Wasabi, Eutrema japonicum, is a native Japanese plant of the Brassicaceae family that has been highly prized in Japan since ancient times for the sharp flavor produced when its stems are grated. Shizuoka region is the origin of worldwide wasabi cultivation, and is believed to have begun approximately 400 years ago, during the Keicho era (1596-1615) in the Aoi district of Shizuoka City.

Traditional cultivation method results in the production of large stems, little crop damage from disease, and little danger of nutrient depletion from repeated cultivation that is so often seen in agriculture; as such, it is a cultivation system with an extremely high degree of suitability for wasabi production. Furthermore, wasabi fields in steep mountainous areas currently possess a structure that is resilient to natural disasters because these fields have high water-holding capacity, and they also function to protect downstream areas from flooding disasters.

Food and livelihood security

Wasabi production in the proposed area has a cultivation area of 113.8 ha, a production quantity (stems) of 227.5 t (2016), and production value of 3.15 billion yen (2015 estimated value). Both the cultivation area and production quantity (stems) are the highest in the country, accounting for 40% of the nationwide production; this forms Japan’s largest wasabi-producing region.

Furthermore, processed wasabi goods have not only been a source of additional income for farmers since ancient times, but they have also led to the establishment of many industries affiliated with wasabi processing in the surrounding area, creating workplaces for local residents.

Besides, in the mountainous district of the proposed region, people cultivate a farm adapted to the environment in which, in addition to wasabi, shiitake mushrooms are cultivated under shade of the forests, and tea and wetland rice are cultivated in the sunny place out of the forests.

Agrobiodiversity

Wasabi is one of 26 species in the Eutrema genus of the Brassicaceae family, and is an endemic species that evolved independently in the Japanese islands. Because it grows wild all over Japan, it is thought to have genetic resources that are not found in other countries. At the Wasabi Branch, there are over 100 cultivars and strains are stored that have been grown by wasabi producers.

Furthermore, in wasabi cultivation direct sunlight must be avoided from spring to autumn, and consequently, East Asian Alder trees that naturally grow in the area are planted in wasabi fields to create shade. This is an example of environmental improvement by using native tree species in agricultural production sites. Indeed, this traditional system is a natural habitat for many endemic fauna and flora species.

Local and traditional Knowledge systems

Local farmers have developed several types of wasabi cultivation. The “Jizawa style” of cultivation was established in the proposed region, and has been used since the beginning of wasabi cultivation. However, today, most of them are replaced by the more profitable “Tatamiishi style”.

In the “Tatamiishi style,” which was developed in the latter half of the 19th century, fields are established with larger rocks in the bottom layer and rocks with gradually reducing sizes in the upper layers. Enormous quantities of spring water flow over these wasabi fields, not only crossing the surface, but also percolating into the soil. Thus, impurities are filtered out, water temperature is stabilized, and nutrients and oxygen are supplied, water flow is slowed down thereby, enabling stable production.

Sloping land is made into a series of terraces, large rocks, stones, and sand are laid. Thus, the irrigation water supplied to the surface soil layer of “Tatamiishi style” wasabi fields flows over the top of the surface soil, although some of it permeates that layer and reaches the “tatamiishi” (rock matting) layer at the bottom of the wasabi field. The “tatamiishi” layer, below the surface soil and the rubble layer. Furthermore, this water is used for downstream rice cultivation, and farming of freshwater fish, that prefer clear streams.

Cultures, values and social organizations

The wasabi fields in the Shizuoka region were privately owned from the start, but those in the Izu region belonged to the Shogunate in the Edo period (1603-1868). To cultivate wasabi on this land, producers had to borrow the land jointly (commons), which became the driving force that created unique production organizations. From the necessity of having to apply to village officials to rent land, organizations that local influential people called “wasabi circles” formed in each settlement and these grew into central organizations for promoting wasabi production.

In the proposed region, local people have a deep faith in the water, and there are many shrines related to water there. Wasabi is used as an offering at harvest festivals, and wasabi is deeply rooted in the resident’s lifestyle and culture.

“Washoku” or Japanese cuisine was registered by UNESCO as an intangible cultural heritage in 2013, and interest in Japanese cuisine is rising around the world. Wasabi, as an essential ingredient in Japanese cuisine, is seeing its cultivation scenery made by producers being introduced. 

Landscapes and seascapes features

The proposed region has abundant rainfall in the mountains, resulting in numerous dense forests and plentiful springs. After experiencing numerous natural disasters, local farmers have achieved a construction that is stable and resilient against disaster. “Tatamiishi style” wasabi fields made in terrace formations slow down the flow of water, and the flowing water is reused as it enters each downstream field in turn. Water source environment management, such as cutting grass in the surrounding area, water level adjustments during typhoons and heavy rain are all done by group effort. In this way, people in the proposed area preserve the forests that foster the sources of water so that they can pass down traditional wasabi cultivation and maintain the wasabi fields; surely, the forests cultivate wasabi, and wasabi cultivates the forests.

Through over 400 years of continuous wasabi cultivation, the wasabi fields extend alongside valleys, surrounded by and merging into the forests. They form villages near mountains together with tea farms and wetland rice in the area, creating superb farm village scenery that shows different expressions with each change of season; this is one of the model scenes of mountainous regions.