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ŠUMARSKI LIST 1-2/2013 str. 37     <-- 37 -->        PDF

The morphological structure of this soil is as follows: Amo,p-IGso-IIGso-IIIGso-IVGso-Gr. Humus accumulative horizon (A-horizon) is loam (30 cm thick) according to the textural type, where all physiological activities are taking place (Ivanišević, 1991, Galić, 2010). The humus content in A-horizon exceeds 2,33% (table 1). Due to a layered configuration the textural composition changes with the depth, mainly the sandy fraction increases. Humus fraction declines with depth, indicating a type of accumulative distribution of organic matter in the profile (Ivanišević, 1991, Ivanišević and Milanovskij, 1991). Ground water oscillates at the depth of 80 to 220 cm, which allows favorable moisturizing of the physiologically active profile, i.e. active rhizosphere zone (Pekeč, 2010).
This form of fluvisol in the physiologically active part of the profile, contains on the average some 7500 t·ha–1 of dust+clay fraction, 163 t·ha–1 of humus, and can potentially store some 2150 m3·ha–1 of useful water (Ivanišević, 1991, Ivanišević, et al. 2000). Hence, from the aspect of benefits in terms of technological production of poplar biomass in short rotations this soil belongs to habitats of high fertility potential.
The climate in the tested area is moderately continental (Katić et al. 1979), with certain specificities. The coldest month was January with the mean air temperature of 1.1 °C, and the hottest one July with 20.3 °C, the mean annual air temperature was 10.9 °C.
Average rainfall for the area in which the testing was done was 592 mm. From the mean annual amount of rainfall some 333 mm or 56% fell during the vegetation period (Katić et al. 1979).
Under such ecological conditions soil cover was formed on alluvial deposits of pronounced variable textural composition, with abrupt changes of microrelief on small areas (Rončević and Ivanišević, 1982; Živanov and Ivanišević, 1985).
2.2 Working method – Metoda rada
Trial stand with four clones and three planting distances was established with the aim to discover the most favorable technology for production of biomass in stands with a two-year rotation period, under field conditions.
I. Clones
1) Populus deltoides Bartr. ex Marsh. cl. 457
2) Populus deltoides Bartr. ex Marsh. cl. 450
3) Populus deltoides Bartr. ex Marsh. cl. 618
4) Populus deltoides Bartr. ex Marsh. cl. 55/65
II. Planting distances
a. 1.20 × 1.00 m (8330 plants.ha–1)
b. 1,20 × 0.75 m (11110 plants.ha–1)
c. 1.20 × 0.50 m (16660 plants.ha–1)
Within these studies the production of biomass for energy is analyzed in two production cycles.
When establishing the first cycles cuttings of 20 cm to 25 cm long were soaked in water for 24 hours before planting on a well-prepared soil.
According to the set research goals, hoeing around the plants and inter-row processing were performed for each of the applied treatments at the same time and in the same manner. Results of the survival of the trial stand per treatment were determined in the first half of September of the same year the trial stand was established.
At the end of the first year the diameters and heights were measured, in the second year the measurements were performed just prior to felling, and the samples for laboratory testing were taken.