In the global climate change scenario, application of biochar in soil has become one of the important management practices for carbon sequestration, soil health improvement and climate change mitigation. In this study, an attempt was made to see the effect of biochar prepared from weed biomass on soil properties in subtropical northeast India. Biochar were prepared from seven locally available weed biomass viz. Ageratum conyzoides, Lantana camera, Gynura sp., Setaria sp., Avena fatua, Maize stalk, Pine needles and were characterised. Apot experiment was conducted with maize, where biochar was applied alone and in combination with fertilizers. Results revealed that biochar had significant impact on soil pH, SOC, and available nutrients like N, P and K. It also had significant impact on maize biomass yield. All biochar contained more than 50% stable carbon. Increase in soil pH was in the range of 0.26 to 0.3 and that of SOC from 1.62% in control to 1.74% in biochar added treatments. Biochars alone improved the available nitrogen ranging from 4.5 to 21.3 mg kg(-1), available P from 3.32 to 3.68 mg kg(-1) and increased K content by 20% above control. Weed biomass can be potential alternative to enhance soil and crop productivity through conversion into biochar.