Continuing on with our series on using biochar to improve animal husbandry, this week we will overview the use of biochar as a bedding material within pens / livestock houses. For previous posts on biochar, which covers biochar as a livestock feed, see (parts 1, 2, 3 and 4)
Applying biochar to livestock bedding has been demonstrated to be a simple method to control the challenges associated with the accumulation of livestock waste in pens, which has considerable financial cost and effort associated with its management, with inappropriate treatment leading to significant environmental and social impacts. The use of biochar in bedding and manure treatment also has the potential to improve the health and comfort of penned livestock.
Sánchez-García et al. (2010) found that adding straw (22% dry weight) and biochar (3% dry weight) to poultry manure (78%) led to a 20% increase in the rate of composting and degradation of the manure and overall decreases of gaseous emissions (N2O, H2S and NH3) and losses of N. This was attributed to biochar increasing the temperature of the composting process and as a result decreasing the time for compost to reach a maturation phase. Additionally, biochar reduced clumping of the manure increasing the surface area of manure and decreasing hotspots for anoxic conditions, and reduced runoff of effluent from pens into receiving environments.
Biochar mixed with manure controls odour and treatment of manure and effluent and reduces losses of nutrients into receiving environments.
Similar results were also observed in studies by Malińska et al. (2014) and Jia et al. (2015) respectively, in which biochar mixed as a bulking agent to manure/sewage sludge from pens increased the temperature and duration of the thermophilic composting phase and reduced ammonia emissions, which is known to be a disease causing factor in livestock pens.
The study by Jia et al. (2015) focussed heavily on the ways that biochar could reduce emissions of the potent greenhouse gas – N2O from manure. Jia attributed the action of increasing composting rates and reducing gaseous emissions to the porosity and pH buffering capacity of biochar, specifically:
- Biochar helped aerate and absorbed moisture in the manure increasing the action of aerobic microbial processes essential to composting; and
- Biochar increased the pH of the manure, which resulted in lower populations of N2O producing bacteria and higher populations of N2O consuming bacteria.
Biochar has also been shown to reduce disease from livestock pathogens, which proliferate under high stocking conditions. In particular, footpad disease, which is caused mainly by overly wet litter/bedding and high levels of ammonia (NH3). These factors are a major cause of poor quality and welfare of poultry. Exposure to ammonia damages the mucous membranes and lungs of the animal and degrades the immune system, making the animal more prone to disease caused by the various pathogens present in the pen. This can lead to drastic decreases in livestock welfare conditions and performance.
Gerlach et al. (2012) noted that biochar significantly reduces moisture and ammonia levels in bedding litter, resulting in lower incidences of footpad disease and populations of other pathogens laden in livestock litter e.g. E. coli, clostridia, coccidia and mycobacteria. The adsorption capacity of biochar deprives the bacteria of moisture and nutrient in the manure effluent decreasing bacterial growth. Further, the use of biochar can replace the need to add lime to litter, which decreases the pH of the manure resulting in lower emissions of ammonia.
It is recommended that biochar be applied to manure at a rate of 5-10% of the normal litter volume. Gerlach et al. (2012) also suggested that by incorporating biochar into bedding adds value to manures when sold as a fertiliser product by controlling odour and increases the energy potential in manures when burnt or digested for biogas.
As can be seen, biochar provides a number of benefits to control the challenges of housing livestock in pens not just in terms of livestock health and performance but also in terms of waste management, which comes at an enormous cost and effort to farmers.
Further reading:
Biochar in poultry farming - by Henning Gerlach & Hans-Peter Schmidt. See: https://www.biochar-journal.org/en/ct/10
Gerlach, H. and Schmidt, H.P., 2012. Biochar in poultry farming. Ithaka Journal, 2012(1), pp.262-4p.
Jia, X., Yuan, W. and Ju, X., 2015. Effects of Biochar Addition on Manure Composting and Associated N 2 O Emissions. Journal of Sustainable Bioenergy Systems, 5(02), p.56.
Malińska, K., Zabochnicka-Świątek, M. and Dach, J., 2014. Effects of biochar amendment on ammonia emission during composting of sewage sludge. Ecological Engineering, 71, pp.474-478.
Sánchez-García, M., Alburquerque, J.A., Sánchez-Monedero, M.A., Roig, A. and Cayuela, M.L., 2015. Biochar accelerates organic matter degradation and enhances N mineralisation during composting of poultry manure without a relevant impact on gas emissions. Bioresource Technology, 192, pp.272-279.