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Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Pp. 409-434 in Animal Agriculture and the Environment: National Center for Manure and Animal Waste Management White Papers. J. M. Rice, D. F. Caldwell, F. J. Humenik, eds. 2006. St. Joseph, Michigan: ASABE.  .(doi:10.13031/2013.20260)
Authors:   Jeffery Lorimor, Charles Fulhage, Ruihong Zhang, Ted Funk, Ron Sheffield, D. Craig Sheppard, G. Larry Newton

A number of manure management strategies are used for both open lot and confinement facilities in the U.S. The primary control strategies for open lots are solids removal using settling basins and containment followed by land application of the liquids. These management strategies are dictated by federal law for large open lots. Smaller lots may or may not capture and land apply the runoff liquid. Both large and small lot operators must haul and distribute manure solids on the land. Solid manure spreaders that apply uniform rates is a major research need.

Confinement facilities rely primarily, but not exclusively, on liquid handling systems. Two general categories of liquid systems are pits, or slurry systems, and lagoons, primarily anaerobic lagoons. Anaerobic lagoon design has been researched and is well known to environmental engineers. Anaerobic lagoons work better in warm climates where biological activity continues most of the year. Anaerobic digesters with controlled temperatures can be used to produce biogas and reduce pathogens, but are difficult to justify due to high capital costs, high management requirements and a lack of incentives for using the systems. Covered lagoons and anaerobic digesters can significantly reduce odors and releases of unwanted gases.

Naturally aerobic lagoons can reduce nitrogen in the liquid significantly, but are impractical because of large size requirements. Mechanically aerated lagoons are sometimes used. Autothermal thermophilic aerobic digestion, biofilm reactors, sequencing batch reactors, and combinations of anoxic and aerobic treatments are being researched, and offer advantages of odor reduction, and waste degradation and stabilization. Additional research is needed to optimize these systems for nutrient reduction, pathogen destruction, and energy use.

Solid-liquid separation can be used for both open lots and confinements. Open lots typically use settling basins. Confinements typically use mechanical separators. The efficiency of a separator depends on the type of waste and the separator. Its difficult to achieve high efficiencies of separation without pretreatment with coagulating chemicals. Solids from both separators and from open lots are sometimes composted.

Wetland treatment of manure liquids has received some research attention. It has been shown to offer some nutrient reduction advantages when designed properly. Initial design parameters have been determined for animal waste systems, but continued research is needed to adapt wetland systems to different types of livestock operations.

Chemical amendments remain a question. Both feed additives and manure additives have been tested by a number of researchers, and have achieved only moderate success at best. Much research is needed before chemical additives will be major contributors to manure control solutions. Land application systems are well developed, but always need continued work to improve efficiencies and effectiveness. One of the primary areas of research needs currently is for injection units that minimize disturbance of the soil and crop residue cover.

Insect digestion of manure solids has been well researched in laboratory settings. Effective field production systems need to be devised, and uses for the resultant high protein feedstuffs need to be developed.

Many of the above technologies can be combined into integrated treatment systems that protect soil, air, and water quality.

Manure management strategies are different for manure from a confinement system (used here to mean a totally roofed facility) and from an open lot, or partial open lot system. Because open lots are subject to hydrologic phenomenon such as rainfall, runoff, sunlight, and evaporation, they are very different from confinement systems. Although there are some similarities, there are many differences.

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