The application of fertilizers in agriculture produce some solute displacement below the root zone and this situation has provoked great impacts, besides the economic damages, causing groundwater contamination. The present work has as the objective of monitoring the displacement process of the potassium (K+) in lysimeters filled with soil, sandy texture and cultivated with peanuts (Arachis hypogaea L.) under different conditions of reducing solar radiation by using plastic films with different thickness (100 and 150 µ). The potassium displacement was monitored by soil solution extractors installed in different depths (15 and 25 cm) and the fertigation management was accomplished by tensiometers. It was concluded that low incident solar radiation in the two environments with plastic coverings negatively affected peanut's yield; the period that the peanut demands larger amount of potassium happens from 30 to 55 days after sowing; peanut plants did not present nutritional deficiency with a smaller leaching of K+ for the deepest layers of soil; in the lysimeters with plastic covering of 100 and 150 micras occurred a larger concentration of K+ in the soil surface.
solute dynamics; soil solution extractor; radiant flow
