Value of Manure
Farmers are seeing fertilizer prices soar in 2021 and 2022. Extreme weather, plant shutdowns, sanctions, and rising fuel and energy costs, and high grain prices are driving fertilizer prices higher. Fertilizer prices are at their highest level in more than a decade.
Fertilizer prices for nitrogen (N) have soared from around $400 to $450 per ton for anhydrous ammonia (82% N, 1640# N/ton) to currently $1100 or more. The cost per pound of actual N in anhydrous has gone from $.27 to about $.67 per pound. Many farmers use 28% liquid N (560# N/ton) which is safer to use and current costs are around $475 per ton or $.85 per actual pound of N. Phosphorus (P) and potassium (K) prices have also soared. Phosphate fertilizer (60% P, 1200# P /ton) is currently being priced at $829 to $840 per ton or about $.70 per pound. Potassium (K) or potash (60%, 1200# per ton) is at $725 per ton or $.60 per pound.
Manure can be an alternative to fertilizer but putting a value on manure is dependent upon how much will be around and is plant available. Generally, 80-90% of the phosphorus (P) and potassium or potash (K) will be available the first year. On nitrogen (N), which is more volatile, it depends upon how it is applied. Farmers can use their own numbers and assumptions to modify their own manure calculations.
The following is adapted from an article by Mary Wicks, Ohio State University to help with assumptions on putting a value on manure. Manure varies with fresh manure being a mixture of feces and urine that may include livestock bedding or poultry feathers. Manure species, age of the animal, type of feed, moisture content, bedding, application method (incorporation vs broadcast), weather, and time of year affect nutrients availability next year. Manure contains many nutrients including N-P-K, micronutrients, and organic matter. Manure has value but it can be difficult to put a fair value on it compared to commercial fertilizer.
Animal manure varies by species, age, and nutrition. Fresh manure from a broiler chicken is 4.91% N and 2.99% P on a dry basis, while a dairy cow is 5.44% N and 0.80% P, and a hog is 7.66% N and 4.78% P. Manure nutrient content also varies within a species and differences in feeding programs can affect nutrient content. Modern feed rations match animal nutrient needs very closely, so this reduces nutrients lost in the manure.
Manure properties are affected by bedding, water, and storage. Organic bedding such as straw or sawdust can absorb water in manure – up to 2.2 pounds per pound of bedding. Bedding has less nutrient value than fresh manure causing the nutrient content of the mixture to be diluted. Sand used for bedding at dairies, does not absorb water or contain nutrients but does increase volume, diluting the nutrient value.
Manure is handled as a dry or wet material depending on its water content. Dry manure, with less than 88% water, is removed from the barn and stockpiled or placed in a storage area. Fresh poultry manure is handled as a dry material, while dairy and hog manure usually are in a liquid form unless bedding has been added. Dairies that use minimal bedding or sand often scrape or flush manure into a storage pond. The ponds are often outdoors and open, where more water is added from precipitation. Hog barns that do not use bedding typically have a storage pit beneath a slatted floor.
Small operations may remove and land apply manure daily, but most farms store the manure so that it can be land applied based on weather conditions and crop needs. During storage, N may be lost to the atmosphere through volatilization, precipitation can dilute nutrients, and methane and odors may be released.
Applying manure to cropland at the right time and agronomic rate optimizes nutrients for crop production and improves soil health. Because nutrient content can vary due to many factors, a lab analysis prior to application is recommended. Solid manure is applied with a spreader and liquid manure is applied via a hose or tanker, either on the surface or incorporated into the top layer of soil. Incorporation may require specialized equipment, but it reduces the risk of runoff, odor emissions, and N loss. Applying manure nutrients to a growing crop or cover crop increases nutrient retention and reduces nutrient losses. For more information, visit the OSU-OCAMM website (ocamm.osu.edu) with links to manure resources. Next week, this information will be used in some examples to put a value on poultry, hog, and dairy manure.