Effect of biochar amendment on the properties of growing media and growth of containerized Norway spruce, Scots pine, and silver birch seedlings

Abstract

Common practices and several studies have demonstrated the positive effect of biochar amendment on climate change mitigation, soil properties, and plant growth. We performed a greenhouse experiment to assess the potential of wood biochar to improve the properties of the growing media and the growth of seedlings in boreal tree species. We added willow biochar (0%, 5%, 10%, and 20%) to raw peat and measured the growth of Norway spruce (Picea abies (L.) H. Karst.), Scots pine (Pinus sylvestris L.), and silver birch (Betula pendula Roth) seedlings. In addition, the co-effect of biochar amendment with 0%, 50%, and 100% fertilization was estimated. We found that using up to 10% of biochar did not reduce the water retention capacity of the growing media significantly. Moreover, biochar amendment significantly increased carbon, nitrogen, potassium, and phosphorus concentrations and had a significant liming effect on the growing media. The biochar amendment increased the aboveground growth of spruce seedlings and root biomass, as well as the root collar diameter, of birch seedlings. Biochar amendment did not affect the quality of seedlings, estimated by the Dickson’s quality index, for spruce and pine, while the quality of birch increased. Based on our results, biochar has potential in forest seedling production.