Having an agitator is not the same as having the right agitator. This is a distinction that many producers only realize after installing the equipment and not seeing the expected results.
An undersized agitator is one of the most silent problems in the management of manure lagoons. The equipment is there, functioning, consuming energy, but it cannot efficiently homogenize the lagoon's volume. The crust continues to form, the sediment continues to accumulate, and the biofertilizer continues to come out with inconsistent quality.
The producer doesn't know if the problem is the equipment, the management, or something else. And the result falls short of what it could be.
In this article, we explain what an undersized agitator is, how to identify if this is the case for your pond, and what changes when the equipment is the right size for your pond.
What does an undersized agitator mean?
An undersized agitator is one whose power, length, or type is not suitable for the volume, depth, and substrate type of the pond where it is installed.
Proper agitator sizing takes into account a combination of factors:
-
Lagoon volume: the larger the volume, the greater the power and movement capacity required of the agitator.
-
Pond depth: the agitator length needs to be compatible with the depth to ensure that the movement reaches the bottom — where sediment accumulates.
-
Substrate type: swine manure has a different solids content and viscosity than bovine manure. A denser substrate requires more power to be homogenized.
-
Type of agitator: fixed electric agitators and tractor-mounted agitators have different capacities for different situations.
When any of these factors are not considered at the time of purchase, the result is an agitator that operates at or below the limit of what the pond requires.
How to identify if the agitator is undersized
An undersized agitator rarely gives obvious signs of failure. It works, makes noise, moves the substrate—but doesn't deliver the expected results. The signs are subtle and progressive.
Persistent crust on the surface
If crust continues to form on the surface of the pond even with the agitator operating regularly, it is a clear sign that the movement is insufficient. A properly sized agitator breaks up the crust and prevents its reform. An undersized one creates movement only in the area near the equipment—leaving the rest of the surface practically static.
Sediment accumulating at the bottom
After pumping, if the pond level drops but the sediment layer at the bottom continues to grow, the agitator is failing to resuspend this material. The accumulated sediment progressively reduces the pond's usable volume—and the farmer notices that the pond "fills up faster" without an increase in the herd.
Biofertilizer of inconsistent quality
Samples of the biofertilizer collected from different points in the lagoon show very different compositions. This indicates that the material is not homogeneous—and that the agitator is not managing to mix the contents uniformly throughout the volume.
A lagoon that does not homogenize even with prolonged agitation.
If the producer needs to agitate for many hours to achieve a reasonable result—or if even then the result is not satisfactory—the agitator is working at the limit of its capacity for that pond.
High energy consumption for the result delivered.
An overloaded agitator consumes more energy than it should for the result it delivers. If power consumption is high but homogenization remains poor, it is a sign of equipment overload.
What changes when the agitator is the right one?
The difference between an undersized agitator and a correctly sized one is not just technical—it directly affects the lagoon's performance and the return on investment for the property.
Efficient homogenization throughout the volume.
A properly sized agitator moves the substrate throughout the entire volume of the lagoon—not just in the area near the equipment. This ensures that the biofertilizer has a uniform composition, that the sediment remains in suspension, and that crust does not form.
Less stirring time for the same result.
With the right equipment, the time required to homogenize the lagoon before pumping is reduced. This means less energy consumption, fewer tractor operating hours (in tractor-driven models), and greater operational efficiency.
Biofertilizer of consistent quality
With a homogeneous lagoon, the biofertilizer pumped to the field has a predictable composition — the producer knows what they are applying and can calibrate the doses more precisely. The agronomic value of the material increases.
Lagoon with preserved usable volume.
Without sediment buildup, the usable volume of the lagoon is maintained for longer. The producer does not need to perform frequent cleanings, and the storage capacity is preserved.
Lower risk of flooding
With the lagoon operating efficiently without accumulated sediment and with regular pumping facilitated by proper homogenization, the risk of overflow drops significantly.
What to consider when choosing the right size
If you have identified that your agitator may be undersized, or if you are evaluating the purchase of new equipment, the main criteria are:
-
Total lagoon volume: the starting point. The power and type of agitator need to be proportional to the volume to be moved.
-
Depth: the agitator length needs to reach the sedimentation zone at the bottom. A short agitator in a deep pond will not homogenize the total volume.
-
Substrate type: Swine manure, with up to 6% of solids, has different characteristics from bovine or agro-industrial substrates. The choice of model and power needs to take this into account.
-
Lagoon geometry: long and narrow, round or irregular lagoons may require specific agitator positioning or more than one piece of equipment to ensure homogenization throughout the volume.
-
Agitation frequency: whether the agitator will be used only before pumping or continuously/on a programmed basis influences the choice between a fixed electric agitator and a tractor-driven agitator.
These factors need to be evaluated together, and the decision deserves specialized technical guidance. An oversized agitator also generates problems: excessive turbulence, unnecessary energy consumption, and interference in the biological process in some systems.
Undersized or overdue for maintenance?
Before concluding that the agitator is undersized, it's worth ruling out another common problem: delayed maintenance.
A properly sized agitator, but with poor maintenance, can exhibit the same symptoms as an undersized one: decreased performance, poor homogenization, and high consumption. Worn seals, unlubricated bearings, and a propeller with accumulated hardened material significantly reduce the equipment's efficiency.
The correct assessment involves first verifying the maintenance status of the equipment and only then evaluating whether the problem is related to its sizing.
The right agitator makes the pond work right.
Having an agitator is the first step. Having the right agitator for your pond is what ensures it delivers the results your property needs.
A crust that keeps forming, sediment that keeps growing, uneven biofertilizer – these are signs that something is wrong. And in most cases, the cause lies in the equipment's sizing.
The undersized agitator is working. It just isn't delivering what the lagoon needs.
Do you want to check if your agitator is correctly sized?
AGTO manufactures tractor-driven and electric agitators in different lengths and power ratings, developed for the realities of Brazilian rural producers. Our technical team analyzes the characteristics of your pond – volume, depth, substrate – and recommends the ideal model for your system.
Get in touch and speak with an AGTO specialist.
