Poor soil has restricted the crop production in semiarid soil. Fulvic acid (FA) is considered to play an significant role in soil fertility. The amount and structure of FA after application of different organic wastes (OWs) was assessed in this work. Six treatments were involved in this experiment: chemical fertilizer combined with chicken manure (CM), sheep manure (SM), maize straw (MS), fodder grass (FG), and tree leaves (TL), while chemical fertilizer only was used as control (CK). The soil FA content (P < 0.05) after the application of TL was the highest than other OWs. The E4/E6 ratios, ΔlogK values, aliphatic C/aromatic C ratios of soil FA after the application of TL were the lowest than other OWs, whereas the C/H ratio was the highest. The specific fluorescence intensities (SFI) of peak A (Ex/Em 260-265/415-430 nm) and peak B (Ex/Em 310-315/415-430 nm) from EEM fluorescence spectrum of FA were the lowest after the application of TL. In conclusion, the application of TL was the most effective for improving FA accumulation, and making FA complex and stability. Thus, TL is the recommended OW for use in semiarid soil under plastic mulched drip irrigation conditions.
Keywords: (13)C CPMAS NMR; E(4)/E(6) ratio; Elemental analysis; Excitation-emission matrix fluorescence; Organic wastes; ΔlogK.
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