The concentration of antibiotics in various soil layers is termed “terracumulation” . Terracumulation will occur if an antibiotic is deposited in the soil at a rate that exceeds its rate of degradation.
Source: http://amrls.cvm.msu.edu/veterinary…/a.-veterinary-antibiotics-in-soil
Rooklidge SJ. 2004. Environmental antimicrobial contamination from terracumulation and diffuse pollution pathways. Sci. Total Environ. 325:1-13.