Composting is a possible solution to the manure storage problems some producers are experiencing this year after a long winter and weather-related spreading dilemmas this spring, according to Chris Augustin, nutrient management specialist at North Dakota State University’s Carrington Research Extension Center.
Composting kills weed seeds, pathogens and reduces manure volume. Research indicates that composting reduces manure piles by half to two-thirds, produces a less-dense material, and reduces hauling costs as a result.
However, there is more to the composting process than piling manure up and letting it sit. “Composting is a speedy decomposition process,” Augustin says. “The bacteria and fungi responsible for composting are indigenous to the pile. It is our job to create a habitable environment for the decomposition organisms.”
Manure composting requires 20 to 40 parts of carbon for every part nitrogen. This is equal to about 80% cattle manure and 20% straw bedding. Manure is the nitrogen source and straw is the carbon source.
The compost pile also must have adequate air and water. Fifty percent of the pore space needs air and the remaining 50% needs to be filled with water. The pile should feel like a well-wrung-out rag. If water drips out of a handful of compost, it is too wet. If it doesn’t feel damp to the touch, then it is too dry, he explains.
After piling, the compost pile should heat to more than 130 degrees F in two or three days. If the pile does not heat, then one of the four elements (carbon, nitrogen, air, water) is not in the pile in the recommended amount. The temperature should remain above 130 degrees F for a couple of weeks and then decline. Once the temperature falls, the pile needs to be turned, Augustin says.
Producers can buy implements designed for turning compost, but turners can be expensive. One alternative is to use bucket tractors to turn piles. Also soil conservation districts in some areas may offer custom turning services.
Turning the pile introduces oxygen into the compost and will stimulate the microbes to continue heating. “The idea is to move materials from the outside of the pile to the inside of the pile and add air to the system,” Augustin says.
The duration of subsequent heating cycles will shorten with each turn. After three to five turns, the manure is composted. Augustin suggests letting the compost sit for a few weeks to allow it to cure. Applying compost that has not cured can cause phytotoxicity issues (poisonous to plants). Once the pile has assumed ambient temperatures, it is ready to be used as a fertilizer.
However, compost needs to be sampled for nutrients before it is applied on a field. About 15% of the total nitrogen, 30% of the total phosphorus and 30% of the total potassium in the compost should be available to the crop that’s planted. Learn more at www.ag.ndsu.edu/.