Manure and the Environment

Manure contains four primary contaminants that impact water quality: nitrogen, phosphorus, bacteria and other pathogens, and organic matter. Achieving a nutrient balance will reduce potential environmental hazards often associated with animal agriculture. An annual crop nutrient management plan is needed to ensure an adequate supply of nutrients to sustain profitable crop production, and to balance nutrient inputs (including manure) with crop nutrient needs.

Understanding Water Quality Issues

Manure contains four primary contaminants that impact water quality: nitrogen, phosphorus, bacteria and other pathogens, and organic matter.

Contaminant Pathways

Water quality can be degraded by contaminants contained in manure, from water used at milking centers, from silage leachate, and from open lot runoff. These potential pollutants typically follow one or more possible pathways to water.

Pathogens and Organic Matter

Pathogens, typically microbes (e.g., bacteria, viruses, protozoa, fungi) or parasitic worms, are organisms capable of causing infection or disease in other organisms, including humans, wild and domestic animals, and plants. Several pathogens naturally occur in livestock and poultry manure and under certain circumstances may pose a risk to human health.

Nitrogen Dynamics

Nutrients in manure are potentially valuable resources for the management of soil fertility, but these nutrients are potential pollutants as well. Only 10 to 40 percent of the nutrients consumed by animals may end up in the marketed product; the rest is excreted in feces and urine. Manure contains all nutrients needed by plants, but nitrogen and phosphate generally have the most agronomic significance in Nebraska.

Phosphorus Loss

Land application of manure can be beneficial to crop production but can result in increased risk of P loss to surface waters. When manure is applied to meet crop nitrogen needs, the amount of P applied is typically much more than the P removed in the harvest of one crop. Effective January 1, 2007, operators of large CAFOs in Nebraska need to assess the risk of P delivery to surface waters from each of their designated fields by using a P index before manure can be applied.

Phosphorous Dynamics

Animal manures contain both organic and inorganic forms of phosphorus. When manure mineralizes, organic phosphorus becomes inorganic phosphorus in solution and is available to plants. Some organic phosphorus is transformed to inorganic form shortly after application but other phosphorus will remain in organic form

Air Quality Issues

The federal Clean Air Act Amendment of 1990 (CAAA) has provisions of importance to producers of agricultural products. Although protecting air quality has inherent implications for livestock and poultry health as well as profitability, the language of air quality is derived principally from environmental regulations designed to protect public health and the use and enjoyment of private property.

Odor Management

Odor emission is of great concern to the general public. An odor management plan is required in the permit application for livestock operations with more than 1,000 animal units. Producers need to understand odor emission from animal housing, manure storage and handling, and land application and available management options.

Controlling Emissions

Good stewardship calls upon livestock and poultry producers to limit emissions of air pollutants where feasible. Odor control practices and technologies may take several forms. Information on control strategies may focus upon the type of emissions controlled or the source of air emissions.

OFT Worksheet Version

Step-by-step instructions for using the worksheet version of the Odor Footprint Tool and an example completed worksheet are provided in the following documents.

Odor Footprint Tool

The Odor Footprint Tool (OFT) estimates the frequency of annoying odor events around an existing or proposed livestock facility and uses this information to determine minimum separation distances that should be maintained around those facilities and to help in siting decisions.

Air Quality

The University of Nebraska is addressing air quality issues associated with animal agriculture in several ways because good air quality is very important to Nebraskans.