A simple paper contact approach with fetida was actually essential in proving the harmful effect. The use of ecologically safe urea dosages revealed the potentially hazardous effects on earthworms when they come into close contact. The results showed that there was a significant increase in mortality after 24 hours of exposure.
Earthworms are important components of soil ecosystems and play an important role in nutrient cycling. They can be exposed to many substances that reach the soil through manure or industrial by-products. Some of these chemicals may be toxic for earthworms, but only if enough are consumed within a short period of time. Earthworms have an efficient detoxification system based on enzymes found in their skin cells and intestinal lining. However, high doses over a long period may cause problems for them. For example, some earthworm species may stop eating if exposed to certain pesticides; therefore, applying pesticide directly onto soil may not allow worms access to it. Pesticides also break down quickly in sunlight and heat, which means that sprinkled on soil or composted material, they may not last long enough to protect earthworms from contamination.
Urea is considered non-toxic to earthworms and has been used as a fertilizer for decades. This study showed that even low levels of urea can be dangerous for them if they are exposed for a long period of time.
Earthworms can be harmed by ammonia and ammonia-based fertilizers. The application of ammonium sulfate, anhydrous ammonia, and sulfur-coated urea on an annual basis has been found to reduce earthworm populations (Edwards et al., 1995). Further research is needed to determine if the use of other types of fertilizer would have a different effect on worm populations.
Ammonia is also a natural component of urine and feces. Too much ammonia in your soil can cause plants to show symptoms of stress. The best way to avoid this problem is to keep manure applications below 30 tons per acre. Any more than that and you should consider using composted manure instead.
Finally, ammonia itself is not harmful to humans or animals. It is the combination of ammonia with oxygen or water that can be toxic. Ammonia is also used as an ingredient in some pesticides. It kills plants by inhibiting photosynthesis (the process by which plants convert carbon dioxide and water into carbohydrates for food).
For earthworms, too much ammonia means death. Even at levels well below what is harmful to plants, excessive ammonia can damage the skin, eyes, and respiratory system of earthworms. The only way to prevent ammonia from harming earthworms is by keeping manure applications low. If you must apply more than 5 tons per acre, try using composted manure instead.
This is most likely related to the fact that these fertilizers reduce soil pH. Direct contact with anhydrous ammonia during application can kill up to 10% of the population. Ammonia gas can also kill earthworms if it is allowed to build up in their habitat.
So, the use of ammonia-based fertilizers should be avoided where possible because they will kill off any earthworms present in your yard. If you do choose to use them, apply them in moderation so as not to cause undue harm.
Ammonia is also a natural product of animal metabolism and has no effect on plants at all unless it is applied to soils in large quantities or over time. Ammonia is the product when meat is burned; it is also produced when nitrogenous compounds are broken down in the intestines of animals such as pigs, cattle, and sheep. Humans also produce small amounts of ammonia through the process of decomposition. The only human-made substance that is an actual fertilizer is synthetic ammonia called ammonium nitrate. It is used as a high-energy explosive and propellant fuel component. Synthetic ammonium nitrate is also used as a source of nitrogen for agriculture.
When ammonium nitrate is exposed to heat or light, its concentration of ammonia increases.