Abstract
The availability of charcoal as vegetable growing media was discussed from the perspective of recycling agricultural wastes. The charcoal was made from pruned shoot of Japanese pear (Pyrus pyrifolia var. culta Rehd.) which is the most abundant agricultural waste product from orchards at the Center for Environment, Health and Field Sciences, Chiba University.
Charcoal mixed with commercial growing media, though the charcoal particle size and mixing proportion varied, hardly affected the growth of Brassica campestris var. peruviridis cv. Gokurakuten. Fine charcoal (0.1 to 1.0cm) mixed at a volume of 20% decreased the amount of NO3-N in discharged water, especially during the early part of cultivation. At the end of cultivation, the cation exchange capacity (CEC) of the media tended to be increased by raising plant, not by mixing the charcoal. When charcoal was mixed with clay soil without fertilizer, coarse charcoal (0.5 to 2.0 cm) improved the soil CEC, and fine charcoal (0.1 to 0.5 cm) increased the soil potassium concentration.
In conclusion, charcoal made from pruned shoots of Japanese pear can be used as vegetable growing media and will improve soil properties, while possibly decreasing NO3-N discharge.
