Effects of biochar mixtures with pine-bark based substrates on growth and development of horticultural crops

Abstract

This study investigates the potential of using biochar as a substrate component to replace pine bark (PB) to produce horticultural crops in containers. Biochar was incorporated in PB at 0, 20, 40, 60, 80 and 100% (by volume) to grow chrysanthemum, tomato, lettuce and basil plants in containers. The responses of plant growth to the percentage of biochar combined in PB mixtures varied among the different crops. Chrysanthemum plants grown in PB mixtures with 80% and 100% biochar had significant higher shoot fresh weight (FW) and dry weight (DW) than plants grown in PB alone, while the same treatments resulted in reduced shoot FW, DW, growth index measured at 19 and 33 days after transplanting and root rating of tomato plants. Growing lettuce plants in 100% biochar reduced the FW of the second crop compared to plants grown in PB substrates supplemented with 0, 20, 40, 60, and 80% biochar. For basil, although biochar alone caused lower root rating, it did not adversely influence the fresh basil yield. Generally, no negative effect on plant growth was observed in PB mixes with biochar as high as 60%, which is probably the outcome of similar physical properties of the biochar to the commonly used PB.