Long-term effects of biochar as a soil amendment material on soil biota

We are investigating the long-term effects of spruce and pine- based biochars (BC) on earthworm and microbial community structures in fertile Stagnosol and nutrient deficient Umbrisol soils in Helsinki. BC was applied at rate of 0 and 10 or 30 t ha-1.

The field sampling campaign in 2015: from morning haze to late night!

Earthworm sampling conducted in autumn 2015, four and five years after BC application, showed no significant differences between the biochar and control treatments. The species composition of earthworms was in both sites typical for Finnish arable soils, dominated by endogeic Aporrectodea caliginosa Sav. Total earthworm density in Stagnosol was double the amount than in Umbrisol, but interestingly, we saw evidence of biochar particles being ingested by earthworms. This may suggest its enhancement of the microbial processes in earthworm digestive system.

Soil microbial samples were collected, and soil DNA was already extracted from 2015 samples, and is currently in a process of sequences analysis. In addition we measured soil CO2, CH4 and N2O fluxes in autumn 2015, using a closed dynamic chamber method. Preliminary analyses shows no significant effect of biochars on above mentioned gas fluxes.

In addition to above study, Mr. Jure Zrim has recently started working on effect of recycled organic fertilizers (including BC) on soil properties, crop growth and microbial community structures in (Tila)Hykerrys project, where four new experimental sites have been established since June 2016.

Read more from: Zrim, J., Nuutinen, V., Simojoki, A. & Tammeorg, P. 2017. Effects of biochar on earthworms in two long-term field experiments in Finland. IX Maaperätieteiden päiviät (Conference poster), Pro Terra, 71: 99-100.