Lantana is an obnoxious weed in the pastures and forest land. The prospect of utilizing its huge biomass as an organic source of nutrient compared to Sesbania, wheat straw, mustard straw and chickpea straw was studied under submerged field conditions. These were chopped, taken in nylon mesh bags and then placed (0-10 cm) in a puddled field. One set of bags was dipped in butachlor solution (3000 ug/ml) prior to its placement in field. Three replicates of each treatment were taken out periodically and analysed for NPK and S content. The butachlor showed no effect on dry matter decomposition rate. The decomposition half-life of Lantana (26 d) was lower than that of wheat (45 d), mustard (41 d) and chickpea (34 d) straws and similar to Sesbania (26 d). Lantana was also superior to wheat, mustard and chickpea straws, and comparable to Sesbania in terms of NPS mineralization