are large simple, tent–like shelters that can be used for pigs. The pigs are kept inside the hoop structure and large bales, e.g. straw or cornstalks, are used for bedding. A typical hoop structure (10x30 m) holds about 200 market pigs. Bedding is added every two to six weeks as needed until the pigs are marketed at which time clean out occurs. Three demonstrational trials were conducted in Iowa. The pigs were fed from 26 to 117 kg. Pig performance in hoops was acceptable (ADG=.83 kg/d, FE=3.42 kg feed/kg gain) with 9% poorer feed efficiency in winter. Growth rate was equal to or slightly more than typical for pigs in conventional confinement. Pig mortality was less than 3%. Average bedding use was 100 kg per pig in winter and 55 kg per pig in summer. The hoop manure can be composted readily. The bedding pack was variable with some areas actively composting on site in the hoop, generating temperatures up to 62C. An economic analysis showed similar total costs of production with the hoops having lower fixed costs and higher variable costs than in conventional confinement. The higher variable costs are due to bedding and extra feed and labor. Hoop structures offer a feasible alternative production system for sustainable swine production in Iowa and surrounding areas

Soil Contamination Caused by Emergency Bio-Reduction of Catastrophic Livestock Mortalities

Catastrophic regional losses of poultry and livestock have caused environmental officials in North America to seek emergency on-farm disposal alternatives that pose less pollution risk to soil and shallow groundwater than burial. Bio-decomposition of remains followed by land application of the resulting product is used throughout the U.S. and Canada for management of routine poultry, swine, and cattle mortalities, and is often cited as being more environmentally friendly than burial since it recycles nutrients and other potential pollutants into the topsoil and crop production cycle, rather than placing them deeper in the ground and closer to groundwater. During emergencies, however, when time and resources are limited, bio-reduction is likely to be done in unsheltered windrows constructed on unprotected soil—conditions that could cause localized soil pollution. Pollution associated with emergency bio-reduction procedures was assessed by comparing pre- and post-bio-reduction concentrations in soil beneath the bio-reduction sites. Small but statistically significant (p \u3c 0.05) increases in chloride at depths of 1.2 m indicated that bio-reduction leachate reached this depth. Significant increases in % total nitrogen and % total carbon were observed only in the top 15 cm of soil, but large increases in total ammonia–nitrogen were observed at depths of 30–90 cm. The total mass of N added to soil by bio-reduction was 10–25% of the estimated total N in the cattle carcasses, indicating that bio-reduction poses a lower pollution threat to soil and shallow groundwater than burial

Environmental Impact and Biosecurity of Composting for Emergency Disposal of Livestock Mortalities

A two-year project was begun in Iowa in 2002 to test the decay performance, air and water environmental impacts, and bio-security of using composting for emergency disposal of cattle carcasses in the event of a foot-and-mouth disease outbreak. Of the three emergency cover materials tested to date, silage produced the highest and most sustained internal heat, the most rapid and thorough carcass decomposition, and the most rapid destruction of avian vaccine viruses introduced into the piles for bio-security testing. Although internal temperatures within ground cornstalk cover material were much lower than in the silage, carcass decomposition appeared to occur almost as rapidly as in the silage. The cornstalk material produced more collectable leachate with higher pollutant concentrations than the silage. Downwind odor from test units constructed with ground cornstalk, which has a much higher air permeability coefficient than silage, appeared to be strongest and more frequent during the initial 2–3 weeks following construction of the piles

Imaging starspot evolution on Kepler target KIC 5110407 using light curve inversion

The Kepler target KIC 5110407, a K-type star, shows strong quasi-periodic light curve fluctuations likely arising from the formation and decay of spots on the stellar surface rotating with a period of 3.4693 days. Using an established light-curve inversion algorithm, we study the evolution of the surface features based on Kepler space telescope light curves over a period of two years (with a gap of .25 years). At virtually all epochs, we detect at least one large spot group on the surface causing a 1-10% flux modulation in the Kepler passband. By identifying and tracking spot groups over a range of inferred latitudes, we measured the surface differential rotation to be much smaller than that found for the Sun. We also searched for a correlation between the seventeen stellar flares that occurred during our observations and the orientation of the dominant surface spot at the time of each flare. No statistically-significant correlation was found except perhaps for the very brightest flares, suggesting most flares are associated with regions devoid of spots or spots too small to be clearly discerned using our reconstruction technique. While we may see hints of long-term changes in the spot characteristics and flare statistics within our current dataset, a longer baseline of observation will be needed to detect the existence of a magnetic cycle in KIC 5110407.Comment: 32 pages, 15 figures, accepted to Ap