Fontes de fertilizantes nitrogenados e seus efeitos no crescimento da mamoneira (Ricinus communis L.).

Abstract

Nowadays, the world is seeking alternative sources of energy to replace petroleum and coal, due to theis harm to the environment, specialy the greenhouse effect. In teh next 20 or 30 years this alternative source will probably come from biomass. Ethanol and biodicscl are two examples of that. In the Northeast region of Brazil, the castor plant (Ricinus communis L), due to its drought resistance and sunlight tolerance, is one of the few crop options, specialy in rainfed condition.The yield of this crop is very low and there is scarcity of information about its response to organic fertilization like sewage sludge and presscake. This study was made in order to measure the effect of doses of some organic and mineral fertilizer in the initial growth of castor plants, cv. BRS Nordestina, in a greenhouse condition in Campina Grande, at Embrapa Algodão (National Research Center of Cotton). The trial was set up in randomized block design with three replications and 13 treatments in a factorial distribution of 4 kinds of fertilizers (bovine manure, domestic sewage sludge, castor presscake and urea) x 3 doses (85, 170 and 255 kg/ha of N) with an additional treatment with no fertlizer. P and K were supplied in all treatments in the dose of 80 kg/ha for both, applied in the planting moment, using Triple superphosphate and potassium chloride as sources. A reduction in pests and illness in the castor plants was visually observed and reflected in the plant height, leaf area, stem diameter and shoot dry weight when compared to the control treatment. In orthogonal contrasts evaluations, the fertilizers increased the growth of this oilseed. Among the fertilizers the presscake had the most intensive growth promotion potential, cause it, beside Nitrogen, is rich in fiber, more than 35%, wath helps to increase physic properties of the soil.