When animal manures are stored inadequately or applied as fertiliser, this can then spread bacteria to crops and into run-off water.[5][77] Antibiotics have been found in small amounts in crops grown in fertilised fields,[79] and detected in runoff from animal waste-fertilised land.[80] Composting has been shown to reduce the presence of various antibiotics by 20-99%,[77] but one study found that chlortetracycline (CTC), an antibiotic used in livestock feed in China, degraded at different rates dependent on the animal it was fed to, and that manure composting was not sufficient to ensure the microbial degradation of CTC.[81]