How much rice did the early Japanese produce and eat?
Carbonised rice grains have been found from over 100 sites, for example at Itazuke. Rice stalks have been found at other sites, like Karako Kagi. Some of the quantities recovered have been huge. 350,000 rice grains (approximately 50 litres), 2,100 grains of millet and 130 beans were recovered from no.59 pit house at Hashihara in Nagano prefecture. They had been preserved when the house burned down. Two large restricted-necked pots in the house had been used for storing these grains.
Cultivation experiments and historical records from the ancient period have been used by Terasawa Kaoru, Watanabe Tadayo and Sasaki Komei to estimate the yield of dehulled brown rice per 100 square metres. They suggest that yields were around 100 kg or less. Sato Yoichiro suggested that yields were 260 kg. Kito Hiroshi used historical documents to estimate yields at 124 to 149 kg during the Edo period. Modern yields of dehulled brown rice per are 518 kg per 100 square metres.
Terasawa has suggested that people in the middle and late Yayoi periods needed millets and acorns in order to cover around 30 to 50% of their daily energy needs (around 2,000 kcal a day). Acorns have been found from over 150 sites, including at Karako Kagi, where a pit with acorns was discovered. Millets such as foxtail millet (Setaria italica) and common millet (Panicum miliaceum) have been found from over 100 sites.
It has been found that people used a wide range of food resources to complement their rice-oriented subsistence. Many of these had also been used in the preceding Jomon period.