query: What is Japan's number one crop?
passage: Agriculture, forestry, and fishing in Japan
The most striking feature of Japanese agriculture is the shortage of farmland. The 49,000 square kilometres (19,000sqmi) under cultivation constituted just 13.2% of the total land area in 1988. However, the land is intensively cultivated. Rice paddies occupy most of the countryside, whether on the alluvial plains, the terraced slopes, or wetlands and coastal bays. Non-paddy farmland share the terraces and lower slopes and are planted with wheat and barley in the autumn and with sweet potatoes, vegetables, and dry rice in the summer. Intercropping is common: such crops are alternated with beans and peas.
passage: Saccharina japonica
Saccharina japonica is a marine species of the Phaeophyceae (brown algae) plant , a type of kelp or seaweed, that is extensively cultivated on ropes between the seas of Japan and Korea. It is widely eaten in East Asia. A commercially important species, "S. japonica" is also called ma-konbu () in Japanese, dasima () in Korean and hǎidài () in Chinese. Large harvests are produced by rope cultivation which is a simple method of growing seaweeds by attaching them to floating ropes in the ocean.