Production and composition of biomass from short rotation coppice in marginal land: a 9-year study

Abstract

The production and chemical composition of the biomass of four fast growing woody crops are studied across species and rotation cycles. High-density plantations of poplar, willow, black locust and sycamore were monitored for 9 years over 3-year rotation cycles in marginal land in the Mediterranean area. The fuel quality properties of the produced biomass was assessed using proximate and ultimate analysis, biomass and ash chemical composition (23 elements), and ash melting behaviour. Willow, poplar and black locust energy crops produced 12, 9 and 7 dry Mg ha-1 yr-1 on average, indicating that these species can be well adapted to the unfavourable conditions of poor soils in low productivity areas in the Mediterranean region. In contrast, sycamore was not well adapted to the particular climate and soil conditions and provided very poor yields. The chemical composition of the biomass varied across species and rotation cycles. The results obtained from the chemical analysis of these woody species showed that they provided good quality for use in combustion processes, with low amounts of trace elements and chlorine (≈ 0.01 wt%), sulphur (≈ 0.04 wt%) and nitrogen (≈ 0.5 wt%), with the exception of black locust (N= 0.86 wt%). No sintering problems are expected during the combustion of the studied biomass. This study provides valuable information for the large-scale implementation of fast growing woody species dedicated to energy crops in low productivity areas of the Mediterranean region.