Phosphorus extractants for forest species of different successional groups

Abstract

The Mehlich-1, Mehlich-3, and ion-exchange resin (IER) extractants were compared for their ability to assess phosphorus (P) bioavailability. Five P doses (0, 100, 250, 500, and 800 mg dm⁻³) were applied into a Humic Rhodic Haplustox. Seedlings of pioneer and climax tree species were grown under greenhouse conditions. After 90 days, the plants were harvested and the shoot dry matter, the P content, and the P utilization efficiency were determined. Plant growth was affected by P availability with differences among successional groups and species. The extractants presented similar performance regarding the P availability determination. For the pioneer species, which have faster growth rates, it was found a significant relationship between dry matter yield, P content, and soil available P for all extractants. On the other hand, the climax species, which have slower growth rates, showed low responses to soil P status. The kind of response to nutrient furnishment seems to be conditioning the predictive efficiency of the soil testing procedures for different forest species.

Acknowledgments

The authors acknowledge the financial support of the Energy Company of Minas Gerais, CEMIG, the Research Foundation of the State of Minas Gerais, FAPEMIG, and the Secretary for Support of Personnel, CAPES, for the financial support. The authors also acknowledge the help of Prof. J. J. Marques for reviewing earlier versions of the manuscript.