Effects of pyroligneous acid amendment on avoidance, survival and biomass change of earthworms in an agricultural soil

Abstract

Pyroligneous acid (PA), as a plant growth regulator, pesticide, and soil amendment, has been widely used in agricultural production, attracting more and more attention. As important soil animals, earthworms are an important indicator of soil health due to their growth and activity. However, little research is available on the effects of PA on the growth and activity of earthworms. In this study, a crude PA prepared from pyrolysis of sawdust biomass (Populus trichocarpa) and its three distilled fractions, D1 (98°C), D2 (130°C) and D3 (220°C) were applied to an agricultural soil to explore their effects on the avoidance behavior and growth of earthworms (Eisenia foetida). Results showed that the application of crude PA and its distilled fractions had little significant effect on the avoidance response of earthworms. Earthworm survival was significantly reduced by 55.6% following the application of D3 (diluted 300 times), whereas no significant effects were observed from other treatments. Accordingly, crude PA and its distilled fractions significantly decreased earthworm weight change rates by 12.5% to 62.5 %, indicating that crude PA and its distillation fractions help to slow down earthworm growth. According to our study, the application of crude PA and its distilled fractions had a negative effect on the growth of earthworms. This would be an important contribution to filling in the data gap on the effects of PA on earthworms and would provide theoretical support for a comprehensive understanding of how PA affects soil health.