Sub-lethal effects of a binary mixture of urea and diammonium phosphate (DAP) on earthworm, <i>Eisenia fetida</i> biomass accumulation and body wall histology

Chemical fertilizers have increased agricultural yields and fed thousands of people for over 60 years. Synthetic additives (Urea and diammonium phosphate) increase yield but also increase soil contamination, residual chemical bioaccumulation, and impacts on soil fauna. Additionally, earthworms and other soil-dwelling microorganisms are at risk due to the use of chemical fertilizers. Urea and diammonium phosphate are commonly used fertilizers for cash crops (wheat, rice, maize, and soyabean) in managed agro-ecosystems. The present experiment aimed to study the impact of using chemical fertilizers in agricultural practices on soil-inhabiting earthworms, Eisenia fetida and the imposition of significant risks to farmers' friends. The present study was designed to raise earthworms, E. fetida, in laboratory conditions according to OECD guidelines (1984) number 207, using artificial soil treated with a binary combination mixture of urea and DAP (LC10Urea+LC10DAP) for 60 days. Results showed that the presence of chemical fertilizers (LC10Urea+LC10DAP-a binary mixture) in the treatment exerted a sublethal toxicological effect on earthworms' E. fetida capacity for biomass accumulation. On days 15 and 60, histological observation were also noted in the body wall of the earthworm, E. fetida. The number of galandular cells in the epithelial layer increases on day 15 to 60. On day 60 of E. fetida treatment group, a slight rupture in the epithelial layer is observed. The present study demonstrated that the detrimental effects of nitrogenous fertilizers on earthworms can have significant ecological repercussions for the entire terrestrial ecosystem, in addition to harming important soil fauna.