Obtainable in multiple styles and sizes, manure spreaders fill an important role in dairy farm management. While having so many choices is wonderful, it can create a confusing and stressful decision for a producer when purchasing a machine for the first time or updating an old spreader.
Choosing a rear-discharge box style or a side-discharge V-bottom machine will significantly affect how the spreader performs on your operation.
Let’s dig in and examine the benefits and drawbacks of using each of these common spreader styles on dairy operations.
Rear-discharge box spreaders
The rear-discharge box design dates back to the earliest horse-drawn manure spreaders, making it the most traditional and widely available choice. These spreaders excel in handling drier manure and offer multiple beater options to fit diverse needs.
The three most common beater types available are horizontal, vertical and spinner modules. Each type carries its own advantages and limitations for dairy applications.
Horizontal beaters offer a low price point and relatively low horsepower requirement. They will apply a significant amount of nutrients per acre without having to overlap passes. Quick unloading rates allow for hauling multiple loads in a short period of time.
This speed comes in handy when you have a lot of manure to move between freeze-thaw cycles. However, high volume may be a detriment in areas with tight regulations on nutrient management. Typical spread patterns are slightly wider than the spreader itself, so complete field coverage will require more passes.
More passes through the field can increase soil compaction, especially in muddy conditions. Since the development of box spreaders and horizontal beaters, other styles have evolved to improve spreading in various situations.
Spinner modules have the dual advantages of control and width. They perform best with loose, flowable solids at rates of 1 to 15 tons per acre. Typical spread patterns of 45 to 60 feet wide lower the number of passes required to complete a field, a major plus in areas battling compaction.
Materials are broken up and unloaded much more consistently with spinners. Combining good breakup with high accuracy at low rates results in the most controllable, precise application available in a box spreader. On the downside, this does limit performance at high application rates, especially with solids that do not flow freely. Spreading stickier solids at high rates and wide widths is best left to a machine with vertical beaters.
Vertical beaters strike a middle ground by combining some of the benefits of both horizontal and spinner beaters. They maintain fairly high unloading rates, break up material well and spread an even pattern roughly 20 to 30 feet wide.
A simple center driveline into an integrated gearbox eliminates the chain system of other styles, which can reduce maintenance concerns as the machine ages. Though vertical beaters provide a favorable compromise in many situations, they cannot spread quite as wide as spinner modules or quite as much tonnage per pass as horizontal beaters.
While box spreaders do an excellent job with drier forms of manure, a more versatile option is available if you handle manure with higher levels of liquid.
Side-discharge V-bottom spreaders
Many dairy operations must spread “soupy” materials containing large amounts of liquid as well as solid manure. In these situations, box spreaders, regardless of beater style, will struggle to keep the box sealed. A side-discharge V-bottom spreader is the best tool for such a task.
These units are the most versatile spreaders on the market today, with the ability to haul and spread the widest range of materials. Pen pack manure with some bedding mixed in can be spread with ease, and greater sealing allows them to handle liquid material containing as little as 7 percent solids.
The side discharge breaks up and expels material very consistently. Most machines on the market also feature an adjustable discharge door so the operator can change the spread pattern from narrow to wide depending on the conditions and material.
Which to choose?
Now that we have considered the common spreader styles available today, let’s discuss which one is best for your operation.
The shortest answer to this question is: “It depends.” Your nutrient application goals and the type of manure you most often encounter dictate the best choice. Rear-discharge box spreaders are an excellent choice for the driest manure.
Fitting them with horizontal beaters applies high tonnage per acre with fast unloading to haul more loads quickly. Vertical beaters add the ability to spread wider and also break up the materials better. If your dairy spreads separated or digested solids, a box spreader fitted with a spinner module will offer wide, uniform spread patterns at lower tonnage rates.
A large percentage of dairy operations favor side-discharge V-bottom spreaders for their liquid-handling capabilities and, more importantly, their overall versatility. Compared to other livestock operations, manure from dairy facilities can vary more, from pen pack and bedding to wet and slurry-like.
These side-discharge spreaders offer excellent spread patterns for the widest variety of materials and superior sealing in liquid-intensive applications.
As with most equipment-related decisions on the farm, the best manure-spreading choice often involves several factors. Visit your local equipment dealer to learn more about the most appropriate manure spreader option for your operation. 
Philip Loduha is a product management specialist with Kuhn North America
