日本岐阜县的山芋产区,部分属黑色土地带。在这些地区的许多栽培田块中,出现株高降低,产量、叶面积、地上部重量明显减少现象。经土壤调查诊断,判明主要是由于土壤中镁钾比例失调所致。在山芋生育正常的田块耕层内,pH 值平均5.8,有效镁43.8毫克,而在山芋生育不良的田块,pH 值平均低于5.5,有效镁30毫克以下,含镁饱和度5%以下的田块占70～ Gifu Prefecture, Japan’s potato production areas, part of the black land. In many cultivated plots in these areas, plant height reduction, yield, leaf area and shoot weight were significantly reduced. Diagnosed by soil survey, found mainly due to the imbalance of magnesium and potassium in the soil. In the field of normal fertility of potato plow, the average pH of 5.8, 43.8 mg of available magnesium, and potato in poor growth of potato fields, the average pH below 5.5, effective magnesium below 30 mg, magnesium saturation less than 5% The field accounted for 70 ~