It may not be the most pleasant part of a dairy operation, but it’s one of the most important: What do you do with all that manure?
Choosing a manure management system is a complex decision, and operators are increasingly considering long-term solutions. Finding the right method for you and your operation involves an assessment of cost, location and nutrient value.
Why store manure?
Storing manure rather than spreading it immediately offers flexibility and convenience. Manure can be hauled less frequently and spread when weather and soil conditions are optimum for nutrient application and utilization.
Nutrients are most available to plants when applied immediately prior to or during the crop-growing season. When nutrients are added close to the time they are needed, they are less likely to escape from plant uptake and move to the environment.
Timing manure application to optimal conditions also reduces the chances of polluting nearby waters.
In addition, storing manure for six to 12 months allows for efficient use of custom applicators, who can empty storage on a planned schedule for a reasonable cost.
What matters most?
When looking at various manure storage systems, perhaps the most important question to ask is: In what form would you prefer the final product?
- Solid manure (greater than 15 percent dry matter) can be stored and handled as a solid by front-end loaders and beater-type applicators. Keep in mind solid manure contains bedding, reducing the concentration of nutrients.
- Slurry (5 to 10 percent dry matter) requires pumps, liquid manure spreaders or drag-hose injection systems to apply.
- Nutrient-rich liquid (less than 5 percent dry matter) can be applied by an injection or irrigation system. The necessary added water can make use of wastewater from parlor and equipment washing as well as rainwater.
The type of manure you desire for your cropfield needs plays a crucial part in determining the type of storage you require.
The geography and topography of your land play a role, as do local, state and federal regulations. Proximity to neighbors can be a factor. And every climate and region has specific concerns.
In some parts of Wisconsin, bedrock is so close to ground level that storage has to be built aboveground. Clay lagoons can be utilized in numerous regions. Meanwhile, in some regions, the walls of manure pits are straight up and down. Other places do banksides, with a berm around the lagoon built up from ground level. The slope of this berm is an important design element.
Beware of running water. Gutters and downspouts on nearby buildings will prevent fresh water running into the pit and increasing the volume and cost of application.
For every type of long-term storage system, runoff and seepage must be contained and managed according to environmental regulations.
What about cost?
Make no mistake, long-term manure storage can be a costly but long-lasting investment. Researchers caution the cost of manure storage should be considered in the context of the entire manure management system.
According to one study, a basin in clay soil costs approximately $37 for every 1,000 gallons of storage. (Regional construction costs will vary.) Whereas, a glass-lined steel tank could cost around $198 for 1,000 gallons of storage.
The value of the applied nutrients is part of the equation, along with labor and equipment.
So what’s best for me?
Luckily for dairy operators, there are options when choosing long-term storage.
- Solid manure. If you’re dealing with solid manure, building long-term storage that consists of concrete walls and bottom can confine the solids, prevent leakage and curtail runoff. Manure can be easily handled with common equipment. Solid manure storage should be used when there is little or no water added to the system.
- Slurry manure. When handling slurry manure, earthen basins are an economical solution for collecting runoff from open lots. A seal, generally clay or concrete, must be constructed to control seepage, and most states require soil evaluation to assess the appropriateness of the site.
Manure can be scraped from the barn into the lagoon via push-in ramps or pumped directly to the lagoon. Agitation is required to stir the slurry for equal nutrient distribution when pumping from the lagoon.
You will need to address agitation with the correct equipment based on size and content of the storage. In addition, access ramps must be placed strategically. In sandy areas, agitator pumps are effective at incorporating 70 to 90 percent of sand particles.
Be sure to include an access road for equipment in the plan.
If you’re in a northern climate, be sure to include a plan for handling frozen manure. A top-loaded lagoon can freeze in layers and create challenges.
In some locations, the area surrounding the lagoon must be fenced to avoid drowning accidents. Grass-covered berms, dams and slopes must be mowed and maintained – including burrowing rodent control.
- Nutrient-rich liquid. This type of manure can be transferred to long-term storage by pumping or gravity flow. Nutrient-rich liquid manure has the highest nutrient density of the three forms and can be easily applied in its current form.
No matter the type of long-term storage selected, manure storage should be considered an enclosed space for worker safety. Proper ventilation and protective equipment is essential.
It is crucial to consult the professionals, regardless of storage type or location. Miscalculations can result in headaches down the road.
Storage needs to accommodate around 20 gallons of manure and urine per cow per day, based on a 90-pound cow. A Jersey farm can reduce that. Larger cows will produce more. Any water added to the system from parlor or barn yards must be calculated in the total storage as well. Most local regulations require a 2-foot allowance in the storage receptacle for a 30-year rainfall event.
Current studies suggest that robotic barns produce as much wastewater as traditional operations.
If you want to make the investment, you may also want to consider converting manure to dischargeable water. The storage and equipment cost is balanced against value of the nutrient-dense solid and recycled water produced by the process.
Whatever your choice, make sure your storage is adequate for your manure production, designed for the manure consistency you desire and convenient to access and empty. It needs to be built and managed to protect water quality and comply with regulations. And, most of all, remember, long-term storage is one part of your waste management and nutrient source strategy.
Discuss the pros and cons of each type of storage with your manure management specialist. PD
Jeramy Sanford is a field manager and manure specialist with GEA Farm Technologies. He can be contacted by email.
References omitted due to spacebut are available upon request. Click here to email an editor.
PHOTO 1: When handling slurry manure, earthen basins are an economical solution for collecting runoff from open lots. A seal, generally clay or concrete, must be constructed to control seepage and most states require soil evaluation to assess the appropriateness of the site. Access ramps must also be placed strategically.
PHOTO 2: Agitation is required to stir the slurry for equal nutrient distribution when pumping from the lagoon. You will need to address agitation with the correct equipment based on size and content of the storage.Photos courtesy of GEA Farm Technologies.