Irrigation and nitrogen fertilization in cultivation and oil quality jatropha

Abstract

The imminent scarcity of fossil fuels and the possible global energy crisis are the main reason for an increase of researches with the objective to search alternative energy to replace the primary energy used in the world. Since biodiesel can be used to generate alternative energy against oil diesel, it influenced several new research with oilseed cultures. Jatropha nut (Jatropha curcas L.) is a specie from Euforbiácea family that stood up because some characteristics such as perennial tree, rusticity, and with high oil production. Irrigation and nitrogen fertilization effects on jatropha nut cultivation is necessary in order to understand crop management. The objective of this study was evaluate the effects of different levels of nitrogen fertilization and water management on productivity, vegetative growth development and oil quality of jatropha nut cultivation. The experiment was conducted in the experimental area of the Department of Biosystems Engineering at ESALQ/USP, in Piracicaba-SP. The studies were conducted during 2013/2014 and 2014/2015 crop year, with plants with three year old with 3 x 4 m arrangement (833 plants ha-1). The treatments were arranged randomly in blocks with four repetitions, including two water management factor (center pivot irrigation and rainfed) and four doses of nitrogen fertilization (150, 100, 50 and 0% of N requirement). Each cultivation area was made by the type of water management adopted and the data analysis was made jointly as analysis experiments groups. Irrigation and nitrogen levels had a positive influence on growth variables such as height, crown diameter and canopy volume. Leaf area index increased as nitrogen levels increased, however, with lower values for the irrigated treatments. In all chlorophyll levels evaluated, it was observed higher values with irrigation and higher nitrogen levels, but despite this difference, all treatments showed low correlation with leaf nitrogen content. Jatropha seed and oil productivity also responded positively to all treatments reaching three times more with irrigation and nitrogen fertilization. The oil content did not vary in all treatment for seed weight, and only water management influenced the values of some oil quality indices such as acidity, iodine, peroxide and oxidative stability with higher values for the irrigated treatment. Thus, it is concluded that even with adverse conditions of climate and soil nutrition, jatropha nut responds well to irrigation practice and nitrogen fertilization, increasing their productivity and improving their vegetative growth and oil quality for biodiesel production.