Los ácidos húmicos de leonardita sobre características espectroscópicas de la materia orgánica de un suelo en la cuenca del lago de Valencia

banana (musa aaa) farmers in the valencia lake basin, venezuela, apply 15% of leonardite humic acid solution to the soil every three month during the banana cycles production. the possible effects of these applications on soil humic acid were evaluated. soil humic acids were obtained from fields which received no leonardite humic acid (t0) and soils with one year (t1) and tow years (t2) of application. soil humic acid were characterized by elemental analysis and spectroscopic techniques: fluorescence, fourier transforms infrared and electron spin resonance. results indicate that the effects of leonardite humic acid applications on the structure of soil humic acids are limited: only an increasing trend of oxygen contents and free radical concentration in the soil's hunmic acids was observed.