Here are a few suggestions to help keep sand in its place and help you gain all possible advantages for manure management systems, bedding benefits and overall farm efficiency.
Sand is a weighty subject
Sand-laden manure is heavier than manure alone.
Because of this difference, sand does not remain in suspension indefinitely, eventually settling out from manure. Storing sand and manure solids separately from effluent whenever possible should be your first choice.
This premise is also a good reason to incorporate sand separation into manure management systems. Doing so avoids costly storage facility cleanouts while allowing dairies to capture, recycle and reuse sand.
With the right sand and a properly designed and managed sand separation system, most farms achieve more than 90% sand recovery rates. These solutions allow you to repeatedly reuse sand bedding, saving purchase costs.
Sand doesn’t mix with anaerobic digesters
Without sand separation beforehand, sand-laden manure is largely incompatible with anaerobic digester systems.
However, with sand separation, achieving greater than 90% sand recovery and capturing an additional 5% of fines is possible. Sand separation technology allows sand bedding to be a viable option for dairies adopting anaerobic digester technology.
It may take several steps to harvest the maximum amount of sand from manure before digestion. Work with your manure management partners to ensure you are properly equipped to meet the requirements for successful digester function.
Sand influences soil
The impact of applying sand-laden manure in fields varies depending on location and soil texture, but it does build over time. After repeated application, sand has been shown to influence several important soil characteristics and change the composition of soils. 1
Many dairies have a land base of two to five acres per cow. At that rate, if equally spread, a farm will add between 4,550 pounds and 9,125 pounds of sand per acre per year. Depending on tillage, application levels, soil type and other factors, in 25 to 50 years, the soil sand percentage will increase by 20%.2
Perhaps more important is that repeated sand application to fields may change soil texture and decrease infiltration capacity over time. This means water is not as easily absorbed by the soil. Eventually, the reduction may potentially lead to increased field runoff, taking valuable water and nutrients with it.
Also, note that the quality per volume of manure is diminished when sand is added. As sand is added to the manure, the percentage of nitrogen, phosphorus, potassium and sulfur diminishes.2
Removing sand before field application of manure will help dairies and their crops benefit more from this organic fertilizer.
Conclusion
To get the most from your sand investment, you must keep sand in its place and working for cows.
Cows and farms benefit from sand remaining in the places where it provides the most advantage – under cows and not in storage facilities, anaerobic digesters or fields.
