This chapter describes the history of the use of “night soil” in Japan, using agricultural manuals and records left by individuals dating from the Edo period to the modern period in order to consider possible future developments. The use of human excreta as fertilizer evolved in terms of the objectives and the techniques utilized, and it remained in use until the period of high economic growth. With the rapid technological innovation in the field of toilets and sewage systems after WWII, recycling systems have been reevaluated in recent years and efforts have been made to improve and promote the use of sewage sludge by companies that specialize in recycling technologies.

Introduction

With advanced toilet and sewerage technologies, many people in today's modern society believe that discussing human excrement is taboo, and people have almost no opportunity to engage in an in-depth discussion of the topic. This predicament, however, has developed relatively recently in society. In the past, human waste was used as fertilizer in Japanese farmland. The technique of returning composted human waste (known as shimogoe in Japanese and “night soil” in English) was prevalent and was actively utilized, particularly in suburbs of major urban centers such as Osaka and Edo (the former name of Tokyo).

Watanabe, for example, wrote about the relationship between vegetable cultivation and the use of urban waste, including night soil, that developed in the suburbs of the city of Edo, as part of his historical exploration of fertilization in suburban areas during the Edo period (1603–1867). This also included a comparison between Osaka and Kyoto in the West. Watanabe concluded the following: “local systems of organic material circulation formed between the early modern cities and the surrounding agricultural villages; the return of returned urban waste to the surrounding villages.” Watanabe also discussed how, during the Taishō period (1912–1926), the commercialization of urban human waste began to fade away gradually, and human waste was relegated to the status of waste. The relationship that had existed between urban and suburban areas finally ended during the post-WWII period of high economic growth. Thus, the use of night soil in Japan did not end with the Edo period but continued through the early modern period and up until the post-WWII period of rapid economic growth.