Is Manure Harmful to a Lawn?

Fresh Manure

• Fresh manure is not recommended for use in lawns or other areas, because it contains harmful disease-causing pathogens. The most important among these are the salmonella bacteria, which can cause serious illness in humans. Fresh cattle manure is likely to contain pathogenic strains of the E.coli bacteria. Manures obtained from carnivores and swine may contain helminthes, a certain form of parasitic worms that live in soil for extended periods of time. To avoid the risk of infection, it is best not to use fresh manure especially in food crops.

Safe Use

• It is best to use composted manure for fertilizing lawns as the high temperatures during the composting process kill the infectious pathogens, including helminthes. Even then, it's important to ensure the manure has been composted according to health safety standards prior to use, warms the Pacific Northwestern Extension. Obtain treated or composted manure from reliable sources.

Recommended Manures

• The use of treated horse and cow manure is recommended in landscapes and lawns as a good soil conditioner. The treatment process prior to use effectively removes any weed seeds and insect eggs. It can be used by itself or in combination with compost. Other manure types suitable for lawns include composted or treated sheep, chicken or swine manures.

Use Suggestions

• Perform a soil test in the lawn to check the alkaline or salt levels. Avoid using horse or cow manures in alkaline soils, as these manures already have a high salt content that seriously affects the germination of seedlings. Fresh manure will cause more harm than good in lawns, as the gases emitted by the ammonia in manure can fatally damage grass roots. Avoid buying manures directly from a farm, warns Denny Schrock in "Ortho Home Gardener's Problem Solver." Recommended rates of application are 12 lbs. of dry cow manure or 6 lbs. of dry poultry manure for every 100 square feet of lawn.