1, sensory identification: General acidic soil wet paste rotten, dry to form larger lumps, put bitter taste in the little entrance. In alkaline soil, after the rain, the surface crust, dry loose. The loose soil into the water to stir the muddy, clarify the clarification of the liquid to boil dry, the bottom has a little cream. Of or for red or yellow soil is acid, such as yellow soil, upland soil, red soil land etc.. The general red soil pH value was 4.56.0, soil acidity, pH value is 4.05.5.