Resumo

MEZA, Carlos A.; FERNANDEZ, Shirley M.  e  MELENDEZ, Lenny M.. Roca fosfórica de riecito tratada con vinaza y altas temperaturas como fuente de fósforo para el maíz. Agronomía Trop. [online]. 2003, vol.53, n.3, pp.315-330. ISSN 0002-192X.

Phosphoric rock of Riecito was evaluated in its natural state (RFN) and modified by calcinations (RFC) and by acidification with vinaza (RFV). Three experiments were carried out: a) in a acid soil pH 3,7; b) whitewashed at pH 5,7; e) whitewashed at pH 6,8. Maize var. UCLA 1 was used as indicator. Phosphate sources evaluated were: rock of Riecito in its natural state (RFN), calcinated at 900 ºC by 7 hours (RFC), acidulated with vinaza in proportion 1/1 (RFV), an ammoniacal phosphate (MAP) and a control without phosphorus (Te). The dose used was 300 mg kg^-1 of P. Plants were collected 30 days after planting to determine dry biomass, P in the stem and the agronomic index of efficiency (IEA). In the acid soil (pH 3,7), the treatment RFV produced values of dry biomass and P in stem similar to MAP and higher than those obtained in treatments RFC, RFN and Te. In the whitewashed soils (pH 5,7 and 6,8) the treatrnents with MAP showed the highest values of dry biomass, P in stem and IEA. Results obtained suggest that acidification of phosphoric rock with vinaza increases its soluhility. The effect is limited to soils with pH less than 5,7.

Palavras-chave : Thermo-phosphate; vinaza; phosphoric; maize.