Microseason: Earthworms Appear
SUMMER
SUMMER RISES
EARTHWORMS APPEAR
10 - 14 May
Earthworms hatch during this microseason, and come into full activity by mid Summer. A small but profound signal of the earth’s awakening. Like in many cultures around the world, earthworms are referred to as "nature’s plough". They turn and aerate the soil through their constant burrowing, enriching the earth as they go.
By moving through the soil, earthworms improve its structure, draw oxygen, and support microbial life with their nutrient-rich castings, providing ideal habitat for flora and fungi. They initiate a chain of fertility that ultimately nourishes all life.
The appearance of earthworms has traditionally been taken as a sign of fertile, living soil. The phrase makoto no tsuchi or "absolute soil", can be found in the historic text, Aizu Uta Nōsho. Makoto, a hybrid of the words absolute, true, honest, genuine, is used to express rich earth appropriate for each unique terroir in which flora thrive. As it should, makoto no tsuchi is not the same everywhere. The archipelago’s volcanic origins, varied climate zones, and long history of cultivation have given rise to remarkably distinct regional soil.
Kurobokudo
Region: Found widely in volcanic uplands such as the Izu Islands, Kanto Plain, Aso, Hokkaido
Formation: Derived from volcanic ash and pumice
Qualities:
Spongy, rich in humus and organic matter
Excellent water retention and drainage
Easy to till
Uses:
Ideal for leafy vegetables, grains, and tea cultivation
Terraced coastal farming in volcanic zones
Bonsai cultivation thanks to its drainage and structure
Akatsuchi
Region: Okinawa, Kyushu, and parts of Shikoku
Formation: Weathering of basaltic rocks in warmer, humid climates
Qualities:
High in iron and aluminum oxides
Low in nutrients without organic enrichment
Good drainage, but prone to erosion
Uses:
Sugarcane and sweet potato cultivation
Okinawan earthen walls
Pigment and temper in traditional pottery glazes
Haibokudo
Region: Near active volcanic zones like Sakurajima or Mount Fuji
Formation: Recent volcanic ash with little organic development
Qualities:
Small amount of wood-derived humus content
Good for acid-loving plants
Suppresses soil-born pathogens
Uses:
Often reclaimed for use in horticulture or reforestation
Praised in organic produce cultivation for its mineral content
Kurotsuchi
Region: Musashino Plateau , Tokai, and Chubu regions
Formation: Combination of volcanic ash and rich organic decomposition
Qualities:
Deep, dark color from high humus content
Soft, aerated structure
Uses:
Home gardens, farmland, and even animal fodder crops
Frequently mentioned in classical agricultural texts as makoto no tsuchi
The emergence of the earthworm is not merely a sign of the season, but a reminder of the enduring logic of nature. As humble as they may seem, are a living indicator of the health of an entire community. Regional soils not only support agricultural cultivation, but have also shaped local architecture, pottery, and garden design.
Photo credit: Cainz