Hợp tác xã Nông nghiệp Hữu cơ Hạ Long Xanh, Đinh Thu Thủy A Maize Experiment in Northern Vietnam: Vermicompost, Compost and Biochar Doan and colleagues' 2015 study examined vermicompost, compost and biochar on degraded Acrisol soil in northern Vietnam. The notable point is not a promise of a fixed yield increase, but variation in ... May 25, 2026