The evaluation of biomass and energy productivity of common mugwort (Artemisia vulgaris L.) and cup plant (Silphium perfoliatum L.) in Albeluvisol

Abstract

Research on perennial coarse-stemmed herbaceous energy plants, common mugwort {Artemisia vulgaris L.) and cup plant (Silphium perfoliatum L.), was carried out in Vezaiciai Branch of the Lithuanian Research Centre for Agriculture and Forestry in Western Lithuania. The soil of the experimental site is naturally acid moraine loam Eutri-Hypostagnic Albeluvisol (ABj-w-eu). Field experiments were established in 2008, according to a two-factor design including three levels of liming (not limed, limed with 3.0 and 6.0 t ha"1 of CaC03) and three levels of nitrogen fertilization (0, 60 and 120 kg ha"1). Common mugwort accumulated 2.76-5.74 t ha-1 of dry matter in 2009; the next year, however, the parameter decreased to 2.38-3.83 t ha"1. In 2009, the cup plant dry matter productivity was 4.42-8.51 t ha"1; while in 2010, it considerably increased and reached 11.37—21.94 t ha"1. Liming positively influenced the cup plant dry matter productivity; however, there was no significant effect on the change in the common mugwort dry matter increase. The application of 120 kg ha"1 nitrogen rate significantly enhanced dry matter increase of both species (although not always significantly at 95% probability level). The energy analysis of the growing technology in 2010 indicates that the mineral and lime fertilizers as indirect energy costs accounted from 32.75% to 76.07% of the total energy input (including direct and indirect costs, machinery energy consumption and human labour input). The highest energy output (187.6-361.9 GJ ha"1) as well as energy use efficiency (ratio of energy output to energy input) was determined for the cultivation of cup plant. However, the application of lime and nitrogen fertilizers caused a substantial decrease of energy output and energy use efficiency.