As fertilizer costs move higher, livestock producers may be sitting on an opportunity. If you feed cattle, it’s definitely in abundance…yes, it’s manure.
Applying manure to fields as soon as possible after pens are cleaned is one option. Another is to stockpile the manure—an easy and, in some places, the most economical option. Then it can be used as needed for your own crops or to share with neighbors. The downside is that manure can be heavy and costly to haul. That’s why most people limit movement to areas nearby.
For others, however, composting manure offers an opportunity. Compost can be bagged and sold to retail outlets or nonagriculture businesses that need fertilizer. Composting improves the handling of manure since it can reduce the volume and weight. In addition, composting can kill pathogens and weed seeds.
Composted manure is basically aerated manure that becomes a stabilized, humus-like product. Composting is the aerobic decomposition of organic materials in the thermophilic temperature range (104° to 149°F).
Some benefits of composted manure, as opposed to stockpiled manure, are reduced odor, reduced weed seeds and reduced bulk for lower transport costs, says Charles Wortmann, a soil specialist at the University of Nebraska–Lincoln. In addition, since compost has a finer texture and less water than the raw material, it can be applied more uniformly and with better control.
There are a number of ways to compost, but for cattle producers, the most common is windrow composting. This involves creating 3'- to 6'-high windrows that are turned on a regular basis with either a front end loader or a special machine called a windrow turner.
Illinois farmer Dale Pfundstein started composting mainly because he had no place to go with the manure from his 900-head monoslope feedlot. "In the summer, there was nowhere to put the manure, so that was the main reason we started composting," he says.
He still applies some regular manure to his corn fields but he spreads the composted product on some of his hay fields to improve yields. He sells the rest as organic fertilizer. He’s found that stockpiled manure where he lives in Illinois can get too hot and destroy some of the nutrient content, especially in the summer.
The process. Due to the seasons and state regulations, Pfundstein composts from April to Thanksgiving. The process takes about 12 weeks. It requires a mixture of different ingredients to get the right texture and nutrient values.
Because composting can lower the nitrogen content, Pfundstein uses a certain type of clay in his mixing process to help hold nitrogen. He also includes other inputs. One key ingredient is water. During the summer, nearly 4,000 gal. of water are applied per day.
"Composting is like baking a cake, making sure the mixture of ingredients and temperature are right," Pfundstein says. "It may not turn out like you expected."
Nutrient values. Composting is also dependent on the manure type. Wortmann says that in the western Corn Belt and on the High Plains, where beef feedlots are often open, soil-surface lots, the feedlot manure itself often contains up to 70% soil. That makes the manure and the compost less valuable from a nutrient standpoint compared to manure collected from a concrete surface. Another concern is nitrogen loss and nitrogen availability to the crop.
"Research at the University of Nebraska shows substantial loss of nitrogen due to ammonia volatilization during composting compared with stockpiling feedlot manure. We are also concerned that the release of organic nitrogen to crops is slower with compost than with raw manure, giving relatively little nitrogen availability to the first crop," Wortmann says.
- Mid-February 2011