Page 59 - Nutrient Management Planning Guide

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Chapter 2.3

High NO

3

- levels in drinking water can also affect livestock productivity.

s i d e b a r

N losses via agricultural runoff are generally minor in comparison to P losses.

s i d e b a r

water tables. It can also happen when contaminated runoff enters groundwater through an improperly installed or poorly maintained well.

The Walkerton Tragedy

In 2000, seven people died and over 2300 became ill in the rural community of Walkerton, Ontario when the town’s water supply was contaminated with E. coli and Campylobacter. These potent pathogens are often implicated in food and water-borne illness.

The contamination source was runoff from a recently manured field, which entered the water system through an improperly protected well. While the producer was not responsible for the tragedy, it underscores the importance of doing a thorough site assessment prior to manure application.

Source: Ontario Ministry of the Attorney General

Surface Water »

Agricultural runoff contaminated with nutrients and pathogens is the primary risk to surface water quality. Eutrophication is the enrichment of surface water bodies by nutrients, particularly N and P. Phosphorus is often the first limiting nutrient in surface water ecosystems. Excess P entering surface water from runoff or P contaminated groundwater can result in increased algae production. Large algae blooms can significantly deplete oxygen levels when they die and decompose. Oxygen depletion will negatively affect aquatic animals. Blooms of blue-green algae (cyanobacteria) can also release toxins that are harmful to aquatic life, livestock and wildlife if they ingest the water. Eutrophication is a natural occurrence that is accelerated by human activities.

Transmission of manure pathogens to surface water is more likely than groundwater contamination. Surface water contamination by manure pathogens can occur on fine textured soils prone to erosion, or in situations where manure is applied or deposited too close to surface water bodies. For example, livestock that have direct access to water bodies can pose a significant risk to surface water quality.

Risks to Air Quality

Manure and fertilizer application can also adversely affect air quality. For example, ammonium (NH

4

+ ) in manure or fertilizer converted to ammonia (NH

3

) gas can be lost to the atmosphere. This is a particular concern with unincorporated surface applications of manure or urea (46-0-0). Ammonia losses are reduced with subsurface applications and when surface applied products are thoroughly incorporated.

Odour emissions are a risk when surface applied products are not incorporated.