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Pesquisa Agropecuária Brasileira

Print version ISSN 0100-204XOn-line version ISSN 1678-3921


CARNEIRO, Roberto Guimarães et al. Soil biological indicators associated to the phosphorus cycle in a Cerrado soil under no-till and conventional tillage systems. Pesq. agropec. bras. [online]. 2004, vol.39, n.7, pp.661-669. ISSN 1678-3921.

The objective of this work was to evaluate the effects of no-till, conventional tillage and cover crops on biological indicators associated to the P cycle. The work was carried out on three adjacent areas on a Red-Yellow Oxisol: area I, a two-year experiment comparing the two management systems; area II, a six-year experiment, and area III, a native Cerrado vegetation. The soil was sampled at two depths (0-5 cm and 5-20 cm) in July/1998 and January/1999. The biological indicators evaluated were microbial biomass P, acid phosphatase activity, phosphate-solubilizing and total soil fungi and bacteria. Acid phosphatase activity and number of phosphate-solubilizing microorganisms, at the 0-5 cm depth, were significantly greater in the no-till soil, as compared to the conventional tillage. Differences between the tillage systems, regarding the biological indicators evaluated, were more pronounced in area II in which the no-till system had been established for a longer period. Microbial P decreased in the no-till Raphanus sativus treatment. P-solubilizing fungi increased in the presence of Cajanus cajan and Raphanus sativus, whereas the P-solubilizing bacteria increased in the presence of C. cajan. Highest activities of acid phosphatase were detected in the soil under native vegetation, evidencing the importance of organic P mineralization in this ecosystem.

Keywords : microbial biomass P; acid phosphatase; phosphate solubilizing microorganisms; cover crops.

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