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Title: The Effects of Two Different Biochars on Earthworm Survival and Microbial Carbon Levels

Author
item LIESCH, MANDY - University Of Wisconsin
item Weyers, Sharon
item GASKIN, JULIA - University Of Georgia
item DAS, K - University Of Georgia

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/6/2010
Publication Date: 8/6/2010
Citation: Liesch, M., Weyers, S.L., Gaskin, J., Das, K.C. 2010. The Effects of Two Different Biochars on Earthworm Survival and Microbial Carbon Levels. In: Gilkes, R.J., Prakongkep, N., editors. Proceedings of the 19th World Congress of Soil Science: Soil Solutions for a Changing World, August 1-6, 2010, Brisbane, Australia. p. 67-70.

Interpretive Summary: Biochar, a material created from the thermoconversion of biomass through pyrolysis, is a proposed soil amendment as it retains a portion of the carbon, nitrogen and other important plant nutrients in the feedstock. Soil amendment with biochar may also be a means to sequester carbon and offset the release of carbon dioxide from energy production which may be contributing to climate change. Management strategies for the use of biochar as a soil amendment are still in development, and the effect of adding biochar to soil on soil processes, in particular in the presence of earthworms, is virtually unknown. Incubation experiments with two field-collected soils were used to determine if addition of poultry litter and pine chip biochars affect earthworms and soil microbial biomass. In both soils at increasing application rates, poultry litter biochar adversely affected earthworms; however, pine chip biochar had little effect on earthworms. The toxicity of poultry litter biochar to earthworms could be due to pH, salt or metal content all of which increased with application rate. In general, microbial biomass was stimulated in both soils at increasing application rates of poultry litter biochar but was not affected by the addition of pine chip biochar. The potential for positive or negative impacts on soil biota, either earthworms or microbes, with the addition of industrial biochars is apparently dependent on the type of biochar and the soil to which it is applied. These results implicate the need for soil incubation testing in order for scientists, land managers, policy makers and others involved in the process to develop recommendations for the land application of biochars.

Technical Abstract: Biochar is a material created from the thermoconversion of biomass through pyrolysis for the production of bio-energy. The use of biochar as a soil amendment has been proposed as a means to sequester carbon, thus offsetting the release of carbon dioxide. Management strategies for the use of biochar as a soil amendment are still in development, and the effect of adding biochar to soil on soil organisms, in particular earthworms, is virtually unknown. We studied the effect of two different biochars, pine chip biochar and poultry litter biochar, on earthworm growth and survival in incubated mesosocoms in two different field soils, as well as the effect of the two biochars and earthworms on soil microbial carbon biomass. The poultry litter char adversely affected earthworm survival, but resulted in higher levels of microbial carbon, especially at the higher rates of application, especially in the Tifton loamy sand. The pine char treatments had a higher earthworm survival rate; however, microbial biomass with pine char application did not show any change in the Tifton soil, but had a slight decrease in the Cecil sandy loam soil.