Managing manure storage structures
Additional rain this spring could compromise manure storage structures if not monitored.
Recent rains have made planting crops difficult and slowed progress on all field work. However, the excess rains have had another side effect: an increasing level of manure in storage structures on dairy farms. Most dairy farms have some type of in-ground storage for manure. Excess clean water such as roof run-off is most often diverted around such storage structures to maximize capacity, but with the high amount of rain, it is inevitable that some structures are nearing capacity.
When structures fill sooner than expected, it can be difficult to find areas for application. An adequate freeboard must be maintained. Storage structures are not designed to be “full” and that additional pressure on the system can harm the integrity of the structure, cause a breech or overflow, all resulting in issues that can harm your farmstead and the environment.
The Generally Accepted Agricultural Management Practices (GAAMPs) for manure state that all manure storage structures shall maintain a minimum freeboard of twelve inches (six inches for fabricated structures) plus the additional storage volume necessary to contain the precipitation and runoff from a 25-year, 24-hour storm event. Freeboard means the distance from the level of manure to the top of the storage structure. This “storm event” amount is about an additional 4 inches here in Michigan. That means concrete structures need to have at least 10 inches of freeboard and earthen storages need 16 inches of freeboard at all times to be in compliance with GAAMPs and Right-To-Farm.
Maintenance and inspection is always important, but even more so this spring. Monitoring the storage with a visual inspection around the entire perimeter can catch potential problems before they create major issues. Identify any items that might minimize integrity, such as animal burrows, trees and shrubs growing on the berm. On earthen storage, also look for a smooth, regular shape to the berm, not one with cuts and scrapes from emptying. These periodic inspections can help insure wall integrity.
For more information on the manure GAAMPs, please visit www.michigan.gov/mda. Under the farming tab, you can find all the GAAMPs for your reference.