Growth and productivity of some cultivars of energy willow, depending on the degree of soil moisture

Abstract

Purpose. To determine the optimal soil moisture conditions for intensive growth and high productivity of energy plantations of some willow cultivars in the conditions of Kyiv Polissya.

Methods. The object of the study was the energy plantations of three willow cultivars: Salix viminalis L. cv. ‘Ternopilska’, S. triandra L. cv. ‘Yaroslava’ and S. dasyclados Wimm. cv. ‘Khors’. Plantations were created in 2009 in Boyarka forestry (Boyarka Forest Experimental Station). The soil is clayey-sandy. Plantations grew on three sites with different degrees of soil moisture: slightly-moisturized, well-moisturized and strongly-moisturized.

Results. After two years of cultivation, the highest ‘plant survival rate’ was peculiar for well-moisturized soil. It was 98.5% for ‘Ternopilska’, 97.1% for ‘Yaroslava’, and 89.6% for ‘Khors’ varie­ties. The highest average height of two years old plants was observed on a well-moistened soil – 3.2±0.06 m (‘Yaroslava’ variety). ‘Ternopilska’ variety on less-wetted soil had the highest height. The plants of ‘Khors’ variety had near-the-same height, regardless of the level of soil moisture. Study of these plantations in the age of eight years, when the age of their above-the-ground part was of 5 years old, showed that ‘Yaroslava’ cultivar significantly exceeds the productivity of ‘Ternopilska’ and ‘Khors’, when grow on slightly- (122.0 t/ha) and well-moisturized soils (128.2 t/ha of raw biomass). The productivity of ‘Ternopilska’ and ‘Khors’ cultivars significantly decrease with the soil moisture increasing. ‘Ternopilska’ plantations produce 46.4 t/ha of raw cut mass after 5-year cultivation on slightly-moisturized soil, and only 19.8 t/ha on strongly-moisturized soil. ‘Khors’ variety characterized by the higher level of productivity on diffe­rent soil moistening (from 39.4 to 67.0 t/ha).

Conclusions. Among the three studied cultivars of willow the highest growth and productivity indexes on clayey-sandy soils of the Kyiv Polissya has ‘Yaroslava’ cultivar. Optimal conditions for intensive growth of ‘Yaroslava’ cultivar peculiar to energy plantation on well-moisturized soils and for ‘Ternopilska’, and ‘Khors’ – on slightly-moisturized and well-moisturized soils. Over-moisturized, poorly drained soils are of little use for the efficient cultivation of energy willow raw materials.