China has a vast territory and many soil types, many of which are beyond the reach of other countries. Especially as an ancient agricultural country, its artificial soil is special, among which paddy soil, which accounts for a quarter of the world area, has the most China characteristics. As early as the end of 1930s, Song Daquan and other scholars in China thought that paddy soil was a brand-new soil type through a lot of research, especially through the study of its profile and hydroponic maturity process, so they decisively divided paddy soil into an independent soil type, and pointed out that the formation process of this soil was essentially different from that which people always thought was formed under the condition of soil ashing process, and its original innovation was beyond doubt. In the research of soil classification presided over by Song Daquan, together with his colleagues, he included the "artificial soil" in the highest classification system unit "soil class" in the newly proposed latest soil classification system, which also reflected that the above-mentioned original innovation was well inherited. Song's innovative research achievements in paddy soil can be found in the papers written and published in collaboration with Zhu Lianqing, Ma, Hou Guangjiong and others in the 1930s.