Manure is a natural material for improving turfgrass health. This organic matter, typically decomposed animal waste, serves as a slow-release natural fertilizer and a beneficial soil conditioner. Utilizing manure correctly transforms it into a valuable tool for cultivating a denser, greener, and more resilient lawn.
How Manure Enhances Lawn Health
Manure supports turfgrass health by supplying balanced nutrition and physically enhancing the soil environment. The material contains the fundamental macronutrients—Nitrogen (N), Phosphorus (P), and Potassium (K)—which are necessary for plant growth.
Nitrogen encourages lush, green blade growth, phosphorus supports robust root development, and potassium aids in overall plant strength and stress tolerance. These nutrients are released gradually as microbes break down the organic matter, reducing the risk of nutrient leaching and over-fertilization.
Manure’s physical contribution is its ability to improve the soil structure where the grass roots reside. For lawns with dense clay soil, the organic matter introduces pore spaces, which allows for better aeration and drainage, preventing waterlogging and promoting deeper root penetration. Conversely, in sandy soils, the fibrous content acts like a sponge, increasing the soil’s capacity to retain moisture and nutrients near the root zone. This modification of soil texture creates a more stable and hospitable foundation for the grass.
Selecting and Preparing Manure for Lawns
Selecting the appropriate manure source and ensuring it is properly treated are necessary steps. Different animal manures offer varying nutrient concentrations. Chicken manure typically has a higher nitrogen content than cow or horse manure, making it a more potent fertilizer source.
Cow and horse manure, while lower in nitrogen, offer a greater volume of fibrous organic material, making them excellent soil conditioners. The most important consideration is preparation, which involves aging or composting the material. Fresh manure contains high levels of ammonia, salts, pathogens, and weed seeds, which can damage the lawn.
Only well-aged or fully composted manure should be used on an existing lawn. Composting utilizes heat to neutralize excessive salt and nitrogen levels, kill weed seeds, and eliminate pathogens. Commercially bagged manure is typically sterilized and aged, offering a safer and more uniform product. Using fresh, or “hot,” manure can severely injure the grass blades, leading to patches of brown, desiccated turf.
Applying Manure Effectively
The safest method for applying prepared manure to an established lawn is topdressing. This involves spreading a thin, uniform layer of the material directly over the grass blades. The goal is to lightly dust the lawn with the amendment, not to bury the turf entirely.
An appropriate application thickness is generally no more than one-quarter inch, or approximately 3 to 5 millimeters, ensuring the grass tips remain visible. This thin layer allows sunlight and air to reach the grass while the manure slowly filters down to the soil surface.
The best time for application is during the lawn’s active growth periods in the early spring or the early fall. After the manure has been spread, it should be lightly raked or brushed into the turf canopy to ensure it settles near the soil. Immediate and thorough watering is then required to help the beneficial microbes and soluble nutrients begin leaching into the soil and to wash any residual material off the grass blades, minimizing the chance of localized burn.
Common Mistakes When Using Manure on Grass
The most common error is applying fresh, unaged manure, which contains salts and high concentrations of rapidly available nitrogen and ammonium. These components draw water away from the grass roots and leaves, causing desiccation and browning.
Applying an excessively thick layer of even composted manure is another frequent misstep. A layer thicker than the recommended quarter-inch can smother the grass, blocking necessary sunlight and air exchange, which promotes disease and die-off.
Another concern with uncomposted material is the introduction of weed seeds, which pass undigested through the animal’s digestive tract. Properly composting the manure heats the material sufficiently to kill these seeds, but improperly prepared material can introduce a new weed problem. Furthermore, homeowners must be cautious about persistent herbicides, such as aminopyralid, which can sometimes be found in the hay or feed given to the animals, leading to long-term soil contamination that is harmful to turf and other plants.