Dynamics of earthworm species at different depths of orchard soil receiving organic or chemical fertilizer amendments

Abstract

We investigated the dynamics of different earthworm species through the soil profile,which had received short-term amendments of either organic or inorganic fertilizer in anorchard during the spring of 2016. Earthworm populations were sampled at twoconsecutive depths of soil on 20 and 60 days after addition of fertilizers. The dominantearthworm species were Eisenia fetida (Savigny, 1826), Dendrobaena veneta (Rosa, 1886),Dendrobaena hortensis (Michaelsen, 1890), Lumbricus terrestris (Linnaeus, 1758) andAporrectodea longa (Ude, 1885). Seven different types of fertilizers including Urea,Ammonium sulfate (AS), Diammonium phosphate (DAP), Solupotas, NPK (15-5-25),(NPK+OM) and organic manure (OM) as experimental treatments were studied.Fluctuations in earthworm numbers and biomass were attributed to changes in time anddepth of sampling, in addition to the types of fertilizers. The results of the meanscomparison showed that on the 20th day, at 0-20 cm soil depth, E. fetida speciesabundance was decreased significantly in AS and Urea treatments compared to the controlplot (p˂0.05). We highlighted that from epigeic group, D. hortensis species had a betterchance to survive and its population in AS treatment was more than that of Ureatreatment. Results also showed that the anecic L. terrestris, had a greater tolerance tochemical fertilizers compared to the A. Longa species. The results of this study outlinemore clear horizons in managing the use of chemical fertilizers while simultaneouslymaintaining the biodiversity of soil organisms.