Keywords: productivity, growth analysis, Miscanthus, Giant reed, nutrient uptake, second generation bioethanol
Abstract
The growing interest in bioenergy crops is leading up to new aims to achieve.
In fact, most of these crops lack of knowledge in terms of suitability to specific environmental conditions and of behavior to different cropping management.
Nonetheless, the evaluation of biomass quality, strictly related to the supposed end use, has a fundamental relevance on the biomass system efficiency.
The aim of these study was to compare giant reed (Arundo donax L.) and miscanthus (Miscanthus × giganteus Greef et Deuter), two promising lignocellulosic energy crops in southern Europe, in terms of: (i) productivity, through growth analysis, in order to understand environmental and/or management constraints to crop development; (ii) nutrient requirements and their dynamics in the above- ground biomass; (iii) cellulose, hemicelluloses and lignin content, since a second generation biofuel production was supposed.
The research was carried out in 2009, in San Piero a Grado, Pisa (Central Italy; latitude 43°41’ N, longitude 10°21’ E), on a seven year-old crops, in a loam soil characterized by a good nutrient and water availability.
Results confirmed high yields in both species, about 40 t ha-1 year-1 in miscanthus and 30 t ha-1 year-1 in giant reed, achieved in the second half of October.
Different growth strategies were pointed out as miscanthus developed a greater number of stems per square meter, although it showed minor basal stem diameter and leaf area.
Maximum nutrient uptake in shoots was found at the beginning of August in both crops (130 kg ha-1 for N, 40 kg ha-1 for P and 350 kg ha-1 for K), while it subsequently decreased, suggesting remobilization from above ground biomass to rhizomes.
Finally, from July onward, in both crops stable values of cellulose, hemicelluloses and lignin were highlighted, equivalent to 38%, 25% and 8%
respectively.
In the end, miscanthus and giant reed seems suitable to be introduced in current cropping systems for energy purpose. In fact, despite the different growth strategies, they showed similar nutrient uptakes and great attitude for second generation biofuel production. Further researches are required in order to evaluate ecological and productive performances in marginal lands, in particular those where water availability may result a limiting factor.
