PTO vs Engine-Driven Manure Pumps: How to Size One
For most farms running their own manure with existing tractors in the 200 to 300+ horsepower range, Hoover Ag’s PTO pump covers the job.
In a manure lagoon, light solids float, heavy solids settle to the bottom and liquid stays on top, Over time, the settled solids build up. What started as a one-foot solids layer becomes seven feet, then ten. The lagoon’s usable storage volume shrinks even though the perimeter and depth haven’t changed.
Skip the cleanout long enough and three things happen. Available storage drops below what your operation needs, which forces application decisions on the wrong days. The solids layer starts to interfere with pump intakes and application equipment. And the nutrients in the solids (which are the most concentrated and valuable part of what’s in the lagoon) never make it out to the field.
Cleanout schedules vary by operation, but most well-managed lagoons need serious attention every three to five years, with lighter agitation and drawdown more frequently. Here’s how the job actually gets done.
Lagoon cleanout isn’t one operation. It’s usually a combination of three approaches, applied in the order that fits the lagoon’s condition.
Agitation and pumping. The most common approach. High-volume agitation pumps or propeller agitators mix the settled solids back into the liquid, and the resulting slurry is pumped out through a dragline system for land application. Works well when done on a consistent basis
Dredging. For the heaviest solids at the bottom, or for lagoons where the sludge has hardened past the point where agitation will work, dredging is the answer. A floating dredge or long-reach excavator physically removes the material and moves it to a spreader, truck, or field application setup.
Most cleanouts use one of these methods, sometimes both. Agitation and pumping handles the bulk. Dredging finishes the deep sludge.
Agitation is where most cleanouts start. The point is to suspend the settled solids in the liquid so the whole lagoon becomes a pumpable slurry.
Common agitation equipment includes high-volume pumps that recirculate lagoon contents back into itself at high pressure, creating turbulence that lifts settled material. Propeller agitators mounted on tractors direct a stream of flow into the solids layer. Some operations use both, with the propeller agitators working close to shore and the pump running from a central location.
Agitation is slower than most operators expect. A well-settled lagoon can take hours or days of continuous agitation before the solids are fully suspended. Rushing this step means pumping thin liquid off the top and leaving the solids behind, which defeats the purpose of the cleanout.
Once the lagoon contents are agitated into a pumpable slurry, the pumping side of the operation moves it through a dragline system to the field.
A typical setup uses a PTO pump or engine-driven pump to push the slurry through mainline hose to the field, where a hose reel deploys drag hose to the tractor pulling the application implement. The implement can be a 50 foot dribble bar for surface application or a dragline injector if the plan calls for injection. Full component detail on the equipment side is in the Hoover Ag manure equipment lineup.
The pumping side has to be sized for the material. Cleanout slurry is thicker and harder to pump than routine lagoon contents because it has more suspended solids. If your pump is barely adequate for normal application, it may struggle during cleanout. This is worth talking through with a custom applicator or dealer before the job.
Some lagoons reach a point where agitation and pumping can’t finish the job. The material at the very bottom has compacted into a dense sludge that resists mixing, or a corner of the lagoon has accumulated material that agitation can’t reach.
Dredging solves this. A floating dredge is a barge-mounted pump with a cutter head that physically breaks up the sludge and pumps it out through a hose. A long-reach excavator working from a bank can scoop material and load it into a spreader truck. Some operations use a track loader working from a dewatered corner of the lagoon after the liquid has been pumped down.
Dredging is the most expensive of the three approaches, both in equipment cost and time. It’s also the approach that recovers the most concentrated nutrients, which is why the material dredged out is usually spread on fields that need the biggest phosphorus and organic matter contribution.
Most operations plan for a partial drawdown every year (agitation and pump-down to reduce solids buildup) and a more thorough cleanout every three to five years. Waiting longer than that usually means the lagoon has reached a point where dredging is needed, which is more expensive than staying ahead of the buildup.
Cleanout timing has to work with your storage cycle, your application windows, and the weather. A few principles.
Empty enough storage first. You can’t clean out a full lagoon. Most operations time the cleanout for after the fall or spring application push, when storage volume is lower and there’s room to work.
Match to application windows. The slurry coming out of the cleanout goes on fields, so cleanout has to happen when application is legal, safe, and agronomically sound under your nutrient management plan. Winter cleanouts run into Pennsylvania’s winter application restrictions. Wet-ground cleanouts run into compaction problems.
Plan for weather. A three-day cleanout window can turn into a two-week window if the weather doesn’t cooperate. Agitation works better in warm weather. Pumping and application need firm enough ground to move equipment across.
Coordinate with a custom applicator early. If you’re hiring the cleanout out, the good applicators book up months in advance, especially for the traditional spring and fall windows.
Lagoon work is dangerous in ways that don’t get talked about enough. A few things to keep in mind.
Gases. Agitation releases hydrogen sulfide, methane, and other gases from the settled solids. Concentrations near an agitating lagoon can be high enough to cause loss of consciousness in seconds. Never lean over or work directly downwind of an active agitation operation.
Drowning. People fall into lagoons every year. Manure slurry does not support a person’s weight the way water does, and once you’re in, the sides are usually too steep and slick to climb out. Anyone working near the edge should have a lifeline, a spotter, or both.
Equipment near the edge. Lagoon banks are not always as stable as they look, especially after a heavy rain or during a drawdown when the water level has changed. Keep heavy equipment back from the edge unless you know the ground can carry it.
Vehicles and children. Anyone not part of the cleanout operation should be kept away from the site. A cleanout in progress is not a place for farm visitors.
Not every cleanout is a complete emptying. Most operations do partial cleanouts more often than complete ones.
Partial drawdown. Pumping the liquid layer down to reduce volume and apply the nutrients to fields. Doesn’t touch the settled solids. Fast, routine, and often part of the normal fall or spring application schedule.
Solids agitation and pumping. Agitating the top of the solids layer back into liquid, then pumping the slurry out. Reduces solids buildup but doesn’t reach the compacted bottom material. Done every few years.
Deep cleanout. Agitation plus dredging to remove essentially all the solids down to the liner. Done every five to ten years, or when the lagoon is being inspected or repaired.
Different operations run on different cleanout cycles. Some do partial drawdowns twice a year and never let the solids build up enough to need deep cleanout. Others let it accumulate for a decade and then do a full deep cleanout in a single project.
For the pumping and application side of a lagoon cleanout, most of the Hoover Ag manure equipment lineup applies. The PTO pump handles pumping duties for operations with the tractor horsepower to drive it. Hose reels manage the drag hose during application. The 50 foot dribble bar handles surface application, and dragline injectors handle injection when the plan calls for it.
Cleanout-specific equipment (agitation pumps, dredges, chopper pumps) is typically owned by custom applicators who specialize in cleanout work. Most farm operations don’t own this equipment because they only need it every few years.
If you want to talk through your cleanout planning or spec application equipment to match the volume you’ll be moving, call Hoover Ag at (610) 468-9666 or get in touch.
For most farms running their own manure with existing tractors in the 200 to 300+ horsepower range, Hoover Ag’s PTO pump covers the job.
If you haul or broker manure commercially in Pennsylvania, you need a certification, you need to maintain it with continuing education, and you need to keep records that prove you’re doing the work within the rules.
Biosolids are the nutrient-rich organic material produced when wastewater treatment plants treat sewage sludge to meet federal and state standards for beneficial use.