Productivity of some varieties of basket willow during the third three-year growing cycle

Abstract

Purpose. To establish biometric indicators of the productivity of energy plantations of basket willow biomass after the third three-year cultivation cycle on leached chernozems in the Right-Bank Forest-Steppe, under different planting schemes and nitrogen fertiliser application rates. Methods. In the spring of 2015, plantings of the ‘Tora’ and ‘Ternopilska’ varieties were established in two rows on the experimental field of the Institute of Bioenergy Crops and Sugar Beet of the NAAS (IBCSB). The planting density of cuttings was 12, 15 or 18 thousand per hectare (ha), with a row-to-row distance of 0.75 m and a row-to-row distance of 1.50–2.50 m. Ammonium nitrate (34.5% nitrogen) was applied at rates of 100 or 200 kg per ha in spring, before the start of the second and third three-year cycles. Fertilisers were not used on part of the area (control variant). The third growing cycle lasted from March 2022 to November 2024. The number of shoots, their average height and diameter, and the yield of three-year energy biomass were determined. Results. During the first three-year growing cycle (2015–2017) without the use of fertilisers, yields ranged from 25.1 to 34.7 t/ha for ‘Tora’ and from 16.0 to 27.9 t/ha for ‘Ternopilska’. During the second cycle, these figures increased to 65.3 t/ha (‘Tora’) and 55.6 t/ha (‘Ternopilska’). Applying 100 or 200 kg/ha of ammonium nitrate increased yields to 68.1 or 74.1 t/ha (‘Tora’) and 59.3 or 64.9 t/ha (‘Ternopilska’) respectively. Studies conducted during the third growing cycle revealed a significant impact of the planting scheme on the density of energy plantations. With a row spacing of 1.50 m, the number of ‘Tora’ shoots was 121.2–178.1 thousand/ha; with a row spacing of 2.50 m, it was 63.1–134.8 thousand/ha. For the ‘Ternopil’ willow, these figures were 59.6–191.4 thousand shoots/ha and 55.8–149.8 thousand shoots/ha, respectively. The same dependence was observed in terms of yield. For the ‘Tora’ variety, the yield was 43.1–54.3 t/ha at a row spacing of 1.50 m, and 36.8–50.8 t/ha at 2.50 m. For the ‘Ternopilska’ variety, the yield was 37.5–49.3 t/ha and 28.8–39.2 t/ha respectively. The lowest yields were observed for 'Tora' (36.8–48.2 t/ha) and ‘Ternopilska’ (28.8–42.1 t/ha) in the variant without the use of fertilisers. These increased to 38.2–50.2 t/ha (‘Tora’) and 30.5–45.3 t/ha (‘Ternopilska’) when 100 kg/ha of ammonium nitrate (N₃₅) was applied to the soil. Doubling the rate to N₇₀ contributed to an increase in dry biomass yield to 42.6–54.3 t/ha for ‘Tora’ and 33.6–47.4 t/ha for ‘Ternopilska’. Conclusions. The highest biometric indicators of plants and energy biomass productivity (54.3 t/ha) during the third three-year cycle were observed in the ‘Tora’ variety at a distance of 1.5 m between rows, a planting density of 15,000 cuttings/ha, and the application of 200 kg/ha of ammonium nitrate (N₃₅). The maximum productivity of ‘Ternopilska’ willow plantations (49.3 t/ha) was recorded using the same cultivation technology and planting density of 12,000 cuttings/ha. In general, the analyzed indicators after the third cycle were lower than those after the second cycle.