SCIENCE & TECHNOLOGYYOUNG MINDS APPLY TRADITION TO SUPPORTGLOBAL FOOD
PRODUCTION
A team of high school students has devised a functional water-collection systemthat applies tataki, a traditional Japanese technology for soil solidification, with hopes that it canhelp tackle food shortages in arid regions like those in Africa.
As indicated by the goal of “zero hunger”
mentioned in the Sustainable Development Goals(SDGs), creating stable supplies of food is a global
challenge. There are quite a few regions in theworld experiencing difficulties in increasing foodproduction, owing to the inability to secure water
for agricultural use and soil degradation caused bysurface runoff during the rainy season. West Africa is
one such region.
A system developed by a team of high school
students from Japan, however, might provide asolution to this problem. The students, part of theEnvironmental Research Team of Aomori Prefectural

The Winner ofthe Stockholm
Junior Water
Prize
2020

Nakui Agricultural High School, devised a system
to retain rainwater that applies tataki, a traditional
Japanese soil-solidification technology. Tataki
involves adding slaked lime and magnesium chloride
to red clay and gravel, and then mixing, pounding,and hardening the compound. The resultant increasein viscosity and strength has led to the use of tataki ina variety of venues, ranging from the earthen floors of
traditional Japanese homes to irrigation channels andthe floors of sumo rings.
West African farmers use a traditional system
known as zai, in which they dig earthen pits tocollect water. A drawback to the system, however, is

its tendency toward soil erosion, as the pits are madesimply by mounding soil. The Japanese students
had learned in class about the challenges to zai, so
they took the initiative to study ways to improve
the system. The idea for using tataki came from theearthen floor at the home of one of the student’s
grandfathers. It was a suitable choice because it canbe made from readily-available materials, whileproviding the needed durability.
The students searched for a design that could
facilitate water retention, and after much trial
and error, decided upon a wing shape. They also
reproduced African soil and water quality conditions
when conducting tests to confirm if tataki would
work in Africa. In the process, they discovered thatthe nutrients mixed in during the tataki process
gradually seeped out into the surrounding ground.
Using that to their advantage, they modified thetataki mixture to include phosphoric acid, which islacking in West African soil, in order to enrich thesoil.
The students’ project won the Grand Prix of the2020 Stockholm Junior Water Prize, awarded to an
outstanding water-environment project conductedby young people. Team member MIYAKI Takuma
recalls, “I had been impressed by the other countries’
excellent presentations, so I was totally overjoyedwhen the presenter, Crown Princess Victoria ofSweden, uttered the word ‘Japan.’”
The team’s name is Treasure Hunters. According
to NAKATSUTSUMI Yasuhito, “We chose thename with the hope that our technologies would
be treasured by people around the world.” In 2018,
their high school had come in as runner-up for
the Stockholm Junior Water Prize, for a project
employing a natural water-purification method

Tataki has been used from the days of old for earthen floors in traditional Japanesehouses (left) and the floors of sumo rings (right).

The members of Treasure Hunters at the online presentation for theStockholm Junior Water Prize. From left to right: NAKATSUTSUMI
Yasuhito, MATSUHASHI Hiroki, MIYAKI Takuma, and TAMURA Yusei.

It took the students a year and a half to conduct their research. Although theyfound it difficult to harden the materials sufficiently, they confirmed that tataki
would remain durable even after one year.

Water
Water

Valley sideseeds

Tataki arranged in a semicircular shape is installed on the valley side of thehole to catch the water runoff. The students devised an optimal shape toretain the water more fully and curb soil erosion.

combining plants with high transpiration rates andmicroorganisms. Having watched their seniors rack
their brains to find a solution to a global problem
inspired Treasure Hunters to do the same two years
later, and their efforts were duly rewarded.
MATSUHASHI Hiroki analyzes the reason for
their win: “Although tataki—a process of hardening
soil by mixing it with water—is a traditional Japanesetechnology, it can be easily applied anywhere inthe world. I think it got high marks for being an
inexpensive and simple approach that can support
sustainable agriculture.” An increasing number ofinquiries have come in regarding their study, andtalks are also underway with a nonprofit organization
active in Tanzania.
The members of Treasure Hunters will graduate
from high school this spring. TAMURA Yusei, whowill be going on to a vocational school for agriculture,
speaks of his future aspirations ambitiously: “I aminterested in the world’s agricultural issues, and want
to do my part in contributing to their solutions.”
Given how these young people devoted themselves
to studying the local environment and adapting aJapanese method to suit West African conditions,they will undoubtedly continue to blaze new trailswith their inquisitive minds in the future to findsolutions to agricultural challenges.