東急が運営するオープンイノベーション拠点「SOIL（SHIBUYA OPEN INNOVATION Labo）」の広場で3月2日、資源循環イベント「コンポストを桜へ施肥するイベント」が開かれた。昨年11月の「コンポストの作り方講座」、1月のフォロー講座に続く第3回目の開催。地域で育てた堆肥を桜の根元に施し、4月の観桜会へとつなげる取り組みだ。

An event held in the plaza (outside area) of the open innovation hub "SOIL (SHIBUYA OPEN INNOVATION Labo)" (Shibuya 3-chome)

会場は、渋谷三丁目にあるSOIL施設前の広場（外構部）。三丁目で暮らす住民や、グーグルや渋谷ストリームなどで働くオフィスワーカーら約25人が参加し、それぞれの家庭や職場で熟成させた堆肥を持ち寄った。

各自の堆肥を合わせ、多様な微生物が混ざり合う

On the day, they mixed the compost they had brought with them with Akadama soil in a ratio of about 1:3. By combining compost with different properties based on each person's diet, a variety of microorganisms can mix together, resulting in more balanced soil.

First, we explained how to make soil using the compost that each person had matured.

Yasuko Kamiyama, a compost advisor for Local Food Cycling (LFC) who served as the lecturer, said, "If the type of food waste you put in is different, the microorganisms that will grow will also be different.Even if there are differences in color and texture, they are all correct."

バック型コンポストを開くと、色味や湿り具合などがそれぞれ異なる堆肥が顔をのぞかせた。食生活はご家庭ごとに異なり、野菜中心の家庭もあれば、タンパク質や油分が多い家庭もある。その違いが微生物の種類や堆肥の状態に反映されるという

神山さんは一つ一つのコンポストに手を入れ、熟成具合などを確認。「水が足りない」「まだ熱があるので、もう少し熟成が必要」など、適切なアドバイスを与えていく。「生ごみであれば、何を入れても大丈夫。骨も問題ありませんが、貝殻は分解しません」と説明。また、栗の皮やタケノコの皮、トウモロコシの外皮など、繊維が強いものは分解に時間がかかるという

The bag-type food waste compost was developed by Fukuoka-based LFC (Local Food Cycling), and its unique feature is that it does not contain microorganisms themselves, but instead uses a "substrate" that naturally grows on vegetables and other foods, making it easy for the naturally occurring microorganisms to work. It can process about 400 grams of food waste per day, for a total of about 40 kilograms.

"There is no need to drain the water. Composting does not cause food to rot, but rather leads to fermentation and decomposition. Many people are surprised at how much food waste it reduces," says Kamiyama.

Each person adds their own unique compost to the Akadama soil.

赤玉土３：堆肥１の割合で、両手を使ってよくブレンドしていく。単一の堆肥よりも、各自持参の堆肥を少しずつ混ぜることで、栄養バランスの取れた土ができるという

Participants commented, "It was a refreshing experience to touch the soil," and "I realized that our food waste can become nutrients for the cherry blossoms."

ブレンドした土は、桜の苗を一回り大きな鉢へ植え替える際に使用。空いた隙間や表面に土を入れ、手でやさしく押さえていく

From a "city of consumption" to a "city of circulation"

Ai Yasue of Tokyu, who organized the event, explained the background to the event, saying, "I wanted to make SOIL Plaza a place that is open to the local community." Although there is a sign at the entrance that reads "Anyone is welcome," it can actually be difficult to get in. First of all, she wanted to host the event herself and increase her connection with the local community.

Through soil preparation and replanting, local residents and workers come together, creating new connections and communication.

「渋谷は“消費の街”という印象が強い。でもこれからは循環型社会の時代。地域で出たごみを地域で循環させる“小さな循環”をつくりたい」（安江さん）といい、自身も昨年11月から自宅でコンポストに取り組む。「どれだけ生ごみを出しているかを意識するようになり、食べ残しを減らそうと思うようになった。においも減り、意識の変化が一番大きい」と話す。

Cherry blossoms connect the community

The trees fertilized this time are the same variety of Yokouzakura cherry trees as those along Meiji Dori. The same cherry trees were chosen with the flow of the approach leading from Meiji Dori to Konno Hachimangu Shrine in mind. A cherry blossom viewing event is planned for March 26th, and the area hopes to become a place where local residents and business people can gather.

"The project is about getting everyone to enjoy the cherry blossoms that we have grown with our own hands. We hope to create interaction not only between local people, but also with companies that we have not had contact with before," says Yasue.

The cherry blossom pots were fertilized during this event. This year, temperatures are higher than usual, and the cherry blossoms are expected to bloom earlier than usual.

都市の中心で生まれた小さな循環。生ごみは“消費の終着点”ではなく、“春への出発点”へと姿を変える。芽吹く桜は、その成果を映すシンボルになりそうだ。観桜会は誰でも参加できる。コンポストに興味ある人は、足を運んでみてはいかがだろうか。

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Interviews and writing

Editorial Department: Takashi Fujii

Shibuya registrar. In addition to Shibuya of Culture information, seasonal news and topics, it will spell write that feel every day.