%0 Articles
%T Biomass production and control of nutrient leaching of willows using different planting methods with special emphasis on an appraisal of the electrical impedance for roots
%A Cao, Yang
%D 2011
%J Dissertationes Forestales
%V 2011
%N 125
%R doi:10.14214/df.125
%U http://dissertationesforestales.fi/article/1908
%X Willow reproduction can be achieved through vertically or horizontally planted cuttings. Conventionally, plantations are established by inserting cuttings vertically into the soil. There is, however, a lack of information about the biomass production and nutrient leaching of plantations established through horizontally planted cuttings.

A greenhouse experiment and a field trial were carried out to investigate whether horizontally planted Salix schwerinii cuttings have a positive effect on stem yield, root distribution and nutrient leaching in comparison with vertically planted cuttings with different planting densities.

The shoots’ height of horizontally planted cuttings was significantly smaller than that of vertically planted cuttings during the first two weeks after planting in the pot experiment. Thereafter, no significant effect of planting orientation on the stem biomass was observed in the two conducted experiments. In both experiments the total stem biomass increased with the planting density. It was also found that the fine root biomass and the specific root length were not affected by the planting orientation or density, while the fine root surface area and the absorbing root surface area (ARSA) were affected only by the planting density. The planting orientation did not affect the nutrient concentrations in the soil leachate, apart from SO4-S and PO4-P in the pot experiment.

The ARSA in the pot experiment was assessed by using the earth impedance method. The applicability of this method was evaluated in a hydroponic study of willow cuttings where root and stem were measured independently. Electrical resistance had a good correlation with the contact area of the roots with the solution. However, the resistance depended strongly on the contact area of the stem with the solution, which caused a bias in the evaluation of root surface area. A similar experimental set-up with electrical impedance spectroscopy was employed to study the relationship between the electrical parameters and root morphology. A good fit was obtained between the impedance spectra data and the proposed lumped models. The model parameters were correlated with the contact area of roots and/or stem in the hydroponic solution.

In conclusion, the horizontal planting method can be used as an alternative method for vertically planted willow cutting in regard to bioenergy and nutrient leaching. Electrical impedance spectroscopy is a promising non-destructive method in root research, but more laboratory and field studies are needed.