According to Tsukagoshi et al. (2005) [16] the growth of Brassica campestris was not
influenced by Japanese pear charcoal commercial with soil, even though the particle size and
mixing proportion varied. Tsukagoshi et al. (2010) [15] found out other results which were
different from the results of their previous studies that the charcoal amendments, including
thinned Japanese cedar (Cryptomercia japonica D. Don), Moso bamboo (Phyllostachys
heterocycla Matsum.), and pruned shoots of Japanese pear (Pyrus pyrifolia var. culta Rehd.),
inhibited the growth of the first crop.
Plants can absorb only nutrients that are in solution. Nutrients in chemical fertilizers are
usually immediately available to plants. Organic fertilizers may take more time to release the
nutrients as they need some microbial activity to get them working. Therefore, organic fertilizers
(vermicast and commercial bio-extract) may show slower growth in the beginning but when
nutrients and growth hormones are slowly released, plants picks up rapidly growth. Further experiments will be needed to investigate the efficiency of organic fertilizers for vegetable in a
long term.