Cutting agitation and pumping time: what changes when solids liquefy

Agitation suspends solids so you can pump them. It does not reduce them. Every pound of fiber you stir back up settles again after the pump shuts off, minus what left in the tanker. When bacteria digest that fiber instead, there is less material to suspend, so agitation hours, fuel burn, and pump wear all drop.

Why does agitation take so long in the first place?

Because you are not mixing a liquid. You are trying to tear apart a mat.

A stalled pit has three layers. On top, a crust of floating cellulose fiber from undigested feed and bedding, bound together and often dry enough to walk on. On the bottom, a hardpan of settled fiber and grit that has been compacting for years. In between, liquid with gas pockets trapped in it, because the gas cannot get through the crust above it.

Your prop is trying to break the top layer, resuspend the bottom layer, and blend the middle into something a pump can move at a consistent solids content. The top layer is the one everybody notices. The bottom layer is the one that costs the most, because a hardpan that has set up hard enough will not resuspend at all no matter how long you run. You are burning fuel to push liquid across concrete.

That is the part worth sitting with. Some of your agitation hours are not producing anything. They are the hours after the material that will move has already moved.

Does agitation actually reduce solids?

No. This gets said loosely and it matters that it is not true.

Agitation is mechanical suspension. The prop puts energy into the slurry, the settled solids come off the floor and into the water column, and they stay there as long as you keep the energy in. Shut the pump off and they start settling again within minutes. Nothing about that process destroys a single pound of fiber.

The only solids that leave your pit during pumping are the solids that go out in the tanker or the drag line. Everything else is exactly where it was, redistributed. If you agitated eight hours, pumped the pit down, and the hardpan is still there in the spring, that is not a failure of your equipment. That is what agitation does.

Solids reduction is a different process. Fiber only actually disappears when something digests it. In a pit, that something is bacteria, and specifically the population that breaks down cellulose. When that population is healthy, fiber turns into liquid and gas and leaves the system on its own schedule. When it collapses, fiber accumulates, and no amount of horsepower changes the total. That collapse is the root of most crust problems too, which is covered in what causes manure crusting.

Where do the hours and the fuel actually go?

Break your pumping day into pieces and it usually looks like this.

Setup and teardown. Fixed. Additive programs do not change it.

Breaking the crust. Variable, and driven entirely by how thick and how bound the mat is. On a bad pit this is the first two or three hours before you have made any real progress on the rest.

Getting the hardpan into suspension. Variable, and the piece with the worst return on time. Past a certain point, running longer stops producing.

Actual pumping. Driven by pump capacity, but plugging and re-priming come out of this bucket. Fiber wraps impellers and bridges at every restriction in the line.

Waiting. Custom applicator with the meter running, tankers stacked up, the drag hose down while somebody pulls a plug out of the pump. This is real money and it never shows up on a fuel ticket.

Run your own numbers on the fuel side. Take your agitation tractor's burn rate per hour from your own records, multiply by hours per pit, multiply by pits per year. Nobody needs an outside estimate for this. You already own the number.

That last row is a safety item, not a convenience item. Trapped gas coming out all at once when you break a crust is the specific situation that hurts people. Ventilate, get everybody and every animal out, and read up on it before the next pumping day at hydrogen sulfide and ammonia in confinement. NIOSH publishes on manure gas and confined space hazards.

What is hardpan really costing you?

Two things, and only one of them is visible.

The visible one is agitation time. The invisible one is storage. Every foot of hardpan on the bottom of a pit or lagoon is a foot of capacity you paid to build and cannot use. You are pumping more often into a smaller working volume, which means you are pumping on a schedule the pit sets rather than one the weather and the crop set. That is how people end up hauling in November on wet ground.

A livestock producer in Mankato, Minnesota reported recovering approximately 200,000 gallons of usable lagoon capacity after treatment. That capacity was always there. It was under the solids.

The full picture on that is in lagoon storage capacity lost to solids.

What about equipment wear?

Nobody puts a line item in the budget for this, which is why it goes unnoticed until something breaks in the middle of a pumping window.

Pushing a heavy, fibrous, inconsistent slurry loads everything harder than pushing a uniform one. Sheared bolts on the agitator. Driveline and PTO fatigue. Seal wear from grit that hardpan carries. Impeller wear and imbalance from fiber wrapping. Hoses and fittings working at higher pressure than the spec sheet contemplated, because there is a partial plug two hundred feet downstream.

Then there is the failure that costs the most: going down mid-pump. A repair that would be routine in January is not routine on the third day of a four-day window with a custom applicator on site.

Lighter, more uniform material does not eliminate any of this. It reduces the load and the number of restarts, and restarts are where a lot of equipment damage actually happens.

What changes when the fiber digests

The mechanism is worth being precise about, because "the additive breaks down solids" gets used to mean several different things.

Confinement pits stall when the material that should be breaking down, mostly fiber from undigested feed and bedding, stops breaking down. That fiber has nowhere to go, so it floats or it settles. PitCharger products are formulated for specific manure-management problems. Depending on the product, formulations may include aerobic, anaerobic, and facultative bacteria, enzymes, or other specific modes of action. Not every PitCharger product uses the same ingredients or works the same way, and the product is selected based on the problem being treated. As treatment helps break down solids and fibrous material, those solids become easier to suspend during agitation, the crust weakens and moves back into the manure, and the dry surface flies breed on goes away with it.

Nick, who runs pits for a livestock cooperative in central Iowa, put it this way: "Tests were very positive on the reduction of solids. Pits with additive showed significant reduction of solids compared to non-treated pits."

Hog operations commonly start around one gallon per month per 1,000 head, about four gallons a month for a 4,000-head finishing barn. Cattle and dairy commonly start around one gallon per 75 animals. Lagoon rates may be adjusted based on the manure already in the lagoon and the amount expected to be added each month. Most producers should notice a difference within the first month, with continued improvement through the second and third months. Significant results are normally measured after about six months. That is not a minimum program; it is the point where broader changes in the manure system are measured. The treatment calculator will estimate dose and expected agitation reduction for your head count and pit dimensions, and Manure Digester is the flagship monthly treatment for a pit that is no longer keeping up. If a share of your solids is spilled grain, Feed Digester is the specialty product for heavy grain buildup. The full picture is laid out at how PitCharger works.

How do you measure this on your own operation?

Do not grade it by feel. Write down four numbers before you start and the same four numbers after.

1. Sounding depths. Push rod, same three or four locations, marked. Record crust thickness and depth to hardpan. Monthly.
2. Agitation hours. Actual clock time, same pit, same pump, same operator if you can.
3. Fuel used. Off the tractor's hour meter and your own burn rate, or off the fuel ticket if the pit gets its own fill.
4. Stoppages. A tally mark every time you shut down for a plug or a re-prime. This is the one that surprises people.

Give it time before you compare, and if you have two similar pits, treat one and leave one. That is the comparison worth having, and it is the one Nick was describing.

Frequently asked questions

Will I be able to stop agitating?

No. You still agitate and you still pump. What changes is how long agitation takes and how hard the equipment works while it happens. Any product marketed as a replacement for agitation is overselling.

How long before agitation time changes?

Most producers should notice a difference within the first month, with continued improvement through the second and third months. Significant results are normally measured after about six months. That is not a minimum program; it is the point where broader changes in the manure system are measured. Fiber which took years to accumulate does not clear in one pumping cycle. Odor generally moves before structure does. A year-long Iowa State/Farmland study, as reported by PitCharger, showed approximately a 50% reduction in hydrogen sulfide, ammonia, and overall odor compared with untreated buildings, and some producers have noticed a substantial change within the first 24 hours.

Does this work on a hardpan that has been there for years?

Old hardpan is the slowest thing in the pit to move, because it is compacted and the bacteria have to work in from the surface. It responds, but on a longer timeline than crust does, and the dose and the treatment period both matter more. That is a conversation to have with head count and pit dimensions in hand rather than a yes or no.

Does treating the pit change what I can haul?

More uniform material means loads that are more consistent load to load, which makes your manure test more useful for rate calculations. It also changes the nitrogen picture, since biological activity converts organic nitrogen toward plant-available ammonium. See organic vs. ammonium nitrogen in manure.

Is the product safe to have around during pumping?

It is biological, not caustic. Safe around cattle, horses, pets, children, and vegetation. The hazard on pumping day is manure gas, and that hazard exists whether you treat the pit or not. Ventilate and clear the barn.