On-Farm Treatments for Pathogen Reduction in Animal Manure

Patricia D. Millner

The treatment of animal manure to reduce pathogens and excess nutrients, odors, and other gaseous emissions can be considered a part of the repertoire of resource conservation approaches available to livestock and poultry producers, farmers, and natural resource managers.

The benefits of manure application to crop productivity and soil quality are well-known and appreciated. The need for appropriate and economical treatment and storage technologies mainly have emphasized nutrient and odor factors. However, the ability of a treatment technology to reduce pathogens should also be considered. Untreated manure may contain pathogens and parasites that can survive for various periods of time even after land application. Pathogens may be transported by run-off to waterways that are used as irrigation or drinking sources, or to sites other than those designated for application. Some recent foodborne illness reports and trace-back studies involving E. coli O157:H7, salmonellae, and Cryptosporidium parvum indicate that the public health implications of farm and food production practices associated with animal manure can be significant, especially when manure products are used in or contact vegetable and fruit production operations.

Field and operational practices for manure treatment and handling must provide barriers for inadvertent introduction of pathogenic contaminants from fecal matter into growing and handling environments. Manure may be composted, dried, digested, lime or alkaline stabilized, or lagooned. Each of these processes can reduce the concentration of pathogens below that of untreated manure, but they differ in the amount and types of pathogens and parasites that are reduced. The level of pathogens remaining after treatment could be used to guide appropriate uses of the product in various sectors of agriculture and horticulture. The more effective the pathogen reduction, the less restrictions would be needed on the use of the materials. For manure products that are intended for either distribution to the general public or production of fresh fruits and vegetables, more intensive treatments, processes, monitoring, and management are needed.

Manure blended with other organic or inorganic materials can enhance handling, market appeal, or horticultural properties of the products. Inorganic by-products, such as cement kiln or rock dust, aggregate fines, or coal combustion ash, can help further reduce pathogens, as needed. The resulting ‘bio-mineral’ products provide stabilized organic materials augmented with mineral components useful in agriculture, horticulture, landscaping and reclamation.

Patricia D. Millner
Soil Microbial Systems Laboratory
USDA-ARS-BARC
1680 Madison Ave.
Beltsville, MD 20705
Tel: (301) 504-8163
millnerp@ba.ars.usda.gov

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