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Manure Management

Manure management is a nice way of talking about one of the dirty jobs of raising livestock–getting rid of animal waste. What do farmers do with it? The most common practice is to use water to wash the raw waste out of barns into earthen lagoons. A lagoon is a big pit in the earth, sometimes lined with clay or a plastic liner. When a lagoon is full, the mixture is pumped out and sprayed onto fields as fertilizer.

But the earthen lagoons aren’t perfect. Lagoon leaks and ruptures in the lining can allow waste to slowly seep into underground water sources. Large spills and lagoon overflows can dump thousands of gallons of waste directly into surface waterways, resulting in huge fish kills and environmental damage. The largest spill in Iowa happened on July 16, 1995, on a Hamilton County Farm. One and a half million gallons of hog manure flowed from an earthen lagoon, through an underground tile line, into the South Fork of the Iowa River. That spill killed nearly 9,000 fish and countless other aquatic life.

(http://www.earthweshare.org/n/fishcharts.htm ).

What are the options? One option is to require the construction of cement structures for manure storage. These structures are less likely to leak or rupture and are considered to be safer for the environment.


When manure is applied to the land in proper amounts, the nutrients it contains (nitrogen and phosphorous) help crops grow. The land can only absorb so much manure and nutrients. So if too much manure is applied, some of it runs off the land and into waterways. When manure gets into water, it can cause a variety of problems:

  • The nutrients spur aquatic plant growth, like algae blooms, which in turn can trigger a condition called hypoxia–a lack of oxygen. The cycle of algae blooming and decaying sucks up oxygen in the water, leaving levels of oxygen too low to support aquatic life.
  • High levels of nitrates in drinking water can cause a serious, even life-threatening condition in children under six months. The condition, called blue-baby syndrome, prevents babies’ blood from carrying the necessary oxygen.
  • Manure can contain disease-causing bacteria that threaten human health. The most common is E. coli, which is routinely tested for in drinking water.

These Best Management Practices act as guidelines for manure application.

  1. Test the soil to see what the current nutrient levels are.
  2. Test the manure to see what nutrient levels it contains.
  3. Use only as much manure as the crop needs and the soil can hold. (That will avoid soil contamination, crop damage, runoff and contaminated tile flow.)
  4. Check soil moisture before applying liquid wastes, and adjust application rates to avoid runoff. Frozen ground can't absorb liquid and wet ground can't absorb more liquid.
  5. To avoid runoff, do not apply manure to frozen or saturated soils.
  6. Use raw or untreated manure to reduce odors and nitrogen losses.



Explore More: Water Quality
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