Manure Takeaways
Takeaways are key points detailed and referenced in the Manure & Other Outputs section
The Manure Problem
Factory farming has transformed manure from a high-value product to one that is regularly viewed as a waste product that must be disposed of.
This is mostly due to the massive amounts of manure generated by huge numbers of animals in small geographical areas.
Because of high manure transport costs, there is not enough cropland within economically profitable distances; the convenience and predictability of chemical fertilizers further lowers manure’s value.
Manure storage facilities (lagoons, pits, etc.) disperse manure nutrients (nitrogen and phosphorous) through both planned and catastrophic releases; ammonia volatilization and the eutrophication of waterways are pervasive and costly environmental problems.
Large amounts of nitrogen in factory farm manure are volatized into ammonia causing significant damages to air quality and to plant life and waterways due to deposition; perhaps about a third of the nitrogen in factory farm manure volatizes into ammonia within hours or days of excretion.
Runoff and volatilization from systematic manure over-application on crops add to the pollution.
Despite decades of research, regulations, and incentives, nutrient pollution from factory farm manure persists; the eutrophication of the nation’s waterways and ammonia pollution (including deadly PM2.5 pollution) are central costs of the factory farming system.
Manure Amounts / Nutrient Amounts
Animals raised for food generate approximately 1.2 billion tons (2.5 trillion pounds) of manure per year, about 6 times as much as total human waste.
Factory farmed animals generate approximately 740 million tons (1.5 trillion pounds) of manure per year, about 4 times as much as total human waste.
A typical pig factory farm generates about 900 tons of manure per week, about equal to the weekly human waste from a city of 80,000 people.
The amounts of nutrients in all farmed animal manure are approximately half of the totals in all chemical fertilizers; the amounts in factory farmed manure are about one-fourth to one-third the nutrients in chemical fertilizer.
The cropland that has manure applied is less than one-tenth the size of the cropland that receives chemical fertilizers; a large portion of that manure is applied in addition to full applications of chemical fertilizers.
Almost 80% of applied manure is spread on land that is controlled by factory farm producers. Generally, their purpose in owning or controlling the land and growing crops (usually corn) is to have a place to get rid of the manure.
Manure is often land-applied as a semi-legal method of dispersal into waterways via runoff.
After all the planned and unplanned runoff, leaching, and volatilization, a very small share of nitrogen in manure is applied to crops: we estimate that about 10% of manure nitrogen generated on factory farms is ultimately applied to crops.