Abstract
Teak (Tectona grandis L. f.) seedlings planted in sandy soil in northeastern Thailand often experience suppressed growth due to nutrient deficiency and drought stress. Based on a preliminary field pot experiment, it was observed that biochar increased the root growth of the seedlings. To verify the effects of biochar under field conditions, teak seedlings were planted in a sandy soil treated with 1 kg of biochar in July 2014 (2.5 Mg ha−1), and were cultivated until November 2015. Biomass, photosynthetic rate, and the concentrations of elements in soil and plant materials were compared between biochar and control (no application) treatments. The biochar used in this study contained nitrogen, calcium, and potassium, and thus acted as a fertilizer. Its application accelerated the growth of teak seedlings, increased their photosynthetic rates, and chlorophyll and calcium concentrations in plant tissues. It was concluded that biochar is a useful material to improve the quality of sandy soils and accelerate the growth of teak seedlings.
