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Agriculture

Online ISSN: ISSN 2077-0472

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Publisher: MDPI
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Evaluation of CO2 Application Requirements for On-Farm Mass Depopulation of Swine in a Disease Emergency

Author(s):

Larry Stikeleather -- William Morrow -- Robert Meyer -- Craig Baird -- Burt Halbert


Abstract
| Pages: 599-612
When an emergency swine disease outbreak, such as foot-and-mouth disease (FMD), occurs, it will be necessary to rapidly and humanely depopulate and dispose of infected and susceptible pigs to limit viral replications and disease spread. Methods other than handling individual pigs will be required to achieve the necessary rapidity. Suitable and practical on-farm methods will require depopulating large numbers of pigs at a time outside confinement buildings. The process must be easily implemented with readily available materials and equipment, while providing for the safety and well-being of personnel. Carbon dioxide gas (CO2) is the means of choice, and this study analyzed the methods and requirements for delivering the gas into large volume truck bodies, corrals, dumpsters or other such chambers that may be used. The issues studied included: How the gas should be introduced to achieve the needed spatial distribution; whether plenums are required in the chambers; and the importance of sealing all chamber cracks and edges except around the top cover to limit CO2 dilution and leakage. Analysis was done using computational fluid dynamics (CFD) software, and primary results were verified experimentally. The CFD findings and experimental results are compared, and recommendations are discussed.

Casting a Wider Net: Understanding the “Root” Causes of Human-Induced Soil Erosion

Author(s):

Michele A. Whitecraft -- Bruce E. Huggins Jr.


Abstract
| Pages: 613-628
Although science has helped us to identify and measure the threat of soil erosion to food production, we need to cast a wider net for effective solutions. Honest assessment suggests, in fact, that this kind of eco-agri-cultural issue exceeds the traditional boundaries of scientific interest. The issue of soil erosion spills out so many ways that it demands a holistic interdisciplinary approach. In this paper we explore a systems “in context” approach to understanding soil erosion built upon the interplay of Aristotle’s virtues of episteme, techne, and phronesis. We model the synergy of collaboration, where diverse ways of knowing, learning and being in the world can offer proactive soil conservation strategies—those that occur from the inside-out—instead of reactive policies, from the outside-in. We show how positivist scientific attitudes could well impede conservation efforts insofar as they can inhibit educational pedagogies meant to reconnect us to nature. In so doing, we make the ultimate argument that disparate fields of knowledge have much to offer each other and that the true synergy in solutions to soil erosion will come from the intimate interconnectedness of these different ways of knowing, learning and being in the world.

Role of Arthropods in Maintaining Soil Fertility

Author(s):

Thomas W. Culliney


Abstract
| Pages: 629-659
In terms of species richness, arthropods may represent as much as 85% of the soil fauna. They comprise a large proportion of the meso- and macrofauna of the soil. Within the litter/soil system, five groups are chiefly represented: Isopoda, Myriapoda, Insecta, Acari, and Collembola, the latter two being by far the most abundant and diverse. Arthropods function on two of the three broad levels of organization of the soil food web: they are plant litter transformers or ecosystem engineers. Litter transformers fragment, or comminute, and humidify ingested plant debris, which is deposited in feces for further decomposition by micro-organisms, and foster the growth and dispersal of microbial populations. Large quantities of annual litter input may be processed (e.g., up to 60% by termites). The comminuted plant matter in feces presents an increased surface area to attack by micro-organisms, which, through the process of mineralization, convert its organic nutrients into simpler, inorganic compounds available to plants. Ecosystem engineers alter soil structure, mineral and organic matter composition, and hydrology. The burrowing by arthropods, particularly the subterranean network of tunnels and galleries that comprise termite and ant nests, improves soil porosity to provide adequate aeration and water-holding capacity below ground, facilitate root penetration, and prevent surface crusting and erosion of topsoil. Also, the movement of particles from lower horizons to the surface by ants and termites aids in mixing the organic and mineral fractions of the soil. The feces of arthropods are the basis for the formation of soil aggregates and humus, which physically stabilize the soil and increase its capacity to store nutrients.

Managing Soil Erosion in Northern Ireland: A Review of Past and Present Approaches

Author(s):

 Karl M. Wantzen -- Jan H. Mol


Abstract
| Pages: 660-683
In recent decades, the off-site transport of sediment and nutrients from agricultural land into the neighbouring natural and built environment has become a more pressing environmental sustainability issue than the on-site threats of soil erosion in many of the world’s temperate regions. In the temperate region of Northern Ireland, recent studies have highlighted the off-site issue of soil erosion by water in the present day, and projected that the problem may become more widespread and serious in a changing climate. This review paper examines how this problem is being managed in the present day, and draws on examples of policy in other countries to consider how the role of policy needs to be modified for more effective management. Farmers are generally not adhering to present-day policy and “keeping their land in good agricultural and environmental condition”. A range of suggested changes in policy and practice is offered, ranging from educating farmers on erosion mitigation and remediation to developing specific policies aimed at targeting soil erosion and conservation as their sole objective. An increase in the evidence base from measured erosion rates in the field is postulated to be the most likely route to achieving policy changes.

Managing Soil Erosion in Northern Ireland: A Review of Past and Present Approaches

Author(s):

Donal Mullan


Abstract
| Pages: 684-699
In recent decades, the off-site transport of sediment and nutrients from agricultural land into the neighbouring natural and built environment has become a more pressing environmental sustainability issue than the on-site threats of soil erosion in many of the world’s temperate regions. In the temperate region of Northern Ireland, recent studies have highlighted the off-site issue of soil erosion by water in the present day, and projected that the problem may become more widespread and serious in a changing climate. This review paper examines how this problem is being managed in the present day, and draws on examples of policy in other countries to consider how the role of policy needs to be modified for more effective management. Farmers are generally not adhering to present-day policy and “keeping their land in good agricultural and environmental condition”. A range of suggested changes in policy and practice is offered, ranging from educating farmers on erosion mitigation and remediation to developing specific policies aimed at targeting soil erosion and conservation as their sole objective. An increase in the evidence base from measured erosion rates in the field is postulated to be the most likely route to achieving policy changes.

Risk Priority Number: A Measuring Instrument for Hygienic Management on Broiler Farms, Reflecting Their Campylobacter Status

Author(s):

Monika Matt -- Hans Peter Stüger -- Peter Pless


Abstract
| Pages: 700-714
Hygiene management is essential for rearing Campylobacter free broiler flocks. In this study, several hygiene factors (e.g., thinning, water supply, stable cloths, stable condition, stable environment, etc.) are categorized and aggregated in a developed risk priority number (RPN). This number is measuring the quality of hygiene management of a broiler farm with one single value (range: 801–4005 points), the higher the RPN, the better is the hygiene status. The distribution of the values is left skewed and none of the 53 examined Austrian broiler farms reached the maximum. Cecal samples (n = 610) from broilers at the point of slaughter determined the Campylobacter status of the farms. Farms with a high RPN consistently produced more Campylobacter free batches than farms with a low RPN. Ranking of the broiler farms based on their RPN was significantly correlated with their microbiological results for Campylobacter detection (Spearman’s correlation coefficient = 0.646). The risk priority number is an easy tool for the assessment and measurement of the hygiene management system at a broiler farm. Besides the educational benefits of the RPN, benchmarking against the mean value or the maximum is possible.

Practicality of Biochar Additions to Enhance Soil and Crop Productivity

Author(s):

David M. Filiberto -- John L. Gaunt


Abstract
| Pages: 715-725
The benefits of biochar to soils for agricultural purposes are numerous. Biochar may be added to soils with the intention to improve the soil, displace an amount of conventional fossil fuel based fertilizers, and sequester carbon. However, the variable application rates, uncertain feedstock effects, and initial soil state provide a wide range of cost for marginally improved yield from biochar additions, which is often economically impracticable. The need for further clarity on optimizing biochar application to various crop yields is necessary if it is to gain widespread acceptance as a soil amendment.

Temporal Variation of SOC Enrichment from Interrill Erosion over Prolonged Rainfall Simulations

Author(s):

Yaxian Hu -- Wolfgang Fister -- Nikolaus J. Kuhn


Abstract
| Pages: 726-740
Sediment generated by interrill erosion is commonly assumed to be enriched in soil organic carbon (SOC) compared to the source soil. However, the reported SOC enrichment ratios (ERSOC) vary widely. It is also noteworthy that most studies reported that the ERSOC is greater than unity, while conservation of mass dictates that the ERSOC of sediment must be balanced over time by a decline of SOC in the source area material. Although the effects of crusting on SOC erosion have been recognized, a systematic study on complete crust formation and interrill SOC erosion has not been conducted so far. The aim of this study was to analyze the effect of prolonged crust formation and its variability on the ERSOC of sediment. Two silty loams were simultaneously exposed to a rainfall simulation for 6 h. The ERSOC in sediment from both soils increased at first, peaked around the point when steady-state runoff was achieved and declined afterwards. The results show that crusting plays a crucial role in the ERSOC development over time and, in particular, that the conservation of mass applies to the ERSOC of sediment as a consequence of crusting. A “constant” ERSOC of sediment is therefore possibly biased, leading to an overestimation of SOC erosion. The results illustrate that the potential off-site effects of selective interrill erosion require considering the crusting effects on sediment properties in the specific context of the interaction between soil management, rainfall and erosion.

Effect of Different Feed Structures and Bedding on the Horizontal Spread of Campylobacter jejuni within Broiler Flocks

Author(s):

Beate Skånseng -- Birger Svihus -- Knut Rudi -- Pål Trosvik -- Birgitte Moen


Abstract
| Pages: 741-760
In this study, we investigated the effects of different feed structures and beddings on the spread of C. jejuni in broiler flocks, and the effect on the cecal microbiota. Broiler chickens raised in 24 eight-bird group cages on either rubber mat or wood shavings were fed either a wheat-based control diet (Control), a diet where 50% of the ground wheat was replaced by whole wheat prior to pelleting (Wheat), or a wheat-based diet, such as the control diet diluted with 12% oat hulls (Oat). Samples from the cloacal mucosa of all birds were taken daily for C. jejuni quantification and cecum samples were collected at the end of the experiment for C. jejuni quantification and microbiota analyses. We have shown a statistically significant effect of increased feed structure on the reduced spread of C. jejuni in chicken flocks, but no significant differences were detected between types of structure included in the feed. No significant changes in the dominating microbiota in the lower lower gastrointestinal (GI) tract were observed, which indicates that feed structure only has an effect on the upper GI tract. Delaying the spread of C. jejuni in broiler flocks could, at time of slaughter, result in fewer C. jejuni-positive broilers.
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