GET THE SAND OUT OF MANURE

EFFECTIVELY MANAGE SAND-LADEN DAIRY MANURE WHETHER YOU HAVE AN ANAEROBIC DIGESTER OR NOT

Sand bedding is ideal for dairy cows, but it doesn’t always mix well with manure management systems. This is especially true with anaerobic digesters. However, well-designed, robust sand-manure separation systems are proven to help recycle sand bedding efficiently and economically, enabling users to recoup and recycle the vast majority of sand. Plus, these sand separation systems can also increase anaerobic digestion utilization by virtually eliminating sand from the digester-feeding manure stream.

Here’s how you can create a favorable manure management environment with sand bedding on your dairy farm, even if you don’t have a digester yet.

Why sand?

“Sand is the gold-standard bedding choice because of its cow health and milk production benefits,” says Renee Schrift, Business Line Director – Agricultural Systems at McLanahan Corporation. “It has so many advantages because it’s a forgiving, drier, comfortable surface for cows, and it’s inorganic, so the stall bacteria load is usually extremely low.”

According to researchers at the University of Wisconsin and USDA, the use of sand bedding compared to manure solids and mattresses results in higher milk production, lower mastitis treatment rates and lower somatic cell count.

Using sand bedding isn’t necessarily difficult, it is simply different to manage than using organic bedding.

Physics at work

How do you optimize the benefits of sand bedding while reducing challenges for manure handling systems? Separate and recycle it, of course.

“Success begins with capitalizing on physics, gravity and engineering know-how,” explains Schrift.

Keep in mind:

• Sand is abrasive, so choose equipment designed and proven to withstand the harshness of sand. This means equipment that operates at low speeds and is constructed using wear-resistant materials like abrasion-resistant steel plate or rubber. Components in high-wear situations must either be harder than sand grains or resilient enough to deflect without deforming.

• Secondly, sand is more than twice as dense as manure and therefore settles, making sand separation a realistic proposition.

“In fact, our systems can capture 95% of sand for recycling while removing an additional 3% of fines from manure,” Schrift adds.

As a result, dairies that recycle sand can cut their bedding cost significantly. For example, a 500-cow dairy using 50 pounds of sand per cow per day at $15 a ton spends $68,438 a year on sand. With a sand separation system that conservatively recovers up to 90% of sand for reuse, the dairy can save $61,594 a year by recycling their sand bedding.

These figures demonstrate that with a well-designed sand-manure separation system, high sand recovery is possible and economically beneficial for herds of all sizes.

What about digesters?

Since sand separation technology can virtually remove most sand from manure, these systems go hand-in-hand with anaerobic digesters.

Without separation beforehand, sand bedding is incompatible with anaerobic digestion systems.

With sand-manure separation, sand can be recycled for reuse as freestall bedding, and the manure effluent can be anaerobically digested for optimal digester efficiency and gas production.

The key is to collaborate with your partners to design the best system to fit your needs. Also, every farm is managed differently, so it’s important to determine the total solids in manure effluent, knowing there may be seasonal fluctuations.

“Be sure to choose an anaerobic digester partner who can design and build a digester to suit the way you manage your dairy, taking into consideration first and foremost what is best for the cows,” suggests Schrift.

Ultimately, effective sand recycling helps improve a dairy’s bottom line, whether you invest in a digester for your system or not.