Effects of cultivation technologies on woody biomass yielof various willow (Salix spp.) cultivars

Abstract

A strong interest in renewable energy is currently a world-wide trend. The European Union stresses the importance of the biomass application and diverse development opportunities and promotes the use of plant biomass as a renewable energy source. The short rotation energy plants, including willow and poplar are promising in this respect. This research aims to explore the changes in biomass dry matter yield and other biometric characteristics of three willow (Salix spp.) cultivars ‘Tora’, ‘Tordis’ and ‘Gudrun’ as influenced by nitrogen fertilization rates, cutting frequency, planting density and year of growing. A field trial was performed at the Vokė Branch of Lithuanian Research Centre for Agriculture and Forestry on a light textured soil, sandy loam Haplic Luvisol (LVha) in the climatic zone of south-eastern region of Lithuania during 2005–2014. In the spring of 2005, cuttings of willow were planted in rows at 0.65 and 0.50 m distances. Before planting, the entire field was fertilized once with mineral P K (60 kg ha -1 P O, 80 kg ha -1 K O) rate. In May, when cuttings fully took roots, the following rates of nitrogen were 60 80 applied once according 2 5 to the 2 experimental design: N (unfertilized), N (30 kg ha -1 N), N (60 kg ha -1 N), N (90 kg ha -1 N) and N (120 kg ha -1 N). In 2006, 2012, 2013 0 and 2014 the 30 plants were repeatedly 60 fertilized. In early 90 spring of 2006, part 120 of the willows were cut, others were left to grow. Salix spp. cultivars ‘Tora’ and ‘Tordis’ produced higher biomass dry matter yields than ‘Gudrun’ (p < 0.05). The longest shoots were produced by ‘Tora’ and ‘Tordis’. N and N fertilizer rates had the strongest impact on biomass dry matter yield of willows and increased biomass 90 yield. 120 Biomass dry matter yield of willows, cut after the first growing year (in spring 2006), was greater than that of not cut ones. Maximum biomass dry matter yield was produced in the plots, where willows had been planted in rows at a distance of 0.5 m between the plants.