CC BY
11NAUKI ROLNICZE | CEAbCK0X03flMCTBEHHblE HAYKM
CULTIVATION OF ENERGY WILLOW UNDER THE CONDITIONS OF THE CENTRAL
FOREST-STEPPE OF UKRAINE
Humentyk M.,
Institute of Bioenergy Crops and Sugar Beet NAAS of Ukraine,
Candidate of Agricultural Sciences
ABSTRACT
The article presents findings on examining specifics of growth, development and productivity of high-yielding energy willow varieties as affected by certain elements of cultivation technology under the conditions of the Central Forest-Steppe of Ukraine. Key words: energy willow, biomass, timing of planting, cultivation, elements, productivity.
Problem statement. Technological and social development of society leads to aggravation of energy, economic and environmental problems associated with depletion of fossil fuel resources and constant increase in their prices. To address these problems, scientists actively search for the effective ways of alternative renewable energy sources utilization. One of the most promising renewable energy components is bioenergy that grounds on the utilization of biomass energy, which does not contribute to the global greenhouse effect [3, 446-448; 4, 99-105; 5, 18-19]. Recently, energy policy of Ukraine was marked by positive changes to promote biomass as a universal source of energy and increase awareness of its technical rationality. Nowadays, domestic market of solid biofuels has been emerging, which creates a need for high-quality raw materials for their production. One of the most efficient crops for production of solid biofuels is willow. New energy willow hybrids ensure particularly high efficiency biomass for biofuels. Their dry biomass yield and efficiency of solar energy accumulation exceed those of ligneous crops [5, 18-19].
Given the high priority of biofuels production from energy crops, researcher of the Institute of Bioenergy Crops and Sugar Beet (NAAS of Ukraine) have been working over the technological elements of growing willow materials purposed for production of fuel chips and pellets suitable for soil and climatic conditions of Ukraine.
The research purpose and objectives were to study specifics of growth and productivity of two varieties of energy willow, namely basket willow Ternopilska (Salix viminalis L.) [1] and almond willow Panfylska (Salix triandra L.) [2] as affected by various methods of establishing and tending plantations under the conditions of the Central Forest-Steppe of Ukraine.
Materials, methods and conditions of research. The experiment was carried out in 2013-2015. It was located at the experimental field of IBCSB NAAS (EFEF Salyvinkivske, Ksaverivka-2, Vasylkiv District, Kyiv Region) and arranged in randomised split plots design with four replications. The soil type for the experiment was fresh chernozem. Experimental plot measured 1.40 ha. The scheme of the experiment was arranged in such a manner as to ensure examining energy willow productivity as affected by row spacing and tending crops practices.
In the experiment, convenient methods of research were used. Measuring height of willow shoots was carried out with
measuring bar accurate within 1 cm, and diameter by electronic calliper accurate within 0.1 mm. Processing of obtained data was performed using software Statistika.
According to the data of meteorological observations, temperature conditions of 2013-2015 did not fluctuate significantly. However, they exceeded the average long-term values. In 2013, the temperature during growing season exceeded long-term value by 1.3°C. The amount of precipitation was higher above the average long-term value by 75.4 mm; however, in April, July and October, amount of precipitation was lower than long-term values by 18.8, 55.2 and 27.5 mm, respectively.
In 2014, the temperature during growing season exceeded long-term value by 1.1°C. Rainfall was not even in 2014. In April, May and June: the amount of precipitation exceeded the average long-term values by 19.7, 88.3 and 28.6 mm, respectively, whereas in July it was less by 9 mm, and in August and September higher by 11.7 and 1.0 mm, respectively.
In 2015, the temperature during growing season exceeded long-term value by 2.1°C, whereas, contrary to previous seasons, the amount of precipitation in the period from April to August was lower by 34.5, 13.8, 44.3, 59.6 and 55.8 mm, respectively, which slightly exceeded the average long-term values in September (7.7 mm).
Results. The efficiency of energy willow cultivation depends on timely and quality preparation of soil that allows timely and quality planting of cuttings as well as controlling weeds, diseases and pests, maintaining optimal water and nutrient regimes of soil. Application of energy-saving technologies in cultivation energy willow makes it possible to reduce chemical load on the environment, especially in tending plantations, through the use of effective inter-row soil loosening and earthing up weeds with soil in rows, and other farming practices [4, 112-113].
One of the main specifics of energy willow is slow development of the plants in early months, because cuttings spend nutrients containing in them to form their root system. Another reason is intensive plant growth at the end of growing season, which promotes efficient use of the conditions for growth and development, accumulating a significant amount of dry substances during the growing season. At the same time, being under specific soil and climatic conditions energy willow plants require appropriate agronomic practices. For all we know, primary tillage is one of the most energy-consuming
technological elements affecting the soil system [4, 114-115].
Perennial weeds and soil-inhabiting pest's larvae pose significant danger to energy willow plantations, especially in the first year of vegetation. Therefore, the field purposed for growing energy willow must be treated with non-selective herbicides. Besides, soil treatment must be carried out in a quality manner. These measures not only contribute to the reduction of weed-infestation, but also significantly reduce the population of pests in arable soil layer.
The best planting material for establishing energy willow plantations are one-year-old woody cuttings of 20-30 cm in length and 5-15 mm in diameter. There are different ways of planting them [6, 18-19 ]. In our research we proved the feasibility of planting them vertically full length. This method promotes rooting of cuttings (increases percentage of rooted cuttings) and increases shrubs dimensions. When planting at the angle of 45° or horizontally roots grows only from the underside of a cutting; therefore only half of the available root bases start their developing. By contrast, vertical placing of cuttings allows developing roots out of all available root bases leading to formation of more extensive root system in this way promoting better establishment and growth of shoots. Vertical planting also contributes to reaching deeper and better provided with moisture soil horizons by cuttings. Besides, if planting is carried out in autumn, this can prevent pushing out cuttings from soil when it is freezing.
When considering time of planting, soil and weather conditions must be taken into account. One positive side of autumn planting is early start of growth, better utilisation of soil moisture, no need for storage of planting material (and saving costs therefore). In addition, autumn is characterized by the lowest ground water level, which allows involving machinery into the works on establishing plantations on waterlogged soils.
Our research provided determination of percentage of rooted cuttings, examination of specifics of growth and development of energy willows plantations as affected by timing of their establishing. Planting of cuttings was carried out in four different periods: two in autumn, and two in spring. According to the results of growing season 2014, it was found that planting carried out in late September and in October provided 80 and 85% established cuttings, respectively. When planting in spring (early and late April) establishment of the
cuttings made up 75 and 80%.
For all we know, willows, in particular those used for obtaining biomass for energy are light demanders: they are very sensitive to shading by weeds and require careful tending both in and between rows, especially in the first year [4, 115116]. Loosening soil between rows is advisable to start at the beginning of growing season. Subsequent loosening should be carried out depending on the density of soil (1.2-1.25 g/cm2 and more) and the presence of weeds. At the same time, we can ensure weeds growth inhibition by having equipped cultivator with special claws-razors to earth up the weeds in row. The most effective this will be at the early stages of weeds development, as willow shoots reach a height of 5-10 cm. This measure provides killing more than 50-60% weeds. Upon reaching the height of 20-30 cm, to earth up the weeds in row retooled protective discs are used. The number of necessary earthing ups will be determined by the intensity of weeds emergence in rows. To earth up weeds, tractor MTZ-82 with cultivator KRNV-5.6-02 was equipped with retooled protective disks at the angle of 12-14° to row direction. The distance between row and the nearest point of blade was within 7-9 cm. Behind the earthing up working body a rotary battery was mounted on two razor-holders. To carry out earthing up weeds during summer (but not later than June) each front cultivator's beam was equipped with a razor-paw, whereas each rear beam (or movable central holder) with retooled protective disks.
Intensive shoot growth (June-August) started, soil loosening must be stopped because of possible damage to the aerial parts of shrubs. If necessary, loosening can be carried out again after technological cutting shoots has been done and after each harvesting before young willow shoots start regrowing [6, 57-59].
According to the research, it was found that the annual growth of basket willow of the second year of growth under given soil conditions exceed that of almond willow (Figure 1).
From the figure, one can see that the average height and diameter of the shoots of basket willow shrubs in May amounted to 104 cm and 5.8 mm, whereas of almond willow to 98 cm and 4.5 mm, respectively. This trend continued until the end of growing season. The most intensive growth of plants was observed in summer. In September, the growth slowed down dramatically and ceased in October.
One-year height increment of energy willow at the third year of
vegetation
□ Basket willow ■Almond wilow
350 -|
~300--
E -
— 250 ---l—|- «<-
=>200 --l-!- B- B- B
"5
= 150---b- ■- ■- ■-
100 ——_— B— B— B— B— B 50 — B— B— B— B— B— B—
0 -I—I---T----1----T----T----T----
May June July August September October
Figure 1: Growth dynamics of the energy willow on the second vegetation season, EFEF Salyvinkivske, Ksaverivka-2.
To the date, shrubs height in basket willow averaged of 304 cm and in almond willow of 291 cm. The annual height increment made up 160 and 123 cm, respectively.
On the third growing season, willows increased their height more significantly: basket willow up to 181, and almond willow to 164 cm. The average height of a three-year-old plant in experimental plantations of basket willow when cuttings were planted in September and October made up 4.4 ± 0.12 and 4.3 ± 0.16 cm, respectively, whereas that of almond willow was 3.5 ± 0.14 and 3.6 ± 0.16 cm, respectively (Table 1).
Slightly lower productivity showed basket willow shrubs planted in late October (32.3 t /ha). Productivity of almond willow in this variation was higher when planted in September
Given in the table data demonstrate that all variations of the experiment were marked by high level of plants survival, with basket willow values being higher as compared with almond willow. This circumstance, along with higher height, diameter of shoots and average weight of shrub contributed to higher productivity of basket willow. Thus, the highest yield of basket willow fresh cut biomass (54.6 t/ha) was obtained from the shrubs planted in late September. In almond willow this value made up 27.7 t/ha.
Table 1
and amounted to 30.9 t/ha.
Sufficiently high performance was typical of the variations where shrubs were harvested in spring (2015) after two years of
Survival, growth and productivity of the three-year-old energy willow plantation, EFEF Salyvinkivske, Ksaverivka-2
No Characteristics of plantation Survival (%) Height (m) Diameter (mm) Weight of bush (kg) Green mass productivity (t/ha)
at the ground level at the half-height level
1 Almond willow (3-year-old, planted in late September) 82.1±7.37 3.5±0.14 29.0±1.21 13.9±0.48 2.6±0.30 27.7
2 Almond willow (3-year-old, planted in late October) 78.6±7.90 3.6±0.16 32.8±2.14 14.7±1.07 3.0±0.29 30.9
3 Almond willow (3-year-old, planted in late September) 89.3±5.95 4.4±0.12 32.2±1.20 18.5±0.66 4.7±0.46 54.6
4 Basket willow (3-year-old, planted in late October) 85.7±6.73 4.3±0.16 32.2±2.17 17.3±0.92 2.9±0.34 32.3
growing (Table 2).
Table 2
Productivity of the one-year-old energy willow plantation on the third vegetation season, EFEF Salyvinkivske, Ksaverivka-2
No Type of energy willow Survival (%) Height (m) Diameter (mm) Weight of bush (kg) Green mass productivity (t/ha)
at the ground level at the half-height level
1 Almond willow 75.4±6.8 3.2±0.14 18.0±0.55 11.8±0.47 1.5±0.26 14.7
2 Basket willow 81.6±6.8 2.7±0.82 15.3±0.67 9.6±0.86 1.2±0.14 12.7
As shown in the table, despite the vegetation season of 2015 being the most arid, the increment of cut shrubs for one vegetation season made up (on the average) 3.2 ± 0.14 m in almond willow and 2.7 ± 0.82 m in basket willow. Besides, the yield of ligneous mass was significant: 12.7 t/ha in basket willow and 14.7 t /ha in almond willow. Thus, one-year yield of almond willow made up a half of the three-year one (see Table 1), indicating the feasibility of growing basket willow in two-year cycle, whereas almond willow in three-year cycle.
Conclusions
1. Biomass of energy willow, unlike many other renewable energy sources, is cheap and readily available local fuel. Therefore an actual problem is the development of effective cultivation practices of growing energy willow adapted to various soil and climatic conditions of Ukraine, in particular of the Central Forest-Steppe.
2. The best planting material for establishing energy willow plantations is one-year-old woody cuttings of 20-30 cm in length and 5-15 mm in diameter planted full length vertically. Such method of planting contributes to reaching deeper and better provided with moisture soil horizons by cuttings. In addition, it prevents pushing out cuttings from the soil when it is freezing in case cuttings were planted in autumn.
3. Autumn planting (late September and October) provided higher percentage of energy willow cuttings establishment as compared with spring planting (early and late April) on the average of 6.5%.
4. Soil treatment between rows is advisable to start at the beginning of growing season and carry out depending on the density of soil (1.2-1.25 g/cm2 and more) and the presence of weeds. At the same time, we can ensure weed control in rows having equipped cultivator with special claws-razors to earth up weeds in row, which allows reducing weeds number by 5060%.
5. When harvesting carried out all along three-year period (under the conditions of the experiment, i.e. fresh chernozem) basket willow was marked by higher productivity (54.6 t/ha of fresh cut mass). In almond willow this index made up 27.7 t/ ha. Two-year-old shrubs of almond willow provided 14.7 t/ ha of one-year ligneous mass, which made a half of its total productivity over three years. This indicates the feasibility of growing basket willow in two-year cycle and almond willow in three-year cycle under the conditions of the Central Forest-Steppe of Ukraine.
References
1. Fuchylo Y.D. 2003. "Plant Variety Name: Ternopilska. Taxon: Basket Willow (Salix viminalis L.)". Inventor's Certificate 04194 Ukraine [in Ukrainian].
2. Virovka V.M., Sbytna M.V., Sliusar I.T., Tkachov V.O., Tkachov O.I., Fuchylo Y.D. 2014. "Plant Variety Name: Panfylska.Taxon: Almond Willow (Salix triandra L.)". Inventor's Certificate 140495 Ukraine [in Ukrainian].
3. Humentyk M.Y. 2012. "Growing and Utilization of Organic Raw Materials for the Production of Energy", in Scientific Papers IBCSB NAAS: New Technologies of Growing Crops. 14: 446-448 [in Ukrainian].
4. Roik M.V., Humentyk M.Y., Sinchenko V.M., Fuchylo Y.D., Pyrkin V.I., Hanzhenko O.M., Humentyk M.Y. et al. 2015. "Energy Willow: Growing and Utilization". Vinnytsia, Ukraine: Nilan [in Ukrainian].
5. Roik M.V., Humentyk M.Y., Mamaisur V.V. 2013. "Prospects of Growing Energy Willow for the Production of Solid Biofuels". Bioenergy. 2:18-19 [in Ukrainian].
6. Fuchylo Y.D., Onyskiv M.I., Sbytna M.V. 2006. "Biological and Technological Basics of Growing Forest Plantations". Kyiv, Ukraine: Institute of Agrarian Economics [in Ukrainian].
