“They’re eating the carbon, they’re eating the nitrogen, they’re producing water and temperature”
Composting manure is nothing new for producers, but it needs to be done properly to make it work, says Jennifer Neden, nutrient management specialist with Alberta Agriculture in Airdrie.
Composting is different from simply stockpiling manure, Neden told the Smoky Lake Grazing School for Women last month. Composting is a controlled process which breaks down manure into a stable material. The process requires oxygen, moisture, carbon, nitrogen and microbes. Above all, temperature plays a major role.
Compost ing speeds the decomposition of manure as it provides an ideal environment for microbes. The result is a dark, crumbly earthy-smelling product which feels and looks a lot like dirt.
Carbon materials required in composting are often referred to as “drys” or “browns,” while the nitrogen components are often referred to as “wets” or “greens.” The carbons may include components such as straw, sawdust and shavings, while the nitrogen components consist of manure or wet grass clippings.
Microbes such as fungi and bacteria are an essential part of the composting process as they break the manure down into a stable material. The microbes create a lot of heat and water during the process.
Stockpiled manure does not contain as much oxygen, will often be covered with flies, have significant odour, and will leach liquids and waters onto the ground.
“Part of the composting of manure is the turning of the pile. The reason why you’re doing that is because you’re introducing oxygen to the process, which is one of the key parts of composting,” Neden said.
HOT BUT NOT TOO HOT
“In a compost pile, the temperature goes up rapidly because the microbes are active. They’re eating the carbon, they’re eating the nitrogen, they’re producing water and temperature,” said Neden.
The microbes will generally raise the temperature of the compost pile to about 60 C. When the temperature rises to about 70 C, the microbes will start to get too hot and will die off, and the overall temperature will decrease, which means turning is needed.
When composting you can use a long thermometer to take the temperature of the manure pile, or can just guess by feeling or looking. The ideal goal is to turn the pile so the inside material is moved to the outside and the outside material to the inside every couple of weeks. Neden said most people use a front-end loader or bobcat to turn compost piles.
Moisture is essential to the process so when composting you may have to add a bit of water to the pile to speed things up. Eventually the overall temperature of the pile decreases as the microbes have less to work with and the pile becomes a stable product.
Besides reducing mass and volume of manure, making it easier and cheaper to transport, composting kills intestinal parasites, eggs and larvae and may destroy weed seeds. The process may also reduce fly numbers by eradicating their breeding grounds.