Why are there regulations on manure use for food safety?

Wisconsin State Farmer
A handful of composted manure contains carbon, nitrogen, and phosphorus. All of these are important for plant growth.

Regulation on manure and food safety is helping growers and consumers alike, a blog from Soil Science Society of America explains.

Manure, quite plainly, is animal refuse. It’s not the same as human refuse, because cows, horses, sheep, etc. eat a plant-based diet. This means their wastes are made mostly of digested grains and forage grasses. 

“Manure contains a lot of nutrients that can benefit the soils and the farmers’ crops,” says Jodie Reisner, a conservation agronomist with the U.S. Department of Agriculture (USDA) Natural Resource Conservation Service (NRCS).

Manure contains nitrogen, phosphorus, carbon, and other nutrients that plants need to grow. Studies have shown that adding manure to fields increases the soil organic matter. This is important because the more organic matter a soil contains, the more moisture and nutrients it can hold–and release–for crops.

Growers use manure because it benefits soil health in the following ways:

  • Manure benefits the living part of the soil called soil biology. It is a source of energy for soil life to grow, reproduce, and feed.
  • Manure helps the soil absorb rainfall for the crops.
  • Manure also provides nutrition to the plants as they grow.

On the down side, manure contains microbes. Microbes live inside the gut of animals just like humans. They help animals–and humans–digest our food. When applied to the soil in manure, the microbes can add much to the biodiversity of the soil. However, there is the potential that manure can contain microbes that can cause disease. 

E.coli and Salmonella are examples of these organisms inside cattle and chickens. The main problem occurs when manure comes in contact with food. It could be a source of trouble for food consumers if swallowed.

Foods that are especially vulnerable to contact with manure are leafy vegetables and root vegetables. The FDA has created standards to protect our food supply from dangerous microbes.

The manure is a relatively cheap nutrient source, especially if growers have their own animals. Some farmers lack the equipment to compost properly and end up using raw manure. That can be dangerous; the FDA regulations (see above) require a 120 day waiting period. Researchers are studying the best methods of composting manure. This is important because one cow can generate 43-120 pounds of manure a day.

“Regulations on manure use for food safety provides consistent information to farmers who want to use manure, and safety to the consumer,” Reisner says.

Farmers can also receive training on the regulations and details about protecting and preparing the food they sell. Farmers who produce our food in this country desire healthy soils because it is the foundation of growing abundant food for people.