Short answer: They are two different products doing two different jobs, and they are not interchangeable. Net wrap (or twine) is the inner binding that holds the bale's shape — it is porous and does not seal anything. Plastic stretch film is the outer airtight barrier that excludes oxygen so the forage can ferment into baleage. Net wrap cannot make a bale airtight, and film is not a substitute for binding. If you are wrapping high-moisture forage you need both: an inner binding — net wrap or suitable twine — plus outer stretch film.
Most of the people who land on this page are trying to sort out one thing: what is "plastic bale wrap", and how is it different from the net wrap the baler puts on? They look similar from the road — both are plastic, both go around a round bale — and the terms get used interchangeably in conversation. They are not the same product and they do not do the same job.
This guide separates the two, then walks through what actually matters if you are making baleage: moisture, timing, layers, storage, inspection and removal — with the source for every number, because published guidance genuinely differs between states.
Net wrap and stretch film: two jobs, not two brands of the same thing
| Net wrap (or twine) | Plastic stretch film | |
|---|---|---|
| Applied by | The baler, in the chamber | A separate bale wrapper, after the bale leaves the baler |
| What it is | An open knitted mesh, or strands of twine | A continuous, stretched plastic sheet |
| Job | Mechanical — binds the bale and holds its cylindrical shape for handling and transport | Barrier — excludes oxygen so the forage can ferment anaerobically |
| Airtight? | No. It is a mesh; air passes straight through it | Yes, when applied in enough overlapping layers and kept intact |
| Used on dry hay? | Yes, routinely | Sometimes used as a weather cover, but a different, much lighter package — not the baleage wrap. See below |
The distinction shows up clearly in how Extension writes about the process. Purdue Extension treats them as two separate steps — bale binding first, then "tightly wrap each bale with six to eight layers of good-quality, 1-mil-thick plastic that is resistant to sunlight." Penn State attributes the fermentation itself to the film, describing ensiling as the conversion of sugars to acids after oxygen is eliminated from the bale. The binding is not part of that seal.
One important distinction: wrapping dry hay is not the same job, and not the same package. Plastic film and sleeves are sometimes used on dry hay for weather protection, and that is a legitimate use — but it is deliberately a lighter application than baleage, and the difference matters for safety.
University of Kentucky sets out what dry-hay weather wrapping actually looks like: apply only enough film to cover the bale — typically about two layers at roughly 20% overlap, put ventilation cuts in the film, and only wrap hay that is genuinely dry, below about 20% moisture.
Do not put a baleage package on dry hay. A 6-to-8-layer airtight seal is designed for forage wet enough to ferment. Applied to dry hay it traps whatever moisture is present with nowhere to go, and there is no fermentation to acidify and stabilise the bale. Sealing dry hay does not turn it into baleage — and hay baled above the dry-hay moisture range still carries the heating and spontaneous-combustion risk that applies to any wet hay.
Does the inner binding have to be net wrap?
No — and it would be dishonest of us to tell you otherwise. We manufacture net wrap, so take this section as us reporting what the published guidance says rather than what we would like it to say.
Extension baleage publications treat net wrap and twine as both acceptable. Purdue's instruction is explicit: "Use plastic or untreated sisal twine, or plastic net wrapping to bind the individual bales at baling. Avoid treated sisal twine." No preference is expressed between the two.
The one baleage-specific advantage we could find published for net wrap is modest and advisory. Iowa Beef Center notes that wrapping in net wrap "can also be beneficial to prevent twigs and stems from puncturing the plastic" — a real point on stalky crops, since a puncture is what ends a bale's seal, but stated as a possible benefit rather than a requirement.
Beyond that, we could not find any published study comparing net wrap against twine specifically under stretch film, either for individually wrapped bales or in-line/tube systems. The net-wrap-versus-twine research that does exist — such as University of Georgia's comparison — is about dry hay stored outdoors, which is a different question from fermentation quality under film. Anyone claiming a measured baleage advantage for one binding over the other should be asked for the study.
What producers do report is a handling difference at feed-out. One Wisconsin operator who ran both:
"I used sisal and plastic twines under plastic wrap for a year or two on wet wrapped bales. The problem I had was finding the twine to take it all off when I took the plastic bale wrap off to feed. Netwrap is SO much easier to take off after removing the outer plastic wrap."
— Jim, Driftless SW Wisconsin · AgTalk thread 1196628, message 11175956
That is one operator's experience, not a trial, and we are presenting it as such. It is consistent with what we hear, but it is not evidence that twine ferments worse. If your twine comes off cleanly and your bales hold shape, the published guidance gives you no reason to change. Our net wrap vs twine comparison covers the general trade-off for dry hay, where the evidence is stronger.
Moisture: what the states actually publish
This is the number that decides whether you get baleage or a problem, and the published windows differ. Each row is one source's own figure:
| Source | Crop / scope | Published moisture guidance | What the source says goes wrong |
|---|---|---|---|
| Penn State | Baleage generally | Fermentation possible 30–70%; ideal 45–60% | Increased spoilage outside the 45–60% band — too dry as well as too wet; two extra wraps advised outside it |
| Iowa Beef Center | Baleage generally (beef systems) | 40–60% | Above 60%, clostridium and botulism risk |
| Iowa State Crop News | First-crop alfalfa specifically | 50–60% | Too wet gives clostridial fermentation, butyric acid, protein degradation, reduced intake and slimy "stinky" baleage |
| Purdue | Baleage generally | 50–60% | Poor fermentation raises botulism and listeriosis concerns; those toxins cannot form once pH falls below 4.5 |
Note the scope column. These are not all answering the same question — the Iowa State figure is written for first-crop alfalfa, while the others address baleage generally. Reading across them, 40–60% is the common ground and 50–60% is where most converge, but take the number from guidance written for your crop and your state.
The failure modes run in both directions. Penn State is explicit that spoilage increases outside the 45–60% band — too dry is a problem as well as too wet, because dry forage does not ferment properly and traps more air. On the wet side, Iowa State describes clostridial fermentation in first-crop alfalfa producing butyric acid, degraded protein, reduced intake and slimy "stinky" baleage. Purdue frames the risk differently: poor fermentation raises botulism and listeriosis concerns, and those toxins cannot form once pH falls below 4.5 — which is why achieving a proper fermentation, not merely sealing the bale, is the safeguard. Seepage from over-wet bales is a related nuisance, though none of the sources reviewed here quantifies it.
How fast to wrap after baling
Published figures differ, and they are source-specific rather than a single agreed deadline:
- Purdue: within 4 hours is the ideal.
- Iowa Beef Center and Iowa State Crop News: within 12 hours.
- Penn State: within 24 hours, and "as quickly as possible".
The common thread across all three is "as soon as you can" rather than a universal cut-off, and the reason is heat: an unwrapped high-moisture bale keeps respiring, internal temperature climbs, and above roughly 120°F protein begins to be heat damaged — quality you do not get back. Penn State frames the goal as keeping the bale below that temperature. Take the figure your own Extension service publishes rather than splitting the difference.
Film layers, and what a "layer" means
First, a distinction that is easy to misread: layers and mils are not the same thing. Some guidance specifies film thickness in mils and some specifies the number of layers. Penn State's "6 to 8" figure refers to mils of film thickness, not to a layer count. Purdue separately calls for six to eight layers of good-quality 1-mil film that resists sunlight, and Iowa Beef Center also gives 6–8 layers. Check which quantity a given recommendation is talking about before you set the wrapper.
Treat six layers as the normal working minimum. Ohio State advises going to eight where the forage is more mature, drier or has sharper stems — the conditions that make a puncture more likely. Penn State adds two extra wraps where moisture falls outside its ideal band.
Layers are not machine revolutions — individual bale wrappers only. On an individual wrapper run at 50% overlap (University of Georgia; University of Kentucky), one complete whole-bale coverage pass provides two layers. Repeating that pass gives four layers — the 2+2 method; three complete passes give six layers (2+2+2).
Do not equate a pass with one machine revolution. How many turntable or sweep-arm revolutions make up one complete coverage pass depends on wrapper type, dispenser count, bale size and film width. Take that count, and your layer and overlap settings, from your own wrapper's operator manual. This is a machine specification, not an Extension recommendation, and the manual also governs the machine's safety procedures.
In-line and tube wrappers work differently, and the 50% figure above does not transfer to them. Bales are wrapped end-to-end into a continuous tube rather than sealed individually, so both the overlap setting and the pass arithmetic are governed by that machine's own specification — for example the Tube-Line TL5500 AX2 manual. It also changes feed-out: University of Kentucky notes that with in-line wrapped baleage the bales must be consumed as the line is opened, because opening one exposes the next.
Bale density
Density is the quiet variable. Penn State reports that maximising bale density brings several forage-quality benefits: greater density means the bale stays viable longer for feeding after the plastic comes off, and produces greater acid content, lower pH and lower residual sugar — all indicating a proper fermentation. Purdue puts the mechanism simply: a dense, tight bale improves fermentation because less pore space is occupied by air. Iowa Beef Center's practical route to it is a slow ground speed through the windrow.
This is also where the inner binding genuinely does its job — a bale that holds its shape between the chamber and the wrapper gives the film a uniform surface to seal against.
How long before you can feed it
The sources differ substantially here, so we are not going to give you one number:
- Penn State: fermentation takes 14 to 21 days to become stable.
- Iowa State Crop News: a minimum of 30 days to fully ensile.
- Iowa Beef Center: wait at least 6 weeks to ensure proper ensiling.
- University of Kentucky: wait at least 8 weeks after wrapping before feeding, noting full fermentation occurs within 6 to 8 weeks and usually in under 4.
Kentucky is the most conservative and Penn State the most permissive. If the forage was high-risk going in — a drought-stressed or heavily stressed crop where nitrate or prussic acid is a concern — the longer end is the sensible choice, and a test before feeding is better than either.
Storage, inspection and repair
Site. Purdue is the source for the drainage point: place the bales on a well-drained site. Penn State contributes two different details — line bales up north to south to slow UV degradation of the plastic, and wrap as close to the storage site as possible, since every move is a chance to tear film.
The sources reviewed here do not address stacking individually wrapped baleage bales, so we are not going to offer guidance on it.
Inspection and repair. This is the maintenance job that decides whether the crop survives:
- Penn State: wrapped bales should be checked frequently for holes, and as soon as a hole is found it should be taped and sealed completely with plastic silage tape. Oxygen entering after fermentation causes spoilage.
- Purdue: inspect often, and cover holes with UV-protected plastic tape from the plastic supplier — explicitly not duct tape.
- Purdue on bird damage: storing individually wrapped bales on end reduces holes caused by raptors, because there is more wrap overlap on the ends.
Feed-out
Once the seal is broken, the clock starts. University of Kentucky's guidance is that an individually wrapped bale can be fed at any point if there is a dire need, provided it is quickly — under 24 hours — and completely consumed. For in-line wrapped baleage, bales have to be consumed as the line is opened, because opening one exposes the next.
On how long wrapped baleage keeps, the only numeric figure we found in Extension guidance is Purdue's: use the bales within a year to limit storage loss. No fetched Extension source publishes a UV-resistance rating or a film service life in months, and we are not going to repeat manufacturer durability figures as though they were research.
Removing both layers — and why it matters
Both the film and the binding come off before the forage reaches the animal. Purdue states the film part plainly: unwrap the plastic just before feeding. The binding is the part more often skipped, and the consequences are documented.
University of Nebraska–Lincoln BeefWatch summarises the research:
- NDSU work shows rumen microbes do not digest plastic net wrap or biodegradable twine.
- Sisal twine is digested, but far more slowly than hay — so it too should be removed.
- In an SDSU study, cows fed ground, net-wrapped hay for 140 days accumulated a softball-sized mass in the rumen of 0.8 to 1.1 pounds of net wrap. Grinding may reduce particle size, but health issues can still occur — processing is not a substitute for removal.
- There is no treatment for accumulated binding material in the rumen. Prevention is the only control.
- An SDSU survey found only 54% of producers removed net wrap or twine when feeding whole bales, and 11% when grinding.
The same point applies to our own product, which is why we say it here rather than in the small print. See cattle eating net wrap.
On the machinery. We could not find an Extension publication covering bale-wrapper operating safety specifically, so we are not going to invent one. Follow your wrapper's operator manual: shut down and isolate the machine before clearing a wrap or working on it, keep clear of the crush path of a turning or tipping bale, and never work under a suspended bale. These are general machinery-safety principles and the manual is the authority for your machine.
What to do with the used plastic
This is where a lot of marketing gets ahead of reality, so here is what is actually documented. Wisconsin DNR states that in Wisconsin and other parts of the country, options for recycling silage bags, bale wrap and bunker covers are limited, with the main obstacle being the cleaning, collecting and transporting of used film.
- Stretch film is recyclable in principle, and some regional programmes accept silage bags, bunker covers and greenhouse film.
- Net wrap and plastic twine are generally not accepted — the Minnesota programme excludes net wrap. In most jurisdictions it goes to landfill.
- Do not burn it. Wisconsin DNR notes burning ag plastic releases toxic and potentially carcinogenic compounds including dioxins and furans, and open burning is illegal in Wisconsin. Their guidance is to send what cannot be recycled to landfill rather than burning or burying it on your land.
Rules differ by state — the Wisconsin position above is that state's, not a national one. Check your own state's regulations and ask your supplier what take-back exists locally. We make no biodegradability or recyclability claim for net wrap.
The bottom line
Net wrap and plastic bale wrap are not competing products and not two names for the same thing. The binding holds the bale together; the film keeps the oxygen out. Baleage needs both — an inner binding, net wrap or suitable twine, plus outer stretch film — and the published evidence supports either binding — with net wrap's one documented baleage-specific advantage being that it can help keep stems from puncturing the film on stalky crops.
Where the real quality is won or lost is elsewhere: baling in the 40–60% moisture band, wrapping within 4 hours and no later than 12, applying six to eight layers — three complete coverage passes at 50% overlap on an individual wrapper, or your machine's equivalent setting — building a dense bale, storing on drained ground, taping every hole the day you find it, and taking both layers off before anything reaches the feeder.
If you need net wrap that runs cleanly and comes off in one piece, see our XES® bale net wrap and the net wrap sizes guide to match it to your baler.
Frequently asked questions
Can I wrap dry hay in plastic the same way as baleage?
No, and it is not the same package. University of Kentucky describes dry-hay weather wrapping as applying only enough film to cover the bale, typically about two layers at roughly 20 percent overlap, with ventilation cuts in the film, and only on hay that is genuinely dry at below about 20 percent moisture. A 6 to 8 layer airtight baleage package on dry hay traps whatever moisture is present with no fermentation to stabilise the bale. Sealing dry hay does not turn it into baleage, and hay baled above the dry-hay moisture range still carries the usual heating and spontaneous combustion risk.
Is net wrap the same as plastic bale wrap?
No. Net wrap is an open knitted mesh applied by the baler to bind the bale and hold its cylindrical shape; air passes straight through it. Plastic bale wrap, or stretch film, is a continuous plastic sheet applied by a separate bale wrapper to exclude oxygen so high-moisture forage can ferment into baleage. Net wrap cannot make a bale airtight and film is not a substitute for binding. Baleage needs both: an inner binding — net wrap or suitable twine — plus outer stretch film, per Purdue Extension.
Does net wrap go on under the plastic stretch film for baleage?
The binding goes on first in the baler and the film goes over it afterwards. Purdue Extension treats them as two separate steps and calls for an inner binding — net wrap or suitable twine, avoiding treated sisal — plus outer stretch film. Net wrap is not specifically required. Iowa Beef Center does note that net wrap can be beneficial for preventing twigs and stems from puncturing the plastic, which matters most on stalky crops.
Is net wrap or twine better under film for baleage?
Extension publications treat both as acceptable and do not express a preference. Purdue says to use plastic or untreated sisal twine, or plastic net wrapping, and to avoid treated sisal twine. We could find no published study comparing net wrap against twine specifically under stretch film; the net-wrap-versus-twine research that exists concerns dry hay stored outdoors, which is a different question. The one baleage-specific point published for net wrap is that it can help prevent stems puncturing the film.
What moisture should baleage be baled at?
Published windows differ by state and by crop. Iowa Beef Center gives 40 to 60 percent for baleage generally; Purdue gives 50 to 60 percent; Iowa State Crop News gives 50 to 60 percent specifically for first-crop alfalfa; and Penn State gives an ideal of 45 to 60 percent within a possible 30 to 70 percent range. Common ground is 40 to 60 percent, with most converging on 50 to 60, but take the number from guidance written for your crop and state. Penn State notes spoilage increases outside the ideal band in both directions. On the wet side Iowa State describes clostridial fermentation in first-crop alfalfa giving butyric acid, degraded protein and reduced intake, while Purdue frames the risk as botulism and listeriosis concerns from poor fermentation, noting those toxins cannot form once pH falls below 4.5.
How soon should baleage be wrapped after baling?
Published figures are source-specific rather than a single agreed deadline. Purdue gives 4 hours as the ideal, Iowa Beef Center and Iowa State Crop News give 12 hours, and Penn State gives 24 hours while saying as quickly as possible. The common thread is as soon as you can, and the reason is heat: an unwrapped high-moisture bale keeps respiring, and above about 120 degrees Fahrenheit protein begins to be heat damaged. Take the figure your own Extension service publishes.
How many layers of plastic does baleage need?
Watch the units first: Penn State's 6 to 8 figure refers to mils of film thickness, not layers. Purdue calls for six to eight layers of good-quality 1-mil film that resists sunlight, and Iowa Beef Center also gives 6 to 8 layers. Treat six layers as the normal working minimum; Ohio State advises eight where forage is more mature, drier or has sharper stems, and Penn State adds two extra wraps where moisture falls outside its ideal band. On an individual bale wrapper run at 50 percent overlap, per University of Georgia and University of Kentucky, one complete whole-bale coverage pass gives two layers, so six layers means three complete passes. In-line and tube wrappers work differently and that overlap figure does not transfer to them. Take the revolution count and your layer and overlap settings from your own wrapper manual.
How long after wrapping can baleage be fed?
Sources differ significantly. Penn State says fermentation stabilises in 14 to 21 days, Iowa State Crop News gives a 30 day minimum, Iowa Beef Center says at least 6 weeks, and University of Kentucky says wait at least 8 weeks while noting full fermentation occurs within 6 to 8 weeks. Kentucky is the most conservative. If the crop was stressed and nitrate or prussic acid is a concern, take the longer end and test before feeding.
Do I have to remove the net wrap as well as the plastic film?
Yes. University of Nebraska-Lincoln BeefWatch reports NDSU research showing rumen microbes do not digest plastic net wrap or biodegradable twine, and that sisal twine digests only slowly. In an SDSU study, cows fed ground net-wrapped hay for 140 days accumulated a softball-sized mass of 0.8 to 1.1 pounds of net wrap in the rumen, and grinding may reduce particle size but health issues can still occur. There is no treatment for accumulated binding material, so removal is the only control.
Can bale wrap and net wrap be recycled?
Only partly, and net wrap generally cannot. Wisconsin DNR states that options for recycling silage bags, bale wrap and bunker covers are limited, the main obstacle being cleaning, collecting and transporting used film. Stretch film is recyclable in principle and some regional programmes accept silage bags and bunker covers, but net wrap and plastic twine are generally excluded and go to landfill. Do not burn it: Wisconsin DNR notes burning releases dioxins and furans and open burning is illegal in that state. Rules vary, so check your own state and ask your supplier about local take-back.
Written by the XES Netting team. We manufacture bale net wrap, which is why this article is explicit about where the published evidence supports net wrap and where it does not. Every farmer quote is verbatim with a link to the original thread.
Sources: Purdue University Extension, Pest & Crop newsletter, "Baleage Practices for Success" (Keith Johnson) — binding options, 50–60% moisture, 6–8 layers of 1-mil film, 4-hour wrapping target, well-drained site, UV-protected tape and the duct-tape warning, raptor damage, unwrap just prior to feeding, use within a year (extension.entm.purdue.edu, accessed August 16, 2026); Penn State Extension, "Baleage" — 30–70% possible and 45–60% ideal, oxygen elimination and fermentation, bale density research, 14–21 day stabilisation, well-drained storage, north–south orientation, frequent inspection and plastic silage tape (extension.psu.edu, accessed August 16, 2026); Iowa Beef Center / Iowa State University, "Baleage," Growing Beef, May 2024 — 40–60% moisture, 6–8 layers within 12 hours, slow ground speed for density, at least 6 weeks before feeding, net wrap and stem puncture (iowabeefcenter.org, accessed August 16, 2026); Iowa State University Extension Crop News, "Considerations for Baleage in First-Crop Alfalfa," 2019 — 50–60% moisture for first-crop alfalfa, 12-hour wrapping, 30-day minimum ensiling, butyric acid and protein degradation (crops.extension.iastate.edu, accessed August 16, 2026); Tube-Line TL5500 AX2 bale wrapper operator manual — wrapper settings and safety procedures (tubeline.ca, accessed August 16, 2026); University of Kentucky Forage Extension baleage FAQ — at least 8 weeks before feeding, feed-out within 24 hours of unwrapping, in-line feed-out sequence, 50% overlap on individual wrappers, and dry-hay weather wrapping at about two layers with roughly 20% overlap and ventilation cuts on hay below about 20% moisture (forages.mgcafe.uky.edu, accessed August 16, 2026); University of Georgia Extension, "Baleage Frequently Asked Questions," B1508 — 50% overlap on individual wrappers (fieldreport.caes.uga.edu, accessed August 16, 2026); Ohio State University Extension, "Fall Baleage Production," 2018 — eight layers for more mature, drier or sharper-stemmed forage (u.osu.edu, accessed August 16, 2026); University of Georgia Extension Forage Team, "Choosing the Right Wrap," 2020 — net wrap versus twine for dry hay outdoor storage (site.extension.uga.edu, accessed August 16, 2026); University of Nebraska–Lincoln BeefWatch, "Hold the Net Wrap and Twine," 2024 — NDSU and SDSU rumen research, sisal digestion, grinding, producer survey (beef.unl.edu, accessed August 16, 2026); Wisconsin Department of Natural Resources, agricultural plastics recycling (dnr.wisconsin.gov, accessed August 16, 2026); Recycle Minnesota, agricultural plastic recycling programme scope (recycleminnesota.org, accessed August 16, 2026). Published guidance differs between states; figures are attributed to the institution that published them and are for orientation. Follow your own Extension service, your wrapper's operator manual, and your veterinarian or nutritionist for feeding decisions.
Hero image: Wrapped silage bales — photo by Jean Barrow on Wikimedia Commons, licensed under CC BY-SA 2.0.
