Adsorcao de nitrato em Latossolos sob vegetacao de cerrado

Abstract

Adsorption of nitrate by nine oxisols collected in cerrados (savannah) from Brazil was measured in solutions containing graded amounts of KNO, Nitvate adsorp-tion for B-horizons varied from 0.11 mmol/100 g for soil suspensions of pH values ranging from 4.4 to 5.0. The amount adsorbed increased with decreasing pH. At given pH, adsorption was concentration-dependent in a manner consistent with the Langmuir equation

In soils with similar chemical and mineralogical compositions in the Ap and B horizons, the lower nitrate adsorption of the Ap horizons was attributed to the dif-ferences in the organic matter content

To determine the nitrate vemaining in the supernatant liquid, the nitrate elec-trode method and the spectrophotometric method using the ultraviolet range (200 mm) were used, which were checked against the phenoldisulfonic method.