Abstract: The effects of four levels of nitrogen, N0 (without nitrogen), N1 (100mg.kg⁻¹), N2 (200mg·kg⁻¹) and N3 (300mg·kg⁻¹) on soil properties, N₂O and CO₂ emissions in dry red soil and latosol were analyzed by laboratory incubation experiments. The results showed that nitrogen fertilizer significantly declined soil pH and organic carbon content. Compared with N0, N1, N2 and N3 treatments decreased pH and organic carbon by 8%−18% and 4%−12% in dry red soil, respectively, and latosol decreased by 5%−23% and 3%−15%, respectively. The total nitrogen content in dry red soil and latosol increased by 15%−54% and 13%−52%, respectively. Nitrogen application increased the contents of NH₄⁺−N and NO₃⁻−N, and the contents of NH₄⁺−N and NO₃⁻−N were N3>N2>N1>N0. Nitrogen addition promoted soil N₂O and CO₂ emissions. Compared with N0, cumulative N₂O and CO₂ emissions in dry red soil increased by 1176%−2425% and 124%−281%, respectively, and those in latosol increased by 1054%−1887% and 138%−256%, respectively. Nitrogen application rate and soil type are important factors affecting soil N₂O and CO₂ emissions. There was a significant linear correlation between soil N₂O and CO₂ emissions and nitrogen application rate. Reducing fertilization is the most direct and effective measure to reduce soil N₂O emissions. Compared with latosol, N₂O and CO₂ emissions were more sensitive to nitrogen addition in dry red soil.

Key words: Dry red soil, Latosol, Nitrogen fertilizer rate, N2O emissions, CO2 emissions