What is manure

Manure is a valuable source of nutrients for crops and can improve soil productivity. Manure properties depend on several factors: animal species; diet, digestibility, protein and fiber content; and animal age, housing, environment, and stage of production. Manure is characterized in several ways. Important properties for manure collection, storage, handling and utilization include the solids content (the percent of solids per unit of liquid) and the size and makeup of manure solids (fixed and volatile solids, suspended solids, and dissolved solids). Nutrient content, primarily nitrogen, phosphorus, and potassium, is important as it affects land application rates and treatment techniques.Manure components can be characterized as organic and inorganic. To help control disease and parasites, human wastes should not be mixed with animal manures. Handling Characteristics The quantity, composition, and consistency of manure greatly influence livestock manure facility design. The handling characteristics of manure vary, depending primarily on the amount and type of solids present, Figure 1. The boundary between handling classifications is not fixed, but varies with specific composition. Manure can be classified, in general, based on how manure must be handled. Manure handling characteristics vary as consistency changes from liquid to solid. On one end of the spectrum is lagoon liquid with a very low solids content (less than 1%) that can be handled using conventional centrifugal pumps. Lagoon liquid can be irrigated using either big guns or center pivot irrigation systems with small nozzles. On the other end of the spectrum is solid manure that must be handled with front-end loaders and/or pitchforks. Solid manure normally has more than 20% solids. In between are the more difficult to handle manures, the ones containing from 5 to 20% solids. The moisture content of the manure is the main determining characteristic, although solids size, and the presence of bedding also can influence the equipment needed for handling, treating, and transporting. Solids generallytend to settle, but very thick manures (more than 10% solids) hinder settling, and may result in a more uniform manure than a settled, thinner one. Sand is another challenging solid that’s sometimes used as dairy bedding. Sand requires special settling and handling procedures due to its high density and abrasiveness. Nutrient values are related to solids concentrations. In general the higher the solids concentration, the higher the nutrient concentration. Estimates are available for most manure types, but to really know what manure contains, representative samples must be analyzed. Estimates and tabular values must be used with caution. They are useful for planning purposes, but once a facility is established, the best way to determine nutrient and handling characteristics is to obtain good representative samples and have them analyzed. Liquid Manure with up to 4% solids content can be handled as a liquid with irrigation equipment. Liquids that have had the larger solids removed, or manure with dilution water added may contain 4% or less solids. Properly designed and managed anaerobic (or aerobic) lagoon treatment systems should have less than 1% solids, typically from 0.1 to 0.5%. However, it’s not uncommon for overloaded lagoons to reach as high as 2% solids. Slurry Manure with 4 to 10% solids content can be handled as a slurry, but may require special pumps. Swine pit manure typically contains between 2 and 6% solids. Deep pit manure will be toward the upper end of the range, while manure in outside pits will be more liquid. Outside pits may be either concrete, steel, or earthen. When wet-dry feeders or swinging waterers are used, the animals waste less water so solids content may increase to 8 to 12%, resulting in a thicker slurry. Dairy manure with milking parlor washwater added typically is handled as slurry. Semi-solid In the 10 to 20% solids content range, handling characteristics vary by the type of solids present. In this range, the percent solids content does not have as much effect on handling characteristics as does the type of manure and the amount of bedding present. Figure 1. Relative handling characteristics of different types of manure for various species. NOTE: "As excreted" lines represent the common solids content of manure excreted from a healthy animal. 4 Manure Management Systems Series This range of solids can be very difficult to handle and is typical of many dairy operations. The manure is too thick to pump, and too thin to scoop. Producers with this thick slurry type of manure may have to add water to handle the manure as a liquid, and will need special pumps to agitate and move the manure. Usually, handling the manure with a frontend loader doesn’t work well because the liquid runs around the bucket during forward movement. Transfer equipment, such as augers and flight elevators, is sometimes used. Mechanical scrapers or skid loaders with tires attached to the bucket also can be used for manure collection.

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