The dissertation is devoted to the scientific substantiation of the selection of promising basket willow (Salix viminalis L.) varieties for the establishment and efficient use of energy plantations under the conditions of the Right-Bank Forest-Steppe of Ukraine. The relevance of the research is determined by the need to expand the raw material base for solid biofuel production, increase national energy independence, ensure the rational use of low-productive lands, and introduce renewable energy sources into the agricultural sector.
The aim of the research was to evaluate the biological, growth, productive and qualitative characteristics of different basket willow varieties, determine their bioenergy and economic efficiency, and improve scientific approaches to the establishment and use of energy plantations under the soil and climatic conditions of the Right-Bank Forest-Steppe of Ukraine.
The object of the research was the processes of growth, development and productivity formation of basket willow energy plantations depending on varietal characteristics and biomass harvesting cycles. The subject of the research included the varieties ‘Tordis’, ‘Inger’, ‘Wilhelm’, ‘082’ (‘Warm-maz’), ‘1047’ (‘Gigantea’) and ‘1052’, their biometric parameters, fresh and dry biomass yield, qualitative characteristics of raw material, energy output and economic efficiency of cultivation.
During the research, field, laboratory, mathematical-statistical and calculation-comparative methods were used. Field studies included observations of plant growth and development, determination of biometric parameters, biomass yield and regrowth characteristics after cutting. Laboratory methods were used to assess plant weight parameters and the chemical composition of biomass, while calculation-comparative methods were applied to determine the economic and bioenergy efficiency of cultivating the studied varieties.
The scientific novelty of the obtained results lies in the fact that, for the first time under the conditions of the Right-Bank Forest-Steppe of Ukraine, the features of growth, development and productivity formation of six basket willow varieties were established under different cycles of cultivation and harvesting of energy biomass. Varietal differences in growth intensity, tillering capacity, shoot formation, dry matter accumulation and energy productivity were clarified.
It was established that, under a three-year cultivation cycle, the highest productivity was formed by the varieties ‘1052’, ‘1047’ (‘Gigantea’) and ‘Inger’. The highest dry biomass yield was provided by the variety ‘1052’ — 27.81 t/ha. Slightly lower values were obtained for ‘1047’ (‘Gigantea’) — 26.06 t/ha and ‘Inger’ — 23.77 t/ha. The variety ‘082’ (‘Warm-maz’) produced 21.24 t/ha of dry biomass, while the productivity of ‘Wilhelm’ and ‘Tordis’ was significantly lower — 13.61 and 8.85 t/ha, respectively.
It was proven that, under the conditions of the Right-Bank Forest-Steppe of Ukraine, the first harvesting of energy biomass should preferably be carried out at the age of four years, when plants have formed a sufficiently developed root system and aboveground mass. Subsequently, after the formation of a powerful root system, the rotation cycle may be shortened to two or three years. The highest yield of dry annual biomass after cutting was formed by the variety ‘Inger’ — 8.0 t/ha/year.
The assessment of the qualitative composition of biomass showed that the studied basket willow varieties are valuable lignocellulosic raw material for solid biofuel production. The main structural components of biomass are cellulose, hemicellulose and lignin. The qualitative indicators of biomass differed only slightly between varieties; therefore, dry matter yield was the main factor determining energy output per unit area.
The highest calculated energy output from three-year dry biomass was provided by the variety ‘1052’ — 445.0 GJ/ha, or 148.3 GJ/ha/year. The variety ‘1047’ (‘Gigantea’) produced 417.0 GJ/ha, or 139.0 GJ/ha/year, while ‘Inger’ produced 380.3 GJ/ha, or 126.8 GJ/ha/year. The economic assessment showed that cultivation of varieties with the highest dry biomass yield was the most efficient. The highest conditional net profit and profitability level were provided by the variety ‘1052’ — 48.43 thousand UAH/ha and 138.4%, respectively.
The practical significance of the obtained results lies in the substantiation of the selection of basket willow varieties most suitable for cultivation on energy plantations under the conditions of the Right-Bank Forest-Steppe of Ukraine. For practical production use, the varieties ‘1052’, ‘1047’ (‘Gigantea’) and ‘Inger’ are recommended, as they provide high dry biomass output, significant energy productivity, positive economic results and suitability of biomass for use as solid biofuel.
Keywords: basket willow, Salix viminalis L., energy plantations, biomass, dry matter, yield, rotation cycle, bioenergy efficiency
