A case study of woody leaf litter vermicompost as a promising calcium fertilizer

Vermicomposting of organic wastes aimed to obtain fertilizers and other beneficial substances is of major importance in modern bioresource technologies. Earthworms Eisenia fetida may be used for the decomposition of woody leaf litter from Southwestern Siberia. We have analyzed physicochemical and rhizogenic properties of peat moss vermicomposts obtained from tree leaf litter substrate of poplar, Populus nigra L., willow, Salix fragilis L., and birch, Betula pendula Roth., compared to traditional horse manure-based substrate. There is a determination of pH, electroconductivity (EC), K⁺, Ca²⁺, and NO₃ ^--concentrations in water extracts of initial pure substrates (manure and litter) as well as their mixtures with peat moss before and after three-weeks vermicomposting. Among water extracts of prepared peat-based vermicomposts and substrates “manure…poplar…willow…birch”, having EC of 165…121…100…95 µS.cm^-1, pH - 7.0…7.4…7.3…7.2, NO₃ ^--ions of 87…22…19…12 [mEq.kg^-1 of dry weight] and Ca²⁺/K⁺ ratio - 0.47…6…4.5…4, respectively, we have chosen mostly Caenriched vermicompost of peat moss and poplar leaf litter (Ca²⁺-concentration till 100 [mEq.kg^-1 of dry weight). The sprouting of wheat seeds and isolated potato shoots using poplar leaf litter vermicompost extracts resulted in a significant increase (18 and 28%) in the relative weight of the roots compared to the seeds and shoots grown on tap water (12 and 14%) and horse manure vermicompost extracts (12 and 19%).