SummaryA method for extraction and determination of organic phosphorus based on a pretreatment with IM HC1 followed by ultrasonic Vibration in 0.5M NaOH is proposed and shown to be generally superior to two commonly used procedures in terms of efficiency and speed. Determination of organic phosphorus by the proposed technique showed that almost a third of the phosphorus applied to a red‐brown earth growing a mixed legume‐grass pasture has been incorporated into organic molecu