Nitrogen, potassium and phosphorous fertilizer suggestions for australian red cedar in oxisol

Abstract

Forest species present around 75% of their nutrient demand in the initial growth stage. The objectives of this study were: to determine appropriate doses of N, P and K to be applied for Australian cedar cultivation in Oxisols; and to establish foliar contents suitable for the initial stage of plant development. Three concomitant experiments were carried out using randomized blocks design with four replications. In the first, it was provided 5 doses of N, and in the second 5 doses of P2O5, and in the third 5 doses of K2O. In all three experiments, Australian cedar seedlings were planted at 3x2 m spacing. Maximum economic yield (MEY) was achieved when was provided 75 g N, and 80 g P2O5 per planting hole. In this study, could not be established the dose of K2O that allows MEY, because there was no difference in height and diameter of plants as a function of potassium fertilizer rates. The initial K concentration in the soil (around 100 mg.dm-3) seems adequate to meet the nutritional needs to Australian cedar seedlings. Foliar concentrations did not vary with levels of N, P2O5 and K2O applied to soil. Mean content of N, P and K in the leaves of Australian cedar seedlings were 30, 18 and 2 mg.kg-1, respectively.