In Spain, farmers are interested in applying pig (Sus scrofa domesticus) slurry (PS) to their fields throughout the year. During the spring and summer months, ammonia (NH3) volatilization may be high. We studied the potential range of NH3 losses under a warm and a hot period of the year, using available field practices, and two strategies: PS directly incorporated into the soil, in spring (I-spring); and PS applied by splash-plate, in summer time (SP-summer), both to bare soil. Measurements were conducted, after PS application, using the micrometeorological mass balance integrated horizontal flux method. The cumulative NH3-N volatilization was 35% (I-spring) and 60% (SP-summer) of total ammonium nitrogen applied, and half of the total NH3-N losses happened by 17 h and 8 h, respectively, after application. Incorporation strategy was less effective in avoiding NH3 losses than is described in the literature. This fact has important consequences for the implementation of NH3 mitigation measures in Mediterranean agricultural systems.