Measurement of carbon storage in schoolyard grass areas at elementary schools in Kobe, Japan

Abstract In this study, soil samples from the lawns and bare soil of eight elementary schools that are engaged in schoolyard lawn development were collected, and the carbon sequestration amount was measured, in Kobe City, Hyogo Prefecture, Japan. Samples were taken by digging down to a depth that could be dug by hand, both for the grassland and for the bare soil for comparison. The actual sampling depth over which the carbon stock was calculated ranged from 5.0 to 15.3 cm. The samples were divided and tested for their carbon content in three layers (Thatch and Root Horizon + Humus Layer [the section of the soil core that does not contain roots] + Parent Layer) for the lawn areas. For bare soil, the sample was not divided, and the entire sample was tested for its carbon content. Additionally, the depth and weight of the sampled soil were measured. In addition to total carbon analysis using a total organic carbon meter, we also examined the elapsed years the lawn has been maintained as such and the organic status of the soil and attempted to conduct a questionnaire survey to determine any year‐to‐year variations. As a result of the analysis, the amount of carbon on the surface of the lawn (0–20 cm deep) was 152.9 ± 98.7 t‐CO 2 ha −1 . The total carbon stock of the bare land was 149.5 ± 86.4 t‐CO 2 ha −1 , and the increase in carbon stock due to the conversion of elementary school playgrounds was 3.3 ± 1.3 t‐CO 2 ha −1 . The results of this study indicate that the conversion of elementary school playground to grasslands in Japan could contribute to carbon storage.