Calagem e adubação fosfatada para a produção de mudas de Mogno (Swietenia macrophylla King) e Cedro (Cedrela fissilis Vell.)

Abstract

An important and little studied aspect is the behavior of the different phosphated sources and the liming on the production of seedlings of native forest species, amongst them the mahogany and the cedar. It is essential the study of the relation liming x sources of P, so that the nutrition of P in native forest species is optimized and, in function of the degree of acidity of the ground, to exert strong influence on the availability of P. Among the phosphated fertilizers, are commercialized the superphosphate, thermophosphate and rock phosphate produced from sedimentary, igneous or metamorfhic rocks and the efficiency of these sources is affected by several factors, amongst which the acidity of the ground. The present study had as objective to evaluate the efficiency of different sources of phosphorus in the absence and the presence of liming on the growth of seedlings of mahogany and cedar. The experimental delineation used was in randomized blocks with 4 repetitions, in an factorial project 2 x 4, involving absence and presence of liming and 4 sources of P (simple superphosphate, triple superphosphate, rock phosphate reactive Arad and thermophosphate Yoorin). The condition of acidity of the ground together with composition and solubility of the sources of P had affected the behavior of the species. Concerning to the analyzed variable they had been height of the aerial part, col diameter, dry substance of aerial part (MSPA) and of the roots (MSR) and total (MST), relation part aerial/root (PA/R) and content of macronutrients of the total dry substance. The results indicate that the species mahogany and cedar had revealed little responsive to the calcareous rock, and to the biggest efficiency of the sources both in the absorption of nutrients and for the growth of the species was observed for the rock phosphate reactive Arad.