Baling converts standing crop to portable, storable feed. But baling does not stop the biological and physical processes that degrade that feed — it only slows them. From the moment a bale leaves the chamber until it is broken open at the feed bunk, dry matter loss continues. Research consistently puts average outdoor round bale storage losses at 15 to 30 percent of dry matter, with worst-case uncovered bare-ground storage reaching 35 to 45 percent in wet climates. At $80 per bale, a 20-percent DM loss means $16 of feed value disappears per bale before the first animal touches it. Across 300 bales, that is $4,800 of invisible annual loss. Every improvement in round bale storage practice reduces that number — and the improvements are not expensive.
Where Dry Matter Goes: The Four Round Bale Storage Loss Pathways
Understanding where dry matter loss originates is the first step to preventing it. Four distinct round bale storage loss mechanisms are responsible, and each responds to different management interventions:
4 — Animal and Mechanical Damage
1–8% DM loss
Rodent chewing, bird pecking, deer access, and mechanical damage during handling (loader spike punctures, bale drops, net wrap tears) create pathways for moisture entry that accelerate all three biological loss pathways simultaneously. A single loader spike puncture through net wrap on a silage bale creates a 4 to 6 cm² oxygen access point that can support a spoilage zone extending 20 to 30 cm in all directions from the puncture within 3 to 4 weeks.
Storage Site Selection: Six Criteria That Determine How Much You Lose
Round bale storage site selection is the single highest-leverage intervention. No other improvement — net wrap upgrade, tarp covering, or row alignment — returns as much DM preservation per dollar as moving bales from bare, shaded, wet-soil locations to elevated, well-drained, sunny sites. Use the following assessment card to score your current storage site.
Storage Site Self-Assessment — Score Your Current Location
| Criterion |
✔ Best |
△ Acceptable |
✗ Problem |
| Ground surface |
Crushed rock or gravel pad, ≥10 cm depth |
Compacted stone or concrete |
Bare soil, grass, or clay |
| Drainage slope |
≥2% slope away from bales in all directions |
Level site with perimeter drainage |
Low-lying area, water pools after rain |
| Sun exposure |
Full sun all day — no shade from trees or buildings |
Partial shade (under 4 hrs/day) |
Shaded most of day; north-facing slopes |
| Row orientation |
North–South row direction (both sides equal sun) |
±30° of N–S |
East–West rows (one side permanently shadowed) |
| Bale spacing |
End-to-end contact within row; ≥1 m between rows |
30–50 cm between rows |
Bales touching side-by-side between adjacent rows |
| Pest exposure |
No brush/grain nearby; fencing or mesh barrier |
Open field, low deer/rodent pressure |
Adjacent to wooded area or grain bins; high pest activity |
If your site scores 4 or more “Problem” ratings, improving the site before adding other storage enhancements (net wrap upgrade, tarps) will produce greater DM savings per dollar spent.
Net Wrap vs Twine: How Binding Choice Changes Outdoor Storage DM Loss
Twine and net wrap differ for round bale storage in a way that most operators think about only at the baler — cost per bale, wrapping speed, bale shape retention. But their impact on outdoor storage DM loss is equally significant and considerably less discussed. The mechanism is direct: net wrap covers a large fraction of the bale surface with a moisture-resistant barrier; twine covers essentially none.
Twine-Bound Bale — Outdoor Storage
✗ 0% bale surface covered — bale is fully exposed to rain, dew, and sun UV degradation
✗ Moisture channels form between twine wraps — rain runs along twine grooves into the bale interior
✗ Outdoor storage DM loss: 15–30% in humid climates over 6–9 months
✓ Lower per-bale wrapping cost
✓ Suitable for barn-stored or immediately-fed hay
Net-Wrapped Bale — Outdoor Storage
✓ ~60% of bale surface covered — continuous net barrier sheds rain from top and sides
✓ Smooth outer surface promotes water runoff rather than infiltration
✓ Outdoor storage DM loss: 5–15% in same conditions
✓ Bale shape retention improves stacking stability
△ Higher per-bale wrapping cost (+$1.50–3.00 per bale vs twine)
The net wrap payback calculation: At 15% vs 8% DM loss on 200 bales of $80 hay, net wrap saves approximately $1,120 annually (200 × $80 × 0.07 = $1,120). At $2 per bale net wrap premium over twine, the additional cost is $400 per year. Net annual saving: $720. Net wrap pays for itself more than twice over on an outdoor storage program of this size.
Our full range of net-wrap round baler models is configured with continuous net wrap delivery systems whose drive synchronization is maintained by the baler’s main agricultural drive gearbox — ensuring consistent wrap tension and overlap on every bale throughout the production day, not just on the first bale after a fresh net roll.
Six Storage Configurations: Measured DM Loss and Practical Trade-Offs
Research on round bale storage from USDA Agricultural Research Service, University of Wisconsin Extension, and Cornell Cooperative Extension consistently shows that storage configuration is the single largest controllable variable in round bale DM loss. The table below summarizes measured dry matter loss ranges across six common storage configurations, from worst to best:
| Storage Configuration |
DM Loss Range |
Weather Dependence |
Primary Loss Driver |
| Twine, bare soil, shade |
25–45% |
Extreme |
Ground contact + full surface exposure + no UV drying |
| Twine, bare soil, open sun |
18–30% |
Very High |
Ground contact losses + rain channels between twine wraps |
| Net wrap, bare soil, open sun |
12–22% |
High |
Ground contact remains; surface protected by net |
| Net wrap, gravel pad, N–S row |
6–14% |
Modéré |
Mostly surface spoilage; ground contact eliminated |
| Net wrap, gravel pad, tarped or open shed |
3–8% |
Low |
Mostly respiration; surface protection largely complete |
| Net wrap, enclosed barn, dry floor |
1–4% |
Minimal |
Respiration only; all weather exposure eliminated |
DM loss ranges from published agronomic research on 1.2 m diameter round bales over 6–9 month storage periods in temperate U.S. climates. Net wrap: standard 1.5 m UV-stabilized LLDPE, two passes at 50% overlap.
Single Row vs Stacked: DM Loss, Space Efficiency, and Structural Risk
Single-row end-to-end round bale storage is consistently the best configuration for dry matter preservation. The temptation to stack bales — pyramid style or two-high in rows — is driven by space limitations: stacking doubles the number of bales that fit in a given storage footprint. But stacking comes with a DM loss penalty that must be weighed against the land cost it saves.
Single End-to-End Row ✔ Best
end view — single layer, bales touching
✔ Full air circulation on all exposed surfaces
✔ No contact zone between stacked bales — no moisture entrapment at touch points
✔ Lowest DM loss of any outdoor configuration
△ Requires more linear ground footage per bale
Two-High Pyramid Stack △ Acceptable
end view — pyramid, 1 on top of 2
✔ 33% more bales per row length vs single layer
△ Contact zones between top and bottom bales trap moisture — +3–6% DM loss at contact points
△ Top bale net wrap degrades faster from full UV exposure
✗ Requires mechanical handling — no safe manual stacking above single layer
Three-High or Higher ✗ Not Recommended
end view — 3-high, unstable
✗ Bottom bales crushed by static load above — net wrap torn, DM loss at crush zone severe
✗ Roll-off risk becomes significant above 2 high, especially on any slope
✗ Inner bales in deep stacks inaccessible for condition inspection
Covered Storage: When the Investment Pays Off
The progression from bare-soil outdoor round bale storage to a basic open-sided shed represents the largest single DM improvement available — typically reducing losses from 18 to 30% down to 4 to 8%. Whether that improvement justifies the capital cost depends on operation size, hay market value, and how long the building amortizes. The calculation is straightforward:
Annual DM Loss Cost — Bare Soil Outdoor (20% avg)
200 bales × 20% DM loss = 40 bale-equivalents lost
40 × $80 market value = $3,200/yr invisible loss
At 300 bales: $4,800/yr lost
At 400 bales: $6,400/yr lost
With Open-Sided Shed (6% avg loss) — Same 200 Bales
200 bales × 6% DM loss = 12 bale-equivalents lost
12 × $80 = $960/yr loss (saving $2,240/yr)
Simple 50-bale open shed: $5,000–12,000 to build
Payback at 200 bales/yr: 2.2–5.4 years
Break-even calculation assumes $80/bale market value, 20% outdoor vs 6% covered DM loss differential. Actual payback depends on local hay prices, climate, and construction costs. On operations below 100 bales per year, hay tarps ($300–600 for 20-bale coverage) typically offer better ROI than building construction.
Moving Bales to Storage: Why Handling Equipment Matters for DM Preservation
Every handling event in round bale storage between the bale chamber and the storage site is an opportunity for net wrap damage. A front-end loader spike driven through a net-wrapped bale during round bale storage creates a physical hole in the net — and every subsequent rain event channels water through that hole into the bale interior. Within 4 to 6 weeks of a mid-bale puncture, measurable spoilage zones develop around the puncture site regardless of how well the bale is otherwise stored.
The correct handling approach for net-wrapped bales uses equipment that grips the bale without penetrating the net surface: a bale cradle, a bale grapple, or a bale spike that enters from the flat bale end rather than through the curved net-covered lateral surface. The round bale loader and transporter models in our lineup use hydraulic cradle loading that lifts and moves bales by supporting the bale’s curved outer surface — no spike penetration, no net damage, full bale integrity from field to storage site.
For operations moving more than 50 bales per cutting to a central storage site, a dedicated bale transporter also reduces the incidental tire track damage to stored bales that accumulates when tractors maneuver close to existing rows. Each tractor pass near stored bales creates ruts and compaction that eventually deflects drainage away from the gravel pad and toward the bale base — undoing the drainage benefit the gravel pad was installed to provide.
Frequently Asked Questions: Round Bale Storage
How important is gravel vs crushed rock for the storage pad?+
Both work. The key property is free drainage and bale-to-soil separation, not the specific material. Crushed limestone #57 (approximately 19 mm diameter angular aggregate) is the most widely used and cost-effective option — the angular shape compacts less than rounded gravel and maintains a porous structure over multiple seasons. Minimum depth: 10 cm for bales up to 500 kg; 15 cm for heavy silage bales above 600 kg. An alternative to pad construction is using treated or painted railroad ties, concrete blocks, or old tires as bale risers to create 15 to 20 cm of air space under each bale — effective and zero capital cost if the materials are available.
Can I store net-wrapped dry hay bales directly adjacent to each other end-to-end?+
Yes — end-to-end contact within a row is standard practice and is actually recommended because it prevents rain from pooling in the concave gap between adjacent bale ends. The flat bale ends have less net wrap coverage than the lateral surface (net wrap wraps the circumference but the cut ends are exposed), so any gap between adjacent bale ends creates a small precipitation collection zone. Storing bales end-to-end touching eliminates this gap. Between rows, however, maintain at least 1 meter clearance to allow air circulation and to prevent moisture from accumulating in the side-contact zone where two rows meet.
How do hay tarps compare to an open-sided shed for DM preservation?+
A well-maintained, properly anchored hay tarp can achieve DM loss rates of 5 to 9% — similar to a basic open-sided shed (3 to 8%). The difference is durability: a quality hay tarp lasts 3 to 5 seasons if properly stored off-season and not subjected to UV damage from poor anchoring (which allows the tarp to flap and degrade at the edges). An open-sided shed, by contrast, lasts 20 to 30 years with minimal maintenance. The 20-year cost comparison typically favors a permanent structure for operations above 150 bales per year, and tarps for smaller programs or situations where the storage site changes between seasons. Tarps also require labor to place, anchor, and remove — the annualized labor cost is a real addition to their cost calculation.
How much storage DM loss should I expect on a good outdoor site in the U.S. Midwest?+
On a well-managed round bale storage site in the Midwest — net-wrapped bales, gravel pad, north-south rows, full sun, no shade — DM losses over a 6 to 9 month storage period from June baling to March feeding typically run 8 to 14%. This accounts for a summer period of significant precipitation and a winter period with snow load. Operations that push their site management to best practices (elevated bales on generous gravel pad, bales in tight single rows, excellent drainage) can reach 5 to 8%. Losses below 5% for outdoor storage in the Midwest are rare and generally require covered storage. For comparison, well-run Midwest barn storage runs 2 to 4% DM loss annually.
A bale has heavy surface mold when I open it. Is it still safe to feed?+
A round bale with heavy surface mold should be assessed by how far inward the mold extends before feeding decisions are made. Peel away the outer spoiled layer (typically 5 to 15 cm) and inspect the interior hay. If the interior is still bright, dry, and free of mold, the inner hay is generally safe to feed to beef cattle at limited rates (below 30% of total diet). Moldy hay should not be fed to horses, breeding stock, or young animals under any circumstances due to mycotoxin risk. For dairy cattle, heavily molded hay is a feed quality and butterfat risk — have the interior hay tested for mycotoxins before inclusion in dairy rations. When in doubt, consult your extension nutritionist or veterinarian before feeding visibly molded hay to sensitive animals.
Is it worth moving bales from the field to a better storage site vs just storing them where they land?+
On the economics: moving bales to a centralized gravel pad storage site typically costs $1 to $4 per bale in equipment time and fuel. The DM preservation improvement from moving bales off bare-soil field storage to a managed gravel pad site is typically 8 to 15 percentage points. On a $80 bale, that is $6 to $12 of feed value preserved per bale — paying back the transport cost 2 to 3× even on the first season. The case for centralized managed storage is almost always positive on economics for operations above 100 bales annually. Below 100 bales, the break-even depends heavily on your specific field soil conditions and local precipitation. Our bale loader and transporter products are designed for exactly this use case — cost-efficient, damage-free movement from field to storage yard.
Complete Hay System Support
Net-Wrap Balers, Bale Transporters, and Storage Planning — All from One U.S. Warehouse
Our California team advises on net-wrap baler selection for outdoor storage programs, matches bale transporter capacity to your annual bale volume, and can recommend storage site improvements specific to your climate and operation scale.
✔ Net-Wrap Round Balers
Full lineup, California warehouse
✔ Bale Loaders & Transporters
Hydraulic cradle — no net damage
✔ Same-Day Parts Dispatch
Net wrap, belts, bearings in stock
America Ever-Power Forage Baler Equipment INC. | 1401 21st ST STE R, Sacramento, CA 95811
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