Nitrogen losses by surface and subsurface drainage from no-till system

Abstract

Nitrogen losses by surface and subsurface drainage from no-till system(. Nitrogen (N) is an element used in large amount in the agricultural production, being therefore, subjected to great losses affecting water quality. In agriculture, especially in no till system, nitrogen loss is a concern due to the high concentration of this element on the soil surface, what facilitates the transport by runoff. However, the adoption of measures that increase infiltration could hold in the soil bulk the different forms of N. The objective of this work was to evaluate, in no till system under mineral and organic fertilization, the losses of different forms of N in the runoff by rainfall simulation and the leached water by undisturbed soil column. The use of the swine manure resulted higher concentration of runoff total N, except in the lower intensity rainfall. However, independent of the treatments, the concentration of the runoff total N as well as the supernatant runoff total nitrogen was higher in the initial rainfall compared to final rainfall, even being this the highest rainfall intensity. For runoff NH4-N and NO3-N, the swine manure compared with the mineral fertilizer caused the higher concentration. However, the opposite was observed in the leached water, which presented the smaller concentration in all the pore volumes. The soil bulk held more efficiently the NH4-N than NO3-N. All the applied NO3-N was leached out. In the treatment with swine manure, the leaching of the elements was slower compared with the mineral fertilizer treatment.