Harvest Time Optimization for Combustion Quality of Different Miscanthus Genotypes across Europe

Abstract

Delayed harvest can improve the quality of miscanthus biomass for combustion and enhance the long-term sustainability of the crop, despite accompanying yield losses. The aim of this study is to identify the optimal harvesting time, which can deliver improved biomass quality for combustion of novel miscanthus genotypes at various sites across Europe, without high yield losses and without compromising their environmental performance. The relevant field trials were established as part of the European project OPTIMISC with 15 genotypes at six sites across Europe. For this study, the five highest yielding genotypes from each germplasm group and three sites with contrasting climatic conditions (Stuttgart, Germany; Adana, Turkey; and Moscow, Russia) were selected for assessment. The biomass samples were collected between August and March (depending on site) and subjected to mineral and ash content analysis. At Stuttgart, the delay in harvesting time led to a significant variation in combustion quality characteristics, such as N content (0.64–0.21%), ash content (5.15–2.60%), and ash sintering index (1.30–0.20). At Adana, the delay in harvesting time decreased the N content from 0.62 to 0.23%, ash content from 10.63 to 3.84%, and sintering index from 0.54 to 0.07. At Moscow, the impact of delay in harvesting was not significant, except for N, Mg, and ash sintering index. Overall, a delay in harvesting time improved the combustion quality characteristics of each genotype, but at the expense of yield. Yield losses of up to 49% in Stuttgart and Adana and 21% for Moscow were recorded, with variations between genotypes and sites. The harvesting time also affected nutrient offtake, which in turn influences the long-term environmental performance of the crop. The highest N, P, and K offtakes were recorded at Stuttgart for each harvesting time except for final harvest (March), where Moscow had the highest N offtake. This study describes the three criteria (biomass quality, yield losses, nutrient offtake) for determining the ideal harvesting time, which gives the best compromise between dry matter yields and biomass quality characteristics without negatively affecting the environmental performance of the crop.

Marginal Agricultural Land Low-Input Systems for Biomass Production

“…This is a medium DMY level compared with miscanthus grown on good soil [116,120,121]. However, it should be mentioned that miscanthus requires very low nitrogen (N) fertilization [122], especially when harvested for combustion in winter [60,123]. This is because miscanthus has very efficient nutrient-recycling when harvested in winter [79,124].…”

Prospects of Bioenergy Cropping Systems for A More Social-Ecologically Sound Bioeconomy

“…Furthermore, the accumulation of heavy metals within the biomass value chain (e.g., within the biogas value chain) must be avoided. This could be done by using another utilization pathway such as combustion [182,230,231]. For combustion, the heavy metal content will be highly concentrated within the ashes of the processed biomass.…”

Increase of Miscanthus Cultivation with New Roles in Materials Production—A Review

“…An increase in harvesting speed was obtained by using serrated blades to increase the theoretical field capacity from 1.35 to 2.23 ha h −1 [45]. Not only the particle size and storage stability are affected but also the biomass composition, in terms of the moisture and actual chemical component availability, are directly influenced by the harvesting time and on-field processing [4,6,26,46,47].…”

“…The growth and senescence results in morphological differences, such as the leaf-stem ratio in varieties or hybrids, thereby alter the composition of the feedstock and the viability for different applications, like fermentation [62] or direct combustion [46,63,64]. Abiotic stresses influence the growth and senescence cycles, such that varieties may be screened for optimum climate-plant combinations [4,5,46]. Furthermore, variations in the extracted molecules from different plant parts may be expected.…”