MOVEMENT OF NO3-N AND ATRAZINE THROUGH SOIL COLUMNS AS AFFECTED BY LIME APPLICATION

Lime (CaCO3) applied to the soil, to minimize or neutralize the soil p H, can influence the fate and transport of other chemicals in soil. Th is study was conducted to investigate the effect of lime application o n the movement of NO3-N and atrazine through soil columns under satura ted and unsaturated conditions. Six undisturbed and six disturbed soil columns were collected from a chisel plow plot Lime (60% CaCO3) was s urface applied at a rate of 9 Mg/ha on three disturbed and three undis turbed soil columns. The rest of the columns were left untreated. Unde r unsaturated conditions, potassium nitrate (KNO3) and extrazine (21.4 % atrazine - 2-chloro-4-ethylamino-6-isopropylamino-1,3,5 triazine) so lutions (equivalent to 200 kg N/ha and 2.8 kg a.i. atrazine/ha, respec tively) were surface applied to all the columns. An initial irrigation of 127 mm was applied to all columns, and four additional irrigations of 60 mm each were applied at weekly intervals. Subsequently, under s aturated conditions, a solution containing CaCl2 (0.005 M), extrazine (2 000 mu g/L of atrazine), and KNO3 (200 mg/L of NO3-N) was continuou sly passed through each column after saturating them with 0.005 M CaSO 4 solution. Under both saturated and 4 unsaturated conditions, the lea chate was collected and analyzed for NO3-N, atrazine, calcium, and pH. The results of this study showed no significant influence of lime app lication on the leachate flow rates through lime-treated columns. A si gnificantly higher concentration of NO3-N was observed in the leachate from unsaturated undisturbed soil columns treated with lime when comp ared with any other treatments. Atrazine losses in the leachate were g reater for undisturbed, lime-treated columns under both saturated and unsaturated conditions. Column effluent samples did not show any signi ficant effect of lime application on the pH of the leachate. The resul ts of this study indicated that there was a strong correlation between calcium and NO3-N concentrations in the leachate water. No correlatio n was detected between calcium and atrazine concentrations.