Managing That Pile

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With urban development en­croaching on many farms, environmental concerns rising and budgets shrinking, disposing of horse manure is becoming a problem for many operations. What are the options and associated costs?

STOCKPILING

The average, 1,000-pound horse produces over eight tons of manure per year. Add in some bedding material and wasted hay, multiply by thirty or more horses, and you have a big mess to clean up. Because it is the least expensive solution, many facilities stockpile their manure. A huge pile of waste that not only smells bad, but may leach into nearby streams as well as attract flies and irritate neighbors. Are there ways to combat these problems?

“First,” says Natalie Rector, Michigan State University Extension Nutrient Management Field Specialist, “pick a location for the manure that has the lowest risk of anything ever reaching surface water. That means you should not be putting it on an area that slopes toward a creek, stream or wetland. You can impose an earthen berm for added protection; use straw, earth or large concrete blocks that stack up.” How far from wetlands should the pile be? That depends on the land, says Rector: “If there’s a gravel driveway, then the runoff will scoot right across it and go into the wetlands. If there’s a grass pasture, some of it will be absorbed but if the pasture has gone to dirt, then the nutrients can travel. In general, 100 feet is a good distance, but check with your state extension or regulatory agency as rules vary from state to state.”

The biggest problem with stockpiling is that over time, while the nitrogen is either utilized in the breakdown of the carbon mass (bedding, hay) or volatilized into the air, the phosphorous level builds up. The solution, says Rector, is to consider the manure a nutrient resource instead of waste and, if you have the land and equipment, to spread it on your pastures twice a year.

Do you have enough land? Acreage requirements are determined by the amount of phosphorous in the manure. A 1,000-pound horse generates 0.11 pounds of phosphorous per day, multiplied by 360 days. That’s roughly 40 pounds of phosphorous per horse per year. It takes approximately one acre of cropland to utilize this level of phosphorous. So, if you have 50 horses, you will need 50 acres.*

HAULING

In urban settings, hauling may be the only viable solution. Costs vary widely depending on region, from $35 for a small spreader load to $150 per pick-up for a 10-yard dumpster (plus rental fee). Prices continue to climb as the frequency and size of load increase. Note that many haulers will charge less for manure than for a dumpster that is mixed with other trash, so ask about discounts.

COMPOSTING

Composting, explains Dr. Thomas Halbach of the Department of Soil, Water, and Climate at the University of Minnesota, St. Paul, Minn., is “the process of managing the environmental conditions to increase the speed of biological breakdown of carbon. We do that by adjusting the particle size, moisture content, free air space and managing the carbon and nitrogen ratio within the material. If you do a good job of management, it will take six months or less to break down the manure. Otherwise it can take years.” Unfortunately, notes Dr. Halbach, there is a tradeoff because a good management job takes time, money and resources.

A popular composting technique is the inverted windrow system [see the April 2006 Stable Management profile on Crazy Horse Stables]. Two common problems with windrow composting, says Dr. Halbach, are that rows are not high enough and people get carried away with the amount of pile turning. “You want the rows to be at least three feet high, but preferably 5.5 feet high. The vertical height controls the mass, which in turn controls the insulation, and this is a major factor in what the temperature is inside the pile. The temperature needs to be between 131 and 150 degrees Fahrenheit for at least 14 days. Those temperatures will kill pathogens and most weed seeds. Also, if you turn the pile too much, it can’t heat up.”

Turning cylinders are relatively simple to use. Old and new material is mixed fairly easily, and labor costs are substantially less than with windrow composting. The drawback is that they are rather expensive and require frequent maintenance (bearings and the main shaft often need to be repaired). Additionally, problems can arise when the cylinder is too small for the amount of waste it must handle. For composting to work, the initial compost pile within the cylinder must be 65 to 70 percent free air space so that gases can be exchanged—oxygen needs to get into the pile and water vapor and carbon dioxide needs to come out. If the material is packed too tightly within the cylinder, you lose air space and the efficiency of the system suffers.

Another option is aerated composting. A company called o2 Compost (www.o2compost.com) offers systems of all sizes. The composting can be done in bays, or the aeration can simply be done under an outdoor pile. As with other composting methods, turning the pile and keeping it moist are important variables to successful production, as is maintaining the proper temperature (between 130°F and 150°F).

An inexpensive alternative is static bins. “You can use bins that are the right size for your front loader,” explains Dr. Halbach, “but in order for it to be composted, you still have to manage the piles. You need to come in, pick it up, turn it and move it into the next pile. You have to get gas and air exchanged, monitor the moisture and have the right carbon and nitrogen ratio.” Finally, cautions Dr. Halbach, “Don’t assume that urine adds sufficient water because frequently it isn’t enough. It must have a 55 to 60 percent moisture content because the microorganisms that break down the carbon prefer that range. In the winter, people think that they don’t have to add water because it will freeze, but the winter air is very dry. Although the top six to 12 inches may freeze, the inside of the pile may have temperatures of 140 to 150 degrees. If you don’t add water, composting will slow down and you’ll have to restart the microorganisms.”

BUDGET CONSCIOUS SOLUTIONS

Tami Johnson of Windenhill Morgan Farm in Marthasville, Mo., was paying $80 a month to have her manure hauled away. It wasn’t an enormous amount of money, but still, for her small operation, any savings was a welcome relief. Attending a machinery auction last year, she spotted a small, used, six-bushel manure spreader. At a cost of just $375, it paid for itself in less than six months. Now she spreads the manure on her pastures.

Many people interviewed for this article reported finding inexpensive or free disposal alternatives to hauling. Originally, Holly Butterman of Snowview Farm in Reno, Nev., hauled her manure to the local landfill. But when the landfill began charging a dumping fee for manure, she needed to look for a more economical solution. Butterman eventually found a local business making and selling topsoil that was eager to take the manure at no cost. Similar situations exist around the country. Look for landscapers, golf courses or other business where fill is needed.

If you’re willing to deal with strangers coming on your property, another option is to offer free manure to local gardeners. Word-of-mouth, free newspaper ads as well as an Internet chat group called ‘Yahoo Freecycle’ are places that attract people looking for free manure. This may not remove all your manure, but it can certainly help.

Manure disposal is not a popular topic, but it is one that must be addressed. With proper management, you can help the environment, enrich your pastures, and keep your neighbors happy.