Rice production is important in Japan since it is the staple of the Japanese diet. However, rice harvest area and production decreased in Japan from 3.3 million ha and 16 million ton in 1961 to 1.6 million ha and 10 million ton in 2012 (FAO 2014). The decrease in rice production in Japan is attributed to a decrease in consumption
from 120 kg per person per year in the 1970s to 60 kg at present due to changes in the Japanese dietary transition, with people now consuming more milk, meat, and bread than before in 1970s (Smil and Kobayashi 2012). Normal rice consumption has decreased in Japan, but high-quality rice, especiall organic rice consumption, is largely accepted
by Japanese consumers. However, in 2012 only 0.2 % of rice fields were certified organic
(MAFF 2012). The major challenge limiting organic rice production in Japan is achieving weed control without using synthetic herbicides (Hokazono and Hayashi 2012).