Resumo

VON WALLIS, ALEJANDRA; MARTIARENA, RODOLFO; PAHR, NORBERTO  e  TABOADA, MIGUEL ANGEL. Stock de carbono y condición física de un kandiudult bajo distintos manejos forestales en la Provincia de Misiones. Cienc. suelo [online]. 2016, vol.34, n.2, pp.253-261. ISSN 1850-2067.

The maintenance of soil organic carbon content and adequate physical condition is an essential requirement in subtropical soils with excessive rainfall such as those in the province of Misiones, in which traditional soil preparation methods for woodland plantations generate water erosion risks. In a four year old field trial with completely randomized block design (CRBD; n = 5), soil organic carbon contents and stocks (0-10 cm, 10-20 cm and 20-30 cm layers) and different soil physical properties were determined in a Kandiudult soil to assess four soil preparation methods for planting Pinus elliottii var. elliottii ×P. caribaea var. Hondurensis effectiveness. A native forest (NF) neighbor situation was used as a comparative reference. Soil bulk density was low in the NF (0.96 to 1.31 Mg m^-3 in the 0-10 cm, 10-20 cm and 20-30 cm layers), and was significantly (P <0.05) increased by soil harrowing (1.45 Mg m^-3 in the 0-10 cm layer). This excessive compaction decreased significantly (P <0.05) by subsoiling (1.35 to 1.36 Mg m^-3 in the 0-10 cm and 10-20 cm layers). The maximum levels of total organic carbon (24.7 to 14.0 g kg^-1) and carbon stock (63.4 Mg ha^-1) were observed in NF (0-30 cm). Soil preparation methods only affected soil organic carbon contents in 0-10 cm layer, with significantly higher (p< 0,05) values in subsoiling (13,3 g kg^-1) and higher with natural regeneration of conservation of forest residues without plantation (20,6 g kg^-1). Soil carbon stocks (0-30 cm), expressed as NF equivalent soil mass, were significantly higher (P <0.05) with natural regeneration (51.0 Mg ha^-1) than with other more aggressive methods such as harrowing and subsoiling (39.8 and 42 Mg ha^-1, respectively). The structural instability index was little affected by soil preparation methods (88-100% of NF). Residue burning in the field only caused significant bulk density reductions (P <0.05) in the top 20 cm of the harrowed plot. It can be then concluded that the best options for soil preparation in the studied area were: a) subsoiling that decreased excessive soil compaction; and b) forest residues conservation on the surface, which contributed to sequester more organic C in the soil.

Palavras-chave : Native forest; Land preparation; Soil compaction.

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