Abstract

"With the objective of studying N use efficiency and dynamics in a rotation with and without management of residues, a labeled-N (15N) experiment was established, in a volcanic soil (Typic Melanoxerand), under irrigation. 15N-labeled micro-plots were installed on a 4-year rotation. 15N was applied only once, as labeled fertilizer or residue, to later follow its fate in the rotation. Treatments applied were as follows: i) T1, rotation with incorporation of residues and inorganic labeled-N; ii) T2, rotation with incorporation of residues and organic labeled-N; iii) T3, rotation without incorporation of residues and inorganic labeled-N. The DM yields of T1 and T3 after two growing seasons, maize (Zea mays) - wheat (Triticum aestivum) was 32.0 and 30.7 t ha-1, respectively, and no significant differences were observed. In this study, maize residues were not a significant source of N for the next crops in the rotation. Incorporation of residues (additional C input) did not lead to higher N retention in the crop system studied for the period considered."