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Dishing the dirt on factory farming

News Section Icon Published 22/11/2012


We’re dishing the dirt on factory farming this week, looking at how it leads to pollution problems across the planet.

It’s not surprising that factory farming can be such a toxic industry. Cram hundreds or thousands of animals together, stuff them full of feed and you’re going to get a lot of concentrated waste.

Wasting the planet

A single dairy cow can produce 55kg of wet manure a day – it would take 20-40 people to produce the same amount1. Web reports suggest that one pig can excrete about 600 litres of slurry a year2. And animal waste is far more damaging than you might think. Why? Something called "biochemical oxygen demand", or BOD for short. BOD is the amount of oxygen used by micro-organisms to break down organic material. As shown in the diagram below3, farm-animal waste has a relatively huge BOD when compared to human waste. This means that when water courses are polluted with animal waste, oxygen levels can plunge.


Nutrients – friend and foe

It’s not just animal waste that causes problems – a similar impact can arise from the fertilisers used to grow many of the crops fed to factory-farmed animals. Often overused, these nutrient-rich substances can find their way into water courses, hyper-fertilising habitats and encouraging the overgrowth of algae4.

Putting the problem into context

All of this is bad news for water courses: loss of aquatic life, vanishing recreation waters and loss of drinking water are all impacts that arise from manure and nutrient pollution. Here are just two examples:

Chesapeake Bay, United States

In 2007, farm animals in the US excreted many hundreds of millions of tons of nitrogen- and phosphorous-rich waste9. Furthermore, according to The Fertiliser Institute, over 50 million tons of fertiliser was spread over American soils in 200810.

A classic example of the problems arising from this is Chesapeake Bay, Maryland. With ten rivers emptying into it, Chesapeake Bay is the largest estuary in the US. A mass of industrial agriculture around these rivers brings high concentrations of nutrients into the bay and out into the Atlantic. The resulting algal blooms lead to vast oxygen-depleted "dead zones" in which few animals and plants can survive. Despite attempts to minimise agricultural discharge, it is reported that Chesapeake Bay’s dead zone stretched over a record-breaking 130km last year11.

Such is the area’s negative reputation that film director Barry Levinson is soon to release Hollywood horror The Bay, with toxic waters creating chaos for Chesapeake Bay residents12.

West Lower Saxony – Germany

West Lower Saxony is a centre of industrial pig and poultry production. In 2009, the area produced almost 35% of pig meat, 45% of poultry meat and 34% of the eggs in Germany5.

This industry brought affluence to some farmers, but harmed many others. So much manure is applied to the fields that the state’s agriculture minister is claimed to have said that it cannot be reasonably disposed of6.

Despite this, it’s claimed that Dutch farmers also export manure to Lower Saxony, avoiding the stronger regulations in the Netherlands7.

And the result? Some residents are now unable to use their wells and authorities are finding it increasingly hard to supply people with drinking water8.

Looking for solutions

The solution to this problem can be found in humane-sustainable farming. All farm animals produce manure, of course, whether they’re on the farm or crammed into sheds. But the deintensification of animal agriculture can encourage more grazing (grass doesn’t need as much fertiliser as cereals), reduce the concentration of manure and ensure that the manure can be directly absorbed by the land in a more controlled way. All of this reduces the risk of large-scale pollution events.

P.S. It’s not just nutrients that we need to worry about. Bacteria and antibiotics and other drugs given to factory-farmed animals can also end up in the natural environment. More on this in our next post...

Our sources

  1. Animal Feeding Operations (2011), What’s the Problem?
  2. NDR (2012), The Trace of the Pigs (translated from German)
  3. Reading University (2012), Biological Oxygen Demand (BOD)
  4. EPA (2012), Nutrient Management and Fertilizer
  5. Lower Saxony Agricultural Ministry (2012), Animal Production in Lower Saxony (translated from German)
  6. TAZ (2012), Lower Saxony's Water is Full of Shit (translated from German)
  7. NDR (2012), Greens say: Slurry Contamination "Threatening" (translated from German)
  8. NDR (2012), The Trace of the Pigs (translated from German)
  9. EPA (2012) Estimated Animal Agriculture Nitrogen and Phosphorus from Manure
  10. The Fertilizer Institute (2012), Statistics FAQs
  11. Washington Post (2011), Alarming ‘dead zone’ grows in the Chesapeake
  12. The Bay Movie (2012)

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