Slurry Storage: Does Separating Slurry Really Give You More Capacity?
Slurry storage has a habit of looking perfectly adequate in summer and considerably less comfortable once cattle are housed, rainfall increases and winter gets going.
So, can a slurry separator actually give you more storage capacity?
The short answer is yes, potentially. But it doesn't physically make your slurry store bigger. Separation changes how slurry is handled, allowing the liquid and solid fractions to be managed separately and, on the right farm, helping existing storage work harder.
From our experience, that's an important distinction. A separator shouldn't be viewed as a quick fix for an undersized store. It needs to be considered as part of the complete slurry system.
How Does Slurry Separation Affect Storage Capacity?
A slurry separator divides incoming slurry into a liquid fraction and a solid fraction.
The liquid contains less fibrous material and is generally easier to pump, transfer and apply. The separated solids become a stackable material containing organic matter and nutrients that can be managed independently, subject to the appropriate storage and environmental requirements.
This doesn't make slurry disappear, and it doesn't physically increase the size of your store.
If you've got a 2,000m³ slurry store, installing a separator doesn't suddenly turn it into a 2,500m³ store.
What separation can do is remove solid material from the liquid slurry stream so the two fractions can be managed separately in the right system, that can help you make more effective use of your available liquid slurry storage.
How much difference that makes depends on the individual farm and, importantly, what happens to both fractions after separation.
What's Actually Filling Your Slurry Store?
Before discussing separators, this is one of the first questions we'd ask on farm:
“What's actually going into the store?”
Not every slurry storage problem is caused entirely by slurry production.
Rainwater from roofs, yards and poorly directed drainage can enter slurry systems, particularly on farms that have expanded or changed over the years.
Once clean water enters the store, you're paying to deal with it. It takes up valuable storage capacity, dilutes the slurry and eventually needs pumping, transporting or spreading.
That's why one of the simplest slurry storage improvements can also be one of the most worthwhile: keep unnecessary clean water out of the system wherever possible.
Before recommending storage or separation equipment, it's important to understand where the volume is coming from. If clean water is taking up valuable storage capacity, tackling that problem may deliver more benefit than simply adding another piece of machinery.
A Separator Is Only One Part of the Slurry System
One of the biggest mistakes you can make is looking at a separator in isolation.
The separator has to work with the slurry it's being fed, which means the reception pit, mixer and feed pump all matter. The separated liquid then needs suitable storage, transfer and application equipment, while the solid fraction needs its own handling plan.
That is why we always look at the complete journey:
Mixer → Pump → Separator → Slurry Storage → Transfer → Application
Every part needs to work together.
If the slurry reaching the separator varies significantly in consistency, you're making the separator's job harder. Effective mixing and the correct feed pump help provide a more controlled and consistent flow.
Likewise, there's little benefit in improving separation if you simply create a bottleneck further down the system. That's the difference between buying a machine and designing an effective slurry system.
What Happens to the Liquid and Solid Fractions?
The liquid fraction contains less fibrous material and is generally easier to pump and handle than untreated slurry.
That can be particularly useful for umbilical slurry systems and low-emission application equipment, including dribble bars and trailing shoes. A more consistent liquid can reduce some of the handling problems associated with thicker, more fibrous slurry.
But the other half of the equation matters just as much. The solids haven't disappeared.
They still contain organic material and nutrients and need to be stored and managed appropriately. Where they will go and how they'll ultimately be used should form part of the system design from the beginning.
There's little benefit in relieving pressure on your liquid slurry storage only to create another storage or handling problem elsewhere in the yard.
Separation can also give you greater flexibility in how the nutrients and organic matter within slurry are managed. Rather than treating everything in the store as one material, the liquid and solid fractions can be handled according to where they're most useful on the farm.
That's an important part of looking at slurry as a valuable farm resource rather than simply something that needs storing and spreading.
Can Slurry Separation Reduce Handling and Spreading Costs?
Potentially, but we'd be wary of putting a generic saving against it.
Separating the liquid and solid fractions gives you greater flexibility over how each is handled. The more pumpable liquid fraction can suit transfer and low-emission application, while the solid material can be managed separately.
That can influence the efficiency of pumping, transport, spreading and nutrient management. But every farm is different.
Herd size, slurry volume, dry matter, rainfall, existing storage, field distances and application equipment all affect the economics. A separation system that delivers a strong return on one dairy farm might solve a completely different problem on another.
After more than 30 years working with slurry systems, our preference is to start with your farm's figures and work backwards towards the equipment, rather than starting with the machine.
Is a Slurry Separator Worth Installing Just for More Storage?
Not necessarily. If lack of physical slurry storage capacity is your only problem, a separator isn't automatically the answer.
Clean-water ingress may need addressing. Existing storage could potentially be covered, or additional physical capacity may be required.
Separation becomes more compelling when storage pressure exists alongside other challenges like thick or fibrous slurry, difficult pumping, large slurry volumes, application problems or a need for greater flexibility in nutrient management.
It's often the combination of benefits, rather than storage capacity alone, that makes slurry separation worth considering. That's why understanding the problem comes before specifying the equipment.
So, Does Separating Slurry Really Give You More Slurry Storage Capacity?
Potentially, but not by making your slurry store physically bigger.
Separation allows the liquid and solid fractions to be managed independently, which can help some farms make more effective use of existing liquid slurry storage.
But storage capacity shouldn't be considered in isolation. The real value of separation can come from the combination of easier handling, improved pumpability, more flexible application and greater control over the complete slurry system.
Slurry Storage and Separation: Frequently Asked Questions
Does slurry separation mean I need a smaller slurry store?
Not automatically. Storage requirements depend on the individual farm and applicable regulations. Separation should be considered as part of the overall slurry storage and handling system, rather than as a substitute for adequate storage.
What happens to the solids after slurry separation?
The separated solid fraction still contains organic material and nutrients and needs to be stored and managed appropriately. How the solids will be handled and ultimately used should be considered when designing the separation system.
Should I increase slurry storage or install a separator?
It depends on what's causing the pressure. If clean-water ingress or insufficient physical capacity is the main problem, addressing those areas may come first. If storage pressure exists alongside high dry matter, difficult pumping or wider handling challenges, separation may offer additional benefits.
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