Happy Pi Day to all the scientists out there! If you haven’t heard, March 14th is a celebration of the ratio of a circle’s circumference to its diameter. And here at the Cow Docs, we’d like to take this opportunity to talk about another type of pi that we see a lot of at the clinic.
Like all animals, cattle produce feces. Lots of feces. While some might find this as a gross waste product, actually with proper management it is an added benefit from raising cattle in a confinement setting. As any farmer or gardener knows, manure is quite valuable as a fertilizer because of its nitrogen content. Farmers capture the manure their cattle produce and apply it to their fields.
Although manure is great on fields for growing crops, it is also known that manure not properly captured can be a pollutant in both surface and groundwater. That is why farmers that have confined livestock take precautions to keep this from happening. First, even though most feedyards have dirt lots, these lots do not allow manure to leach through the soil into the groundwater. This is because the weight and hoof action of the cattle creates an impenetrable barrier in the soil.
The concern instead comes from rainwater carrying the manure away. Confined cattle farms slope their pens so that the runoff water all goes a certain direction. This runoff water is then held in collection ponds, where it can then be applied to fields at the proper rates.
Once in the pond, nitrogen in the manure is degraded to ammonia because the runoff lacks oxygen. Ammonia cannot move deep through the soil, so it stays above the level of the groundwater. Once the manure is removed from the pond, it is exposed to oxygen again and can be converted back by microbes, which makes it usable for fertilizer. This is why it has to be spread across a field at the correct rate–a rate that is just enough for the plants to use, but not so much it leaches through to the groundwater.
Protecting our water resources is extremely important to those of us in agriculture. Since many of us drink untreated well water and eat fish from the surface waters on our land, we are the most likely people to suffer the effects of poor manure management. This, coupled with the economic value of manure for fertilizer, makes taking care of our “cow pi’s” a top priority for folks on the farm.
Photo credit: http://manure.ucdavis.edu/Illustrations/Dairy_Lagoons/