Public Concerns about Nitrogen Losses to the Environment

Until recently, regulations have focused on controlling N losses to ground water and coastal surface waters. Nitrates in groundwater used for drinking water is a concern because of methemoglobinemia (blue baby syndrome) in infants less than 6 months old. The US EPA has set drinking water standards for nitrate at 10 mg/l nitrate-N. Excess N in coastal surface waters can lead to algae blooms and thereby reduce oxygen levels in marine ecosystems.

In addition to water quality concerns, ammonia losses to the atmosphere are now being raised with the proposed shift in the regulated size of particulate matter size (proposed reduction from 10 to 2.5 microns). The air emissions from animal feeding operations and methods for measuring them have been described in detail (National Research Council, 2003).

The Northeast, particularly Central and Western NY, has areas with the highest concentrations of inorganic N wet deposition from nitrate and ammonium in the United States (National Atmospheric Deposition Program, 2001). Current estimates suggest atmospheric N deposition can contribute 10-40% of new N enrichment of coastal and estuarine waters (Paerl, 1997).

Ammonia is often a preferred N form for biological activity in water and its increasing availability can cause fundamental changes in aquatic algae communities. Additionally, ammonia contributes to the formation of fine particulate matter (ammonium nitrate and ammonium sulfate) in the atmosphere and can affect human health including premature mortality, chronic bronchitis, and asthma attacks (McCubbin et al., 2002).

The dominate source of US ammonia emissions is agriculture with about 70% stemming from livestock operations and the majority of the remainder resulting from post-nitrogen fertilization losses and motor vehicle emissions (McCubbin et al., 2002). Nitrous oxide, a potent greenhouse gas, is of concern as well. Its agricultural source is as variable proportions of animal N excretion and N fertilizer applied to crop land (Johnson et al., 2002).

Therefore, we can expect to see increased emphasis in nutrient management planning on reducing N losses to the atmosphere from livestock operations. Hutson et al. (1998) found that large amounts of N were volatilized on a dairy farm, and occurred at many points between excretion and land application.