ISSN 1392-3196 / e-ISSN 2335-8947
Zemdirbyste-Agriculture, vol. 107, No. 4 (2020), p. 317–322
DOI  10.13080/z-a.2020.107.040

The suitability of perennial grasses for combustion as influenced by chemical composition and plant growth stage



The aim of the study was to evaluate six perennial grass species: lucerne (Medicago sativa L.), reed canary grass (Phalaris arundinacea L.), tall fescue (Festuca arundinacea Schreb.), cocksfoot (Dactylis glomerata L.), switchgrass (Panicum virgatum L.) and ryegrass (Lolium perenne L.), with a balanced composition of organic compounds and minerals, for their suitability for direct combustion in relation to grass species, chemical composition and growth stage. At the regrowth and heading / inflorescence emergence stages, the chemical composition of the biomass of the tested grass species was similar. Before regrowth in spring, the plants contained higher concentrations of carbon, lignin and cellulose and the smallest amounts of ash and nitrogen. Of all the grass species tested, the biomass of lucerne, tall fescue and particularly ryegrass was the most suitable for direct combustion, as it had the highest concentration of carbon (57.55%) and the lowest concentration of nitrogen (0.61%) and ash (4.48%).

The findings suggested that the heating value of the biomass was determined by plant growth stage and chemical composition. It was the highest at the heading stage and before regrowth in spring. It was found that the biomass of lucerne produced the highest energy yield of 303 GJ ha-1 (a sum of two harvests). The biomass of tall fescue produced 185.2 GJ ha-1, and that of cocksfoot – 137.3 GJ ha-1. The biomass of reed canary grass produced a lower energy yield of 93.3 GJ ha-1. The analysis of the relationship between the heating value and chemical composition of the biomass showed a strong correlation between the heating value and acid detergent lignin (ADL) 0.548** (p < 0.01). The heating value was also found to positively correlate (p < 0.05) with cellulose (0.376*) and carbon (0.258*).

Key words: bioenergy potential, biomass, heating value, combustion, energy plant.

Full text: 107_4_str40.pdf