Cow manure fertilizer is a natural soil amendment used widely in agriculture and home gardening. It is a byproduct of cattle digestion, making it a rich source of organic matter and plant nutrients. Farmers have long recognized its ability to improve soil structure and fertility, providing a sustainable resource.
The Physical Source Materials
Raw cow manure consists of several components. The bulk of the material is solid waste, or feces, primarily undigested plant fiber from the cow’s diet of grass, hay, or grain. This solid matter is rich in organic compounds that contribute to soil health.
Liquid waste, or urine, is also a significant part of the raw material. While feces contain solid organic nitrogen, urine holds the majority of the soluble nitrogen, often as urea, which is quickly available to plants. Collected raw manure is often mixed with absorbent bedding materials used in housing, such as straw, sawdust, or wood shavings.
These carbon-rich materials are crucial for balancing the nitrogen content and are integral to the subsequent preparation process. The cow’s diet greatly influences the final makeup, as the animal only retains a portion of the nutrients it consumes, with the rest excreted in the manure.
Essential Chemical Makeup
The fertilizer’s value stems from its complex chemical profile, supplying elements necessary for plant growth. The three macronutrients most commonly tracked are Nitrogen (N), Phosphorus (P), and Potassium (K), referred to by their N-P-K ratio. Percentages are highly variable based on diet and handling, but fresh cow manure often averages around 0.6% N, 0.4% P, and 0.5% K by weight.
Nitrogen exists in organic forms, released slowly as the material decomposes, and soluble inorganic forms, like ammonia and nitrate, which are immediately available. Phosphorus supports root development, and potassium promotes overall plant vigor and water regulation. Cow manure also contains secondary macronutrients like Calcium (Ca), Magnesium (Mg), and Sulfur (S).
It provides a spectrum of micronutrients, including Boron, Zinc, and Copper, vital for specific plant functions. A large portion of the material, often over 80% on a dry weight basis, is organic matter and carbon, which improves the soil’s physical properties, such as its ability to hold water and nutrients.
Preparing Manure for Use
Raw cow manure is rarely applied directly because it contains high levels of ammonia that can damage plants and may harbor human pathogens like E. coli. Preparation transforms the raw material into a safe, stable fertilizer using two primary methods: aging and composting.
Aging involves letting the manure pile sit and break down, which reduces volatile nitrogen and moisture content. However, aging does not reliably generate enough heat to eliminate contaminants. Composting is a more controlled process where manure is mixed with carbon-rich materials and actively managed to raise the internal temperature.
Proper composting requires the pile to reach 130°F to 160°F for a sustained period, which kills weed seeds and harmful bacteria. This heat-driven breakdown stabilizes nutrients, converting volatile ammonia into stable organic nitrogen forms, and reduces the risk of plant burn. The final product is a dark, earthy-smelling material with a lower moisture content and a balanced nutrient profile.