Fig.1 Process of making vermicompost using school food waste

A research group at the Graduate School of Life and Environmental Sciences of Osaka Prefecture University succeeded in composting school food waste amended with shredded paper by vermicomposting technology. The group leaders were Dr. Kumpei SHIRAGAKI who completed a doctor’s course of OPU, as a present address; Postdoctoral Researcher at the Graduate School of Agricultural and Life Sciences, The University of Tokyo, and Shumpei HASHIMOTO who completed a master’s course of OPU, as a present address; third-year doctoral student at the Graduate School of Bioagricultural Sciences, Nagoya University. They done the work under the advice of Professor Motoaki TOJO at the Graduate School of Life and Environmental Sciences of OPU. The research group clarified usefulness of the vermicomposting technology based on the chemical properties and microbial diversity. Most of the school food waste and shredded paper are usually incinerated. However, the results of this study show that it can be recycled as vermicompost available in agriculture and food education (Shokuiku).

This research was published in Japan Agricultural Research Quarterly (JARQ), an international journal published by the Japan International Research Center for Agricultural Sciences (JIRCAS) on Thursday July 1, 2021 (JST).

Paper Information

Journal: Japan Agricultural Research Quarterly

Title: Chemical and Microbiological Evaluation of Vermicompost Made from School Food Waste in Japan

• Japan Agricultural Research Quarterly (JIRCAS Website)

Summary of Research 

Fig. 2 Vermicompost increased the germination index about twice as much as control compost (18 weeks). The horizontal axis shows the number of weeks elapsed since the start of compost preparation.

The Ministry of Environment reported that about 17.2 kg of food waste per student and about 50,000 tons in total were discarded in Japanese elementary and junior high schools in 2013. This is one example of the “food loss” that is currently a problem in many situations. As is the case with Japan, the problem has been serious in other developed countries, such as China and the United States. School food waste must be incinerated, and the carbon dioxide emitted in the process contributes to the greenhouse effect, worsening the global environment. With a new greenhouse gas emission reduction target for fiscal year 2030 announced to be a 46% reduction compared to fiscal year 2013 levels, reducing carbon dioxide emissions is an urgent issue. As one of a solution to this problem, the research group focused on vermicomposting technology. Earthworms have long been known to decompose organic matter in their bodies and make soil more fertile, and technology for making compost through earthworms has been put to practical use.

In this research, the research group clarified whether earthworms could produce vermicompost from school food waste and how useful the compost is. With the cooperation of the Osaka Prefectural Board of Education, the group conducted a compost production and demonstration test at the Osaka Prefectural Fujiidera Support School as a model school. In the experiment, they used earthworms, Eisenia foetida, to make compost from school food waste and paper waste (shredded paper, for moisture control) in composters (plastic containers) set up in the schoolyard. It became compost within 18 weeks from the start. Chemical composition analysis of the compost showed that the C/N ratio (the ratio of carbon to nitrogen) was 11, which is an index of compost properties, and the same level as that of control compost (without earthworms, about 15). The data also revealed that the compost was richer in minerals such as potassium and magnesium as well as nitrate-nitrogen compared to control compost. In a germination test of komatsuna (Japanese mustard spinach) using this vermicompost, the germination index (calculated from the germination rate and root length) was twice as high as that of control compost, the usefulness of vermicompost to plants was also demonstrated (Fig. 2).

As a result of the microbiome analysis based on sequences of 16S ribosomal DNA (rDNA) using next generation sequencing (NGS) machine (owned by Osaka Prefecture University that can read gene sequences at high speed), higher ratios of Bacillus, Pseudomonas, and Paenibacillus species, which may include beneficial bacteria for plant growth, were detected in the vermicompost. These results indicate that it is possible to produce vermicompost from school food waste amended with shredded paper, and that it may be more useful than control compost.

Social Significance

This research has found a new way to use school food waste and shredded paper, which previously had to be incinerated, as vermicompost. The results of this research will not only contribute to the reduction of carbon dioxide emissions and the recycling of resources through the effective use of the school wastes but will also lead to the reduction of the school wastes themselves as children and students become more interested in food and recycling process. Based on this research, the Osaka Prefectural Board of Education is actively working on a resource recycling system for school food.
From a larger perspective, the results of this study suggest that not only school food waste can be recycled, but also general food waste can be utilized as vermicompost. “Food loss” is a social problem that is particularly prominent in urban areas where many commercial facilities and supermarkets are located. In recent years, the importance of urban agriculture and farmland in urban areas has been reaffirmed due to the interest in agriculture and changes in social conditions such as the spread of COVID-19.

Funding Information

This work is supported in part by the Graduate Program for System-inspired Leaders in Material Science (SiMS) of Osaka Prefecture University sponsored by Japan’s Ministry of Education, Culture, Sports, Science and Technology, and the Yanmar Environmental Sustainability Support Association for Dr. Kumpei SHIRAGAKI.

Contribution to SDGs

1: No poverty
2: Zero hunger
3: Good health and well-being
9: Industry, innovation, infrastructure
15: Life on land

Related Information

• Japan International Research Center for Agricultural Sciences  (JIRCAS Website)