Fundamental Study for the Development of Soil Conditioning Agent from Lignin

酸性土壤严重抑制了植物生长，这是灾害地区特别是东南亚地区植被重建面临的一个严重问题。这主要是由于酸性条件下土壤中的高浓度铝离子溶解到土壤中。在森林健全的土壤中，表层土壤中的腐殖质可能具有控制溶铝浓度的作用。以工业木质素（硫酸盐木质素）为原料，通过碱氧氧化和自由基磺化处理，制备了新型土壤调理剂。通过在培养基中添加改性木质素，可以完全消除铝离子对萝卜根生长的抑制作用。5ppm的铝离子对萝卜根生长的影响，在pH4.5下实际上是禁止的，被120ppm的碱氧处理的半木质素去除。就改性木质素的作用机制而言，有趣的是，添加改性木质素可以抑制铝离子在根尖的吸附。

It is a serious problem for the reforestation of damaged area especially in the South East Asia that plant growth is extremely inhibited because of acidic soil. This is basically due to the high concentration of aluminium ions dissolved into the soil water from soil because of acidic condition . In the sound soil in the forest, humic substances in the surface soil may have a function to control the concentration of dissolved aluminium. In this research, new soil conditioning agents were tried to prepare from industrial lignin (kraft lignin) by alkaline-oxygen oxidation and radical sulfonation treatments.It was clearly confirmed that growth inhibition of radish root because of aluminium ions was completely removed by the addition of a modified lignin to the culture medium. Effect of aluminium ions of 5ppm, in which the growth of radish root is practically prohibited at pH4.5, was removed by 120ppm of alkaline-oxygen treated haft lignin.As far as the function mechanism of a modified lignin, it was interesting to note that adsorption of aluminium ions to the tip of root was inhibited by the addition of a modified lignin.