Japanese-style composting: Helping PGS Thanh Xuan farmers take control of their inputs

Composting trial at PGS Thanh Xuan

Testing five composting formulas in Thanh Xuan

This is an early 2025 activity, marking the proactive search for alternative solutions to the shortage of organic production inputs by the Thanh Xuan Inter-group, which has always been a flagship in organic production within the PGS Vietnam network.

From a story about PGS shared by Dr. Nguyen Van Kien, Director of MekongOrganics, during a meeting with Minister of Agriculture & Rural Development Le Minh Hoan, and a subsequent phone conversation with Dr. Kien, the Minister promised to visit the PGS organic production area at the earliest opportunity. A few days later, Minister Le Minh Hoan conducted a working visit to Thanh Xuan commune, Soc Son (Hanoi).

Visiting the PGS vegetable garden, the green of the vegetables intertwined with waving yellow chrysanthemums is truly eye-catching, making it hard for anyone wandering in to keep their phone in their pocket without snapping photos to capture the beautiful moments. The Minister was just like anyone else visiting the garden; the farmers did not know who he was and innocently laughed and chatted about the hardships of vegetable farming and the joy exchanged for their health and income.

As for me, I took the opportunity to recount the hardships and concerns in searching for standard organic fertilizers at affordable prices so that PGS farmers can use them when their self-composted manure is insufficient. Listening to everyone's stories, the Minister suddenly made a phone call to someone who had spent 3 years studying composting in Japan, and handed the phone over for me to speak directly.

The person connected by the Minister to transfer composting techniques was Mr. Pham Huu Loi – Principal of the Japanese Language and Culture Center in Nam Dinh City, who persuaded Nam Dinh province and the Japanese Government to collaborate in building the first Japanese-model agricultural high school in Vietnam. There, he devoted himself to transferring the composting methods he learned and researched from the Land of the Rising Sun into the school to teach students how to farm, how to make compost, and how to nurture the soil to nourish plants.

I really wanted to learn about and master the Japanese composting method, curious to see how it differed from our usual way of composting. A week later, a team of experts led by teacher Pham Huu Loi and engineer Cao Quang Ninh—an officer from the Nam Dinh Department of Agriculture—with the support of the commune's Farmers' Association and the Thanh Xuan Intergroup, came to Thanh Xuan to provide theoretical guidance and demonstrate the first compost pile on June 8, 2024. In the following weeks, the expert team returned on consecutive Saturdays throughout the month to work alongside farmers on the subsequent compost piles.

Compost pile temperatures, measured every morning at 60–75°C, were fully recorded.

Five composting formulas with primary ingredients of chicken manure, cattle manure, and pig manure. Animal manure accounts for 85–95%, purchased from local small-scale farms. The remaining ingredients are straw and rice bran. The ingredients are thoroughly mixed together with clean water to ensure appropriate moisture, then piled up for aerobic composting under shelter. A heavy and challenging task for aging farmers during composting is turning the piles. Therefore, composting is increasingly becoming a burden for PGS farmers when standard commercial organic fertilizers are too expensive, and cheaper ones are not permitted. Weekly turning is the biggest challenge compared to the traditional composting method, which usually only turns once a month. Five compost piles with raw materials ranging from at least 2.4 tons to at most 3.9 tons, of which three piles were mixed and turned weekly by Bai Thuong Cooperative using an excavator, and two piles were mixed and turned manually with hired labor to compare the difference.

Mix and stir by hand to compare the difference.

The compost pile temperature, measured every morning and reaching 60–75°C, was meticulously recorded alongside external weather changes, and shallow and deep temperatures. The composting process was completed after 11 weeks, and five finished compost samples were tested for nutritional content, heavy metal and antibiotic residues, and microorganisms to ensure the compost met the standards for organic vegetable production. All five composting formulas, featuring different animal manure ingredients and proportions, have varying nutritional values that will serve as the basis for calculating recommended fertilizer rates suitable for each crop. Notably, post-composting testing yielded very positive results. There were no antibiotic residues, and heavy metal levels were well below the allowable limits under Vietnamese standard QCVN 01-189:2019/BNNPTNT. To evaluate effectiveness and make recommendations for use, Bai Thuong Cooperative conducted trials on five types of vegetables: tomatoes, green beans, cabbage, spinach, and potatoes. The trials began on November 1, 2024. The compost was incorporated into the soil 10 days in advance at a rate of 1.5 kg – 3.0 kg/m² depending on the crop. Top dressing was applied to fruiting and root vegetables when necessary. Spinach was harvested earliest, 40 days after sowing, and testing showed good results: no heavy metal residues or harmful microorganisms. Other vegetables will continue to be sent for analysis upon harvest.

Farmers participating in the field workshop directly observed the trial crops in the fields and listened to a report by Mr. Hoang Van Hung, Director of Bai Thuong Cooperative, who directly made the compost and tested it on vegetable crops. Experts and farmers exchanged and shared experiences. Group composting, a key solution raised during the workshop, was enthusiastically discussed by farmers. Participating together and sharing collective and individual responsibilities and benefits within the organic farming community is the core value of the PGS Vietnam network.

Testing shows that applying the Japanese composting method reduces the burden of collecting green materials—which usually account for up to 50% of the ingredients in conventional methods. In this method, rice bran and straw are readily available agricultural by-products in rural areas, making up only 1–5%, without relying on EM or exotic microorganisms, and animal manure can easily be purchased from collection facilities.

An excavator mixes the compost pile and turns the manure weekly.

One challenge—the strenuous weekly task of turning compost—was convincingly and confidently addressed by two composting trial farmers, backed by specific recorded figures on machine rental days, hired labor, and materials added to the compost pile. Renting an excavator to mix the compost pile and turn it weekly helps reduce costs and relieves farmers of excessive physical exertion. Sharing benefits, saving costs, utilizing locally available materials, and particularly controlling the composting process to ensure compliance with standards is the approach adopted by smallholder farmer communities in PGS, contributing to the efficient and sustainable development of local organic agriculture.

_(Source: Vietnam Organic Agriculture Association)._