Bozeman, Montana – With energy prices driving up the cost of agricultural inputs, nutrient-rich manure is getting another look.
"Calls to Extension offices from people looking for manure and manure compost have increased in recent months," says Tommy Bass, Montana State University Extension livestock environment associate specialist.
Bass said that this shift in perception is good for water quality, too.
"As manure gains value, it is likely to be used more efficiently and effectively. There's a potential for increased revenue for animal feeding operations," he says.
Though MSU Extension and conservation professionals have taught for years that manure can be a valuable asset, it's often written it off as a difficult-to-manage byproduct with cumbersome regulations. Now, with fertilizer prices hovering at $1,000 per ton, the nitrogen and other nutrients in manure look more gold than brown.
Bass says that a ton of manure contains between $30 to $40 worth of nutrients for the soil, though they're not all available the first year.
"Expect a quarter to a half of the nitrogen to be available in the first season," he says. "The remainder is partially available the next year and partially lost to the atmosphere."
Fresh scraped and stacked dairy and beef manure can have a total content ranging between 12 and 25 pounds of nitrogen per ton of manure, while the same ton may also have 9 to 18 pounds of phosphorus fertilizer equivalent.
"The nutrient content of manure varies for different species and different manure management systems, but it is all valuable," he says.
Nitrogen and phosphorus are not the only valuable nutrients in manure. Potassium and a variety of micro-nutrients are also present. In addition to specific nutrients, the high organic content of manure and manure compost increases soil quality, and its improved texture helps with its water- and nutrient-holding capacity.
About 70 percent to 90 percent of phosphorus and potassium can be available the first year. Phosphorus not used by the plant persists longer in the soil and will remain available if erosion and run-off are controlled.
When applying manure based on the nitrogen needs of a crop, phosphorus will inherently be over applied or exceed the crop's annual use of phosphorus, however it can be taken up by crops in subsequent years. Fields with significant residual soil test phosphorus may need a rest from manure applications. In that case, only a commercial nitrogen product needs to be applied to meet nutrient requirements and production goals.
Considering possible variation associated in nutrient availability from manure, careful consideration should be given to how it is incorporated into an overall fertility plan.
"Attempting to replace all the nitrogen required by a high-value wheat crop with manure sources carries a risk of lost production, if all the projected nutrients do not become available to the plant," Bass says. However, he recommends using manure strategically as a nutrient source in conjunction with commercial fertilizer.
The cost of applying manure also needs to be considered, he says, along with other costs such as renting or hiring of spreading equipment, fuel and an operator's time. Using manure wisely can offset some commercial fertilizer purchases, while providing additional micronutrients and valuable organic matter to the soil.
As with any fertilizer, application rates should be based on a recent soil test and the particular crop's nutrient needs. An overall nutrient management plan is needed to meet production goals and protect natural resources. For some animal feeding operations, such a plan is required as part of their permit.
With recognition of the increased fertilizer value of manure, it is being sold or traded for different services or goods around the country. Historically, manure was only used or shipped within a few miles of its source. In some cases, it is now economically feasible to ship it over increased distances. Manure hauling and brokerage businesses have popped up in which the company will clean out manure storage facilities in exchange for the product; they in turn sell it to another party. Other producers sell and trade with neighbors or build partnerships with commercial nurseries and compost manufacturers. Animal-feeding operations with their own forage or crop production can benefit greatly from onsite manure resources.
Manure is also being used to create energy through digesters that produce bio-gas capable of generating electricity or heat for farm and ranch buildings. Whether it is used for fertilizer, as an ingredient in compost or for energy production, the value of manure is being recognized for a variety of beneficial uses.
"To people making a living off the land, manure smells like money," Bass says.
For more information on manure management, see: "Using Manure as Fertilizer: Tips for purchasers or recipients of manure from animal feeding operations," on the MSU Web site .