Relationships between nutrients in the soil and nutritional status of Pinus taeda stands in southern Brazil

The characterization of nutrients availability in the soil and its relationship with nutritional status and productivity of Pinus taeda stands in southern Brazil is still of concern due the lack of research on this subject. We compared different methods to evaluate P, K, Ca, and Mg in the soil and in plant tissues. We performed the evaluations in six paired plots (control and fertilized) located on different soils conditions in southern Brazil. Availability of nutrients in the soil was obtained after extractions of soil solutions with the extractors Mehlich I (P, K), KCl 1 mol L−1 (Ca, Mg), and 1 % citric acid (P, K, Ca, Mg). Foliar and wood samples were collected to determine the P, K, Ca, and Mg contents in the trees’ tissues. The mean annual increment (MAI) of each plot was obtained from the annual inventories of the P. taeda stands. The contents of P, K, Ca, and Mg in the soil followed similar trends for the different extractors tested, with higher contents of Ca and Mg in the fertilized plots. No differences for P and K in the soil were observed between control and fertilized plots for both methods applied. The fertilized plots showed increase for Ca and Mg in the wood tissues but not in the needles. Positive correlation between wood and needle tissues was observed only for the P content. No correlation between the nutrient contents in the needles and in the soil was observed. But we found a positive correlation between the nutrient contents in the wood and in the soil, mainly for the 1% citric acid method. No correlation was found between the nutrients in the plant tissues and the productivity of Pinus taeda. Our results improved the knowledge concerning the nutrient dynamics in P. taeda stands in southern Brazil showing that citric acid is a good extractor for P, K, Ca, and Mg in the soil, and that determination of nutrients in the wood tissues is a potential method for nutritional diagnosis of P. taeda.