There is a question that gets asked on every haying forum, usually by someone who has just watched a neighbor's merger go by and can't work out what it bought him. A Colorado producer put it about as bluntly as it can be put: he wanted to know why anyone wants one of these things at all. It is a fair question, because on the face of it a merger does exactly what a rake does — it takes two or three swaths and makes them into one — except it costs several times as much and has several times as many parts to break.
The honest answer is that a merger is not a better rake. It is a different machine solving a different problem, and if you don't have that problem you should not buy one. Meanwhile the windrow inverter — the machine most often confused with a merger, and often literally called one — is a third thing again, brilliant at one specific job and frustrating at everything else. Here is what the research measured, what the machines actually cost to run, and how to tell which of the three your operation needs.
Short answer
Buy a rake if you need the most acres per hour per dollar. It is the cheapest way to move a windrow and nothing else comes close on capacity-per-dollar.
Buy a merger if soil contamination is costing you money — you are feeding a dairy ration, filling a self-propelled chopper, working rocky or sandy ground, or moving crop a long way sideways. University of Wisconsin lab data puts the gain at roughly 1 to 2 percentage points of ash versus raking.
Buy an inverter only as a second machine, to flip windrows that are dry on top and damp underneath. As a primary merging tool it is too slow and too narrow, and the people who bought one for that reason mostly regret it.
The three machines are genuinely different (and the names get mixed up)
Before anything else, the vocabulary needs sorting out, because the corpus of forum threads is full of people using "merger" to mean a machine that is not a merger. On one thread about reducing dirt in silage, a poster wrote that "windrow mergers like the NH 166 were all the rage around here for a while" — but the New Holland 166 is an inverter, not a merger. That confusion matters, because the two machines have almost opposite strengths.
Rake — wheel, rotary or bar
A rake moves crop across the ground. Teeth engage the windrow and roll or sweep it sideways into a new one. It is mechanically simple, cheap per foot of working width, and available in every size. It is also the only one of the three machines that is genuinely universal — everyone can justify one. Which family to buy is its own decision, and we have covered that separately in the hay rake selection guide.
Windrow inverter — a windrow flipper
An inverter picks a single windrow up with a narrow pickup, carries it a short distance on a conveyor, and sets it back down upside down and usually slightly to one side. The crop is turned over, not combined. University of Wisconsin Extension is blunt about the distinction: the inverter has "a narrow pick-up width that can only accommodate a narrow windrow," it is "quite a bit lighter-duty than a merger," and — the line that should settle most purchase decisions — "The inverter is not intended as a merging device." Its stated job is "to move an already formed windrow off of wet ground and invert it for faster drying."
How narrow? Extension doesn't publish a figure, but operators running the common New Holland units put it at about five feet, and that number is the reason most inverter purchases disappoint.
"They would work for that but the New Holland only has a 5 foot pick up. Look at a RCI or something built heavier and a wider pick up. I always say New Holland had a great idea for flipping rained on hay but didn't keep up with the demand of how they were used."
— Troy44deere, Manheim PA · AgTalk thread 1106047
Merger — a sideways conveyor
A merger picks the crop up with a full-width pickup head and moves it sideways on a belt or draper, then lays it down on top of another windrow. The crop never touches the ground between pickup and drop. Working widths run from around ten feet to over thirty-six feet, and field speeds can reach twelve miles an hour and beyond, according to Progressive Forage's equipment column. That combination — wide, fast, and no ground contact — is the entire argument for the machine.
What the research actually measured
Most of the published work on this question was pulled together by K.J. Shinners and R.T. Schuler of the University of Wisconsin in Equipment to Rake and Merge Hay and Forage. The results are worth knowing because several of them contradict what people assume.
| Study | Comparison | Finding |
|---|---|---|
| Savoie et al. | Parallel-bar vs. rotary rake | No difference in drying rate. Rotary lost slightly more crop. |
| Ohio / Claas trial | Rotary vs. wheel rake | Rotary produced the driest hay (20.9% vs. 25.0% first cut). |
| Garthe et al. | Parallel-bar rake vs. inverter | No difference in drying rate or crude protein. |
| Shearer et al. | Rake vs. two inverters | No difference in drying rates or losses. |
| Hoover | Inverter + bar rake vs. wheel + rotary | Inverter and parallel-bar rake had significantly less loss. |
| Hoover (rock movement) | Several rakes vs. inverter | Inverter and wheel rake moved significantly fewer rocks; the rotary rake moved the most. |
| Savoie & Beauregard | Four inversions vs. no manipulation | Drying rate significantly increased; an inverter "could advantageously replace a hay tedder." |
Three things fall out of that table. First, merging or raking does not dry your hay faster. That was the Colorado producer's first guess and the research does not support it. The one study that did show a drying gain got it from inverting four times, which makes it a tedding result, not a merging result. If you want faster dry-down, the lever is swath width off the mower, not what you do to the windrow afterwards — see how to make dry hay faster.
Second, the leaf-retention instinct that sends people looking at inverters is correct. Hoover measured significantly lower losses from the inverter and the parallel-bar rake than from wheel and rotary rakes. If crop loss were the only variable, the inverter would win.
And note the rock row carefully, because it is the opposite of what most people assume. It is not "rakes drag rocks, mergers don't." Hoover found the wheel rake among the cleanest machines tested and the rotary rake the worst offender by a distance — which fits, since a rotary sweeps a wide arc close to the ground. Wisconsin's own warning about rotary rakes is to "take care with this rake type not to sweep the ground too aggressively to avoid soil and rock contamination of the windrow."
Third — and this is the honest limitation — Shinners and Schuler note that no research has been published on windrow merger losses specifically. The expectation is that they resemble inverter losses, because both machines pick the windrow up rather than dragging it across the ground. That is a reasonable inference, not a measurement, and anyone selling you a merger on a leaf-loss number is going beyond the data.
The real reason to buy a merger: ash
If drying is a wash and leaf loss is unproven, what is left? Dirt. This is the argument that actually holds up, and it is the one experienced operators lead with.
"Mergers put a lot less rocks in the windrow vs a rake, that is a lot easier on the chopper. Mergers also can put the hay together with a lower ash content which is important for a dairy. If you are moving hay 30+ feet it will stay a lot cleaner riding on a conveyor vs rolling on the ground."
— Scony, Waterville MN · AgTalk thread 1163723
Ash is the mineral fraction left after a forage sample is burned. Some of it is internal — the plant's own minerals, roughly 8% in alfalfa and 6% in grasses. Everything above that came in off the ground. Dan Undersander, extension forage agronomist at the University of Wisconsin–Madison, reports in Reducing Ash in Forage that samples submitted to the UW Soil and Forage Analysis Laboratory average 12.3% ash for haylage and 10.3% for hay — meaning something like four percentage points of a typical sample is soil. Some samples have come in at 18%, which as he puts it means the farmer "have fed almost 1 pound of dirt with each 5 pounds of hay or silage!"
That dirt is not neutral. Because ash is subtracted when non-fiber carbohydrates are calculated, "each 1% ash is 0.98% less NFC (and therefore TDN)." You are buying tonnage and feeding gravel. And it comes straight out of how the crop is handled: ground-driven machines are the biggest offenders, because the wheels are turned by engaging the crop or the soil itself. As one HayTalk member put it after being asked how to keep dirt out of pea-and-oat silage:
"Theoretically, with a really good wheel rake and it set properly, the teeth shouldn't need to touch the ground. It should be the hay that rolls them. But that theory seldom actually works in practice."
— DanielW · HayTalk thread 103548
The one trial that actually compared all four machines
This is the study to know about, because it is the only replicated, peer-reviewed, multi-state comparison of rake types on ash. Neu and co-workers at Minnesota, Wisconsin and Penn State ran two cuttings of alfalfa at three locations, combining two swaths with a wheel rake, a sidebar rake, a rotary rake, or a merger, and sampled the crop at four stages from standing forage through to the bale or the chopper. It was published in Agronomy Journal in 2017.
| Finding | What it means for you |
|---|---|
| Merger and sidebar rake gave the least ash (9.0–13.6%); wheel rake the most (10.0–15.3%) | The real contrast is merger or sidebar rake vs. wheel rake — not "merger beats every rake." |
| Ash differed in five of six site-cuttings | The effect is consistent, not a one-field fluke. |
| First-cutting RFQ higher for merger/sidebar (121–165) than wheel rake (114–160) | On first cutting the ash difference did show up as measurable quality. |
| "Rake type rarely resulted in differences in forage nutritive values." | The honest caveat. Protein and fiber mostly did not move. Don't expect a test-sheet transformation. |
Take those last two rows together, because they are the crux of the buying decision. Ash goes down measurably and repeatably, and on first cutting that showed up in relative forage quality — but crude protein and fiber largely did not shift. A merger reliably buys you cleaner forage; it does not reliably buy you a better protein number. If your buyer, your ration or your chopper cares about ash and grit, that is worth real money. If you were expecting the hay test to look different across the board, it usually won't.
Undersander's separate estimate for the practical gain is 1 to 2 percentage points less ash from merging rather than raking. On a dairy ration that is a real number. On a beef operation feeding your own hay, it is usually not worth the price of the machine — which is exactly why the answer to "should I buy a merger" depends entirely on who eats the forage.
Two things worth noting if you are not buying one: raising a visible cloud of dust while raking is reckoned to add one to two percentage points of ash on its own, and it is better to move two swaths onto a stationary third than to rake everything to one side. Both cost nothing.
So does the setting that experienced merger owners mention in the same breath as ash — cutting height. Leaving a little more stubble keeps every following machine up out of the dirt. Alfalfa can be cut as short as an inch and a half for maximum yield, and every inch above that costs roughly half a ton per acre per year — but lower cutting also raises ash, and the Wisconsin conclusion is that 3 to 4 inches is usually the better trade. (If there is smooth bromegrass, orchardgrass or timothy in the mix, 3 to 4 inches is needed anyway to protect stand life.) The operator running mergers ahead of a chopper put the mechanical half of it plainly:
"If you leave a little extra stubble and keep your teeth out of the ground everything will last longer."
— Scony, Waterville MN · AgTalk thread 1163723
Why the inverter disappoints as a merger substitute
The most instructive thread in the whole corpus is an Alfalfa grower with 100 irrigated acres who wanted exactly what the research says he should want — leaf retention — and went looking for a cheap way to get it. Used New Holland inverters kept appearing at consignment sales, and he reasoned that if the previous owners were trading up to real mergers, the inverters must be worth having at the right price.
"NH 166. I keep seeing these for sale on consignment auctions and under the assumption that the previous owners are updated to an actual merger. I'm looking for an inexpensive merger. $10k or less and I thought a NH 166 may fit the bill. But I have no real world experience or have ever used one."
— welfarehill · AgTalk thread 1106047
Nobody in the thread agreed with him. The objection was not quality — it was throughput.
"We have owned and tried to force ourselves to use those 144 and 166 NH inverters, and just can't get along. They are slow, and too small capacity. They only are good around here at raising my blood pressure. As the other poster said, a rotary rake is much more usable."
— olivetroad, Fulton MO · AgTalk thread 1106047
"I've watched those inverters work, and run the Vermeer Twin Rakes for more than 2 decades now. No way would I put up with an inverter. I would note that the majority of hardcore alfalfa producers in the western US use hydraulic twin bar rakes. I don't think that is by accident."
— Gearclash, Sioux County NWIA · AgTalk thread 1106047
That roughly five-foot pickup is the arithmetic behind all of it. A machine that narrow has to make a pass for every windrow, and it cannot combine two windrows into one in a single pass at all. The gentlest machine in the field is worthless if you cannot cover the acres before the weather turns.
One more warning is worth repeating because it names a specific model: "absolutely do not buy a nh 144 under any circumstances," wrote sparrell in the same thread.
Where the inverter genuinely earns its keep
None of that means the machine is useless. It means it is a specialist. The clearest description of its actual job came from someone who owned one:
"We had a 166. The most effective use was to flip a windrow that had dried out on top but still damp underneath. Could roll after an hour or two of sun with minimal leaf loss. Handy to have around for low spots that transpire more moisture up through the hay."
— bb940p, SE WI · AgTalk thread 1106047
That is the case for owning one: a dry crust over a wet bottom, or a rained-on windrow that has to be opened up without shattering it. A rake tumbles that crop and knocks leaves off; an inverter turns it over intact. If you routinely fight that situation, an inverter alongside your rake makes sense. If you are trying to replace the rake with it, you will be disappointed. For the rained-on case specifically, see what to do with rained-on hay.
Side-by-side: which machine wins on what
| Rake | Windrow inverter | Merger | |
|---|---|---|---|
| How it moves crop | Rolls/sweeps it across the ground | Lifts, turns over, sets down | Lifts onto a belt, carries sideways |
| Working width | Wide, cheap to add — wheel rakes up to 36 ft | Narrow — NH units about 5 ft per operators | 10 ft to 36 ft+ |
| Combines windrows? | Yes, several | No — one at a time | Yes, and can build very large windrows |
| Ash / dirt | Wheel rake highest; sidebar close to a merger | Low | Lowest — 1–2 points less than a wheel rake |
| Rocks | Depends on type — rotary moved the most; wheel rake among the fewest | Measured among the fewest (Hoover) | Expected fewest — inferred, not measured |
| Crop loss | Highest for wheel/rotary; parallel-bar low | Measured lowest (Hoover) | Expected low — not directly measured |
| Drying benefit | None from the pass itself | Only with repeated inversions | None |
| Wet/heavy crop | Ground-driven types struggle | Fair | Best — its home ground |
| Very dry crop | Fine | Fine | Can pile on the belts if not set right |
| Purchase + upkeep | Lowest | Low, often cheap used | Highest on both counts |
What a merger actually costs to own
Progressive Forage's equipment column describes the merger as one of the most expensive machines in the hay lineup, with more moving and wear parts than the alternatives and correspondingly costly upkeep. The forum numbers bear that out — and they also show that the cost is manageable if you turn your own wrenches. (The 300-series machines that keep coming up below are Oxbo, which owners spell several different ways.)
"I have a 12 year old 334 Oxbow. Just got done rebuilding one section. The cam guide Was wore and a piece broke out and would not turn. When it broke we were able to finish merging with just two sections. Kind of nice you can shut Sections off individually. $1100 in parts and a day in our shop was good to go. If you can fix things your self buy used. If you hire all the repairs done buy a new one. Parts online were 1/3 the cost compared to Dealers price."
— Angus8335, Galena IL · AgTalk thread 1163723
Deferred maintenance is where it gets expensive. Scony, who runs mergers ahead of a chopper, laid out the interval that keeps the bill small: cam follower bearings every 3,000–4,000 acres, tine bar bearings every two to three sets of cam bearings, and if you stay ahead of the followers the cams themselves last a long time. Let the followers go and you are replacing cams. A neglected machine, in his words, "can be $15,000 in a hurry."
Two more buying notes from people running fleets of them. On model choice within a range:
"The 330 will have fewer problems than a 334 since the tine bars are shorter. The 330 also follows uneven ground better."
— IAhaymakr, Northwest Iowa · AgTalk thread 1163723
And on the variable nobody thinks to ask about: "soil types have a big impact on the lifespan of parts. Mergers running in sandy soil need parts more often than those run on silty clay soils," the same operator added. Sand is abrasive, and a machine whose pickup runs close to the ground eats it.
For scale on used pricing, one Michigan operator reported paying $35,000 for a used Miller Pro 310 and covering perhaps 1,200 acres a year with it — having rebuilt the center pickup head, drum, bearings, tine bars and cam rollers in the meantime. If your acreage is nowhere near that, the arithmetic points somewhere else. As Progressive Forage notes, hiring a custom harvester who already owns one is often the better answer, because mergers are expensive and are not economical on many farms.
"When the hay is dry it won't move off the belts"
One question in the merger thread never got answered, and it is worth answering because it is the most common complaint from new merger owners:
"High maintenance once they get older. But they're nice. I'm just curious how a merger works compared to a rake with hay, I've tried it a few times and it seems that when the hay is dry it won't move off the belts, it just piles up. Or am I doing something wrong?"
— Ksag@nsfarms, South Dakota · AgTalk thread 1163723
He is not doing anything fundamentally wrong — he is using a wet-crop machine on dry crop. Mergers are, as Progressive Forage puts it, mainly used for moving wet hay, though they can also be used in dry hay. Wet forage is heavy and coherent; it sits down on the belt and tracks sideways. Dry, slippery, low-density hay does not grip the same way, and the standard fix is the windguard and crop net, which hold the crop down against the belt instead of letting it ride up and bunch. Slowing the belt relative to ground speed and merging while the crop still has some moisture in it both help too. If it still piles, the crop is drier than the machine is designed to handle and a rake is the right tool that day.
The other half of the answer is that a merger is at its best when the machine behind it is hungry. That is why the biggest ones exist:
"Its for chopping haylage primarily. A 900 HP forage harvester needs 80+ feet of windrow put together to keep it full."
— matterhan, Mount Upton NY · AgTalk thread 1163723
That is the clearest statement of the merger's purpose anywhere in the corpus. It is a machine for feeding a bigger machine.
The baler version of the same logic
You do not need a chopper to use that reasoning. One operator uses a single merger purely to make baling better — putting the crop on dry ground first, then building the windrow to whatever size lets him run the baler at the speed he wants:
"I actually use my single merger for baling hay. It picks it up and puts it on dry ground (for dry hay) then can come back and put 2,3,4,5 etc together so I can drive slow with the baler. I also like it for baleage a lot of rakes struggle with really wet hay and there again I can put as many or few together I'd like."
— Lost1 · AgTalk thread 1163723
"Puts it on dry ground" is a trick a rake cannot do at all, and the wet-crop point is real — heavy, sappy baleage crop is exactly where rake teeth start dragging rather than rolling.
What cleaner windrows do for the bale itself
There is a downstream effect that rarely gets mentioned. Soil and small stones picked up in the windrow do not stop at the bale chamber — they travel through the pickup, the rolls or belts, and out onto the bale surface, where the net wrap has to hold them.
Grit on the outside of a bale is abrasive against the netting during wrapping and handling, and stones caught in the outer layers concentrate stress on individual net strands rather than spreading load across the width. It is one of the quieter reasons why bales made off rocky or dusty ground tend to look rougher and shed wrap sooner than bales off clean ground, whatever net wrap you are running. A merger will not fix a wrap problem on its own, but the same pass that protects a chopper's knives also gives the netting a cleaner surface to grip.
It matters more for stored-outside bales, where a torn or loose outer layer starts the weathering process early. If you are storing outdoors, the difference between a clean bale and a gritty one shows up months later.
How to decide
- You bale your own beef hay on decent ground. Buy the best rake you can afford and spend the difference elsewhere. Read the rake selection guide and stop there.
- You chop haylage, or sell to a dairy that tests ash. A merger pays. The 1–2 point ash reduction is a feed-value argument and a repair-bill argument for whatever the crop goes into next.
- Your ground is rocky or sandy. A merger's belt is the best answer, and fewer rocks reaching a chopper or baler pickup is worth real money. But if you are staying with a rake, the rock study is worth knowing: the rotary rake moved significantly more rocks than anything else tested, while the wheel rake moved among the fewest. Budget more for merger wear parts on sand.
- You are moving crop a long way sideways. Above about thirty feet of travel, riding on a belt versus rolling across the ground is a large difference in how much soil ends up in the feed.
- You fight dry-crust-over-damp-bottom windrows. An inverter as a second machine, not a first one.
- You are under a few hundred acres. Hire a custom operator who has a merger before buying one. This is the single most common piece of advice from people who own them.
Frequently asked questions
What is the difference between a hay merger and a windrow inverter?
A merger picks the crop up on a full-width head and carries it sideways on a belt to combine two or more windrows into one, at widths from about ten feet to over thirty-six feet. An inverter picks up a single windrow with a narrow pickup — operators put the common New Holland units at around five feet — and sets it back down turned over. The inverter flips one windrow; the merger combines several. University of Wisconsin extension states plainly that "the inverter is not intended as a merging device," yet the two are frequently called by each other's names on forums, which is why buyers end up disappointed.
Does a merger dry hay faster than a rake?
No. The published comparisons summarized by University of Wisconsin Extension found no drying-rate difference between rakes and inverters, and no drying advantage is claimed for mergers. The one study showing a real gain used four separate inversions, which is effectively tedding. Faster drying comes from a wide swath off the mower-conditioner, not from how you move the windrow afterwards.
How much ash does a merger save compared to raking?
Roughly 1 to 2 percentage points, per University of Wisconsin extension forage agronomist Dan Undersander. A replicated three-state trial published in Agronomy Journal in 2017 puts harder numbers on it: a merger or sidebar rake left the least ash (9.0–13.6%) and a wheel rake the most (10.0–15.3%). For context, average submitted haylage runs 12.3% ash and hay 10.3%, against internal plant ash of about 8% in alfalfa and 6% in grasses — so a large share of typical ash is soil. Each point of ash displaces about 0.98 points of non-fiber carbohydrate and TDN. The same trial found rake type "rarely resulted in differences in forage nutritive values," so expect cleaner forage rather than a transformed hay test.
Can I use a New Holland 166 inverter instead of buying a merger?
Experienced owners say no, and University of Wisconsin extension agrees in principle: "The inverter is not intended as a merging device." Its pickup is narrow — operators put the common New Holland units at about five feet — so it cannot combine two windrows in one pass, and people who tried describe it as slow and short on capacity. It is a good machine for flipping a windrow that is dry on top and damp underneath, and for rained-on hay. It is not a low-cost merger.
Why won't dry hay move across my merger belts?
Mergers are designed primarily for wet forage, which is heavy enough to sit down on the belt and track sideways. Dry, light, slippery hay rides up and bunches instead. Check that the windguard and crop net are set to hold the crop against the belt, slow the belt relative to ground speed, and merge while the crop still holds some moisture. If it still piles up, the crop is too dry for the machine that day and a rake is the better tool.
Do mergers really leave rocks in the field?
Probably — but it is an inference, not a measurement. No published study has tested a merger for rock movement. The closest evidence is Hoover's rake comparison summarized by University of Wisconsin extension, which found a windrow inverter and a wheel rake moved significantly fewer rocks than the other machines tested, while a rotary rake moved significantly more. Because a merger handles the windrow the way an inverter does — lifting it onto a belt instead of sweeping it along the ground — extension engineers say it is "safe to imply that the merger would move fewer rocks." Operators running mergers ahead of choppers report the same thing. A pickup run too low will still take stones.
Is a merger worth it for a small hay operation?
Usually not. Mergers are expensive to buy and to maintain, with more wear parts than a rake, and the guidance from both extension sources and owners is that they are not economical on many farms. Hiring a custom harvester who already owns one is often the better route. The break-even is driven by whether ash and rock contamination are actually costing you money — through a dairy ration, a chopper, or a hay buyer who tests.
Related guides
Header image: Kuhn Merge Maxx 1090 windrow merger, by MarcelX42, licensed CC BY-SA 4.0.
