The influence of organic matter vis-a-vis humic acids on the availability of nutrient status and its impact on the cultivation of rice (Variety MTU 1010) followed by mustard (Variety B-9), was studied in Typic Fluvaquent soil under Old Alluvial zone of West Bengal, India. Important physical and chemical properties of the soil texture were identified as sandy clay loam, bulk density 1.34 Mg m-3, oxidizable organic carbon 1.16 g 100gm-1, pH 6.34, total nitrogen 0.14 g 100gm-1, available phosphorus 25.90 kg ha-1, available

potash 127.40 kg ha-1, available sulphate 39.56 kg ha-1, respectively. The C: N ratio of the added FYM, Commercial and FYM extracted humic acid were 32:11, 32:61, and 13:53 respectively. The soil received recommended doses of fertilizer for the cultivation of paddy (N:P2O5:K2O::60:30:30) followed by mustard (N:P2O5:K2O::80:40:40) along with FYM at 5.0 and 2.5 t ha-1, Commercial humic acid at 0.5, 0.25 kg ha-1 and FYM extracted humic acid at 0.5, 0.25 kg ha-1, respectively as per the treatments combination. The

study selected the Randomized Block Design (RBD). Periodical analysis for the collected rhizosphere soil (0-15 cm) and the plant samples in the C: N ratio was done, along with the available amount of phosphate, potash and sulphur with their integral effect on the crops growth. At the panicle initiation

and branching stages of paddy and mustard, the highest content of the available phosphate, potash and sulphur were recorded. This content gradually decreases toward the harvesting stage. FYM extracted humic acid showed the highest availability of phosphate, potash and sulphur whereas Commercial humic acid enhanced the content of potash in soil, which signified the uptake of phosphorus, potash and sulphur within plants, which resulted in the qualitative enrichment through biometric parameters and yield of paddy and mustard.