Movement of nitrate in soil of the series "Itaguaí", under field conditions

Abstract

Migration of nitrates in a red-yellow podzolic soil, Itaguaí series, was measured throughout the year. Measurements were carried out both on unfertilized soil and on soil fertilized with sodium nitrate. The studies were made at two field locations, without vegetation. The measurements made on unfertilized soil showed the following results: a) nitrate contents to a depth of 28 cm varied between 5 to 18 ppm during the year; b) the higher nitrate concentration occurred during the period August to October and the lower concentration occurred during the period of December to January. Both the highest and lowest nitrate contents occurred during the rainy season, the lower occurring after a period of uninterrupted rain.  Measurements of the fertilized soil showed the following results: a) after 145 mm of rain within a 30-day period, all of the applied nitrate disappeared to a depth of 28 cm; b) nitrate was leached to a depth of 14 to 21 cm after a total rainfall of 29.1 mm within 15 days; c) after 145 mm of rain within 30 days, all of the nitrate was leached at a depth greater than 28 cm.