The five-color soil in geomantic omen is

Black soil The northeast plain of China is wet and cold, with weak microbial activity, and the organic matter in the soil decomposes slowly and accumulates more, so the soil color is dark.

Loess The soil on the Loess Plateau in China is yellow, which is due to the low content of organic matter in the soil.

Minerals in the red soil in the south of China, which is hot and rainy, are strongly weathered and completely decomposed. Almost all water-soluble minerals are lost, and only minerals such as iron oxide and aluminum remain in the upper soil, forming red soil.

In the case of poor drainage or long-term flooding, iron oxide in red soil is often reduced to light blue ferrous oxide, and the soil turns gray-blue, such as some rice fields in the south.

Saline soil and alkaline earth with high salt content such as magnesium and sodium are often white.