Mid-rotation fertilization and liming effects on nutrient dynamics of Pinus taeda L. in subtropical Brazil

Since fertilization and liming are unusual practices for managing Pinus taeda L. in Brazil, nutrient exhaustion can occur in the long term. However, recommendations are limited due to lack of studies investigating plant nutrition and nutrient biocycling. Thus, a study was established to investigate the effects of mid-rotation fertilization and liming on foliar, root, and litter nutrient composition. The use of a nutrient omission technique resulted in seven treatments: full (N, P, K, Ca, Mg, B, Zn, Cu, and Mo), -NPK, -micronutrients, -K, -Zn, -lime, and control. Trees were 5 years old when treatments were applied and 12 years old when harvested. At harvest, needle samples from the first and second flushes were collected. Litter layer samples were also collected and divided into four sublayers; the bottom fractions contained roots that were removed and analyzed separately. Fertilizer and lime application increased concentrations of P, K, Ca, Mg, S, Zn, B, and Al in the first and/or second flushes, reduced Mn, and did not change Cu and Fe. Amendment with K resulted in reduced Ca and Mg. Litter layer concentrations of amended elements (Ca, Mg, Cu, Zn, and P) and S were increased, especially in the bottom most fraction. Large accumulations of Ca, Mg, Cu, and Zn were observed in the litter and roots; smaller in K, P, S, B, and Mn were also noted. Degree of litter decomposition led to increased Fe and Al and decreased Mn. Fertilizer and lime application exerted large influences on Pinus nutrition and litter layer chemical quality.