Physical Properties and Plant Growth Appearance of Torrefied Wood Prepared from Pinus densiflora

Abstract

This study evaluated the effects of solid and water-soluble extracts derived from torrefied Pinus densiflora on lettuce (Lactuca sativa) germination and growth, as well as the cultivation efficiency of torrefied materials combined with plant nutrient solutions. Torrefied samples were prepared under various conditions (200°C, 220°C, 240°C for 20–80 minutes) and mixed with sand at ratios from 20% to 100%. Liquid extracts were formulated with macronutrients (N, P, K, Mg) and micronutrients (Mn, B, Fe, Cu) and applied to leafy and root vegetables. Germination tests showed that 60% and 80% torrefied treatments had the highest and most consistent rates, with torrefied samples promoting more rapid and stable germination than controls. A two-way ANOVA indicated a significant interaction between treatment and concentration (p = 0.043), suggesting concentration-specific effects. While shoot length showed no significant difference, root growth was marginally significant (p = 0.064), with washed torrefied material producing the longest roots. Physical analysis revealed that torrefied materials improved soil thermal retention and moisture-holding capacity. However, increasing torrefied content reduced porosity, likely due to fine particles filling soil pores. In conclusion, torrefied P. densiflora materials exhibit strong potential to enhance germination, root development, and soil condition. Optimal results were achieved with 40–60% solid mixtures for germination and 60–80% diluted extracts for rapid and consistent seedling growth. When optimally applied, they may serve as effective, sustainable amendments in cultivation systems.