Paddy development and operation
Using data from historical sources it is possible to estimate Yayoi rice harvests. As described above, the paddy fields at Nakanishi were established and used during the early Yayoi period, after which they were abandoned.
While their overall area, estimated as being as much as 100,000 m2, seems very large given the limited time they were in use, how much rice could actually have been cultivated there? Research by a group led by Kaoru Terasawa suggests that paddy fields from the early to middle Yayoi could be expected to have yielded similar quantities to what are historically described as low-yield (geden) or very low-yield (gegeden) paddies.[827] In experiments carried out by Yukiko Kikuchi and Nobuaki Miyoshi, red-kernelled rice yields supported this estimate, although the results did vary depending on the kind of rice sown, the method of sowing (direct sowing or transplantation of seedlings), and the density of sowing.[828] According to Goichi Sawada, on whose research the estimates provided by the Terasawa group were based, gegeden produced the lowest yield from ancient paddies, calculated as 31.75 kg (0.244 koku) of unpolished rice (genmai) per tan (991.74 m2). This is close to the average yield achieved by the Kikuchi experimental group for directly sowed tsutsu-variety rice. Geden yielded twice as much as gegeden, i.e. 63.5 kg (0.488 koku) per tan. This value is also close to the average yield of tsutsu rice when densely planted during experiments. Whether or not the transplantation method was used during the early Yayoi remains under discussion. The remains of rice stubble found at Nakanishi-Akitsu indicate that the estimates should range between gegeden (lowest) and geden (highest).One tan (991.74 m2) is equal to an area which yielded one koku (180 litres or 150 kg of rice).
Very low-grade rice paddy (gegeden) was considered to yield one quarter of a koku, while the next grade up, low-grade paddy (geden), yields half of one koku of rice. If one koku of rice was normally consumed by an adult in a single year, then four tan ofgegeden (3,966.96 m2) or two tan ofgeden were needed to supply sufficient rice for a year for one adult. We can then estimate the number of people that the paddies at Nakanishi would have supported: while 25,000 m2 have been found so far, it is estimated that the total area of paddy is between 50,000 and 100,000 m2, i.e. yielding enough rice to support a minimum population of 12.6 people, and a maximum of 25.21 people (50,000 m2), and between 25.21 and 50.42 people (100,000 m2). These figures remain speculative, however, as we do not know how much rice was actually consumed by individuals during the Yayoi period. Contemporary Japanese people consume on average 59 kilograms of rice in a year, as part of their mixed diet. On this basis, the number of people the Nakanishi paddies could support would double.
More on the topic Paddy development and operation:
-
World history -