Square baling looks simple - drive up the field and the baler does the rest - but the difference between a shed full of tight, well-tied bales and a run of loose or burst ones comes down to two things, and neither is the one most people reach for. Most failures are the knot opening, not the twine snapping. And thicker twine is no longer the safe answer: modern polymers mean a thinner twine ties a more secure knot, packs a denser bale and runs more smoothly through the knotter. What follows is twine choice by job, the knotter settings that keep knots shut, and the density, moisture and timing figures that decide whether a bale holds through the winter.

Get the twine right first

Twine choice is one of the biggest factors in bale quality, and the old thinking has changed. For years thicker twine was seen as the safe bet, but modern polymers mean a thinner twine now ties a more secure knot, packs a denser bale, and runs more smoothly through the knotter - with more bales per spool and less downtime.

Match the material to the job:

Polypropylene (PP): durable and UV-stable, the choice for bales stored outside.
Natural fibre (sisal): biodegradable but less hard-wearing - best for dense bales kept indoors.
Recycled-content twine: Tama’s TamaCycle is made from at least 30% reclaimed twine and performs like standard PP, if you are looking to cut down on plastic.

Tama’s IMPAX range is built to handle the shock loads that cause most twine failures - compression, knot formation, ejection, and the bale hitting the ground - while running around 20% thinner than traditional heavy-duty twines.

It is usually the knot, not the twine

Most twine failures happen after the bale leaves the chamber, and not because the twine snaps - because the knot opens. A few things keep knots tight:

On double-knotter balers, never mix twine types or diameters between the upper and lower twine - different twines slipping against each other is what pulls knots open.
Keep knotters clean and lubricated, and check needle alignment and timing against the plunger stroke.
Carry spare knotter parts and a spare spool. A bad knot or a broken part can stop you dead mid-field.

Density, moisture and timing

Density: for small squares, aim for around 8-12 lb/ft³ and adjust chamber tension to keep bale shape and length consistent.
Moisture: bale small squares at 18-20% and large squares at 14-16%. Too dry and you lose leaf; too wet and you risk mould, heating and, in a bad case, fire.
Windrows: wide, even windrows feed best - rake at 40-50% moisture to hold the leaf, and keep a steady ground speed so the baler feeds evenly.

Look after them once they are made

Good bales can still spoil in the stack. Keep them off the ground on pallets, gravel or concrete, a few inches clear of the walls, and let the air move through. Outdoors, elevate the bales, sheet them with a UV-resistant cover and give the stack some fall for drainage. Keep an eye on stack temperature in the weeks after baling.

Get the full guide

There is a lot more in Tama’s guide - knot types by baler make, a full pre-baling checklist, troubleshooting and sustainable options. You can download it from Tama here: Practical Guide to Square Baling (opens in a new tab).

We stock Tama twine here at D G Jones Agri. If you want a hand picking the right twine for your baler and your crop, have a word before the season gets going.