Elucidating the fertility and microbial changes of red paddy soil and their interactions is conducive to revealing the mechanism underlying the fertility evolution of red soil and providing a scientific reference for rational fertilization in red paddy fields. The evolution of soil fertility is a relatively long process, whereas a long-term field experiment serves as a key approach to deciphering such evolution. At the beginning of its establishment, the Ecological Experimental Station of Red Soil, Chinese Academy of Sciences, based on barren land, established two groups of long-term field experiments on red paddy fields focusing on fertilization regime and nutrient cycling, and organic matter accumulation and balance. These experiments focus on studying the fertility, microbial changes, and their interrelationships, and have obtained some preliminary findings. This paper summarizes the relevant research progress and provides a preliminary outlook on future research.