The study was undertaken to compare the level of total phenolics and the allelopathic potential of Pluchea lanceolata in soils cultivated once or twice a year. Thirty-five cultivated fields were sampled from seven sites in three different seasons. The leaf area, leaf weight, height, and density of P. lanceolata plants were measured. Leaves of P. lanceolata were analyzed for nine chemical characteristics: leaf ash, total phenolics, phosphate, Cu, Zn, Na, K, Mg, and Ca. Weed-infested topsoil and subsoil were analyzed for pH, electrical conductivity, organic carbon, chloride, bicarbonate, total carbonate, phosphate, total phenolics, Zn, Na, K, Mg, and Ca. Fields cultivated twice a year were designated as Group I, while those cultivated once a year were designated as Group II. Biotic and chemical characteristics of plants of Group I and II were not different. Topsoil and subsoil of Group II had higher values for Ca, while topsoil of Group I had higher values for total phenolics. The higher phenolic content of Group I topsoil was probably due to greater incorporation of weed plant parts into the soils as compared to Group II fields. Seedling growth of crop plants such as radish, carrot, maize, mustard, tomato, turnip, and wheat was affected more by soil from P. lanceolata-infested fields that were cultivated twice a year than those cultivated only once. A correlation between higher total phenolic content of P. lanceolata-infested topsoil with two cultivations, and growth response of crop plants was recorded.