Pig pee adds to the stench of the waste lagoons used to collect the runoff from some types of hog farms and can contaminate water sources if the stinking slurry escapes the lagoon. Even if the rancid reservoir doesn't burst, the ammonia in the pig urine evaporates into the air. When the ammonia precipitates out of the atmosphere it can contaminate soil and water hundreds of miles away with an excess of nitrogen.

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A new technique developed by the U.S. Department of Agriculture (USDA) extracts the ammonia from hog urine. In a series of experiments, the USDA's Agricultural Research Service decreased the amount of ammonia in liquid pig waste by approximately 95 percent, according to a press release.

The extracted ammonia can then be used as nitrogen rich fertilizer.

My observation: one possible application of this technology would be to combine ammonia extraction with a system to produce methane from pig feces, a Mad Max-esque technique Discovery News reported on last year.

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The noxious waste stream from hog farms could thereby become a revenue stream

for farmers, provide renewable energy and produce large quantities of

organic fertilizer without the need for industrial chemical plants.

Currently, a fossil fuel intensive technique known as the Haber–Bosch process is used to produce much of the world's nitrogen fertilizer by combining natural gas (methane) with nitrogen from the atmosphere at high pressure. Some are concerned that as energy prices rise the cost of producing nitrogen fertilizer also will continue to rise. Expensive fertilizer means expensive food. It also hobbles the economies of small and subsistence farms.

Synthetic nitrogen fertilizers have allowed agricultural production to skyrocket and with it the human population. If the industrial production of fertilizer were to falter, global starvation could be a consequence. Perhaps pig pee can provide a safety net or even eventually supplant the Haber–Bosch process and thereby reduce demand for natural gas.