The study looked at how nitrogen fertilizer affects tobacco leaf nitrogen levels and enzyme activities in dry land and paddy fields. They found that nitrogen concentration in tobacco leaves peaked during early growth stages but decreased after harvesting. Enzyme activities also increased initially but then decreased gradually after nitrogen application. Paddy fields had higher nitrogen concentration and enzyme activity compared to dry land, but dry land had higher Glutamine synthetase activity. Overall, nitrogen fertilizer improved nitrogen levels and enzyme activities in tobacco leaves, with ammonium nitrogen being more effective than nitrate nitrogen.