Impact of application of urea modes and rates on yield and nitrous oxide emissions in grapevine (Vitis vinifera L.) on sandy soils in subtropical climate

Grapevines subjected to applications of nitrogen (N) doses on the soil surface can use only a small amount of the nutrient, probably because of losses, such as nitrous oxide (N2O) emis-sions to the atmosphere. An alternative to reduce these N losses may be the application of N via fertigation. The study aimed to evaluate the N2O emissions and grape yield (Vitis vinifera L.), in grapevines submitted to the application of modes and doses of N cultivated in sandy soil in a subtropical climate. 'Alicante Bouschet' grapevines were subjected to a factorial scheme with three N rates: 0, 40 and 80 kg N ha-1 year-1; and two application modes: surface (NS) and via fer-tigation (NF). Evaluations of N2O emissions and ammonium (NH4+) and nitrate (NO3-) contents in the soil, N concentration in leaves, grape yield, and number of clusters per plant were carried out. Grapevines cultivated with applications of 40 and 80 kg N ha-1 yr-1, in NF and NS modes, respectively, present-ed higher N2O emissions. N2O emission peaks occurred in the first 9 days after N application. Cumulative N2O emissions ranged from 161.74 +/- 34.67 to 496.18 +/- 37.00 g ha-1 of N2O-N, in soils that received 0 and 40 kg N ha-1 yr-1, respectively, both in NF mode. Accumulated N2O emissions had a linearly posi-tive relation with the mineral N content in the soil (NH4+and NO3-) and these had a negative relation with grape yield.