Resumo

MARCANO, Lily  e  ELIZALDE, Graciano. NITRATE LEACHATE FROM UNDISTURBED SOIL COLUMNS FROM TWO SOILS IN THE VALENCIA LAKE BASIN. Rev. Fac. Ing. UCV [online]. 2010, vol.25, n.2, pp.67-72. ISSN 0798-4065.

Nitrate leaching was assessed in undisturbed soil columns in two agricultural soils. Initially, nitrate content at different horizons was much higher in lacustrine soil than in the alluvial soil. In lacustrine soil, nitrate leaching gradually increased, reaching the highest peak at day 72, when it started to decrease, while the alluvial remained virtually constant throughout the experiment. Nitrate leaching concentration in lacustrine soil (50.48 mg L^-1) is 5 times higher than the maximum tolerable limit for environmental standards. In alluvial soil it was lower (20.78 mg L^-1), but it is still twice the maximum acceptable concentration. Therefore, it is considered that irrigation acts as a promoter of the processes of nitrification produced by microorganisms in the soil at the expense of organic matter, which leads to loss of NO₃- through lixiviation. Because of the higher content of organic matter, high permeability and higher requirements of irrigation water, the absolute amounts of nitrate leaching in lacustrine soil were much higher (436 mg) than that of alluvial soil (30 mg) after 4 months

Palavras-chave : Nitrate Leaching; Undisturbed columns; Agricultural soil; lacustrine soil; Lysimeter monolithic.