Correlations between several chemical parameters of soil and earthworms’ density depending on plant culture and organic-mineral fertilization

Affiliation: Mădălina Iordache, Ionel Gaica, Iacob Borza, UASVM of Banat, Timisoara; Valentina Andriucă, Daniela Gîrla, State Agrarian University of Moldova.

Researches have been carried out on the land of Didactic Station of UASVMB Timişoara, on a cambic chernozem, low gleyed. Identification of the pedological conditions and the morphological description of soil profile, as well as soil identification by type, respectively by subtype, have been made according to Romanian System of Soil Taxonomy (SRTS, 2003). Soil sampling was made by genetic horizons in natural arrangement and disturbed arrangement. Two types of organicmineral fertilizers with granules coated with humic-potassic acids have been tested, noted L200-HUM and SH-120. The researches have been carried out in two plan cultures, maize (Zea mays L.) and sun-flower (Helianthus annuus L.). On the soil of these crops the organic-mineral fertilizers have been applied in dose of 83 kg active substance (N)/ha. Earthworms’ extraction from soil has been realised using formaldehyde method according to ISO 23611-1/2006. There was found a higher earthworm number in maize culture than in sunflower culture. In fertilization with L-200-Hum was found that earthworm number was considerably higher than in fertilization with SH-120. In sunflower culture the tendency is similar, under action of fertilizer L-200-Hum was recorded a larger number of earthworms as compared to fertilization with SH-120. Generally, the values recorded for earthworm weight are related to values describing earthworm density, with several exceptions depending on species size, as well as different weights of individuals from different development stages, because juveniles weigh less than adults. The achieved results have been correlated with values of several chemical indices of soil: pH and content of total organic carbon (TOC).