The objective of this study was to determine the effect of application of different amounts of N fertilizer added by fertigation and different mulches on the total mineral N in the plough soil layer and yield of tomatoes. The two-year study (2007 and 2009) was conducted on hydromeliorated deep Terra Rossa near Pula. In two-factor experiment, set in a split-plot design, the main factor was N fertilization (NF) in three levels: 60 (NF1), 120 (NF2), and 180 (NF3) kg N ha^-1. Subfactor was soil mulch (M), also in three levels: without mulch (WM), straw mulch (SM), and mulch with black polyethylene film (BPM). Different NF significantly affected the amount of N min in the soil. Only in 2009, mulch as well as interaction between NF and DAT had significant impact on the amount of N min in soil. Nitrogen fertilization did not significantly affect the total yields of tomatoes, except the application of NF2 and BPM that generated significantly higher yields of tomatoes in 2007. Recommended technology is application of NF2 and BPM, but with ecological point of view it would be justified to use the nitrogen fertilization with only 60 kg N ha^-1.

Key words: fertigation, mulch, soil, mineral nitrogen, tomato