Yield and energy productivity of energy crops grown together in phytocenosis

Abstract

Sustainable development of the energy sector is a topical issue for Ukraine today. Among the available energy sources, many scientists believe that the most affordable is the energy from plants, the so-called energy crops. These crops are biologically perennial, adapted to growing conditions, and highly productive. These plants include: willow clones (Salix), miscanthus (Miscanthus), sorghum (Sorghum) and switchgrass, as well as other less widespread plants. This publication will focus on the aspects of growing low spread energy crops (Indiangrass, Sorghastrum nutans (L.) Nash. and Andropogon gerardii Vitman) together with well- known and better studied crops: Panicum virgatum L., Sorghum almum Parodi. In the future, this will involve the development of ergonomically sound rec-ommendations for their cultivation for sustainable phytomass and biofuel production. The aim of our research was to determine the influence of joint cultivation of energy crops on the yield of their aboveground vegetative phytomass and the energy productivity of the crops. The general and special (experimental) research methods were applied in the field experiment. According to the approved methods and recommendations, the moisture content in phytomass was determined, raw and dry biomass yields were recorded, and the energy productivity of the crops was identified. The application of the analysis of variance and correlation made it possible to assess significant differences between the variants of the experiment. The research results allowed us to establish the variability of phytomass yield with a variety of combinations of energy crops in joint crops. In terms of the dry biomass volume, the most productive were the following grass mixtures of energy crops: Switchgrass and Indiangrass (13.1 t/ha), Switchgrass and Big bluestem (12.8 t/ha), Indiangrass and Big bluestem (12.5 t/ha). The same variants were characterized by high energy produc-tivity, ranging from 217.6 to 224.0 GJ/ha. The dry biomass yield was at a level of the standard on the variants of joint cultivation of Switchgrass and Sorghum perennial and Indiantgrass and Sorghum perennial (12.3 t/ha). Signif-icantly lower dry biomass yield compared with control and other experimental variants was at joint cultivation of Big bluestem and Sorghum perennial (11.8 t/ha). Thus, to obtain a high biomass yield (12.5-13.1 t/ha) when growing low-energy crops together, Switchgrass and Indiangrass, Switchgrass and Big bluestem should be sown together. This will also help to obtain an energy yield in the range of 217.6-224.0 GJ per hectare.