Research Article
Structural Analysis of Humic Acid in Soil at Different Corn Straw Returning Modes through Fluorescence Spectroscopy and Infrared Spectroscopy
Figure 1
Infrared spectra of humic acids: (a) topsoil (5–20 cm); (b) subsoil (20–40 cm). No straw was applied (CK), straw returning to topsoil (St), straw returning to subsoil (Ss), straw mixing with topsoil (Smt), and straw mixing with subsoil (Sms).
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