Since humans first evolved from nomadic hunters to settled farmers tens of thousands of years ago, humanity has doubly benefitted from animal husbandry, not only in the meat and clothing they provide but also in using their manure on our crops.
Today’s animal farms have grown larger to cope with the growing demand for meat, but livestock populations are now creating too much waste to be used as fertilizer.
This excess waste can leak into water systems, creating health problems for humans and animals alike, as well as slowly suffocating lakes, rivers, and waterways. The US Environmental Protection Agency (EPA), which oversees water quality, has attempted to curb pollution through regulation but critics argue this is to limited effect. Last year, more than fifty environmental and citizen groups petitioned the EPA to improve its oversight of water pollution from industrial-scale concentrated animal feeding operations, arguing that stricter regulation of large farms is needed to meet the target set by the federal Clean Water Act.
Larger Farms, Larger ‘Outputs’
What used to be known as farms or ranches are now less romantically termed Concentrated Animal Feeding Operations (CAFOs), a regulatory term that describes the living conditions where the vast majority of livestock is kept. Over 90% of animals that are farmed for food will spend most of their lives inside the confined space of a CAFO.
These factory farms are grouped by size: Large CAFOs contain more than 1,000 heads of cattle or 10,000 sheep, while smaller ones may have less than 300 cows or less than 3,000 sheep.
Between 1992 and 2012, the average size of a herd of dairy cows in the US increased almost nine times, from 101 to 900.
“A lack of high-quality water can have a negative impact on our ecosystem as a whole, and negative effects on different species,” says assistant professor Lorrayne Miralha, a hydrologist and water quality expert at the Food, Agriculture, and Biological Engineering Department at Ohio State University.
The CAFO methods of dealing with waste are impacting water, she says. “These food systems tend to produce a lot of ‘output’—and by output, I mean manure.”
“If we think about how we handle our human waste in a city, we directly connect to our sewage systems and the waste management programs we have in place,” she says. “We do not have sewer systems implemented on an animal farm,” so “we have to do something with the waste that all of these facilities produce.”
According to figures released by the US Government Accountability Office in 2008, a dairy CAFO with 1,200 cows can produce 30,500 tons of manure annually. The EPA also has 2007 and 2017 estimates of animal manure nitrogen and phosphorous by each State.
For example, in Iowa there are more than 9,000 animal farms, and manure from animal feeding operations is either stored onsite in a surface lagoon or spread onto farmland. Both methods can lead to leaks into surface water during heavy rain or snowmelt or if the manure spread on top of the ground cannot be absorbed. Manure is heavy and expensive to transport, so farmers tend to dump it close to their facility.
“Iowa is one of the states where we have found associations with CAFOs and nitrogen ground water contamination, as it is just leaking down into the water.”
Prof. Miralha adds: “Iowa is one of the states where we have found associations with CAFOs and nitrogen ground water contamination, as it is just leaking down into the water.”
Nitrogen pollution from farming has decreased Iowa’s drinking water quality, according to a 2021 study by the Union of Concerned Scientists, with rural Iowan dwellers expected to pick up the majority of the bill to pay for the clean-up caused by their CAFO neighbors. While urban Iowans pay $2 per person annually for nitrate treatment of their drinking water, rural residents can pay up to $1,200 per person.
However, CAFOs are not solely to blame. The Practical Farmers of Iowa—a farmers’ investigation and information sharing organization—points out that changes in the landscape and fields not having crops all the year round has led to an increase in nitrogen seeping into the water supply. They suggest pasture growth, diversified rotations, and cover crops year-round to help reduce nitrates in the water supply.
Contrary to popular belief, it is not the larger operators causing the problems. In their report, “The spatial organization of CAFOs and its relationship to water quality in the United States,” Prof. Miralha and colleagues looked at the water quality surrounding both large and smaller farms. It found that the clustering of less regulated smaller CAFOs was associated with higher total phosphorous and total nitrogen concentrations.
Prof. Miralha wanted to investigate how CAFOs were organized and found that smaller enterprises tended to operate in close proximity to each other: “The problem with clustering is that the food system is all in one place. They are producing so much manure that they cannot handle it in the local community; because of that potential for large amounts of manure staying close to the area [where it was created], we have water quality issues.”
Focusing on the smaller farms, she adds: “As they tend to be lightly regulated, they tended to cause more waste. Small farms are taking advantage of their size to do whatever they want—and as the smaller farms tended to be clustered together, they were producing a lot of waste which led to the water quality problem.”
“Small farms are taking advantage of their size to do whatever they want—and as the smaller farms tended to be clustered together, they were producing a lot of waste which led to the water quality problem.”
Manure is rich in nitrogen and phosphorus, so when these nutrients combine, this leads to a huge impact in water. Excessive amounts of these nutrients in water can cause algae blooms that lead to high levels of toxins, killing fish as the green algae consumes all of the oxygen in the water, creating serious health problems.
Furthermore, Prof. Miralha raises concern of CAFOs’ environmental impacts from natural disasters: “If we have more flood events happening in these areas, as is happening in North Carolina where there are thousands and thousands of swine and cattle farms, this becomes a global risk because once it floods in the manure field, it is very likely manure will end up in the water we are drinking.”
She adds while consumers can avoid meat reared on a CAFO by going organic, not everyone can take this approach. “There is a huge demand for people who want to eat meat but struggle to afford it. These animal farms can produce meat in [a] significantly affordable way.”
Prof. Miralha, whose parents are farmers in her home country of Brazil, is not trying to stop these farms from operating, but she does think they should be more highly regulated.
“My role is to create solutions so that we can operate in a smart way, in a sustainable way where we can grow food without destroying our ecosystems by discharging manure into the water.”
Although CAFOs in the US must obtain a permit from the National Pollutant Discharge Elimination System before discharge is allowed, cases of sewage runoff can occur, such as one reported by the Volunteers for Environmentally Concerned Citizens of South Central Michigan in June this year.
“Manure is not waste; it is a very valuable product that can help us grow other types of food. Can we turn these outputs into a good form of waste and create a circular sustainable food system? Can we create something to use all of the manure nutrients and to put manure on the crops we are likely to eat?”
One example of such outputs being put to good use is in the biogas sector.
In Milford, Utah, methane captured from pig manure from twenty-six farms is being converted into energy for homes, businesses, and transportation, reducing annual emissions by 100,000 metric tons. This clean energy releases less greenhouse gas than the original methane while providing enough energy to heat 3,000 homes and businesses when at full capacity.
Innovative ideas such as this are just the modern approach to what farmers have been doing with animal waste for thousands of years.
*Gordon Cairns is a freelance journalist and teacher of English and Forest Schools based in Scotland.