ChileanJAR

In a field trial, with percolation cylinder, six doses of Sodium Nitrate (0-12,8-48-128-480-1,280 kg N/ha) were lixiviateci with 100 mm of destilled water. Nitrates, moisture content, pH (H₂O), pH (KCI), and Al-Morgan were determined, in samples taken from the cylinders at each 5cm depth, down to 90 cm. Comparisons were made among alI treatments on the distribution of these variables according to depth. The amounts of nitrate and water applied, together with nitrogen mineralization, were determinant conditions for the nitrate balance in the soil profile. During summer, the addition of water to the dry soil strongly stimulated nitrogen mineralization down to 20 cm, probably influencing down to 50 cm. The posible redox conditions of this particular soil (Vilcun, Typic Dystrandept) were inadequate for strict anaerobiosis, so no denitrification was observed, down to 90 cm. The different amounts of Sodium Nitrate applied in this experiment did not affect soil reaction or AlMorgan content. With the application of 100 mm of water to the soil, almost ah the nitrate present initially at 55-90 cm depth was lost. The nitrate adsorption, observed in Andepts, had no practical importance in reducing the mobihity of nitrates, due to hixiviation by excess water. As has been observed for other Chilean soils, moisture at 1/3 atm. did not represent well the field capacity condition of this soil. The soil used in this experiment had been under oats the previous sea-son; roots had penetrated about 50 cm, so moisture and nitrates present below that depth was not useful to the plants.