Estern Colombia, the Llanos, is constituted of broad grass formations. These big expanses of savannahs present a huge potential for extensive bovine breeding. Unfortunately, these natural pastures have a low productivity and a feeble quality, due to low fertility soils with a deficiency in phosphorus and a hgih acidity. In regard to the importance of the breeding for the region, it`s essential to know the savannahs `characteristics in order to ameliorate the exploitation which is done of them.

The permanganate oxidation procedure is easily performed and may help monitor large areas for their soil organic matter (SOM) quality and nitrogen (N) availability. Knowledge of the chemical characteristics of fractions that are lost or remain after oxidation will help explain results obtained by this method. We found that amino acid N contributed 22.7% to the permanganate-extractable N fraction (PEN) and amino sugar N 9. 1 %, but the remaining 68.2% of the PEN was of "unknown" N. Stable N had lower amounts of amino acid N (15.5%) and amino sugar N (6.2%).