Eucalyptus x urograndis biomass production for energy purposes exposed to a Mediterranean climate under different irrigation and fertilisation regimes

Lignocellulosic biomass derived from energy crops, a renewable energy source, must be boosted in order to mitigate climate change effects. For this reason, vegetative growth and biomass production of Eucalyptus x urograndis, under a Mediterranean climate, was studied for three years. At the second and the third planting years, 12 treatments were applied combining four irrigation levels during the dry season (0, 325, 646 and 1298 mm of water per year, plus 418 mm of average rainfall) and three fertilisation amounts (0, 150 and 300 kg ha(-1) of N per year with a nutrient balance of 16-8-12 [2 MgO, 12 SO3, 2.6 CaO]). A seasonal growth monitoring of height and diameter was carried out along with dry biomass production and assessment of soil properties before and after of the trial was carried out. Irrigation and fertilisation significantly increased aboveground biomass production, averaging 20.6-55.4 t ha(-1) per year; the combined treatments 0 mm-0 kg ha(-1) of N and 1298 mm-300 kg ha(-1) of N were the least and the most productive, respectively. The data constitute a useful resource for the adjustment of the optimal irrigation (>= 1500 mm per year of rainfall plus irrigation) and fertilisation doses (>= 150 kg ha(-1) of N) applied to plantations, as well as the management of crops to design a sustainable productive system that allows the preservation or improvement of soils. The energy and physical-mechanical biomass properties together with the derived pellets were of high quality, and they show promise for industrial boiler use.