Anthropogenic effect on soil organic phosphorus fractions in tropical ecosystems
2001
Giuffre, L. | Piccolo, G. | Rosell, R. | Pascale, C. | Heredia, O.S. | Ciarlo, E.
Total organic phosphorus (P), labile organic P, and total carbon were determined in composite surface soil samples, with three replicates, in a Kandihumult from Misiones province, Argentina. The analysis was performed on <0.1 mm, 2-0.5 mm, and >8 mm aggregate fractions obtained by dry sieving. Representative situations were selected to evaluate changes in P dynamics by soil use: a native subtropical forest, a degraded agroecosystem with a 50-year yerba mate plantation (Ilex paraguariensis Saint Hill.), and a similar plantation with a 6-year associated elephant grass (Pennisetum purpureum Schumach). Native pristine soil from the forest presented the highest content of phosphorus in more humified fractions (<0.1 mm). Fifty-year cultivation of "yerba mate" produced a degraded agroecosystem with 10% decrease of total organic phosphorus forms in humified fractions. Six-year-old elephant grass mulch incorporation increased total organic phosphorus both in more humified fractions and in macroaggregates (>8 mm), due to addition of decomposable organic materials. Labile organic phosphorus was higher under stress conditions.
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