The Windrow Formation System: Three Operations, One Outcome
A well-formed baling windrow is the result of three sequential operations — mowing swath placement, raking consolidation, and windrow-to-pickup alignment — each of which affects the final windrow shape and density. Treating each operation independently rather than as a system produces windrows that are either wrong in width for the pickup, wrong in density for consistent bale formation, or wrong in straightness for efficient baler tracking.
Mower Swath Width: Balancing Drying Rate Against Windrow Density
The mower’s swath width is the width of the crop mat deposited on the field surface. A wider swath increases the crop surface area exposed to drying — reducing drying time. A narrower swath concentrates crop into a denser mat that dries more slowly but requires less consolidation at raking. The optimal swath width is the widest practical setting that still leaves the windrow narrow enough for the baler’s pickup after raking consolidation.
Maximizes drying surface area — the best practice for first-cut alfalfa and heavy grass in favorable weather. The wide swath dries the crop 20–30% faster than a narrow-swath deposit of the same material. Requires raking to consolidate into a baler-width windrow, but the faster drying more than compensates for the additional field pass in most conditions. Set the mower’s rear deflector to its widest position when field slope and crop stand conditions allow consistent wide swath placement.
Concentrates crop into a smaller area — appropriate when rain is forecast (smaller exposed surface area reduces rain-contact risk) or when the crop is light enough that wide swath placement produces a mat too thin to consolidate cleanly at raking. Narrow swaths take longer to dry but are more rain-resistant and easier to rake cleanly. In humid climates with frequent shower risks, some producers prefer narrow swath placement on premium alfalfa even accepting the slightly longer drying time.
Windrow Density: Sizing the Windrow to the Baler’s Capacity
Windrow density — how much crop mass is deposited per linear foot of windrow — is the most direct determinant of baling efficiency. A windrow that is too thin forces the baler to travel more distance per bale (producing bales slower), and variable windrow density produces variable bale density because the bale chamber receives inconsistent feed rates. A correctly sized windrow fills the bale chamber at a consistent rate that matches the baler’s design throughput.
Formula: Target bale weight ÷ lbs per linear foot = feet of windrow per bale
Measuring windrow weight per foot: Collect all crop from a 10-foot section of windrow, weigh it, and divide by 10. Example: 140 lbs from 10 feet = 14 lbs/linear foot. At this density, the baler makes an 800-lb bale every 57 feet.
Adjusting density: If windrow is too light (baler requires 100+ feet per bale), merge two windrows into one at raking. If too heavy (baler struggles through dense windrow), adjust rake angle to produce a wider, lighter windrow or split the windrow during raking.
Rake Angle and Speed: Setting the Consolidation Parameters
The rake wheel angle — the angle of each rake wheel relative to the direction of travel — controls the rate at which crop material is moved laterally and the resulting windrow width and density. A wider angle (more aggressive lateral movement) produces a narrower, denser windrow. A shallower angle produces a wider, lighter windrow. Most commercial rakes allow angle adjustment per wheel or per section, giving significant control over windrow shape.
| 調整 | Effect on windrow | When to use |
|---|---|---|
| Increase wheel angle | Narrower, denser windrow | Light yield or wide swath where density must increase to reach target bale weight; merging two swaths into one windrow |
| Decrease wheel angle | Wider, lighter windrow | Heavy yield where single-swath windrow is too dense for baler throughput; spreading windrow to expose more surface for drying |
| Increase rake speed | More aggressive tine contact; higher throughput | Use when crop moisture is above 25% and leaves are not at leaf-loss risk; never on dry alfalfa below 15% |
| Decrease rake speed | Gentler tine contact; less leaf loss | Dry alfalfa or orchardgrass where leaf loss is the primary concern; any crop below 18% moisture |
Merging Windrows: When and How to Double Up
In low-yield conditions — thin stands, late-season light cuttings, or short-season native grass — a single-swath windrow may not provide enough material to fill a bale efficiently. Merging two or more windrows into a single baling windrow increases throughput and improves bale density consistency. The decision to merge is straightforward: if a single windrow produces a bale in more than 120–150 feet, merging two windrows will significantly improve baling efficiency.
Yield below 1.5 tons/acre per cutting (single windrow from a 15-foot mower provides less than 6 lbs/linear foot — too light for consistent bale formation at normal baling speed); thin stands with uneven windrow density; native grass or first-year establishment fields with low density; any situation where bale formation time exceeds 3 minutes at normal field speed.
Use the rake on its “merger” setting or make a second rake pass that overlays adjacent windrows onto one another. The merged windrow must end up narrow enough to fit the baler’s pickup width — center the merged mass within the pickup width with 2–3 inches of clearance on each side. Avoid merging more than two windrows into one unless yield is extremely low — a triple-merged windrow in 2+ ton/acre alfalfa will be too heavy for efficient baling at any reasonable field speed.
Windrow Straightness: Why Curved Windrows Cost Productivity
A straight windrow allows the baler to travel at consistent speed in a straight line — the most efficient baling pattern. A curved or zigzag windrow forces continuous steering corrections, reduces effective forward speed, and causes the pickup to periodically miss the windrow edges at bend points. In commercial baling, windrow straightness is a direct productivity factor — an operator managing curved windrows at 3 mph bales slower than one following straight windrows at 4 mph even with identical equipment.
The most common cause is the mower-conditioner drifting off the intended straight pass during the original cutting pass. Asymmetric weight distribution on side-mounted mower-conditioners creates a slight pull to one side; the operator makes continuous minor corrections that produce a gently curved windrow rather than a true straight line. GPS-guided mowing produces nearly straight windrows and significantly reduces the steering workload at raking and baling. Without GPS, using a distant visual reference point (tree, post, barn corner) on every pass produces straighter windrows than watching the mower header.
Minor windrow curvature can be corrected at the raking pass by tracking a straight reference line rather than following the curved windrow. The rake’s working width is forgiving of 6–8 inches of lateral windrow position variation — the tines will collect the crop regardless of the windrow’s exact position within this range. Tracking straight at raking produces a straight windrow for the baler even if the original mowed swath was moderately curved.
The detailed raking technique guide — covering V-rake vs horizontal rake operating parameters, tine height settings, and the specific adjustments that minimize leaf loss at each raking pass — is in the hay raking techniques guide. The mower-conditioner settings — swath width, conditioning intensity, and the deflector configurations that set initial swath placement — are in the mowing and conditioning quality guide. The rake and mower-conditioner gearbox and PTO driveline specifications are in 農業用ギアボックスおよびPTO駆動系部品の仕様.
Field Patterns: Minimizing Turning Loss at Each Operation
The field pattern used for mowing, raking, and baling affects both operational efficiency and hay quality. Each turning pass at the field headland disrupts windrow continuity, creates an area of over-worked or over-exposed crop, and adds time per acre. Minimizing the number of turning passes through better field pattern selection is a genuine productivity improvement that requires no equipment investment.
Starting at the field outside and spiraling inward allows the mower to deposit each swath next to the previous one with a consistent turning radius. The final pass in the center is typically narrower than full cutting width — plan the field dimensions to minimize the number of partial-width passes at the field center. Ending at the field center rather than the headland simplifies headland clearing at the start of raking.
Raking along the longest field axis minimizes the number of turning passes per acre — each turning event interrupts the windrow and requires an extra pass to close the gap at the headland. Pre-clear the headland (rake the headland windrows across the field direction first) so the main raking passes can be driven straight through without stopping at the headland.
After the windrow is formed, the baler simply follows it — the field pattern is determined by the windrow layout, not by the baler. The only baling efficiency choice is whether to eject each bale immediately and continue in place, or to hold each bale while moving to a position that minimizes dead-heading back to the windrow. On long straight windrows, eject in place and continue; on short windrows with frequent turning, evaluate whether a staging area reduces dead-head time.
Windrow Formation FAQs
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