Rice on the upland areas of Vietnam is mostly planted on the soils which are acidic and low organic matters. Biochar could increases pH and organic carbon contents in the soil as well as increasing yields if combined either with compost or with chemical fertilizer. This study investigates effects of biochar as well as biochar-composting on changes in soil organic matters (SOM) and some environmental factors such as pH, Eh, Fe2+, N-NH4 in a sandy clay loam, in suburb of Thai Nguyen city, Vietnam (21°34,275' North
105°46,796' East), This paper reports on the results of the first of a three year field trial. A composite high nutrient biochar was produced by blending buffalo dung, Hybrid Acacia wood, bamboo, rice husk, rice straw. All feedstocks were coated with a mixture of buffalo dung 5 percent, lime 2 percent
10 percent clay
5 percent of rice straw ash to increase the mineral content on the biochar's surface. The mixture of minerals and biomass (rice straw and timber wood) were dried and then pyrolysis in TLUD - drum oven at 400-500°C to produce the biochar. After first year of experiments, the utilization of organic amendments increased the amount of SOM compared to the control soil. Biochar incorporate with compost manure was stable in soil. In addiotion, biochar absorbs ion in mineral-organic complex, reducing iron toxic in paddy field.