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The geochemical nature and agricultural importance of commercial humic matter

1992; Elsevier BV; Volume: 113; Issue: 1-2 Linguagem: Inglês

10.1016/0048-9697(92)90013-i

1879-1026

J. C. Lobartini, K. H. Tan, J. Rema, Alan R. Gingle, C. Pape, D. S. Himmelsbach,

Radioactive element chemistry and processing

The use of commercial humates in agriculture has been received with mixed reactions. Differences in origin between commercial humates and soil humic acids together with a lack of scientific data on the former are perhaps contributing to the controversy. Therefore, this investigation was conducted to determine the geochemical characteristics and effect on plant growth of humic acid (HA) and fulvic acid (FA) isolated from selected commercial humates derived from lignite and non-lignite deposits. Analysis were performed for C, H, N, carbohydrate, aromatic and carboxyl group contents. Spectral characteristics were determined by 13C-NMR and infrared (IR) spectroscopy, whereas effect on plant growth was studied in the greenhouse with corn (Zea mays L.) plants growing in the presence of commercial humates. The commercial humates were composed mostly of HA, and only very small amounts of FA were extracted. The HA fractions from the commercial humates were similar in C and H contents, but HA from lignite humate was higher in N content than HA isolated from non-lignite humate. Lignite-HA was also characterized by a higher carbohydrate content that non-lignite HA. The latter was more aromatic in nature. The IR spectra supported the presence of higher aromatic contents in HA from non-lignite than that from lignite deposits. Commercial humates were comparable with soil HA in their effect on increasing the growth of corn plants. It can be concluded, that the data suggested that HA from lignite deposits resembled HA in Mollisols, whereas HA from the non-lignite deposits was more related to HA from the Bh horizon of Spodosols.