Organic matter in low weathered soils from Pantanal region, Brazil
2007
Dalmolin, R. S. D. | Dick, D. P. | Knicker, Heike | Klamt, E. | Couto, E. M.
Congreso celebrado del 16-19, julio, 2007, en Poitiers, Francia.
Show more [+] Less [-]The organic matter (SOM) from five representative soil profiles from Pantanal region, Brazil, was investigated aiming to evaluate the relationship between SOM composition with the soil class and the environmental conditions. The observed low C soil contents are probably related to the flood pulse and some aspects of climate (high temperatures in dry season), soils (predominance of light textures in the upper horizons) and spontaneous and frequent fire in this region. The N content was comparatively high, resulting low C/N ratios. In comparison to other tropical soils, the proportion of aromatic structures is high and the Oalkyl tends to be low. Considering that the vegetation shows little influence on the SOM composition, these results are most probably related to the annual fires. The increase of both aromatic C and carboxylic C with depth may indicate that aromatic organic acids are migrating along the profile as result of the flood pulse. The input of vegetation residues with high contents of C-O alkyl, on the upper horizons may dilute the recalcitrant groups.
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