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.