Characterization by Fluorescence of Organic Matter from Oxisols under Sewage Sludge Applications
- Larissa Macedo dos Santosab,
- Débora Marcondes Bastosa,
- Pereira Miloria,
- Marcelo Luiz Simõesa,
- Wilson Tadeu Lopes da Silvaa,
- Edenir Rodrigues Pereira-Filhoc,
- Wanderley José de Melod and
- Ladislau Martin-Neto *a
- a Embrapa Agricultural Instrumentation, P.O. Box 741, 13560-970, São Carlos-SP, Brazil
b Univ. of São Paulo, Institute of Chemistry of São Carlos, P.O. Box 369, 13560-970, São Carlos-SP, Brazil
c Federal Univ. of São Carlos, Dep. of. Chemistry, P.O. Box 676, 13565-905, São Carlos-SP, Brazil
d Univ. of the State of São Paulo, Dep. of Technology, Road Prof. Paulo Donato Castellane, km 5, 14884-900, Jaboticabal-SP, Brazil
Sewage sludge from wastewater treatment contains organic matter and plant nutrients that can play an important role in agricultural production and the maintenance of soil fertility. The present study has aimed to evaluate the degree of humification following sewage sludge application of soil organic matter by laser-induced fluorescence and humic acids using ultraviolet-visible fluorescence, and including comparison with Fourier-transform infrared spectroscopy and elemental analysis. Sewage sludge applications to the soil caused a decrease in the degree of humification of the soil organic matter and humic acids for both a Typic Eutrorthox (clayey) soil and a Typic Haplorthox (sandy) soil of around 14 and 27%, respectively. This effect is probably due to incorporation of newly formed humic substances from the sewage sludge into the characteristics of less humified material, and to the indigenous soil humic substances. The minor alterations observed in the clay soil probably occurred due to both the greater mineral association, which better stabilized the indigenous soil organic matter, and the higher microbial activity in this soil, which accelerated sewage sludge mineralization. Sewage sludge applications increased the C content for the clay and sandy soils by 7.4 and 15.4 g kg−1, respectively, suggesting a positive effect on these two soils.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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