Efeito da cobertura do solo e frequência de irrigação na lixiviação de nitrato.

Abstract

The objective of this work was to study "in situ" the leaching of nitrate in a soil without cover and with plastic cover, submitted to the following frequencies and irrigation depths: every 3 days, 12.5 mm (I); every 6 days, 25.0 mm (II) and every 12 days, 50 mm (III). The N0-3N was applied at a dosage equivalent to 400 Kg / ha in the form of potassium nitrate. The experiment was carried out in an Eutrophic Red Yellow Latosol of medium texture, located in the area adjacent to the South of the Irrigation Pilot Piano of the Center for Agricultural Sciences of the Federal University of Paraiba, in Areia-Pb. A randomized block design with subdivided plots was used. The results of this work indicate that the soil with plastic cover presented a higher rate of leaching (significance at the level of 51), which occurred as a result of its higher water content. In soil without cover, evaporation delayed leaching as a result of less water subject to percolation and capillary rise of the soil solution. Although there was a tendency for leaching to increase with increasing irrigation depth, the analysis of variance did not show significant differences between undertreatments. However, the Duncan test revealed significant differences between frequencies I and I I I (51) for the ground without cover. For soil with plastic cover, if obtained differences between frequencies I and I I I at the level of 1% e, I and I I at the 5% level. The observed non-significance between frequencies I and II on the one hand and II and III on the other hand, from the first treatment and II and III from the second, probably due to the rains that occurred during the period and the proximity of the water table. It was found that, in general, the water content of the soil increased with the increment of the irrigation blade, the soil with plastic cover having the highest moisture content throughout the trial period.