What do beef feedlots look like?
Until the 1940's, U.S. beef cattle production from birth to slaughter was largely grass-based. Feedlots became more common as grain production became mechanized and sales terminals (where finished beef cattle were sold) were decentralized. At first, it was typical to see individual farms raise grain and finish a few cattle but over time, feedlots have become much larger and more specialized. Today, there are feedlots with 100,000 cattle. In addition, there continues to be a large number of farmer/feeders finishing a few hundred to a few thousand beef cattle at any one time. Nearly 75% of cattle are housed at operations with more than 2,500 head of cattle (10,229,373 out of 14,386,188 animals according to the 2012 Census of Agriculture). Recommended: Common cattle terms and definitions.
Most beef cattle feeding operations house animals outdoors on earthen lots as shown in Photos 1-4 below. These are called feedlots. A feedlot is subdivided into a number of fenced pens, each with feed bunks, water, and loafing areas. Gates allow cattle to be moved for weighing, vaccinations, or to allow workers to conduct maintenance. Some feedlot may have pens with an area under a roof for shade or to protect the feed bunks from poor weather.
Mud can be a significant challenge in wetter areas of typical cattle feeding regions. There is a raised or built-up area in the pen known as a mound. A mound is a small hill created by piling soil and shaping it to shed water. Rain and snowmelt drain more rapidly from the mound giving the cattle an area to lay down in wet weather.
Beef feedlots are distinct from range or pasture-based operations where animals are outside in areas that maintain vegetation during the growing season. Pasture or range operations do not generally bring feed to the cattle, except in winter, or need to collect and store manure.
Photo 5 below shows a bedded pack beef barn. These are becoming more common in the upper Midwest. In bedded pack barns, cattle are kept entirely under a roof and bedding is added to the building as often as needed to maintain animal comfort.
Other features on a large cattle feedlot will include a feed mill where corn and grain are processed before feeding to cattle. Feed storage areas for hay, silage, or other bulk feeds are also part of the feedlot. Capturing stormwater that may run off from feed storage, especially silage areas, is required of feedlots in some instances. Ensiled feeds, such as corn silage or haylage can be harvested at moisture levels that lead to some liquid discharge. This liquid has a very high oxygen demand and is a strong pollutant if it reaches water. Typically ensiled feeds are managed to avoid this because leachate represents lost feed nutrients. Photos 1 and 2 below show feed mill and storage facilities.
The feeding program, although not part of a regulated nutrient management plan, is a critical component of nutrient planning. Feed commonly represents the single largest source of nitrogen and phosphorus brought onto the farm. As some beef finishing operations have specialized and moved away from growing their own feeds, the importing of feed nutrients means farms are relying on manure export beyond crop fields owned or managed by the farm.
What does it look like inside?
Most beef feedlots are open and have no "inside". Some lots are partially covered. In these lots, the roof is usually over the feed bunk and on the north side of the pen. This area will have a wide aisle to allow equipment to deliver feed.
There are beef operations where the entire lot is covered by a roof (or mostly covered with some outdoor area). Most of these have solid floors with bedding added at regular intervals (see Photo 1 below). The manure pack is allowed to build up, even by several feet with regular, new bedding additions keeping animals dry and comfortable (hence the name "bedded-pack barns"). The material removed from these barns is handled as a solid manure. A variation of barns for beef cattle is one where the cattle are housed on a slatted cement floor and the manure falls into a pit below (see Photo 2 below). This manure is handled as a slurry.
What about the manure?
A feedlot steer can produce approximately 65 lbs of manure per day with over 90% of that being water. Since most feedlots use open earthen pens, much of that water evaporates as the manure dries on the pen surface. A rule of thumb is that the feedlot will collect a little less than a ton of manure per steer each year.
Manure from open lots is handled in solid (excreted solids, nutrients, and soil) and liquid (precipitation runoff with some dissolved solids and nutrients) forms. The solid manure that accumulates in the pens is scraped off; usually twice a year or when the cattle in the pen have been sold and a new group enters the pen. It often contains roughly 50% soil (or ash in the manure sample). Moisture content of the manure will vary with time of the year it is harvested and ranges from 20-60% moisture.
When cleaning pens, it is important to remove as much of the manure as possible. This helps keep pens drier and less muddy when it rains and less prone to dust emissions. It is also important to avoid disturbing too much soil below the manure layer. The soil under a pen forms a compacted layer that makes it more difficult for water to move downward through the soil and carry away valuable nutrients. Earthen feedlot pens are rarely seen as a risk for leaching except following their abandonment.
Once scraped, solid manure can be handled one of two ways. It can be taken to a crop field and spread if the timing is right. Otherwise, it is stockpiled (temporarily stored) in an area of the farm designed and managed for this purpose or stockpiled in the field where it will soon be applied. The rules vary as to where stockpiles can be located in relation to water or other sensitive areas. It is important to divert clean water from running onto the stockpile by using ditches, berms or rain gutters (if a building is nearby) to divert water. It is also important to capture water that leaches or runs off from the stockpile. This is usually done with an earthen berm or a possibly a concrete structure. Locating stockpiles and compost areas within the drainage area of the feedlot and collecting runoff in the feedlot's holding pond is the preferred option if space is available.
Beef feedlots also handle liquid runoff. When there is a significant rainfall or snowmelt, water that runs off the lot surface is captured or slowed down by settling basins. After solids have settled in the basins, the remaining liquid is either allowed to continue to flow by gravity into the liquid manure storage or it can be pumped to the storage structure. Feedlot runoff is typically very dilute and represents less than 5% of the excreted nutrients.
Settling basins are designed for easy access by equipment so that they can be regularly cleaned. Settling basins also require regular inspection and maintenance to remove vegetation or built up manure along the fenceline or drainage ways that could obstruct water from entering the settling basins (and keeping water in the pen where it creates mud.) Solids removed from the settling basins are handled with the solid manure waste stream described above.
In areas with irrigation, the stored holding pond liquid can be applied to crops throughout the growing season. It can also be pumped into a manure tanker and hauled to a field or applied using a long hose that pumps directly from the storage structure and that the tractor drags along with the manure spreading/injecting equipment. In arid climates, operators sometimes use the liquid for dust control in the feedlot.
Are there other ways to handle beef feedlot manure?
The most common manure treatment to be applied to beef feedlot manure is composting. While compost can be applied to crop fields as a fertilizer/soil amendment, the extra expense usually means it is more feasible if there is a value-added market such as garden centers, landscaping companies, or golf courses.
While not yet a commercial reality, one university is looking at a system for anaerobically digesting solid manure like that found in beef feedlots. Most anaerobic digestion systems are designed for slurry manure like that produced in typical dairy or pig systems.
A group of technologies are emerging that are well-suited for use with dry manure like that harvested from open lots. Thermal conversion technologies include gasification and pyrolysis and use varying amounts of heat and oxygen to process manure for energy generation and byproducts that can be used in crop fertilization. These systems are generally prohibitively expensive but new advances will likely continue to lower that barrier.