Fig. 1. Soil DOC content under different fertilization
Notes: Different lowercase letters on the same soil column represent significant (a, b, c) differences between treatments (p<0.05)

Fig. 2. Characteristics of UV-Visible absorption spectrum of soil DOM in different festilization

Fig. 3. Spectral absorption values under four fertilization managements SUVA₂₅₄(a), SUVA₂₆₀(b), SUVA₂₈₀(c)

Fig. 4. Spectral absorption ratio under four fertilization managements A₂₅₀/A₃₆₅(a), A₃₀₀/A₄₀₀(b), A₄₆₅/A₆₆₅(c)

Fig. 5. α(355)of soil DOM under long-term different fertilization

Fig. 6. Two-dimensional correlation spectrum
(a): Synchronous map; (b): Asynchronous map