Resumo

MIRTA, González et al. Comparison of Bray & Kurtz N°1 and Mehlich III methods in the determination of phosphorus availability in soils with continuous fertilizations. Cienc. suelo [online]. 2007, vol.25, n.1, pp.23-29. ISSN 1850-2067.

In this work, we compared two methods of available phosphorus evaluation, Bray & Kurtz I, (the most common in the pampean zone), and Mehlich III, (commonly used in other countries in soils with contionuous P applications). The studied soils received increasing doses of phosphate fertilizer, applied to the beginning of a maize, wheat and soybean rotation. Soil samples were taken in the field, and extractable phosphorus (P) by Mehlich III and Bray & Kurtz I methods were compared. The data were adjusted with the Peto-Wilcoxon test of determination and regression analysis to evaluate the sensitivity of both methods. The results indicated that to low values, these are not different substantially, but from the 15 (mg kg^-1) of P in soil, the Mehlich III method overestimates the value with respect to Bray & Kurtz I. This method was the one that showed greater variation to the added doses of P, showing greater sensitivity between treatments. It was concluded that the Bray & Kurtz I method is the one that better adapts to the practices of diagnosis and recommendations of fertilizer use.

Palavras-chave : Extractable phosphorus; Bray Kurtz I; Mehlich III; Pampean Region.

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