Hay mowing and hay quality discussions in most operations focus on baling, storage, and wrapping — the steps from the second day onward. What gets less attention is that the most important quality window in the entire hay-making process is the period between the blade passing through standing crop and the bale chamber sealing that crop from the atmosphere. That window is controlled by two variables: how fast the crop dries (determined largely by the conditioner) and how much of the crop’s nutritional value is consumed by respiration before drying is complete (determined by how many hours the crop spends in the field). Hay mowing decisions — mower selection, conditioning method, and cutting height — directly control these variables — and all of them have a measurable dollar value at the elevator.
How Curing Speed Affects RFV and Protein: The Respiration Loss You Can’t See
From the moment hay mowing begins, the living cells in the cut crop continue to respire — consuming oxygen and oxidizing sugars, releasing carbon dioxide and heat. This respiration produces no visible symptom. The hay still looks green, smells clean, and feels normal. But the water-soluble carbohydrate (WSC) content — which drives Relative Feed Value (RFV) alongside fiber content — is declining at approximately 0.5 to 1.5% of dry matter per hour in warm, humid conditions. Over 8 additional field hours (the difference between a 4-hour and 12-hour curing period), cumulative WSC loss reaches 4 to 12% of DM — a change that is consistently detectable in certified forage analysis.
The fiber fractions respond inversely: as WSC declines from respiration, the ADF (acid detergent fiber) and NDF (neutral detergent fiber) content of the hay increases on a relative dry matter basis. Higher ADF = lower digestibility = lower RFV score. The elevator does not pay for extra field hours — it pays (or more precisely, discounts) for the fiber content of what you deliver.
Estimated RFV Impact: Field Curing Hours After Cutting (Alfalfa, 2nd Cut)
Baled at 4–6 hrs (conditioned)
RFV 185–195 · Premium grade
████████████████████████████████████████ Minimal respiration loss
Baled at 8–10 hrs (unconditioned, good weather)
RFV 170–185 · Good grade
███████████████████████████████ 3–5% WSC loss from respiration
Baled at 18–24 hrs (unconditioned, cool conditions)
RFV 150–170 · Fair grade
████████████████████████ 8–12% WSC loss; ADF rising
Baled after rain delay (36–48+ hrs exposure)
RFV 120–148 · Below standard
█████████████████ 15–25% WSC loss; leaching
RFV ranges estimated from published USDA alfalfa hay quality data; actual values depend on variety, soil fertility, and weather. WSC % loss from agronomic research on respiration in cut alfalfa.
Scenario A — Conditioned, Baled at 6 Hrs
RFV 190
Elevator price: $110/ton
400 bales × 280 kg: 112 tons
Season gross: $12,320
Scenario B — Unconditioned, Baled at 20 Hrs
RFV 160
Elevator price: $85/ton
400 bales × 280 kg: 112 tons
Season gross: $9,520
Annual Quality Difference: $2,800 on 400 bales — entirely from faster curing
Disc Mower vs Sickle Bar: What the Cut Difference Means for Hay Quality
Both hay mowing machine types cut — but the mechanism, cut quality, and downstream effects differ in ways that matter for hay programs beyond 50 acres. The hay mowing choice between a disc mower and a sickle bar is not primarily about price or forward speed: it is about how the cut interacts with crop moisture, soil contamination risk, and crop flow into the windrow that will be raked and baled.
Mower Selection by Crop Situation — Scenario Guide
| Your Situation |
Disc Mower ✔ |
Sickle Bar ✔ |
Reden |
| Alfalfa, 2nd-4th cut, flat field |
✔ |
OK |
Disc mower cuts cleaner at stem base, less soil contamination, better for high-value hay analysis |
| Mixed grass, rough or rocky terrain |
OK |
✔ |
Sickle bar rides closer to ground contours on irregular surfaces; disc blades more vulnerable to rock strikes |
| Commercial volume, 60+ acres per cutting |
✔ |
Niet aanbevolen |
Disc mower forward speed (up to 12 km/h) vs sickle bar (5-8 km/h) — at 60 acres disc mower saves 3-5 field hours per cutting |
| Small operation, limited capital, flat land |
More expensive |
✔ |
Sickle bar lower initial cost; acceptable quality on grass hay; not ideal for premium alfalfa programs |
| Alfalfa first cut, heavy standing crop |
✔ |
Niet aanbevolen |
Heavy dense first-cut mat overwhelms sickle bar clearing — frequent plugging; disc mower handles it cleanly |
Conditioning: How Crimping and Flailing Change the Curing Equation
Hay mowing conditioning reduces curing time by 25 to 40% compared to unconditioned cutting under the same weather conditions. This is the single most significant quality intervention available in the mowing step — and understanding the mechanism explains both why it works so well and why over-aggressive conditioning reduces the benefit.
How Conditioning Accelerates Stem Drying — Physical Mechanism
🌿
Fresh-cut stem
Intact cuticle (waxy outer layer) blocks moisture escape
→
⚙️
Crimper/flail passes
Compresses or lacerates stem wall → cuticle cracks at node points
→
💧
Vascular bundles exposed
Direct evaporation from stem interior — same pathway as leaf surface
→
☀️
25–40% faster drying
Stem and leaf reach baling moisture simultaneously → uniform bale quality
Crimper vs Flail: The Trade-Off in Aggressive Conditioning
Crimper (roller conditioner): Compresses the stem between two smooth or ribbed rollers at controlled pressure. Creates crimps at regular intervals along the stem without tearing the tissue. Gentle on legume leaves — preferred for alfalfa where leaf shatter is the primary protein-loss risk. Conditioning effect: moderate (25 to 30% drying improvement). Most mower-conditioners in the 3 to 4 meter class use crimper rollers as the standard conditioner type.
Flail (impeller conditioner): Uses a rotating impeller with tines or flails to aggressively lacerate the cut crop. More aggressive stem disruption → faster drying (35 to 40% improvement). But the laceration force also physically detaches alfalfa leaves from stems at the petiole — creating leaf losses of 5 to 12% compared to 2 to 4% for crimper conditioning. For grass hay where leaves are small and tightly attached to stems, flail conditioning produces faster drying with minimal quality penalty. For alfalfa, the leaf loss at flail intensity often negates the quality improvement from faster drying.
The over-conditioning problem: Conditioning aggressiveness can be adjusted on most mower-conditioners via roller gap setting or impeller speed. Over-conditioning (crimper rollers set too tight, or flail speed too high) produces hay that dries extremely rapidly — so rapidly that the crop surface is at 10 to 12% moisture while the center of the stem mat is still above 25%. The resulting bale has a dry outer layer and a moist interior: the worst possible profile for both dry hay storage and silage fermentation uniformity.
The mower-conditioner’s PTO-driven conditioning rollers are powered through a dedicated landbouw aandrijfversnellingsbak that steps down PTO speed to the roller’s rated surface speed — conditioning effectiveness is directly affected by roller speed, making gearbox condition and oil level a maintenance item that connects to hay quality output.
Cutting Height: The 3-Inch Rule and Three Problems It Prevents
Cutting height is the simplest hay quality variable in the mowing step and the one most often set once and forgotten. The 3-inch (75 mm) minimum cutting height for hay production is not arbitrary — it serves three independent agronomic functions that together determine soil contamination risk, stand persistence, and yield trajectory over a multi-year stand life.
Cutting Height Effect — Three-Position Guide
Below 2 inches (Too Low)
✗ Soil contamination: Tines and blades at or near ground → soil inclusions in windrow → elevated ash content in hay analysis → lower RFV score from mineral dilution.
✗ Stand damage: Cutting below the crown (basal meristem) of alfalfa removes the primary regrowth bud. Repeated below-crown cuts thin stands within 2 to 3 years, requiring reseeding 1 to 2 cutting seasons earlier than properly managed stands.
✗ Slow regrowth: Without photosynthate reserves stored in the basal 2 to 3 inches of stem, the plant must regenerate entirely from root carbohydrate reserves — extending the intercutting period and reducing annual cutting frequency.
3–4 Inches (Correct)
✔ Tine clearance: Leaves at least 2 to 3 cm of safety margin between blade path and soil surface — eliminates incidental soil pickup on normal field surfaces including minor ruts and uneven ground.
✔ Crown protection: Preserves the basal meristem above the cut zone. Rapid axillary bud activation within 24 to 48 hours of cutting begins regrowth from above-cut tissue, not solely from root reserves.
✔ Airflow under swath: Stubble at 3 to 4 inches lifts the cut crop off the soil surface, creating an air channel under the windrow that accelerates initial surface drying — complementary to conditioning effects.
Above 5 Inches (Too High)
△ Yield efficiency: Each additional inch above the 3-inch optimum leaves harvestable dry matter in the field. On a dense second-cut alfalfa stand at 5 t/ha, cutting at 5 inches instead of 3 leaves approximately 3 to 5% of total DM in the field — recoverable next cutting, but lost to current-cycle harvest.
△ Baler pickup clearance: Very tall stubble (5+ inches) can deflect the baler’s pickup header upward as it traverses field rows, potentially reducing pickup efficiency on narrow windrows.
Our Mowing and Conditioning Lineup: From 2.5 m to 5.0 m
Ons mowing equipment lineup covers three working width classes designed to pair with the hay rake and round baler system most operations run. Each model is sized to create a matched system where mowing width, raking width, and baling throughput work at the same field pace without one step creating a bottleneck for the next.
Instapmodel / middenklasse
9GD-2.5
2.5 m Disc Mower
▸ Clean disc-blade cut, adjustable cutting height
▸ 2.5 m cutting width — pairs with 9LZ-6.0 or 9LZY-9.0 rake (2-pass merge)
▸ HP requirement: ≥40 kW (54 HP)
▸ Best for: single-tractor small-farm system
Popular
Mid-Range + Conditioning
9GQY-3.2
3.2 m Mower-Conditioner
▸ Integrated crimp rollers — 25–35% faster hay curing
▸ 3.2 m width — pairs with 9LZY-9.0 or 9LZD-9.0 V-rake (3-pass sequence)
▸ HP requirement: ≥55 kW (75 HP)
▸ Best for: alfalfa premium programs where RFV grade matters
Commercial Class
9GS-5.0
5.0 m Suspension Disc Mower
▸ 5.0 m width on a single pass — maximum throughput for large programs
▸ Suspension system follows ground contours across full working width
▸ HP requirement: ≥80 kW (108 HP)
▸ Best for: large commercial programs, custom cutting operations
The full lineup — including tractor HP requirements and cutting width recommendations for pairing with our hooihark assortiment — is detailed on the mowing equipment category page. If you are building a matched mowing-raking-baling system on a specific tractor HP class, our U.S. team works through the width pairing and field-pace matching before anything ships.
Frequently Asked Questions: Mowing and Hay Quality
Do I need a mower-conditioner to produce quality hay, or is a plain disc mower sufficient?+
For grass hay mowing destined for standard commodity markets, a plain disc mower is adequate — grass dries at a reasonable rate without conditioning in warm, dry weather, and the RFV premium for faster curing is smaller on grass than on alfalfa. For alfalfa hay quality destined for dairy, horse, or other premium markets where RFV grade is priced, a mower-conditioner is strongly recommended. The $2,800 annual quality premium illustrated in the RFV calculation above is a realistic number for a 400-bale alfalfa program — conditioning pays for itself in 2 to 4 seasons on programs of this size. For small-volume alfalfa programs (under 100 bales/year), the calculation is tighter and depends on your local hay market price differentiation between RFV grades.
What time of day should I start mowing for maximum quality?+
Mid-morning, after dew has evaporated, is the standard recommendation — typically between 9:00 and 10:00 AM on a clear day. The reason is that cutting before dew evaporation starts the hay’s curing clock while the surface moisture is still high, which is actually beneficial for initial conditioning (more flexible stems, better crimp penetration) but requires more total drying time to reach baling moisture. More importantly, mowing in standing dew removes the visible moisture indicator that tells you the morning rake is ready — when the cut crop in the first windrow looks and feels as dry as the dew-free afternoon windrows, the morning dew has evaporated and raking can begin. On very hot days (above 35°C), some operators prefer early-morning mowing specifically to start the crop curing before peak midday heat — but this requires close moisture monitoring before raking.
My mower keeps leaving uncut strips in the field. What adjustments fix this?+
Uncut strips typically have one of three causes: (1) Blade wear — disc mower blades wear progressively at the tip, reducing the effective cutting radius. Check blade tip condition against a new blade; replace when the tip radius has shortened by more than 15 to 20 mm. Blades should be replaced as a full set on a disc, not individually, to maintain balance. (2) Operating speed too high for standing crop density — in very dense first-cut alfalfa, running above 10 km/h can cause crop to deflect away from the disc cutting zone before the blade reaches it. Reduce speed. (3) Cutting height too high on lodged or bent crop — lodged stems lying at an angle may pass under the blade path if cutting height is set above the stem base. Lower the cutting height by 1 to 2 cm and check clearance against the field surface.
How does mowing width affect field efficiency compared to rake width?+
The key matching principle is that the rake working width should be a multiple of the mower working width — so each rake pass collects from a whole number of mower passes without leaving gaps or double-working overlap. For a 2.5 m mower paired with a 9 m V-rake, each rake pass covers 3.6 mower widths — a non-integer that produces irregular windrow density. The practical solution is either to use a 3.0 m mower width (3 passes = 9 m, clean match) or to make a merging pass with the rake to produce consistent windrows from uneven mower swaths. Our U.S. team works through this matching calculation at time of equipment selection — matching mowing and raking widths is one of the first questions we ask before confirming a system recommendation.
Is it better to mow in the direction of the prevailing wind or across it?+
Mowing parallel to the prevailing wind direction — so the windrow runs along the wind direction — produces the fastest field drying. A windrow aligned parallel to wind allows air movement along the full length of the windrow, lifting and aerating the top layer and drawing humid air out from under the windrow base. A windrow running perpendicular to prevailing wind creates a series of wind barriers that trap humid air in the zones between windrows. In practice, field shape and row alignment usually constrain mowing direction more than wind orientation — but where field shape allows choice, align rows with the prevailing wind for a 10 to 20% improvement in drying speed under moderate wind conditions.
Does cutting alfalfa in the late bud stage really produce better hay than waiting for early bloom?+
Yes, for protein content and digestibility — but with a yield trade-off. Alfalfa in late bud stage (10 to 20% bud development, zero open flowers) contains 20 to 22% crude protein and ADF below 32%. Waiting to early-full bloom (50 to 100% bloom) raises dry matter yield per acre by 8 to 15% but reduces crude protein to 17 to 19% and raises ADF to 35 to 38%. For dairy hay markets where RFV above 170 commands significant premium, cutting at late bud is the quality-optimizing decision. For beef hay or commodity markets with flat pricing across RFV grades, early bloom gives more tons per acre for the same operating cost. Which decision is correct depends entirely on your local market price structure — know your elevator’s RFV price table before making cutting-stage decisions for the season.
Complete Hay-Making System
Mowers, Rakes, and Round Balers — Matched to Your Tractor, Crop, and Volume
Our California team matches mowing width to raking width to baler pickup, confirms tractor HP fits every step, and ships all equipment from the U.S. warehouse with same-day dispatch on replacement parts. From the first blade pass to the last bale ejection — one supplier, one support team.
✔ Mowers & Conditioners
2.5 m to 5.0 m, California stock
✔ Hay Rakes
6 m to 12 m, finger wheel & horizontal
✔ Round Balers
5 models from compact to commercial
Get a System Recommendation
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