Hey gang! I’m Jillian Bailey, an undergraduate researcher at the University of Nebraska-Lincoln studying Biological Systems Engineering. I had the privilege to grow up around agriculture on farms both in Kentucky, raising cattle, and in Nebraska, farming corn and soybeans. These experiences have given me a unique opportunity to compare practices across the United States and agricultural emphases. Here at UNL, my interest in animal science and bioengineering led me to work with Dr. Amy Schmidt, “The Manure Lady,” in her Animal Waste Management Lab. 

As a part of the Schmidt Lab Team, I attended the 2025 Waste to Worth conference in Boise, Idaho, where topics such as manure, mortality, and nutrient management are discussed in detail. I found these discussions to be a great addition to my experiences in the lab, and I came away with a much greater appreciation of some of the complexities of livestock management, including different mortality management practices.  

Mortality management is an essential part of raising livestock. No matter how careful we are to protect and maintain our animals, injury, extreme weather, and disease may result in the death of one animal or sometimes an entire herd. There are many options for handling the resulting carcasses, and each has its pros and cons, including incineration, rendering, burial, composting, and the new variant shallow burial with carbon (SBC). 

Shallow Burial with Carbon 
SBC, also known as trench composting or above-ground burial, is an alternative approach to decomposing waste, which is functionally a combination of burial and composting. SBC begins with excavating a shallow pit (12-24 in) and adding a layer (12-24 in) of carbon material, similar to starting the base of a compost pile. Mortalities are placed on the carbon base, spaced like preparing to compost, but instead of adding more carbon on top of the carcasses, the excavated soil is replaced on top of the pile. In this way, SBC provides some of the benefits of composting, but SBC isn’t as labor-intensive. When composting, producers must monitor piles for temperature, moisture, and periodically add water and turn the piles, whereas SBC does not require additional management after initial setup. Moreover, in regions with high rainfall, SBC has been found to yield less leachate compared to uncovered windrow composting due to less water infiltration through the soil layer (Castro, 2023). This is an important consideration for maintaining local groundwater quality by reducing the load of contaminants entering the soil environment. 

Carbon Material 
An important decision when implementing SBC is deciding on the carbon material to utilize. The carbon material has three different purposes: 
1. Absorb and temporarily trap leachate released from the decomposing carcasses; the slower release allows for improved degradation and reduction of harmful chemicals and pathogens present in the carcasses. 
2. Provide elemental carbon to the microorganisms that function as the primary carcass decomposers in the system. 
3. Temporarily trap oxygen in the system, extending the period of microbial activity and reducing the number of harmful pathogens and chemicals that will be released into the environment. 

Wood products such as chips, shavings, and mulch have been a popular selection in the past. Although wood performs well for this use, it is not widely available at all sites where mortality disposal is required, so researchers have investigated alternative carbon materials. This could be crop residues such as corn stover, rice hulls, straw, or hay. There is ongoing research analyzing the effectiveness of SBC with different materials (hardwood mulch, corn stover, wheat straw, and fescue hay). To date, the data indicates that corn stover has the best leachate adsorption per cost of pile construction (compared to wood chips or processed carbon products like cellulose fiber or paper pulp) but that that most any carbon source will provided an acceptable rate of decomposition of a whole swine carcass (reduced to bones in one year).  

Leachate Management 
Composting, SBC, and burial pits all produce leachate (a mix of water and other fluids present in carcasses that are released during decomposition), which may contaminate groundwater if not correctly managed. With groundwater contamination comes concerns for surrounding livestock and rural populations that depend on water from wells. The benefits of SBC and composting over traditional burial pits involve the addition of a base layer of absorbent material to capture some of the leachate that will be generated. Another essential consideration should be soil type, as constructing the pit over clay or other soils with slow infiltration is one of the best ways to reduce groundwater impacts. Generally, for protecting groundwater, the most important thing to consider regarding mortality management is location.  

Risk Mapping Pile Locations 
One of the projects highlighted at this year’s conference was on mapping risk to groundwater for locating mortality management systems. The research began with understanding the vertical movement of nitrate nitrogen using leachate produced during mortality decomposition based on laboratory soil column experiments. A computer model (HYDRUS-1D) was then used to predict how leachate would behave in soil in the real environment. This information was then linked to known soil and environmental information using GIS to create maps showing the different risks associated with animal burial in a large area. Although this research is based in Nebraska, the same methods can benefit other populations and minimize the risk of swine carcass burial leading to groundwater impairment due to leachate contamination. This study could be replicated to understand the differences and implications of different livestock mortality types where a larger volume of leachate may be produced, as well as an introduction to various soil types around the globe. 

Attending the Waste to Worth conference and participating in university research has given me a deeper understanding of the practical and environmental challenges involved in livestock mortality management. From shallow burial with carbon to GIS-based risk mapping, it’s clear that the future of responsible animal agriculture will depend on innovative, site-specific solutions that protect both livestock health and environmental quality. From my experience at Waste to Worth and college, my enthusiasm to learn more about and contribute to this crucial, although (sometimes) strange, field is ongoing. 

Additional Resources

Burial Setback Guidance
Disposal of Animal Carcass
Emergency Disposal of Livestock Carcasses

Works Cited

Castro García, G. (2024). Managing animal carcass leachate to prevent water pollution. UNL Water. https://water.unl.edu/article/animal-manure-management/managing-animal-carcass-leachate-prevent-water-pollution/.  

Castro García, G., Schmidt, A., Zelt, M., Daigh, A., Mote, B., & Córdova, C. (2025, March 30). Risk Mapping of Potential Groundwater Contamination from Swine Carcass Leachate Using HYDRUS-1D and GIS. Proceedings of Waste to Worth 2025. Livestock and Poultry Environmental Learning Community. https://lpelc.org/risk-mapping-of-potential-groundwater-contamination-from-swine-carcass-leachate-using-hydrus-1d-and-gis/ 

Castro, G., Schmidt, A. (2023). Evaluation of Swine Cadaver Disposal through Composting and Shallow Burial with Carbon (poster presentation). ASABE AIM. Omaha, NE.

Samson, A., Schmidt, A., Zelt. M., & Castro García, G. (2025, March 30). Evolution of material mixtures for leachate absorption during on-farm disposal of animal mortalities. Proceedings of Waste to Worth 2025. Livestock and Poultry Environmental Learning Community. https://lpelc.org/evolution-of-material-mixtures-for-leachate-absorption-during-on-farm-disposal-of-animal-mortalities/ 

Sharara, M., Flory, G., Clark, B., Peer, B., & Hutchinson, M. (2025, April 4). Impacts of Swine Carcass Preparation and Carbon Material on Effectiveness of Shallow Burial with Carbon (SBC). Proceedings of Waste to Worth 2025. Livestock and Poultry Environmental Learning Community. https://lpelc.org/impacts-of-swine-carcass-preparation-and-carbon-material-on-effectiveness-of-shallow-burial-with-carbon-sbc/ 

United States Department of Agriculture, Animal and Plant Health Inspection Service. (2022). Large-Scale Shallow Burial with Carbon Field Study in Oklahoma. https://www.aphis.usda.gov/sites/default/files/large-scale-shallow-burial-ok.pdf.