| Summary: | 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.
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