ST. PAUL, Minn. — Sand bedding is very popular with many dairy producers — until it comes to handling sand-laden manure. Sand is very comfortable for cows to lie on in well designed and managed freestalls. But sand-laden manure is difficult to handle and abrasive to concrete and manure handling equipment.
Several options
There are several options for handling sand-laden manure. Dairy producers need to consider how their sand-laden manure handling fits into the overall bedding and manure handling system, with environmental regulations and with possible odor concerns. The system must be economical to build and operate.
Manure handling systems include collection from manure alleys and holding areas, transport to treatment and/or storage, manure storage and land application to recycle the manure nutrients.
Sand systems may include sand-manure separation so that some sand can be reused for bedding. A skid loader with a half-tire blade is a very common method for collecting sand-laden manure from freestall alleys.
Alleys are scraped while the cows are being milked. The skid loaders can push the sand-laden manure directly into a concrete lined storage or into a manure transfer line that goes either to storage or treatment.
Sand-laden manure can be transported from the barn using scrapers, augers, flush flumes, pumps or gravity flow. Gravity flow systems require sufficient drop (at least 10 feet of height difference) between the barn and the storage to work well.
Practices
A Michigan State University Extension publication described practices for removing stored sand-laden dairy manure for land application.
One method skimmed off liquids and removed the remaining sand-laden manure with a skid or front end loader. This method required both liquid and solid manure handling equipment.
Other options for handling sand-laden manure have been developed, including “weeping” walls, mechanical separators and sand lanes.
Dairy producers using mechanical separators or sand lanes can reuse the separated sand for bedding. Weeping wall is a general term for different types of manure structures with porous walls, panels or screened outlets that allow wastewater and urine to weep or seep out of the sand-laden manure.
The liquids drain into a lined storage until land applied.
Recycling sand
Dairy producers interested in recycling sand have two options, mechanical sand separators or sand lanes. Both systems use recycled wastewater. Mechanical separators typically recover 80 to 95 percent of the sand.
Sand-laden manure is brought to the separator, mixed with recycled wastewater and agitated. The sand separates and settles to the bottom of the separator, then is removed.
Sand lanes are long, gently sloping shallow concrete lanes where sand-laden manure and flush wastewater spread out, and the sand settles out along the lane. A skid loader is used to remove the settled sand from the sand lane.
The wet sand is piled into stacks to drain multiple times, then allowed to dry before being reused for bedding.
