The mixture of urea with fertilizers with acid characteristics applied to the soil can increase the ions H+ concentration close of the granule and promote the reduction of N volatilization losses. The experiment was carried out in pots with 15 kg of a medium textured Red Latossol, under plastic tunnel, in Botucatu, State of São Paulo, in which corn plants were grown (two plants per pot) until tasseling (66 days after emergency - DAE). The treatments comprised application of N-fertilizer (100 mg N dm-3), at the five-leaves stage (30 DAE), using the following fertilizers or mixtures: (1) urea (UR) enriched with 15N; (2) ammonium sulphate (AS) enriched with 15N; (3) "sulfnitro" (80% of N-UR and 20% of N-AS in the same granule); (4) mixture of UR (80% N) and AS (20% N and enriched with 15N); (5) mixture of UR (50% N) and AS (50% N) both enriched with 15N; (6) mixture of UR (50% N) and AS (50% N and enriched with 15N) and (7) mixture of UR (50% N); AS (50% N), both enriched with 15N, diluted in water (solution containing 3% of N), plus a treatment did not receive N. The mixture UR and AS did not affect N recovery by corn plant. Of the total 15N applied, about 67% were recovered by the corn plant (29% in the leaves, 25% in the stem and 13% in the roots) and 6% in the soil, with an estimated loss of 27%. The 15N of urea was recovered in smaller amount in the stem in relation to that from ammonium sulphate.
Zea mays L.; 15N; nitrogen fertilizer; volatilization
