Object: Optimization process of biomass and switchgrass seeds production in the conditions of the forest-steppe of Ukraine, agroecological fundamentals for the formation and implementation of crop yields potential depending on the soil and climatic conditions and agrotechnological factors. Objective: Scientific justification of agroecological fundamentals for switchgrass yield formation for the conditions of insufficient moisture of the forest-steppe of Ukraine and development of the optimized cultivation technology based on the principles of adaptive plant growing. Methods: General scientific, special (field, chemical, computational-weight, physical, comparative- computational), statistical. Novelty: The scientific fundamentals for agrotechnical techniques of switchgrass cultivation for biofuel production have been substantiated and developed for the forest-steppe of Ukraine for the first time. Regularities of plants growth and development under the influence of abiotic factors have been defined. This allowed to optimize technological measures of the switchgrass production for biomass and seeds. The influence of mutual growth of switchgrass with lupine yellow on formation of the yield structure elements and biomass yield, which reduces the dose of nitrogen fertilizers in crop fertilization, has been studied for the first time. The scientific methodology of yield accounting according to dry biomass using the optimal values of the structure elements applied for modeling the switchgrass cultivation technology has been developed. Results: The optimized cultivation technology has been developed for the conditions of the forest-steppe. This technology provides: decrease of the unregulated environmental factors effect, high yields according to dry mass and reduction of resources cost for the biomass production. The application of the optimized technology of switchgrass cultivation on marginal lands, which combined: semi-fallow soil tillage, two spring and presowing cultivations, presowing and postsowing packing of the soil; spring sowing in the second decade of April with the seeding rate of 3 million seeds per 1 hectare; wide-row method of sowing (45 cm), combined with the bean component, spring nitrogen fertilization with a dose of 15-30 kg/ha (beginning from the third year of crop vegetation), allows to increase biomass yields up to 15.0 t/ha, which is by 0.9 t/ha more in comparison with the conventional technology. This complex of agrarian measures reduces the aggregate cost of energy resources per 1 hectare from 73.0 to 65.3 GJ, increases the output of solid biofuel by 1.3 t/ha, energy by 26.2 GJ/ha and raise the energy efficiency coefficient by 0.9 - from 3.4 (low efficiency) to 4.3 (average efficiency). Degree of Implementation: The experimental results have been tested at selection experimental stations of the Forest-steppe zone of Ukraine and introduced at the agricultural enterprises of the Poltava region on the area of 10.0 hectares, Dnipropetrovsk region (15 hectares) and other regions (9.3 hectares). They are used in skills upgrading programs for agribusiness managers and specialists, and are shown on Field Days, seminars, etc. Scope of Implementation: scientific institutions of NAAS and the Ministry of Agrarian Policy and Food of Ukraine, higher educational establishments, agrarian enterprises of Ukraine.
