Tuesday, November 6, 2007
194-16
Effects of Charcoal Application on Radish Growth and N Uptake Estimated by 15N Method.
Hideto Ueno1, Yuichiro Gomi2, Naomi Asagi1, and Takemichi Tsurumi1. (1) Ko 498 Hattanji, JAPAN,Ehime Univ., Ehime University, University Farm, Matsuyama Ehime, 799-2424, JAPAN, (2) Faculty of Agric., Ehime Univ., Matsuyama, Japan
Charcoal was regarded as an useful soil amendment which improve the physical, chemical and biological properties of the soil. But the application effects reported have been inconsistent and varied with cultivation conditions. The purpose of this paper, therefore, to make clear the effect of charcoal with 3 consecutive croppings, several charcoal materials and 15N method by pot experiment. We cultivated radish (Raphanus sativus var. radicula) in a low fertile soil amended with 5 or 10% (v/v) charcoal. Three kinds of charcoal materials made from Japanese cedar (Cryptomeria japonica), Sawtooth Oak (Quercus acutissima) and Moso bamboo (Phyllostachys heterocycla f. pubescens) were used. Consecutive cropping was carried out with 3 times in May, Jun and Aug, 2006. At the first cropping, chemical nitrogen fertilizer was labeled with 15N, and non-labeled fertilizer was applied at the second and third cropping. At the first cropping the growth of radish in all the charcoal plots was lower than control (no charcoal), but the second and third cultivation, they increased with time and were higher than control. Especially charcoal application increased the fresh weight of root (edible part). N use efficiency of N fertilizer in 5 and 10% Japanese cedar charcoal plot and 10% Sawtooth Oak charcoal application were higher than control, but that in Meso bamboo charcoal application was lower than control. In conclusion, some kinds of charcoal application showed a gradual but significant increase in the dry/fresh weight of root system and some part of fertilizer N applied at the first cropping was retained in the charcoal and released during the second and third cropping, leading to the higher N use efficiency.