Readily weathered soils, such as Ultisols and Oxisols, occurring in tropical areas are low in organic matter content. Therefore their chemical and physical properties are determined by the mineralogical componet which are very low in available nutrients mainly phosphorus and bases for crops, Phosphorus added in fertilizers reacts with iron and aluminum present in oxisols and ultisols dimminishing phosphorus solubility and its efficiency of application. During last years chemical industry has developed commercial products containing the active components present in humus. One of this products named CARBOVIT (1 2% humic substancesl was used in the present experiment applied in three doses (2, 4 and 6% ofthe commercial product) on a Typic Hapludult from Puerto Lopez (Meta). Content of solouble phosphorus, iron, zinc, manganese, copper and aluminum were determined attwo different times, 20 and 45 days after planting raddish (Raphanus sativus L.). After 45 days soil chemical determinations indicated that phosphorus and zinc increases their content; iron, manganese, copper and aluminum dimminished their content compared with their initial content. pH values did not change.